Hurricane Update 8/18

The Atlantic Basin Is “About To Come Alive”  

Michael Ventrice, an atmospheric scientist at The Weather Company, tweeted Monday morning, “there’s risk for a hurricane to track towards the Gulf of Mexico in 7-10 days.” 

Readers may recall the 2020 Atlantic hurricane season has been extremely busy, with eleven storms so far, and the risk of two more storms developing later this week.

At the start of the hurricane season, we said: “…this hurricane season could be above average, with 13 to 19 named storms.”

The National Hurricane Center (NHC) published a new five-day tropical weather outlook showing two disturbances developing in the eastern Atlantic.

“NHC is monitoring two disturbances for possible development within the next several days.  A system in the eastern Atlantic has a high chance of development and a system near the Windward Islands has a medium chance of formation,” NHC said.

The next 7-10 days could be a period of heightened activity in the Atlantic and or the Gulf of Mexico. NHC said Disturbance #1 has a 50% chance of developing, and Disturbance #2 has a 70% chance of developing by the end of the week.

Meteorologist James Spann tweeted Monday, “the Atlantic basin is about to come alive.” 


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.

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.


Gulf Woes Persist – BP Denies

Shirking Responsibility in the Gulf

Published: July 30, 2013

BILOXI, Miss. — IF you don’t live near the Gulf Coast, you may have the impression that the area has fully recovered from the BP Deepwater Horizon oil spill in 2010, the largest environmental disaster in American history. Sadly, that’s not the case for tens of thousands of gulf residents still trying to put their lives back together.

That is, however, what BP wants the public to believe — which is why it is now engaged in an aggressive legal and public-relations campaign to limit how much it pays individuals and businesses for the losses its reckless behavior caused. After having a hand in this huge disaster, the company wants to leave these communities to rebuild on their own, even as it takes in record profits.

The spill resulted in the release of more than 200 million gallons of oil into the Gulf of Mexico and the deaths of 11 people. In September 2011 a federal investigation found BP responsible for the leak, and in November 2012 the Department of Justice reached a court settlement with the company that included a $4.5 billion fine.

In 2010 the company set up a $20 billion fund to settle claims arising from the disaster, and since then it has made payments to hundreds of thousands of individuals and businesses affected by the spill. In 2012 a federal court took over supervision of the fund.

But tens of thousands of gulf residents still haven’t been fully compensated for their losses, and many are struggling to make ends meet. Many low-wage workers in the fishing and service industries, for example, have been seeking compensation for lost wages and jobs for three years. In many cases, their claims aren’t successful because they can’t afford the legal help required to navigate the complex claims process.

Their troubles stem in part from BP’s increasingly brazen attempts to stonewall payouts. Most recently, the company made a motion in court to freeze payments on tens of thousands of legitimate claims, arguing that a staff attorney from the Deepwater Horizon Court-Supervised Settlement Program, the program responsible for evaluating compensation claims, had improperly profited from claims filed by a New Orleans law firm. The attorney is said to have received portions of settlement claims for clients he referred to the firm.

But the alleged bad behavior of one attorney does not justify freezing the payment of all claims, as BP has demanded, especially when the firm handled a small fraction of the claims that have been submitted for compensation. In any case, the attorney has resigned, and Carl J. Barbier, the federal judge who is overseeing the settlement, ordered an investigation, which is continuing. So far the judge has refused to freeze payments while the investigation is under way, a ruling that the company is appealing.

Of course, this isn’t really about the possible extent of the damage done by the attorney. BP is using the case to cast doubt, both in public and in the courts, on the entire process. And it’s working: its talking points have been echoed in mainstream media coverage, which has so far featured few voices of actual oil-spill victims.

Such guilt by association ignores the robust measures built into the settlement program to ensure a fair compensation system. The fraud-detection mechanisms are so extensive that the processing of claims is slowed down to accommodate them.

