Tropical Depression Seven continues westward across the central tropical Atlantic with little change in appearance. Looking remarkably like the tropical depression that became Tropical Storm Ernesto last week, TD 7 has a limited region of heavy thunderstorms, as seen on satellite loops. A large amount of dry air to the west and north is visible on water vapor satellite loops, and this dry air is interfering with TD 7’s heavy thunderstorms. Wind shear is a light 5 – 10 knots, which is favorable for intensification. Ocean temperatures are 26.5°C, which is a bit on the cool side, but these temperatures are 0.5° warmer than on Thursday. Winds at the Middle Atlantic buoy 41041 peaked at 29 mph, gusting to 38 mph, at 1:50 am EDT this Friday morning, when the center of TD 7 passed about 40 miles to the south. TD 7 will pass about 60 miles south of buoy 41040 near midnight tonight. The first hurricane hunter mission into TD 7 is scheduled for Saturday morning.
Figure 1. Morning satellite image of TD 7.
Forecast for TD 7
TD 7 formed about 400 miles east-northeast of where Ernesto became a tropical depression, as seen on our wundermap. Atmospheric and oceanic conditions are currently quite similar to what Ernesto experienced, and I expect TD 7 will struggle with dry air like Ernesto did. The SHIPS model predicts that shear will remain light through tonight, then rise to the moderate range on Saturday, when the storm will encounter upper-level southwesterly winds associated with a trough of low pressure. However, ocean temperatures will warm to 28°C, which may partially counteract the increase in shear, as far as maintaining a favorable environment for development. Dry air and shear may be significant enough to destroy TD 7 on Sunday, as predicted by the GFS and ECMWF models. These models tried to kill off Ernesto in a similar situation last week, so I am inclined to believe TD 7 will survive for the coming five days, but struggle. The official NHC forecast of a 45 mph tropical storm moving through the Lesser Antilles Islands Saturday night and Sunday is a reasonable one.
Figure 2. Morning satellite image of Invest 93L.
93L
A strong tropical wave in the far Eastern Atlantic that emerged off the coast of Africa Thursday night was designated Invest 93L by NHC. In their 8 am Tropical Weather Outlook, NHC gave 93L a 50% chance of becoming a tropical depression by Sunday morning. Satellite loops show a pronounced spin to the atmosphere at mid levels, but little in the way of heavy thunderstorm activity. The latest Saharan Air Layer Analysis from the University of Wisconsin shows that while the atmosphere immediately surrounding the disturbance is moist, there is a large area of dry air from the Sahara to the west and north. This dry air will be a significant impediment to development during the coming week. The ECMWF model shows some weak development of 93L over the coming week, and predicts a general west-northwesterly track. The storm may be something Bermuda needs to be concerned about in eight or so days.
It’s mid-July, and we have yet to see a named storm form in the Atlantic this month. The computer models are not predicting any development through at least July 20, and if we make it all the way to the end of the month without a named storm forming, it will be the first July since 2009 without a named storm. Since the current active hurricane period began in 1995, 13 of 17 years (76%) have had a named storm form during July. The busiest July occurred in 2005, when five named storms and two major hurricanes formed. These included Hurricane Dennis and Hurricane Emily–the strongest hurricanes ever observed so early in the season. Only eight major hurricanes have formed in July since record keeping began in 1851. As seen in Figure 1, most of the last half of July activity occurs in the Gulf of Mexico and waters off the Southeast U.S. coast. These type of storms form when a cold front moves off the U.S. coast and stalls out, with the old frontal boundary serving as a focal point for development of a tropical disturbance (as happened for Alberto, Beryl, Chris, and Debby in 2012.) There will be at least two cold fronts moving off the U.S. Mid-Atlantic coast over the next two weeks. The first of these fronts will push offshore around July 20, and we will need to watch the waters offshore of North Carolina for development then. Formation potential will be aided by ocean temperatures that are about 0.7°C (1°F) above average along the U.S. East Coast.
