Typhoon Haiyan

After spending 48 hours at Category 5 strength, the strongest landfalling tropical cyclone in world history, Super Typhoon Haiyan, has finally weakened to a Category 4 storm. With top sustained winds of 155 mph, Haiyan is still an incredibly powerful super typhoon, but has now finished its rampage through the Central Philippine Islands, and is headed across the South China Sea towards Vietnam. Satellite loops show that Haiyan no longer has a well-defined eye, but the typhoon still has a huge area of intense thunderstorms which are bringing heavy rains to the Central Philippines. I’ve never witnessed a Category 5 storm that made landfall and stayed at Category 5 strength after spending so many hours over land, and there are very few storms that have stayed at Category 5 strength for so long.


Figure 1. Super Typhoon Haiyan approaching the Philippines, as seen by the Japan Meteorological Agency’s MTSAT at 0630Z on November 7, 2013. At the time, Haiyan had maximum sustained winds of 175 mph. Image credit: NOAA Environmental Visualization Laboratory.

Haiyan’s place in history
Haiyan hit Guiuan, on the Philippine island of Samar, at 4:40 am local time (20:40 UTC) November 8, 2013. Three hours before landfall, the Joint Typhoon Warning Center (JTWC) assessed Haiyan’s sustained winds at 195 mph, gusting to 235 mph, making it the 4th strongest tropical cyclone in world history. Satellite loops show that Haiyan weakened only slightly, if at all, in the two hours after JTWC’s advisory, so the super typhoon likely made landfall with winds near 195 mph. The next JTWC intensity estimate, for 00Z UTC November 8, about three hours after landfall, put the top winds at 185 mph. Averaging together these estimates gives a strength of 190 mph an hour after landfall. Thus, Haiyan had winds of 190 – 195 mph at landfall, making it the strongest tropical cyclone on record to make landfall in world history. The previous record was held by the Atlantic’s Hurricane Camille of 1969, which made landfall in Mississippi with 190 mph winds.

According to the official “best track” records from the Joint Typhoon Warning Center, here are the strongest tropical cyclones in world history:

Super Typhoon Nancy (1961), 215 mph winds, 882 mb. Made landfall as a Cat 2 in Japan, killing 191 people.
Super Typhoon Violet (1961), 205 mph winds, 886 mb pressure. Made landfall in Japan as a tropical storm, killing 2 people.
Super Typhoon Ida (1958), 200 mph winds, 877 mb pressure. Made landfall as a Cat 1 in Japan, killing 1269 people.
Super Typhoon Haiyan (2013), 195 mph winds, 895 mb pressure. Made landfall in the Philippines at peak strength.
Super Typhoon Kit (1966), 195 mph winds, 880 mb. Did not make landfall.
Super Typhoon Sally (1964), 195 mph winds, 895 mb. Made landfall as a Cat 4 in the Philippines.

However, it is now recognized (Black 1992) that the maximum sustained winds estimated for typhoons during the 1940s to 1960s were too strong. The strongest reliably measured tropical cyclones were all 5 mph weaker than Haiyan, with 190 mph winds—the Western Pacific’s Super Typhoon Tip of 1979, the Atlantic’s Hurricane Camille of 1969, and the Atlantic’s Hurricane Allen of 1980. All three of these storms had a hurricane hunter aircraft inside of them to measure their top winds. Haiyan’s winds were estimated using only satellite images, making its intensity estimate of lower confidence. We don’t have any measurements of Haiyan’s central pressure, but it may be close to the all-time record of 870 mb set by Super Typhoon Tip. The Japan Meteorological Agency estimated Haiyan’s central pressure at 895 mb at 18 UTC (1 pm EST) November 7, 2013. This would make Haiyan the 12th strongest tropical cyclone on record globally, as far as lowest pressure goes.


Figure 2. Damage from Super Typhoon Haiyan in Legazpi city, Albay province, Nov. 8, 2013, about 325 miles south of Manila, Philippines. (Twitter/Ritchel M. Deleon)

Massive damage in the Philippines
Wind damage on the south shore of Samar Island in Guiuan (population 47,000) must have been catastrophic, perhaps the greatest wind damage any place on Earth has endured from a tropical cyclone in the past century. A massive storm surge must have also caused great destruction along a 20-mile swath to the north of where the eye hit, where Project NOAH was predicting a 17’ (5.3 meter) storm tide. Wind and storm surge damage were heavy in Tacloban, population 221,000, the capital of the province of Leyte, according to preliminary media reports. Much of Tacloban is at elevations less than ten feet, and several videos posted on YouTube showed a storm surge of at least ten feet moving through the city. The northern (strong) part of Haiyan’s eyewall made a direct hit on the city. Storm Chaser Jim Edds was in Tacloban, and reported that at least ten crewed boats were in the harbor, attempting to ride out the storm. Haiyan’s winds, rains, and storm surge have caused widespread devastation throughout the Central Philippines, though we do not yet have reports from the worst-hit portions of the disaster zone, including the south shore of Samar Island. Fortunately, the storm’s fast forward speed of 25 mph cut down the amount of rain the storm dumped, compared to typical typhoons that affect the Philippines. Hopefully, this will keep the death toll due to flash flooding relatively low. Flash floods are usually the biggest killer in Philippine typhoons.


Figure 3. Predicted rainfall from the 06Z November 8, 2013 run of the HWRF model, for the 96-hour period ending at 06Z November 12, 2013. A 100-mile wide swath of 8 – 16 inches of rain (medium dark red colors) as well as a 30-mile wide swath of 16 – 24″ (dark red colors) is predicted to affect Vietnam and Laos. Rains of this magnitude are likely to cause a top-five most expensive natural disaster in both nations. Image credit: NOAA/NCEP/EMC.

Haiyan an extremely dangerous storm for Vietnam and Laos
Haiyan will steadily decay over the next two days, due to colder waters and higher wind shear. However, it will still likely be a formidable Category 1 or 2 typhoon when it makes landfall in Vietnam near 06 UTC Sunday. Haiyan is expected to begin recurving to the northwest as it makes landfall, which means that a long 100+ mile stretch of the Vietnam coast will receiving the punishing winds and peak storm surge of the strong northern portion of the typhoon. With part of its circulation still over water, Haiyan will be able to pull in a huge amount of moisture that will create prodigious rains over Vietnam and Laos. I expect that the 12+ inches of rain that the storm will dump on those nations will make it a top-five most expensive natural disaster in their history.

Links
Visible satellite landfall loop from the Korean COMS-1 satellite, courtesy of Scott Bachmeier of the University of Wisconsin CIMSS group.
Damage videos from Tacloban from Marcjan Maloon
Twitter updates from Japan meteorologist Robert Speta.

