TD 2 nearly dead; African disturbance 90L gathering strength
Tropical Depression Two is near death, but is still worth watching. The dry, Saharan air to the north and west of the depression, combined with moderately high levels of wind shear of 15 - 20 knots, have almost completely destroyed all of TD 2's heavy thunderstorms. Satellite loops of the storm show a well-formed circulation, but almost no heavy thunderstorm activity.
Wind shear over TD 2 is expected to remain in the modereate range, 10 - 20 knots, over the next five days. Sea Surface Temperatures (SSTs) are 27°C, but will warm to 28°C three days from now. There is plenty of dry, stable air from the Saharan Air Layer (SAL) to to TD 2's north and west that will continue to cause the storm problems. The relatively cool SSTs and dry air mean that TD 2 will not be able to intensify quickly, and some of the models indicate the TD 2 may get destroyed in the next day or two. However, several models still predict TD 2 will become a tropical storm. The HWRF model predicts TD 2 will become a hurricane five days from now, but this seems unlikely given the dry air and relatively high wind shear affecting the storm.
Figure 1. Tropical Depression Two (left side of image) and tropical wave 90L (right side of image).
African tropical wave 90L
A strong tropical wave with a large circulation and plenty of heavy thunderstorm activity is a few hundred miles south of the Cape Verdes Islands, off the coast of Africa. NHC dubbed this disturbance 90L this morning. This morning's QuikSCAT pass shows that 90L has a very large circulation, and top winds of about 30 mph. Satellite imagery from the European METEOSAT satellite show that the heavy thunderstorms associated with 90L are in two major bands, to the north and to the south of the center. There is no heavy thunderstorm activity near the center yet, and this would have to happen before 90L can be named Tropical Depression Three. Water vapor imagery shows that since 90L is forming several hundred miles south of the dry air of the Saharan Air Layer (SAL), the storm should not be affected by dry air and dust as much as Tropical Depression Two has been. Wind shear is about 20 knots over 90L, and is forecast to remain in the moderate range, 10 - 20 knots, over the next five days. Sea Surface Temperatures are about 28°C, and will remain in the 27 - 28°C range the next five days, which are high enough above the 26°C threshold for tropical cyclone formation to allow some slow development to occur. The GFS and ECMWF models continue to predict the development of this wave, though they are now less aggressive about intensifying it than they were in earlier runs. The consensus among the reliable HWRF, GFDL, GFS, and ECMWF models is to bring 90L to point near or just north of the northernmost Lesser Antilles Islands 6 - 8 days from now. The storm could be at hurricane strength by then, as forecast by the SHIPS intensity model.
I'll have an update Friday morning.
Jeff Masters
Reader Comments
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I thought it was turtle activity to watch out for. :)
OrANGE
ABNT20 KNHC 131732
TWOAT
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
200 PM EDT THU AUG 13 2009
FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...
THE NATIONAL HURRICANE CENTER IS ISSUING ADVISORIES ON TROPICAL
DEPRESSION TWO...LOCATED ABOUT 885 MILES WEST OF THE SOUTHERNMOST
CAPE VERDE ISLANDS.
SHOWERS AND THUNDERSTORMS ASSOCIATED WITH THE BROAD LOW PRESSURE
AREA AND TROPICAL WAVE CENTERED ABOUT 250 MILES SOUTH OF THE CAPE
VERDE ISLANDS ARE SLOWLY BECOMING BETTER ORGANIZED. A TROPICAL
DEPRESSION COULD FORM FROM THIS SYSTEM DURING THE NEXT COUPLE OF
DAYS AS IT MOVES WESTWARD AT 10 TO 15 MPH. THERE IS A HIGH
CHANCE...GREATER THAN 50 PERCENT...OF THIS SYSTEM BECOMING A
TROPICAL CYCLONE DURING THE NEXT 48 HOURS.