Figure 1. Tracks of all tropical storms and hurricanes 1851 – 2006 that formed July 16-31. The U.S. coast from North to Texas are the preferred strike locations. Only a few storms have formed in the tropical Atlantic and Caribbean in July. Wind shear is typically too high and SSTs too cool in July to allow African waves in the Caribbean and tropical Atlantic to develop into tropical storms. However, a few long-track “Cape Verdes” hurricanes have occurred in July, spawned by tropical waves that came off the coast of Africa. African tropical waves serve as the instigators of about 85% of all major hurricanes.
Figure 2. The seasonal distribution of Atlantic hurricane activity shows that July typically has low activity. Image credit: NHC.
Sea Surface Temperatures: slightly above average
The departure of Sea Surface Temperatures (SST) from average over the tropical Atlantic between Africa and Central America was about 0.3°C above average during June (Figure 3.) This figure has not changed much over the first two weeks of July. These temperatures are not warm enough to appreciably affect the odds of a July named storm or hurricane. The strength of the Azores-Bermuda high has been near average over the past two weeks, driving near-average trade winds. The latest 2-week run of the GFS model predicts continued average-strength trade winds through late-July, so SSTs should remain about 0.3°C above average during this period, due to average amounts of cold water mixing up from below due to the wind action on the water.
Figure 3. Sea Surface Temperature (SST) departure from average for July 12, 2012. SSTs were 0.3°C above average over the tropical Atlantic’s Main Development region for hurricanes, from Africa to Central America between 10° and 20° North Latitude. Note the large region of above average SSTs along the Equatorial Pacific off the coast of South America, the hallmark of a developing El Niño episode. Image credit: NOAA/NESDIS
El Niño on the way?
For two consecutive weeks, ocean temperatures 0.5 – 0.6°C above average have been present in the tropical Eastern Pacific, which is right at the threshold for a weak El Niño episode. NOAA’s Climate Prediction Center has issued an El Niño Watch, and gives a 61% chance that El Niño conditions will be present during the August – September – October peak of the Atlantic hurricane season. The likely development of a full-fledged El Niño episode means that Atlantic hurricane activity will probably be suppressed in 2012, due to the strong upper-level winds and high wind shear these events typically bring to the tropical Atlantic.
Figure 4. Sea Surface Temperature (SST) departure from average for the the equatorial Eastern Pacific (the area 5°N – 5°S, 120°W – 170°W, also called the “Niña 3.4 region”). El Niño conditions exist when the SST in this region rises 0.5°C above average. As of July 9, 2012, SSTs in the Niño 3.4 region had risen to 0.5°C above average. To be considered an “El Niño episode”, El Niño conditions must occur for five consecutive months, using 3-month averages. Image credit: NOAA Climate Prediction Center.
Wind shear: above average Wind shear is usually defined as the difference in wind between 200 mb (roughly 40,000 foot altitude) and 850 mb (roughly 5,000 foot altitude). In most circumstances, wind shear above 20 knots will act to inhibit tropical storm formation. Wind shear below 12 knots is very conducive for tropical storm formation. High wind shear acts to tear a storm apart. The jet stream has two bands of strong high-altitude winds that are currently bringing high wind shear to the Atlantic. The southern branch (subtropical jet stream) is bringing high wind shear to the Caribbean, and the northern branch (polar jet stream) is bringing high wind shear to the waters offshore of New England. This configuration often leaves a “hole” of low shear between the two branches, off the Southeast U.S. coast and over the Gulf of Mexico. The jet stream is forecast to maintain this two-branch pattern over the coming two weeks. Wind shear has been about 10 – 20% higher than average over the first two weeks of July, and is predicted to be mostly above average for the coming two weeks. This will cut down on the odds of a July storm.