Video 1. Damaging winds and a potent storm surge from Super Typhoon Haiyan are captured in this video from the capital of Leyte Province, Tacloban, which received a direct hit from Haiyan. Thanks to wunderground member GatorWX for posting this in my blog comments.

from:    http://www.wunderground.com/blog/JeffMasters/show.html

September Heat Records/Billion Dollar Disasters

By: Dr. Jeff Masters, 2:26 PM GMT on October 25, 2013 +24

September 2013 was the globe’s 4th warmest September since records began in 1880, according to NOAA’s National Climatic Data Center (NCDC). The year-to-date period of January – September has been the 6th warmest such period on record. September 2013 global land temperatures were the 6th warmest on record, and global ocean temperatures were the 4th warmest on record. September 2013 was the 343nd consecutive month with global temperatures warmer than the 20th century average. Global satellite-measured temperatures in September 2013 for the lowest 8 km of the atmosphere were 11th or 3rd warmest in the 35-year record, according to Remote Sensing Systems and the University of Alabama Huntsville (UAH), respectively. Wunderground’s weather historian, Christopher C. Burt, has a comprehensive post on the notable weather events of September 2013 in his September 2013 Global Weather Extremes Summary.


Figure 1. Departure of temperature from average for September 2013, the 4th warmest September for the globe since record keeping began in 1880. Record warmth was observed across most of Australia and part of central Asia, as well as part of southwestern Canada. Most of central and northern North America, northern Europe, and much of central and southern Asia were much warmer than average. Cooler and much-cooler-than-average temperatures occurred across much of central and eastern Russia, along with most of eastern Europe and western Greenland. Image credit: National Climatic Data Center (NCDC) .

The five billion-dollar weather disasters of September 2013
Five billion-dollar weather-related disasters hit the Earth during September 2013, bringing the world-wide tally of these disasters so far in 2013 to 32, according to the September 2013 Catastrophe Report from insurance broker Aon Benfield. This is the third highest yearly total for the globe since accurate disaster records began in 2000, according to Senior Scientist Steve Bowen of Aon Benfield. The record highest was 40 billion-dollar disasters in 2010. For comparison, during all of 2012, there were 27 billion-dollar weather disasters; the tally in 2011 was 35 (adjusted for inflation.) The U.S. total so far in 2013 is seven.


Disaster 1. The most damaging billion-dollar weather disaster of September was in Mexico, where Hurricane Manuel made two landfalls along Mexico’s Pacific coast. Flooding from Manuel’s torrential rains caused $4.2 billion in damage and left 169 people dead or missing. According to EM-DAT, the International Disaster Database, this was the second most expensive weather-related disaster in Mexican history, behind the $6 billion in damage (2013 dollars) wrought by Hurricane Wilma in October 2005. In this aerial view, we see the landslide triggered by Hurricane Manuel’s rains that killed 43 people in La Pintada, México, on September 19, 2013. (Pedro Pardo/AFP/Getty)


Disaster 2. Super Typhoon Usagi made landfall near Shanwei, China on September 22, 2013 as a Category 2 typhoon with 110 mph winds, after skirting the Philippines and Tawian. The storm killed at least 37 people and did $3.8 billion in damage. Property damage was widespread in five Chinese provinces as Usagi damaged at least 101,200 homes. This radar image of Usagi shows that the typhoon had multiple concentric eyewalls as it approached landfall. Image credit: weather.com.cn.


Disaster 3. Record rainfall of 8 – 15″ triggered historic flash flooding across in Colorado September 11 – 12, 2013, killing at least nine people and doing $2 billion in damage. The most significant damage occurred in Boulder, Larimer and El Paso counties after several major rivers and creeks crested at all-time highs. The Office of Emergency Management reported that nearly 20,000 homes were damaged or destroyed in addition to thousands of businesses and other structures. One person was also killed by flooding in New Mexico. In this image, we see damage to Highway 34 along the Big Thompson River, on the road to Estes Park, Colorado. Image credit: Colorado National Guard.


Disaster 4. Category 1 Hurricane Ingrid weakened to a tropical storm with 65 mph winds before hitting Mexico about 200 miles south of the Texas border on September 16, 2013. Ingrid’s heavy rains triggered flooding that killed 23 and did $1.5 billion in damage, making the storm the 7th costliest tropical cyclone in Mexican history. In this image, we see Tropical Storm Manuel and Hurricane Ingrid laying siege to Mexico on September 15, 2013. Tropical Storm Manuel came ashore on the Pacific coast near Manzanillo on the afternoon of September 15, and Ingrid followed suit from the Atlantic on September 16. Image credit: NASA Earth Observatory.


Disaster 5. A series of killing freezes during the second half of September led to extensive agricultural damage in central Chile. A state of emergency was declared after farmers reported that frigid air had destroyed 61% of stoned fruit crops, 57% of almonds, 48% of kiwi crops, and 20% of table grapes. Heavy damage to vineyards also affected wine productivity. Total damage was estimated at $1.15 billion.

Neutral El Niño conditions continue in the equatorial Pacific
For the 18th month in row, September 2013 featured neutral El Niño conditions in the equatorial Eastern Pacific. NOAA’s Climate Prediction Center (CPC) expects neutral El Niño conditions to last the Northern Hemisphere spring of 2014, as do the large majority of the El Niño models. Temperatures in the equatorial Eastern Pacific need to be 0.5°C below average or cooler for three consecutive months for a La Niña episode to be declared; sea surface temperatures were 0.4°C below average as of October 21, and have been +0.1 to -0.4°C from average since April 1, 2013.

Arctic sea ice falls to 6th lowest September extent on record
Arctic sea ice extent during September was 6th lowest in the 35-year satellite record, according to the National Snow and Ice Data Center (NSIDC). This was the largest September extent since 2009, and a nice change of pace from last year’s all-time record retreat. The Arctic sea ice reached its minimum extent for the year on September 13, and has now begun re-freezing.

New “Tipping Points” episode, “Dangerous Rise of Oceans”, airs Saturday at 9 pm EDT/8 pm CDT
“Tipping Points”, a landmark 6-part TV series that began last Saturday on The Weather Channel, airs for the second time on Saturday night, October 26, at 9 pm EDT. The new episode, “Dangerous Rise of Oceans”, goes on an expedition from the Great Southern Ocean to the Great Barrier Reef and Tuvalu, to explore the changing currents and oceans that are driving extreme storms, sea surge and changing the landscape of many small South Pacific communities. The series is hosted by polar explorer and climate journalist Bernice Notenboom, the first woman to climb Mt. Everest and walk to the North and South Poles. In each episode, Notenboom heads off to a far corner of the world to find scientists in the field undertaking vital climate research to try to understand how the climate system is changing and how long we have to make significant changes before we reach a tipping point–a point of no return when our climate system will be changed irreversibly.


