TD 2 struggling; new African wave bears watching
Tropical Depression Two is struggling. The depression still has a good chance of becoming the Atlantic hurricane season's first named storm this week, but the dry, Saharan air that surrounds the storm, combined with moderately high levels of wind shear, are interfering with the storm's organization. Satellite loops of the storm show that heavy thunderstorm activity is limited to the west side of the depression. This is due to strong winds out of the southeast that are creating a moderate 15 - 20 knots of wind shear. The intensity and coverage of these thunderstorms is meager, thanks to the large amount of dry air to TD 2's north that is getting wrapped into the circulation. This morning's QuikSCAT pass showed a well-formed surface circulation, with top winds of about 30 - 35 mph.
Wind shear over TD 2 is expected to remain in the moderate range, 10 - 20 knots, over the next five days. Sea Surface Temperatures (SSTs) are a marginal 26 - 27°C, and will not change much over the next three days. There is plenty of dry, stable air from the Saharan Air Layer (SAL) to to TD 2's north 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. However, it does appear likely that TD 2 has enough going for it that it will eventually be able to become Tropical Storm Ana sometime in the next three days. Most of the computer models show some weak development, but none of them predict TD 2 will become a hurricane. It is unusual for storms forming this far north to make it all the way across the Atlantic to hit the Lesser Antilles Islands. For now, TD 2 doesn't concern me as much as the new tropical wave to its southeast, just off the coast of Africa.
Figure 1. Tropical Depression Two (left center of image) and a new tropical wave (right side of image), newly emerged from the coast of Africa.
Elsewhere in the Atlantic
A strong tropical wave with some rotation and plenty of heavy thunderstorm activity left the coast of Africa yesterday, and is located a few hundred miles south of the Cape Verdes Islands. The GFS and ECMWF models continue to predict the development of this wave late this week. Both of these models indicate that the wave would track further south than Tropical Depression Two, and could impact the Lesser Antilles Islands in about seven days. This storm bears close attention over the coming days.
Two other tropical waves, one that just passed through the Lesser Antilles Islands, and one about 300 miles east of the islands, are mentioned in NHC's Graphical Tropical Weather Outlook. Both of these waves have very limited heavy thunderstorm activity that is not increasing, and are not a threat to develop over the next two days. None of the computer models develop either of these waves.
Felicia moves through Hawaiian Islands as a tropical depression
Tropical Storm Felicia weakened to a tropical depression before passing through the Hawaiian Islands yesterday. The storm brought scattered heavy rains of 1 - 2 inches to the islands, and no damage was reported. Felicia is only the 10th tropical cyclone of tropical depression strength or higher to hit the islands since 1950. Four other tropical cyclones have passed within 75 miles of the islands during that time period.
Be careful clicking on external links in blog comments
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I'll have an update Thursday morning.
Jeff Masters
Reader Comments
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He said it has potential to reach the US becuz of its low lat.
well for you i guess the run that brings in practically into alabama is the mos plausible run yet. How about you give us some good facts about why this run is the most plausible according to you
http://www.willitrain.com/lightning.html
Quikscat partial download
since this morning....
Oh, please, not that again. Didn't you learn from last year? I guess the GOM is doomed.
start? well Dmax is an instant technically, the instant before sun rise. The effects start around 1-2 am for that area.
Tks Kman , just realized that was 8:25 this morning I think, maybe they should have named it then. What's your take on apparent wsw movement of TD2?
no it is not
ABNT20 KNHC 122330
TWOAT
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
800 PM EDT WED AUG 12 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 710 MILES WEST OF THE SOUTHERNMOST
CAPE VERDE ISLANDS.
A VIGOROUS TROPICAL WAVE IS EXPECTED TO PASS WELL TO THE SOUTH OF
THE CAPE VERDE ISLANDS WHILE MOVING WESTWARD AT 10 TO 15 MPH ON
THURSDAY. ALTHOUGH THE SHOWER ACTIVITY IS LIMITED AT THIS
TIME...CONDITIONS APPEAR TO BE FAVORABLE FOR SLOW DEVELOPMENT
DURING THE NEXT FEW DAYS. THERE IS A MEDIUM CHANCE...30 TO 50
PERCENT...OF THIS SYSTEM BECOMING A TROPICAL CYCLONE DURING THE
NEXT 48 HOURS.
A TROPICAL WAVE OVER THE EASTERN CARIBBEAN SEA AND THE ADJACENT
ATLANTIC...ACCOMPANIED BY CLOUDINESS AND SHOWERS...IS MOVING
WESTWARD AT 10 TO 15 MPH. UPPER-LEVEL WINDS ARE NOT FAVORABLE 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 AVILA
Here is the steering for a weak system like TD 2. You will see that it is WSW all the way to 50W. If this holds and TD2 is still around it would have a chance to enter the Caribbean as the flow does not change to WNW until near 60W.
I still think it will not enter the Caribbean, at least not as a TS but the prolonged weak state may prove me wrong.
the more WSW it goes the more chance it has to be a caribbean storm
Kman i agree 100%. Have been saying the same thing.....look at post 1732 i showed the BH and how strong it still was...
1773.
I think its safe to say that the CMC is on crack for that one.
Nope, it's not...
Starts at around 11:30 PM and ends at about 5:30 AM, with it being strongest at 5:30 AM.
The WSW flow has actually expanded further W since this morning and if it was a stronger system the steering further up in the atmosphere is even more to the W.
TD2 may become an open wave before we know the answer to this one
dry air is giving the little bug fits.All but dried up.could come back with d-max.
What I said was I did not see it entering the Caribbean. I still think that but hey, if I am worng what does it matter ?
I definitely agree with you there. Look at how quickly the TCHP ramps up around 50W.
What timezone is that in?
local time for the storm.
Viewing: 1751 - 1801
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