Ana and TD 3 take aim at the Lesser Antilles
Tropical Storm Ana was born this morning, when the remnants of Tropical Depression Two made a comeback and organized into the first tropical storm of the 2009 Atlantic hurricane season. Ana is the latest first named storm of the season since Hurricane Andrew got its name on August 17, 1992. The two storms have some similarities, as Andrew formed in the same part of the ocean, and also struggled in its early days with high wind shear and dry air. Let's hope the similarities end there.
Ana is struggling this afternoon. After an modest burst of heavy thunderstorm activity prompted NHC to upgrade Ana to a tropical storm early this morning, Ana has run into strong upper-level winds from the west that are creating high wind shear. This shear was not forecast, and it is not clear how long it will last. The shear has acted to drive dry air into the core of Ana, destroying almost all of Ana's heavy thunderstorms. The low-level center of the storm is now exposed to view, something that often foreshadows the death of a storm. It is possible the shear will destroy Ana, and several models (the GFS and ECMWF) forecast this may be the case. However, the shear forecast calls for shear to drop into the low range, 5 - 10 knots, tonight through Tuesday. If the shear does drop as forecast, Ana should be able to moisten the atmosphere around it sufficiently to protest itself from the dry Saharan air that surrounds it (Figure 1). SSTs are 27°C today, and will increase to 28°C by Sunday. By the time Ana moves into the Bahamas, total ocean heat content rises steeply (Figure 2), and rapid intensification of Ana is possible, if the shear and dry air haven't disrupted the storm. The intensity forecast models, for the most part, predict a steady intensification of Ana to the threshold of hurricane strength five days from now. The HWRF model is on the strong side, predicting a Category 2 hurricane. The GFDL predicts a weak tropical storm five days from now, but that is because the model has Ana passing over the rugged terrain of Hispaniola, something the other models do not predict. In summary, the intensity forecast for Ana has higher than usual uncertainty, and I give equal chances that the storm will be a hurricane--or non-existent--four days from now.
Figure 1. Water vapor image from this morning showing the large area of dry, Saharan air surrounding Ana, and lying to the north of Tropical Depression Three. Image credit: NOAA/SSD
Tropical Depression Three forms, could be Bill later today
QuikSCAT data from this morning and satellite loops revealed that the tropical wave (90L) in the middle Atlantic has finally developed a well developed surface circulation and can be classified as Tropical Depression Three. Recent satellite imagery suggests that TD 3 may already be Tropical Storm Bill. Water vapor imagery (Figure 1) shows that TD 3's center consolidated a few hundred miles south of the dry air of the Saharan Air Layer (SAL). Thus, the storm should not be affected by dry air and dust as much as Ana has been. Ana may also act to moisten the atmosphere in front of TD 3, helping protect the storm from the SAL as it edges farther north over the the three days.
Figure 2. Heat content of the ocean, in kJ per square cm. Oceanic heat content steadily increases for Ana and TD 3 as they approach the Lesser Antilles Islands. Oceanic heat content levels of 90 kJ per square cm are frequently associated with rapid intensification of hurricanes. Image credit: University of Miami.
Wind shear is moderate, 15 knots, but is forecast to fall to 10 - 15 knots on days 2 - 5. Sea Surface Temperatures are about 27.5°C, and will remain in the 27.5 - 28°C range the next five days. The combination of low wind shear and sufficiently warm SSTs should allow TD 3 to intensify steadily, and I expect the storm will be at hurricane strength by Wednesday, when it will be near the northern Lesser Antilles Islands. Most of our reliable intensity models strengthen TD 3 into a hurricane by Wednesday. Oceanic heat content (Figure 2) increases sharply just before the islands, so TD 3 could be intensifying rapidly as it moves through or just north of the Lesser Antilles on Thursday. TD 3 consolidated farther south than expected, so the track models calling for a more northerly path were probably incorrect. In particular, the ECMWF model, which had TD 3 turning sharply northwestward and missing the Lesser Antilles Islands, was probably much too far to the north in this morning's 00Z run. TD 3 will probably pass very close to the northern Lesser Antilles islands on Wednesday and Thursday.