Figure 2. “Tipping Points” host Bernice Notenboom visits the Heron Island Research Station on Australia’s Great Barrier Reef during Saturday’s new episode, “Dangerous Rise of Oceans.”

from:   http://www.wunderground.com/blog/JeffMasters/show.html

Tropical Cyclones & Typhoons

Very dangerous Tropical Cyclone Phailin has made landfall on the northeast coast of India near the town of Gopalpur (population 7,000) at 16 UTC (noon EDT) Saturday, October 12, 2013. Phailin was weakening substantially at landfall, due to interaction with land, and was rated a Category 4 storm with 140 mph winds by the Joint Typhoon Warning Center (JTWC), four hours before landfall. The pressure bottomed out at 938 mb in Gopalpur as the eye passed over, and the city reported sustained winds of 56 mph, gusting to 85 mph, in the eyewall. A 938 mb pressure is what one expects to find in a Category 4 storm with 140 mph winds, using the “Dvorak technique” of satellite wind and pressure estimation. Satellite images show that Phailin’s intense thunderstorms have warmed and shrunk in areal coverage, and radar out of Visakhapanam, India also shows a weakening of the storm’s echoes as it pushes inland. Phailin is bringing torrential rains of over an inch per hour, as estimated by microwave satellite instruments.


Figure 1. Radar image of Phailin at landfall. Image credit: IMD.


Figure 2. MODIS satellite image of Tropical Cyclone Phailin, taken at approximately 07:30 UTC on October 12, 2013. At the time, Phailin was a top-end Category 4 storm with winds of 150 mph. Image credit: NASA.

Damage from Phailin
Phailin is the strongest tropical cyclone to affect India in fourteen years, since the great 1999 Odisha Cyclone. That storm hit with maximum sustained winds of 155 mph, and brought a storm surge of 5.9 meters (19 feet) to the coast. Phailin should be able to drive a similar-sized storm surge to the coast, since it is larger in areal extent than the 1999 cyclone (although somewhat weaker, with winds perhaps 20 – 30 mph lower.) Phailin’s storm surge and Category 3 to 4 winds will cause near-catastrophic damage to a 50-mile wide swath of the coast where the eyewall comes ashore, and to the right. Hurricane Katrina was weaker at landfall than Phailin, but Katrina had hurricane-force winds that covered a much larger area, making Katrina’s storm surge much more devastating than Phailin’s will be. I think the main danger from Phailin will be from its winds. I am particularly concerned about Phailin’s wind damage potential in the city of Brahmapur (population 350,000), the 58th largest city in India. Brahmapur lies about ten miles inland, and will likely experience sustained hurricane-force winds for several hours. Phailin’s flooding potential is another huge concern, as rainfall amounts of 6 – 12 inches will fall along a swath over 100 miles inland, triggering life-threatening flash flooding.

How strong was Phailin?
Questions have been raised about the India Meteorological Department (IMD) assessments of Phailin’s strength, which were considerably lower than that of the U.S. Joint Typhoon Warning Center (JTWC). Both centers use satellite estimates rather than direct measurements of the winds, so we don’t know which center is correct. It is true that satellite estimates using the same techniques give different results for the Atlantic and Pacific Oceans–i.e., a storm with the same appearance on satellite imagery will be weaker in the Atlantic than in the Pacific (see this chart of the differences.) It may be that this is the case in the Indian Ocean as well. IMD has looked at some buoy data to try and calibrate their satellite strength estimates, but high-end tropical cyclones are uncommon enough in the Indian Ocean that I doubt we really know whether or not Indian Ocean cyclones have the same winds as a hurricane in the Atlantic with the same satellite signature. Another thing to consider is that the IMD uses 10-minute average winds for their advisories, and JTWC uses 1-minute, so the winds in the IMD advisories will be lower by at least 6%, due to the longer averaging period. This issue could be cleared up if India had its own hurricane hunter aircraft; there have been some high-level discussions about India getting a C-130 aircraft like the U.S. Air Force uses to fly into tropical cyclones and take measurements of the actual winds.


Figure 3. MODIS satellite image of Typhoon Nari, taken at approximately 02:30 UTC on October 12, 2013. At the time, Nari was a Category 1 storm with winds of 90 mph. Image credit: NASA.

Typhoon Nari hits the Philippines
Thirteen people were killed and 2.1 million people lost power on the main Philippine island of Luzon afterTyphoon Nari hit on Friday night near midnight local time. Nari was a Category 3 typhoon with 115 mph winds a few hours before landfall. The core of the storm passed about 80 miles north of the capital of Manila, sparing the capital major flooding, but the storm dumped torrential rains in excess of ten inches to the northeast of Manilla. Passage over Luzon weakened Nari to a Category 1 storm, but it is already beginning to re-organize over the South China Sea between the Philippines and Vietnam. Nari is under moderate wind shear of 15 – 20 knots, which should keep intensification relatively slow, and increasing interaction with land will act to slow intensification on Sunday and Monday. Nari could be near Category 3 strength with 115 mph winds by Monday, and landfall in Vietnam is expected around 21 UTC on Monday.

Typhoon Wipha a threat to Japan
Category 1 Typhoon Wipha is intensifying as it heads northwest towards Japan, and the storm is expected to reach major Category 3 strength by Monday. By Tuesday, Wipha will recurve to the northeast and begin weakening, passing very close to Tokyo, Japan, sometime between 00 – 12 UTC on Wednesday. High winds and heavy rains from Wipha may be a concern for the Fukushima nuclear site, where workers continue to struggle with high radiation levels in the wake of the 2011 tsunami that damaged the reactors.

98L in the Eastern Atlantic weakening
A tropical wave (Invest 98L) located midway between Africa and the Lesser Antilles Islands is headed west to west-northwest at 10 – 15 mph. Satellite loops show that 98L has lost most of its organization and heavy thunderstorms since this morning. The disturbance is under a high 20 – 30 knots of wind shear, and the shear is expected to remain high for the next three days. The UKMET model shows some weak development of 98L by early next week, but the European and GFS models do not. In their 2 pm EDT Saturday Tropical Weather Outlook, NHC gave the disturbance 2-day development odds of 30%, and 5-day odds of 30%. 98L’s projected west-northwest track is expected take it close to the Northern Lesser Antilles Islands by Wednesday, according to the 00Z Saturday run of the European model.

