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

By: Dr. Jeff Masters , 13:32 GMT le 07 septembre 2011

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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 96L by 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.

Heavy rains from Lee create significant flooding, tornadoes
Tropical Storm Lee is no more, but its remnants are marching slowly northeastwards along a stalled cold front, bringing torrential rains. Fortunately, the dry soils that were present before the event started have helped keep river flooding in the minor to moderate range. No river is currently at major flood stage as a result of rains from Tropical Storm Lee. Soils are at near-average moisture levels in Central Pennsylvania, where Lee's remnants are expected to drop 3 - 5 inches of rain over the next two days. These rains should cause moderate but not major flooding in Pennsylvania. Also of concern is the potential for tornadoes today. NOAA's Storm Prediction Center (SPC) has logged 40 tornado reports over the past four days from Lee, including two in North Carolina yesterday. Most of these tornadoes have been weak EF-0 and EF-1 twisters. A tornado that hit Cana, Virginia at Sunday night ripped the roof off of a gas station and injured two people. More tornadoes are likely today over coastal Virginia, Maryland, Delaware, and Southern New Jersey, where SPC is predicting a "Slight Risk" of severe weather.

Lee's heaviest rain amounts, by state, as of 4 am CDT today:

Holden, LA: 15.43"
Waveland, MS: 14.11"
Fyffe, AL: 12.94"
Cleveland, TN: 12.22"
Rome, GA: 11.01"
Milton, FL: 10.03"
Blowing Rock, NC: 7.18"
Fancy Gap, VA: 6.77"
Cranks Creek Reservoir, KY: 5.49"
Andover, NJ: 5.06"
Montgomery, NY: 4.23"
Pittsfield, MA: 3.90"
Bluefield, WV: 3.76"
Bridge City, TX: 3.12"
Keene, NH: 3.64"
Hagerstown, MD: 3.60"
Norwalk, CT: 3.20"
Wilmington, DE: 2.63"
Woodford, VT: 2.63"
Washington, DC: 2.42"

Jeff Masters

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Hey guys quick tech question.

How do you view this blog on the iphone? Do you use the full site via safari? The mobile version doesnt have comments. Not sure if there is a better way.

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Quoting surfsidesindy:


Very interesting how it builds the high in so far West, but they are all hinting to that according to my untrained eye.
I feel like there's something we are not seeing with the current pattern but im just a noob at this :)
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17. 7544
according to some models looks like soon to be maria will get as close to so fl as irene did as of the latest runs as per the eruro but could she just make it a little further west? this one like all the others will be all about timing so still need to keep one eye on her
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Quoting Gearsts:
Wow whats with the crazy shift with the CMC, It has Maria doing a Hortense track :/


Very interesting how it builds the high in so far West, but they are all hinting to that according to my untrained eye.
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Thank you Dr Jeff for a new update.

Seems like we have a lot going on in the tropics.

Good morning my fellow weather geeks!

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Complete Update

TS BUSTED FORECAST ALIBI





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Thx Dr. M!  mornin' all.. going to be an intersting day in the Tropics no doubt... The effects of Lee over the entire EC is suprising.. so used to storms doing there business and moving on..
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Wow whats with the crazy shift with the CMC, It has Maria doing a Hortense track :/
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Quoting cat5hurricane:
Two recurve storms likely to miss the continental United States as the high builds in. Katia and TD14.

Thanks for the update.


just glancing at the model runs this morning it looks like they are all trying to build in that high once Katia gets past. It will be interesting to see what plays out.
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Member Since: 10 août 2002 Posts: 0 Comments: 1406
Dr. Masters says that our record drought and heat wave "will tend to discourage any tropical cyclones from making a Texas landfall over the coming seven days."
My response? "Hmph! Blame Texas! Don't you know we want to encourage at least a MILD tropical cyclone to come here?"
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Thanks for the update.
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Thanks Dr. Masters. Hope the future Maria follows a path similar to Katia.
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Member Since: 10 août 2002 Posts: 0 Comments: 1406
ATCF says TD14 is Maria already; I assume NHC will upgrade for the TWO.

Those rainfall totals are astounding. Now we have to see what happens if either Maria and/or could-eventually-be-Nate track that same way...
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Thanks! Another possible tease for Texas
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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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