Meanwhile, the company has fought aggressively to undermine individual claims. In some instances, BP has tried to deny payment of claims that its own settlement program had already deemed legitimate.

The company’s efforts know no bounds and have pushed the claimants and their legal representatives to the limit. My organization, the Mississippi Center for Justice, is one of several groups providing pro bono legal assistance. Since 2011, we have helped approximately 10,000 people navigate the difficult claims process and obtain money they are owed by BP.

We have seen firsthand the extent to which BP will go to avoid paying even patently legitimate claims. One claimant with whom we worked, whose employer closed its doors in the wake of the spill, finally received an offer for compensation after two years. Then BP appealed the award, seeking to have it revoked. After he received assistance in countering BP’s appeal, the company finally admitted that he was, in fact, owed money and withdrew its appeal of his claim.

But while we can carry on the battle through lawsuits and in the affected communities, we are outgunned in the court of public opinion. In countless high-priced TV spots and full-page newspaper ads, the company is selling the story that it is committed to helping victims of the oil spill and rebuilding the gulf.

We know different. The company has turned its back on the people whose lives it derailed. BP must end its stall tactics and keep its promises to the people of the gulf.

Stephen Teague is a staff attorney at the Mississippi Center for Justice.


Tropical Storm Andrea Forms in Gulf

The Atlantic has its first named storm of the 2013 hurricane season: Tropical Storm Andrea. An Air Force hurricane hunter plane was able to locate a closed center of circulation, and found surface winds of 40 mph in the large area of thunderstorms on the east side of the center. Satellite loops show that Andrea is a lopsided storm. It’s center of circulation is exposed to view, due to a large region of dry air that covers the entire Central and Western Gulf of Mexico. This dry air is from a trough of low pressure whose upper level winds are also creating moderate wind shear of 15 – 20 knots over Andrea. Wind shear is forecast to rise to the high range, 20 – 40 knots, by Thursday. Andrea is forecast to make landfall along the northern Gulf Coast of Florida by Thursday evening, so the system has a short window of time to intensify. Given the large amount of dry air to Andrea’s west, and the forecast for increasing shear up until landfall, I expect that the strongest sustained winds Andrea could have before landfall are 50 mph. Heavy rains will be the storm’s main threat, though a few isolated EF-0 tornadoes will also be possible in some of the heavier thunderstorms in Andrea’s spiral bands. A storm surge of 2 – 4 feet is predicted for Tampa Bay northward to Apalachicola, and rip currents will be a risk for swimmers who brave the high surf. Fort Pickens, located in Gulf Islands National Seashore on a barrier island offshore from Pensacola, Florida, has been closed to visitors due to the approaching storm. A single 2-lane road vulnerable to storm surges runs to Fort Pickens. Officials want to prevent a repeat of the situation that occurred in September 2011, when Tropical Storm Lee pushed a storm surge over the road that blocked it with sand and debris, trapping numerous campers and visitors in Fort Pickens. As of 7 pm EDT, our wundermap with the storm surge layer turned on was showing storm surge levels were less than 1 foot along the Florida coast.

Figure 1. MODIS image of Tropical Storm Andrea in its formative stages, taken at 12:20 pm EDT Wednesday, June 5, 2013, five hours before it was named. Image credit: NASA.

Andrea’s place in history
Andrea formed in a typical location for early-season storms. The Gulf of Mexico, Western Caribbean, and Bahamas are the usual areas for the genesis of June tropical storms. Andrea’s formation date of June 5 is over a month earlier than the average July 9 date for formation of the season’s first named storm. On average, the Atlantic sees one June named storm every two years. In 2012, we’d already had two named storms by this point in the season–Alberto and Beryl. This year is the second time a storm named Andrea has appeared in the Atlantic. The previous incarnation, Subtropical Storm Andrea of 2007, wandered off the U.S. East Coast in May, and never made landfall. The 2013 version of Andrea is highly unlikely to get its name retired, and we’ll be seeing a third coming of the storm in 2019.