Thanks go to wunderground member thunderfrance for posting the link to the weather station at Gopalpur, India.

from:    http://www.wunderground.com/blog/JeffMasters/show.html

Tropical Storm Karen

Hurricane Watches are flying along the U.S. Gulf Coast as Tropical Storm Karen heads north-northwest into the Gulf of Mexico. Karen, the eleventh named storm of the 2013 Atlantic hurricane season, formed about 8 am EDT Thursday in the Southeast Gulf of Mexico. It’s not often that one sees a new storm start out with 60 mph sustained winds, but that’s what an Air Force hurricane hunter plane found this morning near 7:30 am EDT, when they sampled the northern portion of the storm. A ship located about 50 miles northeast of the northeast tip of the Yucatan Peninsula measured sustained winds of 51 mph near the same time. Satellite loops show that Karen is a medium-sized storm with an area of very intense thunderstorms along its northern and eastern flanks. Wind shear has risen since Wednesday, and is now a moderately high 20 knots, thanks to strong upper-level winds out of the west-southwest. These strong winds are keeping any heavy thunderstorms from developing on the west side of Karen’s center of circulation, by driving dry air that is over the Yucatan Peninsula and Western Gulf of Mexico into Karen’s core. As a result, Karen has a lopsided comma-shape on satellite imagery. Karen has a strong upper-level outflow channel to its north that is helping ventilate the storm, though, and ocean temperatures are a very warm 29°C (84°F). Between 7 am and 9:30 am EDT the Hurricane Hunters made three passes though the center of Karen, and the central pressure stayed roughly constant at 1004 mb, so Karen is not undergoing much change.
Figure 1. Odds of receiving more than 4″ of rain over a five-day period beginning at 2 am EDT Thursday October 3, 2013, as predicted by the experimental GFDL ensemble model.

Forecast for Karen
Wind shear will steadily increase as the storm heads north-northwest, and shear will reach a high 25 knots by Saturday morning as Karen closes in on the U.S. Gulf Coast, according to the latest SHIPS model forecast. The atmosphere will grow drier as Karen moves into the Northern Gulf of Mexico, and the drier air combined with increasing wind shear will retard development, making only slow intensification likely through Friday. A trough of low pressure and an associated cold front will be moving through Louisiana on Saturday, and the associated upper-level westerly winds will be able to turn Karen more to the northeast as it approaches the coast on Friday evening and Saturday morning. The higher shear at that time should be able to induce weakening, and the 8 am EDT Thursday wind probability forecast from NHC gave a 28% chance Karen will be a hurricane at 2 am EDT Saturday, down from 44% on Friday afternoon. Most of the models predict landfall will occur along the western Florida Panhandle Saturday afternoon or evening. The usually reliable European model has Karen making landfall over Eastern Louisiana, though. If Karen does follow this more westerly path, the storm will be weaker, since there is more dry air and higher wind shear to the west. Since almost all of Karen’s heavy thunderstorms will be displaced to the east by high wind shear, there will be relatively low rainfall totals of 1 – 3″ to the immediate west of where the center makes landfall. Much higher rainfall totals of 4 – 8″ can be expected to the east. To judge the possibilities of receiving tropical storm-force winds at your location, I recommend using the NHC wind probability forecast. The highest odds of tropical storm-force winds (45 – 55%) are along the coast from Buras, Louisiana, to Pensacola, Florida.
Read more at http://www.wunderground.com/blog/JeffMasters/show.html#UbifOgDIGFGEKfq7.99

Dr. Masters on August 2013 Extremes

August 2013 was the globe’s 4th warmest August since records began in 1880, according to NOAA’s National Climatic Data Center (NCDC). NASA rated it the 5th warmest August on record. The year-to-date period of January – August has been the 6th warmest such period on record. August 2013 global land temperatures were the 11th warmest on record, and global ocean temperatures were the 5th warmest on record. August 2013 was the 342nd consecutive month with global temperatures warmer than the 20th century average. Global satellite-measured temperatures in August 2013 for the lowest 8 km of the atmosphere were 14th or 11th warmest in the 35-year record, according to Remote Sensing Systems and the University of Alabama Huntsville (UAH), respectively. Wunderground’s weather historian, Christopher C. Burt, has a comprehensive post on the notable weather events of August 2013 in his August 2013 Global Weather Extremes Summary. The big stories that he highlights are the intense heat waves that hit Central Europe and East Asia, which brought all-time national heat records to Austria, Slovenia, and Japan. Ljubljana, the capital of Slovenia, passed its all-time heat record a remarkable five times during the month.


Figure 1. Departure of temperature from average for August 2013, the 4th warmest August for the globe since record keeping began in 1880. Most of the world’s land areas experienced warmer-than-average monthly temperatures, including Australia, northern South America, western North America, Europe, and much of eastern Asia. Far eastern China, part of eastern Russia north of Japan, and part of northeastern South America were record warm for the month. The southeastern United States, Far East Russia, part of South Africa, Paraguay, and Bolivia were cooler than average. No regions of the globe were record cold. Image credit: National Climatic Data Center (NCDC) .

The six billion-dollar weather disasters of August 2013


Disaster 1. The most damaging billion-dollar weather disaster of August was in Northeast China, where the Nei River overflowed, killing 54 and leaving 97 missing in Fushuan. The flooding killed 118 people and cost $5 billion. In this photo, workers use an excavator to clean up mud after heavy rain hit on August 19, 2013 in Fushuan, in the Liaoning Province of China. Photo by ChinaFotoPress/Getty Images.

Disaster 2. Super Typhoon Utor killed 70 people in China and did $2.6 billion in damage. Utor also did $33 million in damage in the Philippines. This video taken by storm chaser James Reynolds shows debris flying as Typhoon Utor hits Zhapo, China on 14th August 2013.


Disaster 3. Torrential rains, due, in part, to moisture from Typhoon Trami, fell in the Philippines August 18 – 21, causing massive flooding on Luzon Island that cost $2.2 billion. Twenty-seven people were killed, and 60% of metro Manila was under water at the peak of the flood. According to EM-DAT, the International Disaster Database, this was the most expensive natural disaster in Philippine history. In this photo, pedicabs and makeshift rafts ferry office workers and pedestrians through flood waters that submerged parts of the financial district of Makati on August 20, 2013 in Makati City south of Manila, Philippines. Image credit: Dondi Tawatao/Getty Images)


Disaster 4. In Pakistan, torrential monsoon rains caused significant flooding that affected 5,739 villages. At least 208 people were killed, 63,180 homes were damaged or destroyed, and 1.4 million acres (567,000 hectares) of crops were submerged. The government estimated economic agricultural losses alone at $1.9 billion. Pakistan’s four most expensive weather-related disasters in its history have been floods that occurred in the past four consecutive years. In this photo, Pakistani residents hold onto a rope as they evacuate a flooded area in Karachi on August 4, 2013. Image credit: Asif Hassan/AFP/Getty Images)


Figure 5. Russia experienced its costliest flood disaster in history beginning on August 4, when the Amur and Zeya rivers in the far east of the country along the Chinese border overflowed, flooding 1.7 million acres, damaging or destroying over 11,500 buildings. It was the 4th most expensive natural disaster of any kind in Russian history. These false-color infrared satellite images of Russia’s Amur River taken a little over a year apart show the extent of the extreme flooding that affected the Komsomolsk-on-Amur area (population 500,000) in August 2013. Image credit: NASA.