SHOWER ACTIVITY EXTENDING FROM THE EASTERN CARIBBEAN SEA ACROSS
HISPANIOLA TO THE TURKS AND CAICOS ISLANDS ARE ASSOCIATED WITH A
WESTWARD-MOVING TROPICAL WAVE. THERE ARE NO SIGNS OF ORGANIZATION
AND UPPER-LEVEL WINDS ARE CURRENTLY UNFAVORABLE FOR SIGNIFICANT
DEVELOPMENT. THERE IS A LOW CHANCE...LESS THAN 30 PERCENT...OF
THIS SYSTEM BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.
ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.
$$
FORECASTER BEVEN
B
000
ABNT20 KNHC 131732
TWOAT
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
200 PM EDT THU AUG 13 2009
FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...
THE NATIONAL HURRICANE CENTER IS ISSUING ADVISORIES ON TROPICAL
DEPRESSION TWO...LOCATED ABOUT 885 MILES WEST OF THE SOUTHERNMOST
CAPE VERDE ISLANDS.
SHOWERS AND THUNDERSTORMS ASSOCIATED WITH THE BROAD LOW PRESSURE
AREA AND TROPICAL WAVE CENTERED ABOUT 250 MILES SOUTH OF THE CAPE
VERDE ISLANDS ARE SLOWLY BECOMING BETTER ORGANIZED. A TROPICAL
DEPRESSION COULD FORM FROM THIS SYSTEM DURING THE NEXT COUPLE OF
DAYS AS IT MOVES WESTWARD AT 10 TO 15 MPH. THERE IS A HIGH
CHANCE...GREATER THAN 50 PERCENT...OF THIS SYSTEM BECOMING A
TROPICAL CYCLONE DURING THE NEXT 48 HOURS.
SHOWER ACTIVITY EXTENDING FROM THE EASTERN CARIBBEAN SEA ACROSS
HISPANIOLA TO THE TURKS AND CAICOS ISLANDS ARE ASSOCIATED WITH A
WESTWARD-MOVING TROPICAL WAVE. THERE ARE NO SIGNS OF ORGANIZATION
AND UPPER-LEVEL WINDS ARE CURRENTLY UNFAVORABLE FOR SIGNIFICANT
DEVELOPMENT. THERE IS A LOW CHANCE...LESS THAN 30 PERCENT...OF
THIS SYSTEM BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.
ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.
Interesting - couple that with an mysterious explosion in the starfish populations in the waters of New England....
haha forgot about the turtles lmao.
000
ABNT20 KNHC 131732
TWOAT
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
200 PM EDT THU AUG 13 2009
FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...
THE NATIONAL HURRICANE CENTER IS ISSUING ADVISORIES ON TROPICAL
DEPRESSION TWO...LOCATED ABOUT 885 MILES WEST OF THE SOUTHERNMOST
CAPE VERDE ISLANDS.
SHOWERS AND THUNDERSTORMS ASSOCIATED WITH THE BROAD LOW PRESSURE
AREA AND TROPICAL WAVE CENTERED ABOUT 250 MILES SOUTH OF THE CAPE
VERDE ISLANDS ARE SLOWLY BECOMING BETTER ORGANIZED. A TROPICAL
DEPRESSION COULD FORM FROM THIS SYSTEM DURING THE NEXT COUPLE OF
DAYS AS IT MOVES WESTWARD AT 10 TO 15 MPH. THERE IS A HIGH
CHANCE...GREATER THAN 50 PERCENT...OF THIS SYSTEM BECOMING A
TROPICAL CYCLONE DURING THE NEXT 48 HOURS.
SHOWER ACTIVITY EXTENDING FROM THE EASTERN CARIBBEAN SEA ACROSS
HISPANIOLA TO THE TURKS AND CAICOS ISLANDS ARE ASSOCIATED WITH A
WESTWARD-MOVING TROPICAL WAVE. THERE ARE NO SIGNS OF ORGANIZATION
AND UPPER-LEVEL WINDS ARE CURRENTLY UNFAVORABLE FOR SIGNIFICANT
DEVELOPMENT. THERE IS A LOW CHANCE...LESS THAN 30 PERCENT...OF
THIS SYSTEM BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.
ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.
$$
FORECASTER BEVEN
Mine crashes easily too. I just have to use my laptop mostly now.