Latest on TS/Hurricane Isaac

Isaac approaching hurricane strength
Posted by: Angela Fritz, 9:14 PM GMT on August 27, 2012 +26

Isaac is walking the line of hurricane status this afternoon after a hurricane hunter mission investigated the storm and found winds of 80+ mph with the SFMR instrument, which looks down at the surface from the plane and estimates what wind speeds are. This instrument has a notoriously rough time in doing so when there’s heavy rain, and since the strongest winds were recorded coinciding with the strongest rain, you can imagine that this region of high wind speed could be suspect. The hurricane hunter mission is still in the storm, so I imagine they will issue a special update if needed. Currently the best estimate of wind speed within the storm is 70 mph. Isaac’s pressure has been dropping today as well and is now 981 mb. Isaac is moving northwest at 12 mph–no change since this morning. Satellite loops show that Isaac remains large, though asymmetric, with most of the strong thunderstorm activity on the west and southwest side. Isaac’s southeast side continues to struggle with dry air and wind shear, which could help to moderate Isaac’s intensity as it approaches the coast.

An oil platform in the northern Gulf of Mexico is reporting sustained winds from the north-northeast at 40 mph this afternoon. A buoy west of Tampa, Florida is recording sustained winds around 30 mph, and platforms south of Louisiana are recording winds from 35-40 mph. The widespread heavy rain of yesterday has lightened up in Florida, but a strong line of thunderstorms in one of Isaac’s outer bands is training northward along and offshore of the east coast of Florida, affecting everyone from Miami to Jacksonville.

This afternoon the AP reported that Isaac’s death toll in Haiti jumped to 19, which puts Isaac’s total death count at 21. It appears most of the deaths in Haiti were due to collapsing structures.

Figure 1. Satellite imagery of Tropical Storm Isaac around 3pm EDT on Monday.

Track forecast:
Models seem to be coming into better agreement today on where Isaac will make landfall, closing in on Louisiana and New Orleans as most likely landfall point. The ECMWF, HWRF, and UKMET all suggest New Orleans as the landfall location. The GFS is only slightly west of that. The GFDL is the farthest west, predicting landfall near the Louisiana-Texas border. Landfall timing remains Tuesday night. Beyond landfall, Isaac is expected to move north toward the Midwest through the rest of this week, however, models are showing that the system will likely slow down around landfall time, prolonging impacts like surge and inland flooding.

Intensity forecast:
The closer Isaac gets to landfall without having formed an eye, the better it is for intensity at landfall. Isaac has strengthened only modestly in the past 24 hours, and is still struggling with a less-than-conducive atmospheric environment. The HWRF remains on the high end of the intensity spectrum, suggesting Isaac will be a weak category 2 upon landfall. Other models suggest it will be a strong category 1, but the difference is splitting hairs. The National Hurricane Center’s official forecast is for Isaac to continue strengthening over the next day, reaching category 2 at landfall.

Figure 2. Tide gauge data from St. Petersburg, Florida. The green line shows the storm surge. As Isaac’s counterclockwise winds blew offshore this morning, water levels feel two feet at St. Petersburg. The winds switched to onshore this afternoon as the center of Isaac moved more to the northwest, bringing a storm surge of two feet to the city.

Storm surge observations from Isaac
This morning, as Isaac’s counter-clockwise winds brought offshore winds to the Tampa/St. Petersburg area, ocean waters fell two feet along the coast. This afternoon, winds have shifted to blow onshore, and a two foot storm surge has been observed at Naples, Fort Meyers, and St. Petersburg on the west coast of Florida. Water levels have also begun to rise along the coast of Louisiana, with a storm surge of 1.5 feet already occurring at Shell Beach on the east side of New Orleans in Lake Borgne.