Figure 5. Vertical instability over the Caribbean Sea in 2012 (blue line) compared to average (black line.) The instability is plotted in °C, as a difference in temperature from near the surface to the upper atmosphere. Thunderstorms grow much more readily when vertical instability is high. Instability has been lower than average, due to an unusual amount of dry air in the atmosphere, reducing the potential for tropical storm formation. Image credit: NOAA/NESDIS/CIRA.
Dry air: above average
As seen in Figure 5, there has been an unusual amount of dry, stable air in the Caribbean this year creating low levels of vertical instability. This has occurred due to a combination of dry air from Africa, and upper-atmosphere dynamics creating large areas of sinking air that dry as they warm and approach the surface. The Gulf of Mexico and tropical Atlantic between the coast of Africa and the Lesser Antilles have also seen low vertical instability this summer. June and July are the peak months for dry air and dust coming off the coast of Africa, and the Saharan dust storms have been quite active over the past two weeks. Expect dry air to be a major deterrent to any storms that try to form in the tropical Atlantic during July.
Steering currents: average
The predicted steering current pattern for the next two weeks is a typical one for July. We have an active jet stream bringing many troughs of low pressure off the East Coast of the U.S. These troughs are frequent enough and strong enough to recurve any tropical storms or hurricanes that might penetrate north of the Caribbean Sea. Steering current patterns are predictable only about 3 – 5 days in the future, although we can make very general forecasts about the pattern as much as two weeks in advance. There is no telling what might happen during the peak months of August, September, and October–we might be in for a repeat of the favorable 2010 and 2011 steering current pattern, which recurved most storms out to sea–or the unfavorable 2008 pattern, which steered Ike and Gustav into the Gulf of Mexico.
Summary: a below average chance of a July tropical storm
Given that none of the computer models are forecasting tropical storm formation in the coming seven days, SSTs are only slightly above average, and wind shear and vertical stability are above average, I’ll go with a 30% chance of a named storm forming in the Atlantic during the remainder of July.
Figure 6. Hurricane Emilia over the Eastern Pacific at 20:35 UTC July 10, 2012. At the time, Emilia was a Category 3 hurricane with 125 mph winds. Emilia peaked earlier in the day as a Category 4 storm with 140 mph winds–the strongest hurricane in the East Pacific so far in 2012. Image credit: NASA.
An active Eastern Pacific hurricane season
It’s been a very active start to the Eastern Pacific hurricane season, where we’ve already had six named storms, four hurricanes, and three intense hurricanes. A typical season has 4 named storms, 2 hurricanes, and 0 intense hurricanes by July 14. The formation of Tropical Storm Fabio on July 12 marks the 4th earliest formation of the Eastern Pacific’s season’s sixth storm. The record is held by the year 1985, when the season’s sixth storm formed on July 2. Record keeping began in 1949.
Have a great weekend, everyone, and I’ll be back Monday with a new post.
An area of low pressure and heavy thunderstorms in the Southern Gulf of Mexico (designated 96L by NHC Thursday afternoon) is a threat to become a tropical depression this weekend, and all interests along the Gulf of Mexico coast should pay attention to the progress of this disturbance. The disturbance is bringing occasional heavy rains to Western Cuba, South Florida, and Mexico’s Yucatan Peninsula. Top winds measured in the surrounding ocean areas this morning were 27 mph, gusting to 34 mph, at the Yucatan Basin buoy between Mexico’s Yucatan Peninsula and the Cayman Islands. Our wundermap for the surrounding ocean areas show a ship that measured sustained winds of 30 mph near the western tip of Cuba this morning. Satellite-based surface wind measurements from the newly-available Oceansat-2 scatterometer, courtesy of India, show no signs of a surface circulation. Visible satellite loops show that 96L is less organized than it was Thursday evening, with only a little low-level spin apparent, and a modest area of disorganized thunderstorms. The decrease in organization is probably due to the moderate to high levels of wind shear of 15 – 25 knots over the region. Water vapor satellite loops show a modest region of dry air over the Central Gulf of Mexico, which is interfering with development. Ocean temperatures are 81 – 83°F in the Western Caribbean and Southern Gulf of Mexico, which is about 1°F above average, and warm enough to support formation of a tropical storm. A hurricane hunter mission is scheduled to investigate 96L this afternoon, but this mission will probably be cancelled due to the disturbance’s lack of organization.