Disaster 6. A severe weather outbreak in the U.S. Plains and Midwest August 5 – 7 brought baseball sized hail and thunderstorm wind gusts over 80 mph to Minnesota and Wisconsin. Two people were killed, and damage was estimated at $1 billion. In this photo, a severe thunderstorm closes in on Edgemont, South Dakota, on August 7, 2013. Image credit: wunderphotographer ninjalynn.

The world-wide tally of billion-dollar weather disasters so far in 2013 is 25, and the U.S. total is six, according to the August 2013 Catastrophe Report from insurance broker Aon Benfield. This excludes the September Colorado flood, whose damages are preliminarily estimated at $2 billion. Ranked in term of cost, here are the 25 disasters:

1) Flooding, Central Europe, 5/30 – 6/6, $22 billion
2) Drought, Brazil, 1/1 – 5/31, $8.3 billion
3) Drought, Central and Eastern China, 1/1 – 7/31, $6.0 billion
4) Flooding, Calgary, Alberta Canada, 6/19 – 6/24, $5.3 billion
5) Flooding, China, 8/9 – 9/5, $5.0 billion
6) Tornado, Moore, OK, and associated U.S. severe weather, 5/18 – 5/22, $4.5 billion
6) Flooding, China, 7/7 – 7/17, $4.5 billion
8) Flooding, Indonesia, 1/20 – 1/27, $3.31 billion
9) Super Typhoon Utor, China and Philippines, 8/12 – 8/15, $2.6 billion
10) Flooding, Australia, 1/21 – 1/30, $2.5 billion
11) Flooding, Philippines, 8/18 – 8/21, $2.2 billion
12 Tornadoes and severe weather, U.S., 5/26 – 6/2, $2 billion
12) Severe weather, Midwest U.S., 3/18 – 3/20, $2 billion
14) Flooding, Pakistan and Afghanistan, 8/3 – 8/31, $1.9 billion
15) Winter weather, Europe, 3/12 – 3/31, $1.8 billion
16) Drought, New Zealand, 1/1 – 5/10, $1.6 billion
16) Severe weather, U.S., 4/7 – 4/11, $1.6 billion
18) Flooding, Toronto, Canada, 7/8, $1.45 billion
19) Flooding, China, 6/29 – 7/3, $1.4 billion
19) Flooding, China, 7/21 – 7/25, $1.4 billion
21) Flooding, Argentina, 4/2 – 4/4, $1.3 billion
22) Flooding, India and Nepal, 6/14 – 6/18, $1.1 billion
23) Winter weather, U.S. Plains, Midwest, Northeast, 2/24 – 2/27, $1.0 billion
23) Severe weather, U.S. Plains and Midwest, 8/5 – 8/7, $1.0 billion
23) Flooding, Russia, 8/4 – 8/31, $1.0 billion

Neutral El Niño conditions continue in the equatorial Pacific
For the 17th month in row, neutral El Niño conditions existed in the equatorial Pacific during August 2013. NOAA’s Climate Prediction Center (CPC) expects neutral El Niño conditions to last though the winter of 2013 – 2014, and the large majority of the El Niño models also predict that neutral conditions will last through the winter. Temperatures in the equatorial Eastern Pacific need to be 0.5°C below average or cooler for three consecutive months for a La Niña episode to be declared; sea surface temperatures were 0.0°C from average as of September 16, and have been +0.1 to -0.4°C from average since April 1, 2013.

Arctic sea ice falls to 6th lowest August extent on record
Arctic sea ice extent during August was 6th lowest in the 35-year satellite record, according to the National Snow and Ice Data Center (NSIDC). This was the largest August extent since 2009, and a nice change of pace from last year’s all-time record retreat. The Arctic sea ice reached its minimum extent for the year on September 13, and has now begun re-freezing. I’ll have a dedicated post on this, probably on Tuesday.

Quiet in the Atlantic
In the Gulf of Mexico, the tail end of a cold front off the coast of Texas has developed a few disorganized heavy thunderstorms. This disturbance has some modest spin to it, thanks to absorbing Invest 95L on Saturday. However, wind shear is high, 20 – 30 knots, and I don’t expect this disturbance will develop. The disturbance is expected to bring 1 – 3″ of rain to Florida later this week, and on Saturday, the Army Corps of Engineers has re-opened the flood gates on Lake Okeechobee to dump water out of the lake in anticipation of the heavy rains. None the reliable models for tropical cyclone formation is predicting development during the coming five days.

In the Western Pacific, Typhoon Usagi has dissipated after hitting China about 100 miles east-northeast of Hong Kong. The storm is being blamed for at least 25 deaths in China and 2 in the Philippines. Preliminary damage estimates are over $500 million.

Jeff Masters

from:    http://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=2531

Dr. Masters on Yosemite Fire

California’s massive Rim Fire in Yosemite National Park continues to grow, but firefighters took advantage of less windy conditions on Tuesday and had attained 23% containment of the fire as of 9:20 am EDT on Wednesday. According to Inciweb, the Rim Fire has burned 187,000 acres. This ranks as the 7th largest fire in state history, and largest fire on record in the California Sierra Mountains, says wunderground’s weather historian, Christopher C. Burt in his latest post, “The Worst Wild Fires in U.S. History”. The Rim Fire will likely climb to be the 5th biggest fire in California’s history by this weekend, but will have difficultly surpassing California’s largest fire on record–the Cedar Fire in San Diego County of October 2003. That fire burned 273,246 acres (430 square miles), destroyed 2,820 buildings, and killed 15 people. California has had its driest year-to-date period, so it is no surprise that the state is experiencing an unusually large fire this summer. It would also not be a surprise if the state sees another huge fire this year, as peak California fire activity usually comes in September and October, during the end of the six month-long dry season, and when the hot, dry Santa Ana winds tend to blow.


Figure 1. California’s Rim Fire as captured by a member of the International Space Station on August 26, 2013. Lake Tahoe is visible at the top, and smoke from the fire obscures the northern portion of Yosemite National Park, and streams into Nevada. Image credit: NASA.