Well, Hello, TS Debby

Dr. Jeff Masters’ WunderBlog

Tropical Storm Debby has formed in the Gulf of Mexico
Posted by: Angela Fritz, 9:18 PM GMT on June 23, 2012 +22
Tropical Storm Debby has been named by the National Hurricane Center this afternoon after hurricane hunters investigated Invest 96L and found a solid closed circulation, with maximum winds of 50mph and gusts up to 65mph. All interests along the Gulf of Mexico coast should pay attention to the progress of Debby. Debby is drifting north at 5mph. The storm has brought heavy rains to Western Cuba, South Florida, and Mexico’s Yucatan Peninsula over the past two days, but the disturbance’s heaviest rains are located well offshore over the Eastern Gulf of Mexico, where heavy thunderstorms are generating winds near tropical storm-force. A buoy 243 miles east of Naples, FL measured sustained winds of 31 mph, gusting to 38 mph, with 10-foot waves, at 8 am EDT Saturday morning. Our Wundermap for the surrounding ocean areas shows a large region of the northern and eastern Gulf of Mexico is experiencing winds of 20 – 30 mph.

Visible satellite loops show an unorganized tropical cyclone with an obvious surface circulation, though the thunderstorm activity is well displaced to the east. The heavy thunderstorm activity is slowly expanding and growing more intense. Upper-level winds out of the west continue to create moderate 10 – 20 knots of wind shear over the region, though that is expected to increase over the next few days. Water vapor satellite loops show a region of dry air over the central Gulf of Mexico, which will continue to interfere with Debby’s development and make it hard for the west side of the circulation to maintain heavy thunderstorms. Ocean temperatures are about 28.5°C (83°F) in the Central Gulf of Mexico, which is about 1°F above average.

Figure 1. Saturday afternoon satellite image of Tropical Storm Debby in the Gulf of Mexico.

Figure 2. Saturday afternoon forecast track for Tropical Storm Debby.

Forecast for Debby
The National Hurricane Center is forecasting Debby to remain a tropical cyclone over the next 5 days as it drifts north and then west toward Texas. The Hurricane Center is forecast a very slow progression of the storm, with a potential landfall not occurring until Friday of next week. However, most of the models that predict the turn to the west suggest landfall will happen before or around Wednesday. The models are still generally split on the forecast for Debby; by Monday, the majority of the reliable models, including the ECMWF, NOGAPS, HWRF, and UKMET, agree that a ridge of high pressure will build in over the Southern U.S., forcing Debby west across the Gulf of Mexico and into South Texas by Wednesday. However, the GFS model, which has been our 2nd most reliable track model over the past two years (behind the ECMWF), 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 Monday. The GFDL model splits the difference between these extremes and takes Debby north to a landfall near the Alabama/Florida border on Tuesday. The predicted track west to Texas is still the most likely outcome, though it remains a low-confidence forecast. In terms of intensity, none of the models is predicting Debby will become a hurricane, nor is the Hurricane Center. Though sea surface temperature is warm (and around 1°F above average), the actual heat content of the Gulf is relatively low, and while wind shear is predicted to remain moderately strong through Sunday, but will increase to 30+ knots by Tuesday.