I'll have an update Sunday.
Jeff Masters
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One word: Humberto.
Yesterday we got some interesting storms around here... but since then no rain so far inland... based on the rainbow I saw earlier this AM towards the coast... there's at least virga to light rain on the immediate coast.
SITUATION OVERVIEW
EXPECTED CONDITIONS AND IMPACTS FOR ALL AREAS:
TROPICAL DEPRESSION FOUR IN THE EASTERN GULF OF MEXICO IS
EXPECTED TO INTENSIFY TO A TROPICAL STORM LATER THIS EVENING
BEFORE MAKING LANDFALL ALONG THE PANHANDLE COAST.
Low Threat - Up to three tornadoes expected.
Impact - Isolated tornadoes possible.
One to three tornadoes possible. These tornadoes will likely be of EF1 intensity or less (winds of 110 mph or less). Tornadoes of this intensity can significantly damage or destroy outbuildings and cause major damage to mobile homes. Older, weaker mobile homes may be destroyed. Numerous trees will be uprooted or snapped by the winds of the tornado.
I see we now have 3 NHC tracks on the map, or as I like to call them, the pink tongues of death...
Radar and satellite imagery over the last 12 to 18 hours indicate that the disturbance in the eastern Gulf of Mexico has become much better organized and is now considered a Tropical Depression. The excellent radar presentation and deep convection seen on satellite imagery indicates to me that this will be upgraded to Tropical Storm Claudette probably as early as late this morning. Overall wind shear is quite low and the intensity guidance from SHIPS, LGEM, HWRF and GFDL all indicate that this storm will make landfall as a 50 to 60 mph tropical storm this evening on the Florida Panhandle between Destin and Panama City. With that said, I am concerned that with the low shear and downright hot Gulf of Mexico waters that more rapid strengthening is possible than what is being forecast. So, folks along the Florida Panhandle should keep very close tabs on this system and in my opinion make preparations for a high end Tropical Storm or a low end Category 1 Hurricane. (65 to 80 mph).
TD 4 is tracking north-northwest at a forward speed of 16 mph and it is forecast to remain on this track and speed right up through landfall. This is a small storm and its effects are likely to remain close to the path of the center.
lol.
But not "CERTAIN DEATH" (yet)
Its small size will only help it even further. It doesn't require as much ambient energy as a mammoth like Bill does. I truly won't be surprised if this become a hurricane.
Sometimes on a late clear night you can pull that station from Denver or Boston out of the dark.
All the elsewheres alter here, as what you remember changes what you think.
Not spider nor plum nor pebble possesses any of the names we give them.
A kite tugging on its string gives you a sense of what%u2019s up there, though it%u2019s translated, and by a string.
Out there, in the dark, the true thing.
by, Susan Hutton
So - 3 named storms in a day and a bit. Based on that we will be on 45 named storms by the end of the month (3 a day for 15 days).
Officially...no, he's still moving west.
TropicalDepressionFour at 27.7N,83.9W
Why two different systems? Traveling at the same speed in the same direction, with less than 55miles/88kilometres from 91L's center to TD4's center.
It won't - it has to wait for the advisory's to kick in...
They are the same systems. Invest 91L became TD 4 this morning.
Don't forget Bermuda.
Thats Wunderground not being awake.
Indeed...
000
WTNT34 KNHC 161139
TCPAT4
BULLETIN
TROPICAL DEPRESSION FOUR INTERMEDIATE ADVISORY NUMBER 1A
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL042009
800 AM EDT SUN AUG 16 2009
...DEPRESSION MOVING NORTH-NORTHWESTWARD...HEADING FOR THE NORTHERN
GULF COAST OF FLORIDA...