Figure 2. Outbuilding and pickup truck burned by the Rim Fire. Image credit: USFS-Mike McMillan

Weather conditions over the next five days where the Rim Fire is burning are expected to near average, with high temperatures in the upper 80s to low 90s and moderate winds. Air quality alerts for smoke have been posted over portions of California and Nevada, and Reno, Nevada is under a dense smoke advisory. The dense smoke will result in unhealthy air quality in the city, and prolonged outdoor activities are being discouraged. Travel may be difficult due to reduced visibility less than five miles on some area highways.

Links to follow
Wunderground’s weather historian, Christopher C. Burt’s latest post, “The Worst Wild Fires in U.S. History”.
Our wundermap with the fire layer turned on is a good way to track the fire perimeter and smoke plume.
Crane Flat webcam
Time lapse of the Crane Flat webcam for 8 hours on Tuesday.
Yosemite Fire Example of How Droughts Amplify Wildfires, August 26 post by Andrew Freedman of climatecentral.org

Tropical wave midway between Africa and the Lesser Antilles downgraded
A tropical wave that came off the coast of Africa on Sunday is midway between Africa and the Lesser Antilles Islands. This disturbance is moving westward at 10 – 15 mph, has a modest amount of spin, but has lost nearly all of the limited heavy thunderstorm activity it had. In their 8 am EDT Wednesday Tropical Weather Outlook, NHC downgraded the 5-day odds of formation of this disturbance from 30% to 20%. Wind shear is a moderate 10 knots over the system, but there is an area of dry air and dust from the Saharan Air Layer (SAL) to the north that is interfering with development. For the next few days, though, the wave will experience upward-moving air from a Convectively-Coupled Kelvin Wave (CCKW) that is moving eastwards across the Atlantic at 25 – 35 mph. This interaction may contribute to development. With the exception of the NAVGEM model, there is little support from the models for developing the disturbance during the next five days. The wave could spread heavy rains and gusty winds to the Lesser Antilles Islands as early as Sunday.

A tropical wave expected to emerge from the coast of Africa on Friday and track over the Cape Verde Islands is developed by the GFS and European models. This wave is expected to take a northwesterly track, and would likely not be able to make the long trek across the Atlantic to threaten North America or the Caribbean Islands.

from:    http://www.wunderground.com/blog/JeffMasters/show.html

Drought Causes Colorado River Flow Cut

For the first time in history, the U.S. government has ordered that flow of Colorado River water from the 50-year-old Glen Canyon Dam be slashed, due to a water crisis brought about by the region’s historic 14-year drought. On Friday, the Federal Bureau of Reclamation–a division of the Department of Interior that manages water and electric power in the West–announced that it would cut water released from Lake Powell’s Glen Canyon Dam by 750,000 acre-feet in 2014. An acre-foot is the amount of water that will cover an acre of land one foot deep; 750,000 acre-feet is enough water to supply at least 750,000 homes for one year. The flow reduction will leave the Colorado River 9% below the 8.23 million acre feet that is supposed to be supplied downstream to Lake Mead for use in California, Nevada, Arizona and Mexico under the Colorado River Compact of 1922 and later agreements. “This is the worst 14-year drought period in the last hundred years,” said Upper Colorado Regional Director Larry Walkoviak in a Bureau of Reclamation press release.

In the winter of 2005, Lake Powell reached its lowest level since filling, an elevation 150′ below full pool. Lake levels recovered some in during 2005 – 2011, but the resurgence of severe to extreme drought conditions have provoked a steep decline in 2012 and 2013, with the lake falling 35′ over the past year. As of August 18, 2013, Lake Powell was 109′ below full pool (45% of capacity), and was falling at a rate of one foot every six days.


Figure 1. Satellite comparisons of water levels in Arizona and Utah’s Lake Powell between 1999 and 2013 show a huge reduction in the amount of water in the lake. Image credit: NASA Earth Observatory.


Figure 2. From October 1, 2012 – July 31, 2013, precipitation over the Colorado River Watershed was about 80% of average. Image credit: Colorado Basin River Forecast Center.

Las Vegas’ Water Supply, Lake Mead, Near a Record Low
Downstream of Lake Powell lies Lake Mead, filled in 1936 when Hoover Dam was completed. Lake Mead supplies Las Vegas with ninety percent of its drinking water, and the water level of Lake Mead is expected to fall by eight feet in 2014 due to the lower water flow levels out of Lake Powell ordered on Friday. Lake Mead has fallen by 100 feet since the current 14-year drought began in 2000, and the higher of the two intake pipes used to supply Las Vegas with water from the lake is in danger of running dry. As a result, a seven-year, $800 million project is underway by the Southern Nevada Water Authority to build a third intake pipe that will tap the deepest part of the reservoir. This so-called “third straw” is scheduled to be available late in 2014, which may be cutting it close, if the Colorado River watershed experiences another year of drought as severe as in 2012 – 2013. Southern Nevada has done well to reduce water usage, though–the region’s annual water consumption decreased by nearly 29 billion gallons between 2002 and 2012, despite a population increase of more than 400,000 during that span.


Figure 3. Lake Mead water levels from 1938 – 2013 in July show a precipitous drop since drought conditions gripped the Western U.S. in 2000. The Lake Mead photo was taken by wunderphotographer LAjoneson June 29, 2007, when the lake had a “bathtub ring” 109′ tall. Water level data from The Bureau of Reclamation.


Figure 4. Workers handle the main drive sections of the tunnel boring machine that is drilling a 3-mile long tunnel through solid rock to supply Las Vegas with water from Lake Mead. The new intake tunnel is designed to maintain the ability to draw upon Colorado River water at lake elevations as low as 1,000 feet above sea level. The lake already has two intake pipes, and the higher of these will go dry when the lake level hits 1050′ – 1075′. As of August 2013, the Lake Mead water level was 1106′ above sea level, which is 114′ below full pool, but 24′ above the record low water level of 1081′ set in November 2010. Image credit: Southern Nevada Water Authority.

Drought conditions worsen over Southwest U.S. in August
According to the U.S. Drought Monitor, the Western U.S. drought peaked in July 2002, when 79% of the West was in at least severe drought, and 45% of the region was in the two highest categories of drought–extreme to exceptional. However, drought conditions have been steadily intensifying this summer. The August 13, 2013 Drought Monitor report showed that drought conditions in the Western U.S. are now the worst since 2004, with 78% of the West in at least severe drought, and 20% in the two highest categories of drought, extreme and exceptional. The latest U.S. Seasonal Drought Outlook, issued on August 15, calls for drought to remain entrenched over the large majority of the Western U.S. through the end of November.