Figure 1. Morning satellite image of the tropical disturbance 96L in the Southern Gulf of Mexico.
Forecast for 96L
Wind shear is predicted to remain in the moderate range through Saturday night, which is likely low enough to allow 96L to develop into a tropical depression; NHC gave 96L a 70% chance of developing into a tropical depression by Sunday morning, in their 8am EDT Tropical Weather Outlook. By Sunday, wind shear is predicted to increase, limiting 96L’s potential for intensification. Where the storm might go is anybody’s guess. The GFS model has consistently been predicting that a trough of low pressure pushing off of the U.S. East Coast will be capable of grabbing the disturbance and accelerating it to the northeast across Florida north of Tampa Bay on Sunday or Monday. However, an ensemble of forecasts from the model created by running the model with slight perturbations to the initial conditions shows a wide range of possible tracks, both to the east over Florida, and to the west towards Texas and Louisiana (Figure 2.) The latest ECMWF model run (00 UTC) predicts that the trough will not be strong enough to pull 96L northeastwards across Florida. The ECMWF predicts that a ridge of high pressure will build in over the Southern U.S., forcing the disturbance westwards across the Gulf of Mexico and into South Texas by Thursday. The UKMET model also favors a track west towards Texas. The NOGAPS model takes 96L to the northwest into Louisiana/Texas by Monday.
Figure 2. Which way will 96L go? The GFS model, when run at low resolution with 20 slightly different perturbations to the initial conditions in order to generate an ensemble of different forecasts, shows two distinct possibilities: a sharp east turn to move over Florida, or a west or northwest motion towards Louisiana or Texas. The high-resolution official GFS forecast is shown in white.
Hurricane Carlotta bears down on Mexico’s Pacific coast
Posted by: JeffMasters, 4:10 PM GMT on June 15, 2012
+32
Hurricane Carlotta has steadily intensified today as it heads northwest towards the Mexican coast east of Acapulco. Recent satellite loops show a well-organized storm with a prominent eye, solid eyewall with cold cloud-tops, and good low-level spiral banding. Carlotta may be undergoing rapid intensification, thanks to favorable sea surface temperatures near 30°C (86°F) and moderate wind shear of 10 – 20 knots. A hurricane hunter mission is en-route, and will arrive at the storm near 2pm EDT on Friday to see how strong Carlotta has become. Carlotta’s rain bands have already moved over the coast of Mexico a few hundred miles east of Acapulco, as seen on Puerto Ánoel radar.
Forecast for Carlotta
Carlotta is likely to continue to strengthen as it approaches the western coast of Mexico east of Acapulco. As a large portion of the hurricane’s circulation moves over the mountains of Mexico on Saturday morning, steady weakening should occur. Heavy rains from Carlotta will be the storm’s main threat, and these rains will steadily progress westwards along the coast, arriving at Acapulco by Saturday morning. With rainfall amounts of 6 – 10 inches possible along the track of Carlotta, the potential for dangerous flash flooding and mudslide will be a concern all along the coast affected by Carlotta.
The Atlantic is quiet
There are no threat areas to discuss in the Atlantic today. The GFS model is predicting that some of the moisture and energy from Carlotta could move into the Gulf of Mexico next week and form a tropical disturbance capable of becoming a tropical depression, but this solution is unlikely.