Futuremet-
Just a comment. You posted an Abolute Vorticity Chart, not a Relative Vorticity Chart. Obviously it still shows 90Ls vorticity well so from that standpoint it's ok.
However, Absolute vorticity includes the effect of latitude on vorticity (which is why the northern part of your chart is more red than near the Equator. Also, south of the equator the Absolute contribution due to latitude is opposite in sign.
ABNT20 KNHC 131732
TWOAT
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
200 PM EDT THU AUG 13 2009
FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...
THE NATIONAL HURRICANE CENTER IS ISSUING ADVISORIES ON TROPICAL
DEPRESSION TWO...LOCATED ABOUT 885 MILES WEST OF THE SOUTHERNMOST
CAPE VERDE ISLANDS.
SHOWERS AND THUNDERSTORMS ASSOCIATED WITH THE BROAD LOW PRESSURE
AREA AND TROPICAL WAVE CENTERED ABOUT 250 MILES SOUTH OF THE CAPE
VERDE ISLANDS ARE SLOWLY BECOMING BETTER ORGANIZED. A TROPICAL
DEPRESSION COULD FORM FROM THIS SYSTEM DURING THE NEXT COUPLE OF
DAYS AS IT MOVES WESTWARD AT 10 TO 15 MPH. THERE IS A HIGH
CHANCE...GREATER THAN 50 PERCENT...OF THIS SYSTEM BECOMING A
TROPICAL CYCLONE DURING THE NEXT 48 HOURS.
SHOWER ACTIVITY EXTENDING FROM THE EASTERN CARIBBEAN SEA ACROSS
HISPANIOLA TO THE TURKS AND CAICOS ISLANDS ARE ASSOCIATED WITH A
WESTWARD-MOVING TROPICAL WAVE. THERE ARE NO SIGNS OF ORGANIZATION
AND UPPER-LEVEL WINDS ARE CURRENTLY UNFAVORABLE FOR SIGNIFICANT
DEVELOPMENT. THERE IS A LOW CHANCE...LESS THAN 30 PERCENT...OF
THIS SYSTEM BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.
ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.
$$
FORECASTER BEVEN
Didn't read the article, but just took a waverunner out in Destin a couple of weeks ago and saw no less than 30 jellyfish around me at all times. Thank God, I didn't roll it messing around!
I know we always joke about the weird animal\insect behavior because some people tend to get overexcited about it on the blog, but there does seem to be at least some sort of coincidence...sometimes.
Hmmpft, I said orange. oh well...
Whoa..thats heading straight for me! (Wilm, NC)
model ERROR Trend 24hr Error. 48hr 72hr Error Day 4 Error Day 5 Error
OFCL INCREASING 29.7 77.6 -1 -1 -1
KHRM INCREASING 68.9 161.8 -1 -1 -1
HWRF DECREASING 86.8 134.4 213.7 -1 -1
GFDL INCREASING 89.3 183.4 271 321.6 -1
BAMD CONSTANT 99.5 214.7 386.2 431 -1
LBAR DECREASING 104.1 273.3 603.1 794.7 -1
MM5E INCREASING 110.6 157.8 -1 -1 -1
MM5B INCREASING 121.4 201.2 257.8 -1 -1
BAMD CONSTANT 99.5 214.7 386.2 431 -1
CLP5 DECREASING 77.8 186.4 355.5 407.7 -1
CMC DECREASING 131.4 106.1 52 -1 -1
LGEM CONSTANT 93.4 215 354.8 420.3 -1
NGPS DECREASING 77.1 236 258.6 -1 -1
XTRP DECREASING 70.5 141 308.7 276.4 -1
I agree with you but,
In looking at the models, would you agree that all of them show a substantial cyclone heading west in the C-Atlantic in 3 days?
I was merely saying that is the only thing the models are consistent on right now thus the only thing you can give a semi-accurate forecast on.
GFDL
With the tropics heating up I say 3906.. lol
funny about alcohol level, does the loser have to buy a round? ;)
lol!!!
HWRF likes to exagerate storm intensity in the moderate to long range with storms that are on the verge of developing.
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