A TROPICAL STORM WARNING REMAINS IN EFFECT FROM THE ALABAMA/FLORIDA
BORDER EASTWARD TO THE SUWANNEE RIVER FLORIDA. A TROPICAL STORM
WARNING MEANS THAT TROPICAL STORM CONDITIONS ARE EXPECTED SOMEWHERE
WITHIN THE WARNING AREA WITHIN 24 HOURS.
FOR STORM INFORMATION SPECIFIC TO YOUR AREA PLEASE MONITOR PRODUCTS
ISSUED BY YOUR LOCAL NATIONAL WEATHER SERVICE FORECAST OFFICE.
AT 800 AM EDT...1200 UTC...THE CENTER OF TROPICAL DEPRESSION FOUR
WAS LOCATED NEAR LATITUDE 28.1 NORTH...LONGITUDE 84.1 WEST OR ABOUT
125 MILES...200 KM...SOUTH-SOUTHEAST OF APALACHICOLA FLORIDA.
THE DEPRESSION IS MOVING TOWARD THE NORTH-NORTHWEST NEAR 16
MPH...AND THIS MOTION IS EXPECTED TO CONTINUE TODAY. ON THE
FORECAST TRACK...THE CENTER OF THE DEPRESSION SHOULD BE VERY NEAR
THE NORTHERN GULF COAST OF FLORIDA BY LATE THIS AFTERNOON.
MAXIMUM SUSTAINED WINDS ARE NEAR 35 MPH...55 KM/HR...WITH HIGHER
GUSTS. STRENGTHENING IS EXPECTED AND THE DEPRESSION IS FORECAST TO
BECOME A TROPICAL STORM PRIOR TO REACHING THE COASTLINE.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 1011 MB...29.85 INCHES.
RAINFALL ACCUMULATIONS OF 3 TO 5 INCHES...WITH ISOLATED MAXIMUM
AMOUNTS OF 10 INCHES ACROSS PORTIONS OF NORTH FLORIDA NEAR THE PATH
OF THE CENTER.
COASTAL STORM SURGE FLOODING OF 3 TO 5 FEET ABOVE NORMAL TIDE
LEVELS CAN BE EXPECTED NEAR AND TO THE EAST OF WHERE THE CENTER
MAKES LANDFALL.
...SUMMARY OF 800 AM EDT INFORMATION...
LOCATION...28.1N 84.1W
MAXIMUM SUSTAINED WINDS...35 MPH
PRESENT MOVEMENT...NORTH-NORTHWEST OR 330 DEGREES AT 16 MPH
MINIMUM CENTRAL PRESSURE...1011 MB
THE NEXT ADVISORY WILL BE ISSUED BY THE NATIONAL HURRICANE CENTER AT
1100 AM EDT.
$$
FORECASTER BRENNAN/ROBERTS
Yes. It looks like he is moving WNW already. We'll see what the NHC says in a few hours.
This place will be nuts when everyone wakes up.
Ummmm where's Ana?
They've got this thing forecast to travel NW. Everything in me says N to NE.
My favorite local met, James Wieland (WPTV - 5), thinks Bill will get sucked up by the trough as well.
The fact that in just the last hour you can see about 4 or 5 distinct bands of heavy rain forming and you can see the rain intensify around the center of circulation is just scary. IF it keeps up THIS pace of strengthening, well, I wouldn't be surprised to see a very strong TS or, crazy enough, the small possibility of a minimal Hurricane. We shall see, but check out the radar loop for a good look at a strenghtening Claudette.
LOL...The little blob at 15N 55W.
stormwatcherCI "It is the same system at different times. 91L became TD4"
IpswichWeatherCenter "Thats Wunderground not being awake."
Thanks for the explanations. That was too weird to deal with before the first cup of coffee.
She's been playing that game for the last several days...