Impact of Tropical Cyclones on drought alleviation in the Atlantic and Gulf Coasts
Dr. Pat Fitzpatrick of the Stennis Space Center in Mississippi discussed how landfalling tropical storms and hurricanes can alleviate drought. The biggest winner tends to be the Southeast U.S. states of Florida, Georgia, South Carolina, and North Carolina, where about 20% – 50% of all droughts between 1960 – 2009 were busted by a landfalling tropical storm or hurricane. It is uncommon for Texas to see a drought busted; less than 10% of all Texas droughts have been ended by a hurricane or tropical storm. This occurs because the Southeast U.S. can receive heavy rains from hurricanes moving up the East Coast, or moving through the Gulf of Mexico, while relatively few storms track over Texas. Over the course of a year, hurricanes and tropical storms contribute 15 – 20% of rain along the Gulf Coast, and 3 – 16% along the East Coast. The length of a drought does not seem to affect whether a drought can be ended by a hurricane or not. Hurricanes have been able to end both short (< 3 month) and long (> 12 month droughts) equally well.
Figure 1. Example of a drought-busting tropical storm. Moderate drought (Palmer Drought Severity Index, PDSI, ≤ –2.0) was present in 52 percent of the Florida, Georgia, South Carolina, and North Carolina climate divisions in May 2006. The percentage decreased to 29 percent after Tropical Storm Alberto passed through on June 11 – 15, 2006. Image credit: U.S. Drought Monitor.
Figure 2. Rainfall in inches from the passage of Tropical Storm Alberto in 2006. Image credit: NOAA/HPC.
According to the U.S. drought monitor, over 90% of the area of Florida, Georgia, South Carolina, and North Carolina are currently in moderate to exceptional drought. There is 1 – 2 inches of rain coming to much of the region over the next few days, but that will not be enough to bust the drought. Based on Dr. Fitzpatrick’s research, there is a 20% – 50% chance that the drought will be broken by a tropical storm or hurricane. The first storm on the list in 2012 is Alberto again; let’s hope we get another Alberto this year that imitates the 2006 version of Alberto.
Patterns of rapid intensification
Peter Yaukey of the University of New Orleans studied patterns of hurricane rapid intensification in the Atlantic from 1950 – 2009. The Gulf of Mexico and Caribbean saw the most rapid intensification events, and the Northeast Atlantic the fewest. Interestingly, he found that rapid intensification events did not peak in September, but tended to be more common in June and July. Hurricane are less likely to intensify in the late afternoon and early evening (near 00 UTC), and more likely to intensify just after midnight, at 06 UTC.
The plume from a lateral blast at Pinatubo in the Philippines seen on June 15, 1991. The eruption may have helped stifle hurricane activity in the Atlantic for three years afterwards.
We have had many discussions over the years here on Eruptions about the relationship betweenvolcanic eruptions and weather/climate (remember, they are different things). Most of the time, the concern is how weather will become worse (i.e., much colder or much hotter) due to volcanic aerosols or ash that are kicked high into the atmosphere during large eruptions. Remember, ash plumes from manyplinian eruptions can tower over 35-50 km up, so material can be injected into the upper atmosphere and spread around the world in a matter of weeks. It would be very surprising if these sorts of eruptions – which are relatively rare, only occurring maybe once or twice a decade – didn’t effect weather and climate for years until the aerosols can all settle out.
So, I was quite interested when I saw a new paper in the Journal of Geophysical Research titled “Atlantic hurricane activity following two major volcanic eruptions” by Amato Evan. My instant thought was I actually wasn’t sure what to expect – I mean, how would a large eruption effect the activity of such major, hemisphere-spanning events like hurricanes? Would it make hurricanes worse? As it turns out, this study suggests that major eruptions in the tropics (or close) might actually subdue Atlantic hurricane activity for years after the eruption.