Debby’s place in history (by Jeff Masters)
Remarkably, Debby’s formation on June 23 comes a full two months ahead of the usual formation date of the season’s fourth storm in the Atlantic, August 23. Debby’s formation beats by twelve days the previous record for formation of the fourth named storm of the year in the Atlantic, set in 2005, when Hurricane Dennis was named on July 5. An early start to the Atlantic hurricane season has been increasingly common in recent years. In 2008, I blogged about the research of Dr. Jim Kossin of the University of Wisconsin, who published a 2008 paper in Geophysical Research Letters, titled “Is the North Atlantic hurricane season getting longer?” He concluded that yes, there is a “apparent tendency toward more common early- and late-season storms that correlates with warming Sea Surface Temperature but the uncertainty in these relationships is high”. Three out of four of this year’s early quartet of storms–Alberto, Beryl, and Debby–formed in ocean areas that were more than 1°F above average, which is an unusually high amount of warmth. We should expect to see more early-season Atlantic tropical storms as a consequence of global warming, since cool ocean temperatures are a key impediment to formation of such storms. However, this assumes that factors such as wind shear and atmospheric stability won’t grow more hostile for tropical cyclone formation during the early part of hurricane season, and this is uncertain. If we do end up seeing a substantial increase in early-season tropical storms as a consequence of global warming, this is not necessarily a bad thing. Early-season tropical storms are often more boon than bane, bringing much-needed drought-busting rains, like Tropical Storm Beryl did for North Florida last month. There is typically a lot of wind shear around in May, June, and July, making it difficult for early season storms to reach major hurricane status. According to Wunderground’s list of major early-season hurricanes, since record keeping began in 1851, there has been only one major hurricane in May, two in June, and nine in July. Three of these occurred in the past ten years, so there has not as yet been a large increase in early-season major hurricanes due to global warming.

Kossin, J., 2008, “Is the North Atlantic hurricane season getting longer?”, Geophysical Research Letters, Vol. 35, L23705, doi:10.1029/2008GL036012, 2008.

Angela and Jeff


Hurricane Potential in The Gulf

Gulf of Mexico disturbance 96L poorly organized, but may develop
Posted by: Dr. Jeff Masters, on June 22, 2012 +27
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.

Jeff Masters


Tropical Storm Nate

Tropical Storm Nate is going to be one to watch over the next several days

Published on September 8, 2011 5:10 am PT
– By Richard McMillan – Writer
– Article Editor and Approved – Warren Miller

( — Tropical Storm Nate is located in the Southern Gulf of Mexico and could actually veer off the official track.

The National Hurricane Center has placed a track on Tropical Storm Nate. Tropical Storm Nate’s track moves north and then west right into Mexico, where it dies. Senior Meteorologist Kevin Martin is open to a second scenario.

“While NHC’s track is valid, there is also another alternative. This alternative brings it towards the Northern Gulf of Mexico where Tropical Storm Lee affected. This is a plausible option and it will need to be watched because a trough to the north is present which may lead Nate northward, not westward where NOAA has him.”

All NOAA models point to the westward track that NHC has so the Gulf of Mexico northward track will be a shot in the dark from Martin.

It could go either way. Nate is just developing and forecasters have a long time to pinpoint a track for it. All residents on the Gulf Coast need to stay tuned for further updates and tracking map information from TWS.


Tropical Storm Update

TD 14 likely to become Maria; new Gulf of Mexico system brewing

Tropical Depression Fourteen formed yesterday from a strong tropical wave that moved off the coast of Africa early this week, and is headed west-northwest towards an encounter with the Northern Lesser Antilles Islands. Satellite loops show a large a steadily organizing system with plenty of heavy thunderstorm activity, good upper-level outflow to the north and west, and some respectable low-level spiral bands beginning to form. TD 14 is probably a tropical storm now, and is very likely to be named Tropical Storm Maria later today. Water vapor satellite images show that 95L is embedded in a very moist environment. Ocean temperatures are near 28.5°C, which is 2°C above the 26.5°C threshold usually needed to sustain a tropical storm. With wind shear predicted to remain low to moderate the next five days, the atmosphere expected to stay moist, and ocean temperatures predicted to gradually warm, TD 14 should generally show a strengthening trend. Curiously, most of the intensity forecast models show little strengthening of TD 14, so NHC is keeping their intensity forecast lower than is typical for a storm in these conditions at this time of year.
The track forecasts for TD 14 from the various models agree that the storm will affect the Northern Lesser Antilles Islands, though there are some differences in forward speed, resulting in some uncertainty whether the storm will arrive at the islands as early as Friday night, or as late as Saturday afternoon. After it passes the Lesser Antilles, TD 14 has the usual amount of high uncertainty in its 5 – 7 day track forecast. The models are split on how strong the steering influence a trough of low pressure along the U.S. East Coast will have. The ECMWF and UKMET models prefer a more southerly track for TD 14 through the Bahamas towards the U.S. East Coast, while the GFS, NOGAPS, and HWRF models predict a more northwesterly track, with a potential threat to Bermuda. It’s too early to guess which track the models will eventually converge on. Climatology favors a track that would miss land, with Dr. Bob Hart’s track history pages suggesting TD 14 has a 22% chance of hitting Canada, 19% chance of hitting Bermuda, and an 11% chance of hitting North Carolina.