It is moving NNW, and will continue along that general NW to NNW path.. There's wayyy too much high pressure to its east and north for it to move NE, or even NNE, and I don't believe we'll even see a N jog. If it does though, we'll remember you called it.. But it's virtually impossible at this point :/
WTNT32 KNHC 161137
TCPAT2
BULLETIN
TROPICAL STORM ANA INTERMEDIATE ADVISORY NUMBER 17A
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL022009
800 AM AST SUN AUG 16 2009
...ANA RACING WESTWARD...
A TROPICAL STORM WATCH REMAINS IN EFFECT FOR PUERTO RICO...THE U.S.
VIRGIN ISLANDS...THE BRITISH VIRGIN ISLANDS...MONTSERRAT...
ANTIGUA...BARBUDA...ST. KITTS...NEVIS...ANGUILLA...ST. MAARTEN...
SABA...AND ST. EUSTATIUS. A TROPICAL STORM WATCH MEANS THAT
TROPICAL STORM CONDITIONS ARE POSSIBLE WITHIN THE WATCH AREA...
GENERALLY WITHIN 36 HOURS.
INTERESTS ELSEWHERE IN THE LEEWARD ISLANDS SHOULD MONITOR THE
PROGRESS OF ANA. ADDITIONAL WATCHES AND WARNINGS MAY BE REQUIRED
FOR PORTIONS OF THESE AREAS LATER TODAY.
FOR STORM INFORMATION SPECIFIC TO YOUR AREA IN THE UNITED
STATES...INCLUDING POSSIBLE INLAND WATCHES AND WARNINGS...PLEASE
MONITOR PRODUCTS ISSUED BY YOUR LOCAL NATIONAL WEATHER SERVICE
FORECAST OFFICE. FOR STORM INFORMATION SPECIFIC TO YOUR AREA
OUTSIDE OF THE UNITED STATES...PLEASE MONITOR PRODUCTS ISSUED
BY YOUR NATIONAL METEOROLOGICAL SERVICE.
AT 800 AM AST...1200 UTC...THE CENTER OF TROPICAL STORM ANA WAS
LOCATED NEAR LATITUDE 14.6 NORTH...LONGITUDE 54.7 WEST OR ABOUT 470
MILES...755 KM...EAST-SOUTHEAST OF THE LEEWARD ISLANDS.
ANA IS MOVING TOWARD THE WEST NEAR 20 MPH...32 KM/HR. A TURN TOWARD
THE WEST-NORTHWEST IS EXPECTED WITHIN THE NEXT 24 HOURS. THE
CENTER OF ANA SHOULD REACH THE LEEWARD ISLANDS BY EARLY MONDAY.
MAXIMUM SUSTAINED WINDS ARE NEAR 40 MPH...65 KM/HR...WITH HIGHER
GUSTS. LITTLE CHANGE IN STRENGTH IS FORECAST DURING THE NEXT 24
HOURS.
TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 70 MILES...110 KM
FROM THE CENTER.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 1005 MB...29.68 INCHES.
ANA IS EXPECTED TO PRODUCE RAINFALL AMOUNTS OF 2 TO 4 INCHES OVER
THE LEEWARD ISLANDS...INCLUDING THE U.S. AND BRITISH VIRGIN
ISLANDS...WITH ISOLATED MAXIMUM AMOUNTS OF 6 INCHES OVER
MOUNTAINOUS TERRAIN.
...SUMMARY OF 800 AM AST INFORMATION...
LOCATION...14.6N 54.7W
MAXIMUM SUSTAINED WINDS...40 MPH
PRESENT MOVEMENT...WEST OR 270 DEGREES AT 20 MPH
MINIMUM CENTRAL PRESSURE...1005 MB
THE NEXT ADVISORY WILL BE ISSUED BY THE NATIONAL HURRICANE CENTER AT
1100 AM AST.
$$
FORECASTER BRENNAN/ROBERTS
Lol. Couldn't see her on that one. But on visible looks like shes trying to make a comeback again. Wrapping convection round her center.
Viewing: 4401 - 4451
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