Figure 2B from Evan (2012) showing the drops in sea surface temperature (SST) in the Atlantic after the eruptions of El Chichón (1982) and Pinatubo (1991)
Evan (2012) looks at two eruptions in particular – the1982 eruption of El Chichónin Mexico and the 1991 eruption of Pinatubo* in the Philippines. Both were large eruptions, ranking as VEI 5-6. Both eruptions injected large volumes of aerosols and ash into the upper atmosphere in the tropics, reducing theoptical depth of the atmosphere to 0.1-0.2 (normally it should be closer to 0.01). To give you an idea, that is almost as bad as other large eruptions such as Krakatau in 1883, famous for the vibrant skies it produced worldwide. All these aerosols in the atmosphere increase the albedo of the planet – that is, the planet will reflect more sunlight back into space. This means less sunlight hitting the surface of the Earth, and in particular, less on the oceans in the tropics. This produces colder surface and near-surface waters in what is called the Atlantic Main Development Region (MDR) for hurricanes – between 8-20°N/20-65°W (see right). This decrease in sea surface temperature, in turn, lead to an increase in vertical wind shear in the MDR.
What Evan (2012) found was that the total number of hurricanes in the three years before each eruption and three years after the eruption were markedly different – ~12 per season prior to the eruption and 6-8 per season after the eruption. Not only that, but the storms in the three years after the eruption were weaker and didn’t last as long as prior to the eruption. Even beyond this, the location that hurricanes formed changed as well, where before the eruptions most hurricanes were found in the MDR, after the eruptions there were dominantly found along the eastern United States. So, the long and short becomes large volcanic eruption leads to lower sea surface temperatures and higher vertical wind shear in the locations where hurricanes form, thus fewer hurricanes occur and those that do are weaker.
Now, bear in mind, this study only looked at two major eruptions in the last 35 years – and unfortunately both coincided with an El Niño, so one can’t conclusively link the eruptions and the change in hurricane activity. Evan (2012) mentions that there are at least three other major eruptions that could effect hurricane activity – Agung in 1963**, Santa Maria in 1902 and Krakatau in 1883. However, no pattern emerges from these eruptions as hurricane activity did decrease after Krakatau, it wasn’t effected by Santa Maria and appeared to increase after Agung. Evan (2012) suggests that the Agung eruption might have cooled the South Atlantic preferentially, causing the increase in North Atlantic hurricane activity.
Hurricane Irene off of Cuba and Florida, seen on August 24, 2011. Can volcanic eruptions help or hinder hurricane activity? It is still unclear.
Clearly, there is still a lot of noise in these correlations of hurricane activity and volcanic eruptions. The eruptions that Evan (2012) examined are the big ones – so, what if any effect would smaller eruptions in the tropics have (such as Merapi in 2010 or Nabro in 2011). Taking a look at the hurricane counts for the past century, you can see a number of periods of lower hurricane activity – can these all be correlated with eruptions like Katmai in 1912 (well out of the tropics) and what is causing the low hurricane counts in 2005-08? There are many unanswered questions here – but clearly, a closer examination looks to be in order – or, as the author of the paper suggests, maybe we need a large eruption in the tropics to test this theory out.
* Lockwood and Hazlett (2010) note that a typhoon/hurricane might have helped cause the cataclysmic eruption of Pinatubo in 1991. The lowest atmosphere pressure from the Typhoon Yunya passed over Pinatubo just 3 hours before the largest eruption. It likely didn’t cause the eruption (that was an injection of magma into the system over the prior few weeks), but it could have played a role in pushing the volcano pass the “tipping point” for an eruption.
** This eruption is listed in the paper as 1964, but the activity lasted from February 1963 to January 1964.
{Hat tip to Alex Witze for pointing out this article to me.}
Image 1: Pinatubo erupting in 1991. Image by Richard Hoblitt/USGS
Image 2: Figure 2B from Evan (2012), Journal of Geophysical Research
Image 3: Hurricane Irene in 2011. Image from the NASA Earth Observatory.
Hurricane Maria heads toward Newfoundland today, but there are no storms behind it….for now.
