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.
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I'll have an update Thursday morning.
Jeff Masters
Reader Comments
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"Dust sweeper" nails it on the head. This year's atlantic basin has been dry and relatively moisture less, so the last two week's increase of tropical activity, has precisely been the "dust sweeper" and is paving the wave for more conducive conditions for tropical development in the coming weeks and into September. All in all, the late start of this hurricane season in terms of tropical convective flare ups in the atlantic, caused by unseasonably high levels of saharan layer of dust, is what may have killed Tropical Depression 2's chances.
Not too bad right now:
Tropical Cyclone Advisory #4
TROPICAL CYCLONE GUILLERMO (EP102009)
9:00 AM UTC August 13 2009
====================================
At 6:00 AM UTC, Tropical Storm Guillermo (999 hPa) located at 16.9N 120.5W or 700 NM west-southwest of the southern tip of Baja California Peninsula has sustained winds of 45 knots with gusts of 55 knots. The cyclone is reported as moving west-northwest at 14 knots.
Gale-force Winds
================
75 NM from the center
Forecast and Intensity
======================
12 HRS: 17.2N 122.6W - 50 knots (Tropical Storm)
24 HRS: 17.6N 125.2W - 55 knots (Tropical Storm)
48 HRS: 18.4N 130.5W - 60 knots (Tropical Storm)
72 HRS: 19.1N 135.8W - 50 knots (Tropical Storm)
Why then, is the NHC monitoring it, and giving it a decent shot at becoming a tropical cyclone within 48 hours?
New Atlantic invest 11.5N 22.0W
High Sea Forecast For The Eastern Atlantic
Tropical depression TWO, 1006, near 14.0N36.3W AT 13/03 UTC, moving
West 12 kt.
Low 1004 over north of Mauritania.
Low 1003 by 13N 19W, moving west, forecast 1010 by 11N 23W at 14/12 UTC.
90L is being monitored by Meteo France
"I was so sure" implied I knew what the NHC has been saying. I merely said the wave behind pre Bill had been consistently appearing more ferocious.
The models are developing a system behind 90L..
I think 90L will become Bill and potentially threaten the Antilles. While there is a chance of a Carolina hit or a recurvature out to sea, I think a Florida hit is definitely possible. With late starting seasons, an Andrew must always be kept in close mind.
islands seem under the gun we just cannot affoed that now
Right now, anyway.
Latest 00Z ECMWF curves it east of the islands.
Maybe a threat to Bermuda only.
Yuck, Dean part 2 if that goes as forecast.
Elongated COC, but more organized than yesterday, and indication 90L's starting to spin up.
I thought the B/H is about normal, 1026mb isn't that strong. Could be wrong, though. Normal is around 1024-25.
It's just hovering around the line between negative/positive for the NAO, most seem to keep it just into the positive.
also invite you to post your Hurricane Charley exprience.
At least it keeps it weak and doesn't send it into the Gulf a la Katrina.
Yup.
Please- 90L? did they invest the african coast blob?
Yes. But a major model, ECMWF, shows it curving east of the islands now.
Read that as 'invest in...'
90L shares up for sale! Profits up! Dow up by 3 points! Buy low, sell high!
Good morning everyone
Look at this. It's an older run, but still scary. Link
Morning Ike. What do you think it will do? Any opinions?
BAMS and BAMD almost the same on 90L, that seems a little odd to me, but I guess the ridge is pretty strong.
Unless something miraculous occurs w/TD2, can't really see it being a HUGE problem.
"LONG TERM...SAT NIGHT THROUGH THU.
AT THE START OF THE PERIOD...THERE IS DECENT MODEL CONSENSUS THAT A
TIGHTENED GRADIENT WILL EXIST ACROSS THE ERN GULF OF MEXICO AS A
TROPICAL WAVE WORKS ITS WAY WWD ACROSS THE CENTRAL GULF. WHILE
THIS WILL PRIMARILY IMPACT THE COASTAL WATERS WITH EXERCISE CAUTION
CONDITIONS...IT WILL ALSO RESULT IN ELEVATED POPS ACROSS THE WRN
ZONES WITH LOWER POPS E. DURING THE WORK WEEK...THE SURFACE RIDGE
AXIS WILL REMAIN IN PLACE N OF THE FORECAST AREA...WHICH WILL KEEP
US IN AN ELY FLOW REGIME. THIS WILL RESULT IN BELOW NORMAL POPS AND
SLIGHTLY ABOVE NORMAL TEMPS. BY WED OR THU...THE REMNANTS OF WHAT IS
NOW TD TWO MAY REACH FL. THE LATEST 00Z EURO SHOWS IT RECURVING OFF
THE E COAST WHILE THE GFS BRINGS AN OPEN WAVE ACROSS S FL. WE BUMPED
POPS BACK UP TO NORMAL FOR THU TO ACCOUNT FOR THE UNCERTAINTY
ASSOCIATED WITH THIS SYSTEM. LOOKING FURTHER AHEAD...MODELS CONTINUE
TO BE IN GOOD AGREEMENT THAT THE POTENT WAVE NOW ORGANIZING JUST OFF
THE W COAST OF AFRICA WILL MARCH ACROSS THE ATLANTIC OCEAN AS A TC
AND APPROACH N AMERICA. WITH A TROUGH DEEPENING OVER THE ERN U.S.,
THIS SYSTEM COULD RECURVE BEFORE REACHING FL. HOWEVER...IT IS
CLEARLY TOO EARLY FOR CONJECTURE WITH A SYSTEM THAT IS ONLY NOW JUST
STARTING TO DEVELOP."
Odds are it will go east of Florida.
Troughs in the eastern USA.....
Good news for us on the Gulf Coast. I hope you're right.
If it follows the current model runs, it will go south and west of Florida. Caribbean tracker. Lets just wait and see what happens first.
Already had enough of rain and cool temps, another spoiled summer. Another 2-4 inches forecasted for tomorrow/Saturday in my part of the world. Ugh. (Higher totals further up North, though, it seems.)
I guess it picked up the fact 90L is barely moving.
A fair few factors right now.
Seems probable at this point with the Bremuda High the way it is. Right now its a wait and see, these things always shift.
Link
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