Figure 5. As of August 13, 2013, severe to exceptional drought gripped nearly all of the Colorado RIver’s watershed in Arizona, Utah, New Mexico, Wyoming, California, and Colorado. Image credit: NOAA/NESDIS/NCDC.

Causes of the great Western U.S. drought
It is well-known that natural variations in sea surface temperature patterns, such as seen from the El Niño/La Niña oscillation, can influence storm tracks and can cause prolonged periods of drought. These natural variations likely had a hand in causing the great 2000 – 2013 Western U.S. drought. However, changes in the amount of sea ice covering the Arctic can also have a major impact on Northern Hemisphere atmospheric circulation patterns. We must consider if global warming, which has led to a 50% decline in summer Arctic sea ice extent since 1979, may be altering storm tracks and contributing to drought. In 2004, Lisa Sloan, professor of Earth sciences at UC Santa Cruz, and her graduate student Jacob Sewall published an article in Geophysical Research Letters, Disappearing Arctic sea ice reduces available water in the American west. An accompanying news release explained that their climate models found “a significant reduction in rain and snowfall in the American West” as a result of Arctic sea ice loss:

What they found was a change in atmospheric circulation patterns that caused a small northward shift in the paths of winter storms over western North America. This shift in winter storm tracks resulted in significantly reduced winter precipitation from southern British Columbia to the Gulf of California. In some areas, average annual precipitation dropped by as much as 30 percent. The reductions were greatest along the West Coast, with lesser changes further inland. But even as far inland as the Rocky Mountains, winter precipitation fell by 17 percent.

The sea ice acts like a lid over the ocean surface during the winter, blocking the transfer of heat from the ocean to the atmosphere, Sewall explained. Where the sea ice is reduced, heat transfer from the ocean warms the atmosphere, resulting in a rising column of relatively warm air. The shift in storm tracks over North America was linked to the formation of these columns of warmer air over areas of reduced sea ice in the Greenland Sea and a few other locations.

A follow-up paper by Dr. Sewall in 2005, “Precipitation Shifts over Western North America as a Result of Declining Arctic Sea Ice Cover: The Coupled System Response”, used a more sophisticated modeling technique but confirmed the results of the 2004 paper. In a June 2013 interview with climateprogress.org, Dr. Sewall commented:

“I think the hypothesis from 2004 and 2005 is being borne out by current changes. The only real difference is that reality is moving faster then we though/hoped it would almost a decade ago.”


Figure 6. The area of the Western U.S. in drought peaked during 2002 – 2004, but during 2013 has been approaching levels not seen since 2004. Image credit: U.S. Drought Portal.

Western North America drought of 2000 – 2004 the worst in over 800 years
The Colorado River’s water woes are due to an extraordinary 14-year drought that began in 2000, which peaked during 2000 – 2004. A 2012 study titled, Reduction in carbon uptake during turn of the century drought in western North America, found that the 2000 – 2004 drought was the most severe Western North America event of its kind since the last mega drought over 800 years ago, during the years 1146 – 1151. The paper analyzed the latest generation of climate models used for the 2013 IPCC report, which project that the weather conditions that spawned the 2000 – 2004 drought will be the new normal in the Western U.S. by 2030, and will be considered extremely wet by the year 2100. If these dire predictions of a coming “megadrought” are anywhere close to correct, it will be extremely challenging for the Southwest U.S. to support a growing population in the coming decades.

Figure 7. Normalized precipitation over Western North America (five-year mean) from 22 climate models used to formulate the 2013 IPCC report, as summarized by Schwalm et al., 2012, Reduction in carbon uptake during turn of the century drought in western North America. The horizontal line marks the precipitation level of the 2000 – 2004 drought, the worst of the past 800 years. Droughts of this intensity are predicted to be the new normal by 2030, and will be considered an outlier of extreme wetness by 2100. The paper states: “This impending drydown of western North America is consistent with present trends in snowpack decline as well as expected in-creases in aridity and extreme climate events,including drought, and is driven by anthropogenically forced increases in temperature with coincident increases in evapotranspiration and decreases in soil moisture. Although regional precipitation patterns are difficult to forecast, climate models tend to underestimate the extent and severity of drought relative to available observations. As such, actual reductions in precipitation may be greater than shown. Forecasted precipitation patterns are consistent with a probable twenty-first century megadrought.” Image credit: Schwalm et al., 2012, Reduction in carbon uptake during turn of the century drought in western North America, Nature Geoscience 5, 551-555, Published online 29 JULY 2012, DOI: 10.1038/NGEO1529, www.nature.com/naturegeoscience.

from:    http://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=2495

TS Erin, Tropical Wave in Gulf

Tropical wave 92L crossed over Mexico’s Yucatan Peninsula overnight, and the center of the disturbance is now located in the Gulf of Mexico along the west coast of the Yucatan Peninsula. Satellite loops show that 92L has a well-developed surface circulation, but there are no heavy thunderstorms near the center. A moderate-sized region of heavy thunderstorms does lie to the northeast and east of the center, over Cancun, Cozumel, and southwards to Belize. An upper-level low pressure system over the Gulf of Mexico is pumping dry air into 92L, slowing development. Wind shear is a moderate 10 – 20 knots over the the wave, which should allow slow development today. The hurricane hunter flight scheduled for today has been cancelled.


Figure 1. Latest satellite image of Invest 92L over the Gulf of Mexico.

Forecast for 92L
The 12Z Friday SHIPS model forecast predicts that 92L will remain in an area of low to moderate wind shear through Saturday, and ocean temperatures will be a favorable 29 – 30°C. The topography of the Southern Gulf of Mexico’s Bay of Campeche can aid in getting a storm spinning more readily, as well. Given these favorable conditions for intensification, 92L should be able to become a tropical depression by Saturday, and a tropical storm by Sunday. A trough of low pressure over the northern Gulf of Mexico will dip down by Sunday over the Central Gulf of Mexico, increasing the wind shear to a high 20 – 30 knots just to the north of 92L. This trough may also be able to pull the storm northwestwards to a landfall in Texas on Monday or Tuesday, as the 00Z Friday runs of UKMET and NAVGEM model predict. If 92L does follow this more northwesterly path, intensification into a strong tropical storm would be difficult, due to the high wind shear. An alternate scenario is presented by our two top-performing models, the European and GFS. They predict that 92L will take a nearly due west track, resulting in a landfall south of Tampico, Mexico on Monday. The storm would have more of an opportunity to strengthen in this scenario, since wind shear would be lower. Either scenario is reasonable, and residents of the Mexican and Texas Gulf Coast should anticipate the possibility of a tropical storm hitting the coast as early as Sunday night. Regardless of 92L’s track, a flow of moist tropical air along the storm’s eastern flank will form an atmospheric river of moisture that will bring a wide swath of 4+ inches of rain to the Gulf Coast from Louisiana to the Florida Panhandle over the next few days. In their 8 am EDT Wednesday Tropical Weather Outlook, NHC gave 92L a 50% of developing by Sunday, and a 60% chance of developing by Wednesday. I put these odds higher, at 70% and 80%, respectively.