CREDIT: NOAA/NASA GOES-13 satellite.
Mid-August marked an uptick in the number of tropical storms and hurricanes forming in the Atlantic Ocean, with one storm always seeming to follow on the heels of another. But lately, the tropics have quieted down.
Hurricane Maria, the third hurricane of the 2011 season, is expected to hit Newfoundland, Canada, today (Sept. 16), but there are no other tropical cyclones (hurricanes and tropical storms) after this one the radar. But don’t think for a second that hurricane season is headed for an early exit, experts say.
“In no way, shape or form is this season over,” said Dennis Feltgen of the National Hurricane Center in Miami.
If, for some odd reason, no other tropical storms were to form this year, it would be the earliest end ever for an Atlantic hurricane season. The earliest date in the satellite era of the last active tropical cyclone in a given year was Sept. 21, 1993. Hurricane season officially ends Nov.1.
Feltgen and others say we’re not likely to set a new record this year.
“I would be incredibly surprised if Maria was the last tropical cyclone in the Atlantic,” said Phil Klotzbach, an atmospheric scientist at Colorado State University in Fort Collins. “While it looks like we’re going into a somewhat quieter period for a little bit, it’s not that unusual to have a quiet period during an active season,” Klotzbach said.
This season was predicted to be a doozy, with 14 to 19 named storms (which include tropical storms and hurricanes), seven to 10 hurricanes and three to five major hurricanes (Category 3 or higher). So far there have been 14 named storms (Nate formed shortly after Maria, but dissipated after striking Mexico shortly after it developed), three hurricanes and two major hurricanes (Irene and Katia).
The tropics seem to have quieted down as storms shift their birthplace to the west in the Atlantic basin. At the beginning of the season, tropical cyclones form near Cape Verde, off the coast of Western Africa. Toward the end of the season, they begin closer to the West Caribbean. This puts the southeastern United Sates in the crosshairs. October is typically an active month for that region.
Most of the global models suggest that another storm should develop in about nine days, Klotzbach said. And with the warm Atlantic waters and La Niña’s return — which has been linked to active hurricane seasons — more big storms could be on the way.
No change to Nate; Maria fizzles; Katia headed to Britain
Posted by: JeffMasters, 3:47 PM GMT on September 10, 2011
+15
Tropical Storm Nate in Mexico’s Bay of Campeche continues to have trouble intensifying. Latest visible satellite loops show that Nate has a large, cloud-filled center, and the storm is probably pulling in dry air to its north into its center. Nate is also likely having trouble with all the cool waters it has stirred to the surface. Assuming Nate is able to close off its center from the dry air, it would take the storm at least a day to tighten up its rather large center, form a solid eyewall, and reach hurricane intensity. Nate doesn’t have enough time before landfall for that to happen, and it is unlikely Nate will ever become a hurricane. The latest wind probability forecast form NHC gives Nate a 13% chance of reaching hurricane strength on Sunday. Latest radar imagery from Alvarado, Mexico shows heavy rains from Nate are affecting the coast near Veracruz, and heavy rains of 4 – 6 inches will be the main threat from Nate.
Figure 1. True-color MODIS image of Tropical Storm Nate taken at 12:45 pm EDT Friday, September 9, 2011. At the time, Nate was a tropical storm with 50 mph winds. Image credit: NASA.
Nate is a small storm, and is not likely to bring significant rains to Texas; only extreme South Texas near Brownsville could see an inch or so of rain on Sunday from an outer spiral band of Nate. Our latest wundermap wind forecast map from the European Center model, with the fire layer turned on, shows that Nate’s wind field on Saturday and Sunday will not be large enough to fan the fires burning in Texas.