Figure 1. Morning satellite image of TD 14.

Gulf of Mexico disturbance 96L
A cold front swept into the Gulf of Mexico off the coast of Texas behind Tropical Storm Lee on Monday, and has stalled out along a line from Tampa, Florida to Mexico’s Bay of Campeche in the southern Gulf of Mexico. Heavy thunderstorms have begun to build along the tail end of this front in the Bay of Campeche, and this disturbance has been designated Invest 96Lby NHC. Latest visible satellite loops do not show that 96L has a closed surface circulation yet, but buoy and surface observations along the coast of Mexico suggest that there may be a large-scale counter-clockwise circulation present over the Bay of Campeche. Sustained winds at Buoy 42055, about 100 miles to the northwest of the suspected center of 96L, were northeast at 27 mph at 6:50 am CDT this morning. Water vapor satellite loops show that here is a large area of very dry air from Texas to the north of 96L, and this dry air may interfere with 96L’s development. A hurricane hunter mission is scheduled for this afternoon into 96L.

Most of the computer models develop 96L into a tropical depression in the next 1 – 2 days, and these same models did very well at anticipating the formation of Tropical Storm Lee in the Gulf of Mexico last week. Given the moderate wind shear, warm waters, and presence of an old cold front to serve as a nucleus for development, I give 96L an 80% chance of becoming a tropical depression over the next tow days, a bit higher than the 60% probability NHC is going with. Steering currents are weak in the Bay of Campeche, making for a lot of uncertainty in where 96L might go. The only model predicting a U.S. landfall is the ECMWF, which predicts 96L might hit between Louisiana and the Florida Panhandle on Monday. A more popular solution is for the storm to meander in the Bay of Campeche for many days, and eventually make landfall on the coast of Mexico between Veracruz and Tampico. None of the models is hinting at a track towards Texas, and the intense dome of high pressure associated with their record drought and heat wave will tend to discourage any tropical cyclones from making a Texas landfall over the coming seven days.

Hurricane Katia 
Hurricane Katia continues to the northwest as a Category 1 hurricane with 90 mph winds. Latest satellite loops show that dry air has eaten into the southwest side of the storm. The computer models continue to agree that a low pressure system over the Eastern U.S. associated with the remnants of Tropical Storm Lee will turn Katia to the north. As the storm moves northwards past North Carolina, Katia will get caught up in west-to-east moving winds associated with the jet stream, and taken northeastwards out to sea. No land areas are in Katia’s cone of uncertainty, and Katia’s outer rainbands should remain just offshore from North Carolina, New England, and the Canadian Maritime provinces at the point of closest approach. Bermuda may see a few rain showers from Katia, but the storm will not cause hazardous weather there. The main impact of Katia will be a multi-day period of high surf leading to beach erosion and dangerous rip currents. The East Coast is lucky that Tropical Storm Lee came along, since Lee helped to create the steering pattern that will keep Katia from hitting the U.S.

Figure 2. GOES-13 image of Hurricane Katia and the remains of Tropical Storm Lee, taken at 11:45 am EDT Tuesday September 6, 2011. At the time, Katia was a Category 3 hurricane with 120 mph winds. Image credit: NOAA Visualization Laboratory.