Figure 2. MODIS satellite image of Tropical Depression Erin taken at 10:30 am EDT Friday August 16, 2013. At the time, Erin had maximum sustained winds of 35 mph. Image credit: NASA.

Tropical Storm Erin
Tropical Storm Erin is over the far Eastern Atlantic off the coast of Africa, and continues west-northwest at 15 mph. Erin is small and weak and has lost nearly all of its heavy thunderstorms, as seen on satellite loops. This is probably due, in part, to the fact the storm is over waters of 25.5 – 26°C, which is a marginal temperature for tropical cyclones. Erin is also having trouble with dry air from the Saharan Air Layer (SAL), and the storm’s west-northwest motion is beginning to cut Erin off from a moist source of air to its south–the semi-permanent band of tropical thunderstorms called the ITCZ (Inter-Tropical Convergence Zone.) The latest 00Z runs of the major global computer models, except for the GFS, call for Erin to dissipate by early next week. Given Erin’s struggles today, I expect the storm will be dead by Sunday.

from:    http://www.wunderground.com/blog/JeffMasters/show.html

Dangerous Typhoon Targets Phillipines

Earth’s strongest and most dangerous tropical cyclone so far in 2013 is Category 4 Super Typhoon Utor, which is closing in on the northern Philippine Island of Luzon with 150 mph sustained winds. Landfall is expected at approximately 20 UTC (4 pm EDT) Sunday near Casigran. Satellite imagery shows a formidable storm with well-organized spiral bands, a prominent 15-mile diameter eye, and good (but not excellent) upper-level outflow. Ocean temperatures are very warm, about 30°C (86°F), which is approximately 0.5 – 1.0°C above average. These warm waters extend to tremendous depth, giving Utor a huge source of energy to tap into. Wind shear is low, 5 – 10 knots. Theoretically, the Maximum Potential Intensity (MPI) that Utor can achieve under these conditions is sustained winds of 185 mph. However, Utor will not have time to reach that strength before encountering Luzon. Utor is a very wet storm, and will likely bring a large swath of 8+ inches of rain across Luzon. These rains will cause dangerous flash flooding and mudslides. Utor will likely weaken to a Category 1 storm as it passes over Luzon, but is expected to re-intensify to a Category 2 storm before hitting China a few hundred miles south of Hong Kong about 20 UTC on Tuesday.

Utor is a Marshallese word for squall line, and has been used for three tropical cyclones in the Western Pacific–in 2001, 2006, and 2013. Typhoon Utor is called Typhoon Labuyo in the Philippines. Utor’s 150 mph winds make it the strongest tropical cyclone globally so far in 2013. Earth’s previous most powerful tropical cyclone of 2013 was Typhoon Soulik, which reached Category 4 strength with 145 mph winds on July 10. Soulik weakened to a Category 2 storm before hitting Taiwan on July 12.


Figure 1. MODIS satellite image of Typhoon Utor taken at 04:30 UTC on Sunday, August 11. Image credit: NASA.

The Philippines no stranger to powerful typhoons
The Philippines lie in the most tropical cyclone-prone waters on Earth, and rarely escape a year without experiencing a devastating typhoon. Usually, these storms impact the northern Philippine island of Luzon, but last year, Earth’s deadliest weather disaster of 2012 occurred on the southern Philippine island of Mindanao, where Super Typhoon Bopha struck as a Category 5 super typhoon with winds of 160 mph (260 km/h), on December 3. Bopha made two additional landfalls in the Philippines, on central Visayas and on Palawan, on December 4. The typhoon left 1901 people dead, mostly on the island of Mindanao, making Bopha the 2nd deadliest typhoon in Philippine history. Bopha affected over 5.4 million people and left over 700,000 people homeless. With damages estimated at $1.7 billion, Bopha was the costliest natural disaster in Philippines history.


Figure 2. December 7, 2012: rescuers and residents look for missing victims amongst toppled tree trunks and coconut shells after flash floods caused by Super Typhoon Bopha hit Compostela Valley on Mindanao Island in the Philippines on December 3 – 4, 2012. (AP Photo/Jay Morales, Malacanang Photo Bureau, HO)

Quiet in the Atlantic
There are no tropical cyclone threat areas in the Atlantic to discuss today. Some of the models are suggesting a strong tropical disturbance capable of becoming a tropical storm could form by Saturday in the Gulf of Mexico near Mexico’s Yucatan Peninsula, in association with a stalled cold front expected to push off the Southeast U.S. coast late this week.

from:    http://www.wunderground.com/blog/JeffMasters/show.html

TS Dorian Making a Comeback?

After a long trek over the Atlantic Ocean from the coast of Africa, the remains of Tropical Storm Dorian (now called Invest 91L) have finally arrived at the shores of North America. Ex-Dorian is nearly stationary, and is situated over the Northwestern Bahama Islands, just off the coast of Southeast Florida. Satellite loops and Melbourne, Florida radar images show that ex-Dorian has only a limited amount of heavy thunderstorms, which are not well-organized. There does appear to be a surface circulation center trying to form just north of the storm’s heaviest thunderstorms, about 70 miles east of Vero Beach, Florida. However, dry air to the northwest, as seen on water vapor satellite loops, is inhibiting development. WInd shear is moderate, 10 – 20 knots, but is expected to rise to the high range, 20 – 30 knots, by Saturday morning. Ex-Dorian is expected to move slowly northwards and then north-northeastwards on Saturday. This motion will get ex-Dorian tangled up with a cold front that extends from Northern Florida northeastwards, just offshore from the Southeast U.S. coast. Before it merges with the front, ex-Dorian has some potential for regeneration into a tropical depression, and in their 8 am Friday Tropical Weather Outlook, NHC gave ex-Dorian a 30% chance of becoming a tropical cyclone by Sunday. Ex-Dorian will likely bring heavy rains to the Northwest Bahamas on Friday, and these heavy rains may also clip the coast of Southeast Florida. However, the bulk of ex-Dorian’s rains should stay offshore.


Figure 1. Morning radar image of ex-Dorian from the Miami radar.

from:    http://www.wunderground.com/blog/JeffMasters/show.html