Tropical Storm Maria Tropical Storm Maria doesn’t look much like a tropical storm–on the latest satellite imagery it looks like a squashed question mark instead of a spiral. The surface circulation center is very poorly defined, and moderate wind shear of 15 – 20 knots has really done the Lesser Antilles Islands a big favor by ripping up Maria. It is doubtful this storm will generate any sustained winds of tropical storm force in the islands, and it is a 50/50 proposition that Maria will degenerate into a tropical disturbance and become ex-Tropical Storm Maria later today. Martinique radar shows heavy rains from Maria are mostly east of the islands, and the thunderstorms are not well-organized into spiral bands. The wind shear affecting Maria will probably last through Sunday. By Monday, wind shear is predicted to fall enough so that Maria could potentially organize again. However, the storm is expected to be far from land when that occurs. Bermuda could see a few rain showers from Maria on Wednesday, and Maria may be a threat to southeast Newfoundland late next week.
Figure 2. Morning satellite image of Tropical Storm Maria shows the the storm looks like a squashed question mark?
Hurricane Katia Hurricane Katia brushed by Newfoundland, Canada this morning, and is now racing east-northeast at 52 mph into the open Atlantic. With water temperatures 19°C (66°F) underneath it, Katia has lost its tropical characteristics, and has transitioned to a powerful extratropical storm. Extratropical Storm Katia will continue east-northeastward towards Europe, and on Monday, the storm will pass very close to northern British Isles. The offshore waters of Northern Ireland and Western Scotland can expect storm-force winds of 50 – 60 mph on Monday as Katia roars past to the north. The storm will bring 2 – 4 inches of rain to the coast, and likely cause significant tree damage and power failures.
Figure 3. Image of Hurricane Katia taken from the International Space Station at 15 GMT September 9, 2011, by astronautRon Garan. At the time, Katia was a Category 1 hurricane with 85 mph winds. Long Island, New York is visible at the lower left.
Harvey drenching Belize; 97L a threat to the Caribbean and U.S.
Posted by: JeffMasters, 4:16 PM GMT on August 20, 2011
+21
Tropical Storm Harvey is closing in towards a landfall this afternoon in Belize, and is dumping very heavy rains on northern Honduras, northern Guatemala, and Belize as it steadily moves west near 12 mph. A personal weather station on Roatan Island on the north coast of Honduras has received 6.68″ of rain as of 10am EDT this morning from Harvey, and had a peak wind gust of 42 mph. The Roatan airport has received 3.55″, and had a peak wind gust of 40 mph. The first significant spiral band from Harvey moved over Belize City at 7am local time, dropping nearly an inch of rain on the city. Belize National Meteorological Service radar shows that Harvey has appeared to close off an eyewall as of 11:30am EDT, which may allow the storm to intensify another 10 – 15 mph before landfall. The 11am NHC wind probability forecast gave Harvey a 3% chance of making it to hurricane strength, but the discussion noted that it wouldn’t be that hard for Harvey to gain another 10 – 15 mph before landfall. I estimate there is a 30% chance that the winds along a 10-mile stretch of Belize coast where the eyewall makes landfall will reach hurricane force.
Figure 1. Radar image of Harvey taken at 11:30am EDT on Saturday, August 20, 2011, a few hours before landfall in Belize. A small closed eye is visible just south of the offshore islands of Belize. Image credit: Belize National Meteorological Service
Potentially Major Hurricane Hitting The United States
Posted: August 18, 2011 by Storm Central in Uncategorized
Good Morning Everyone. We could have a serious situation going on here come 8 days from now if this all pans out. Models have been very consistent on this wave that came off of Africa 2 days ago. We have been on current watch of this since this morning as i checked the models and i saw a very big center of circulation over the Bahamas come day 7. (My Outlook is posted below) Here is the information on this:
I pin-pointed it for you so it is easier to see the exact location. Please note: That is the location via lat and long at 3:00AM CDT and those estimates at long and lat are just estimates. Using Google earth, I estimated the location being about 1,400 Miles from Barbados Island. (Lat and Long are there on the graphic)
Below is the Current Observations on the projected cyclone:
