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
Reader Comments
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Hey Pat - I knew it! I went to sleep with local met saying "little chance of development" and BAM i's at red - what is going on? *still wiping eyes*
post the 5am advisory when it comes out. dont hit and run.
Sure I will be glad too. :)
Does anyone know? I wasn't here for Humberto.
i know but the system has been going on since the cape verdes and it regenerates. so
thats a fact too.
Bill is up to 45mph.
Also the gas prices has gone up almost 10 cents from yesterday....
Taco :0)
dont see that here...
Doing a full scan now... It may or may not be related to the blog. I was entering a link when it happened..
Unrecognizable.
Yes, it can happen...has many times in the past.
Thanks
you can bash him all you want, but thats true
Thats old. lol
The models were run with the data of Bill up to 45mph. Look back a few pages.
We'll see....but I dont think so! :)
maybe this will help
Uh the NHC says so! Dvorak estimates of 2.5 and 3.0 blend to make 40knots.
i was here when we started talkin bout it at about 1pm edt? i get confused about my time zone lol
? I just bought gas today and yesterday, same price, and no one I've talked has even mentioned the storm or lack of warnings.
AL, 03, 2009081606, , BEST, 0, 114N, 374W, 40, 1002, TS,
rapid intensification poster boy, indeed
actually, it doesn't "skip" TD status, it just happens to develop so fast that it beats the forecasters to the punch. I've seen it happen a few times with these close-in systems and with hybrids.
Yeah, this one definitely developed quickly...
It best shows how rapidly the LLC of Ana is running away from...well, theres not much convection to speak of at this point.
those are the winds and direction reported by buoys, ships and coastal stations in the last hour. The arrows are wind direction while the numbers below the arrows are the speed of the wind.
If you look closel, you see that arrows curve or veer around the area of low pressure.
How? Look at those SSTs
Ok we shall see! :) That's what Im going to say! :)
i dont get it, it says 6:45 UTC which would be 30 mins behind from my current hour?
BULLETIN - IMMEDIATE BROADCAST REQUESTED
SPECIAL MARINE WARNING
NATIONAL WEATHER SERVICE TAMPA BAY AREA - RUSKIN FL
311 AM EDT SUN AUG 16 2009
THE NATIONAL WEATHER SERVICE IN RUSKIN HAS ISSUED A
* SPECIAL MARINE WARNING FOR...
WATERS FROM ENGLEWOOD TO TARPON SPRINGS FL OUT 20 TO 60 NM OVER
GULF OF MEXICO WATERS...
COASTAL WATERS FROM ENGLEWOOD TO TARPON SPRINGS FL OUT 20 NM OVER
GULF OF MEXICO WATERS...
* UNTIL 500 AM EDT
* AT 306 AM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
THUNDERSTORMS...PRODUCING STRONG WINDS 34 KNOTS OR GREATER...
COVERING MOST OF THE GULF WATERS BETWEEN 15 AND 60 NM OFFSHORE
FROM ENGLEWOOD NORTH TO CLEARWATER BEACH. THESE STORMS ARE
ASSOCIATED WITH AN AREA OF LOW PRESSURE MOVING NORTHWEST THROUGH
THE EASTERN GULF. THE STORMS ARE MOVING NORTH AT 25 TO 30 KNOTS.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
MARINERS CAN EXPECT STRONG WINDS...HIGH WAVES...DANGEROUS
LIGHTNING...AND HEAVY RAINS. WATERSPOUTS WILL ALSO BE POSSIBLE IN
SOME OF THE HEAVIER RAIN BANDS. BOATERS SHOULD SEEK SAFE HARBOR
IMMEDIATELY.
&&
LAT...LON 2805 8385 2811 8309 2690 8262 2670 8340
2707 8364 2752 8381 2790 8387
TIME...MOT...LOC 0706Z 176DEG 27KT 2721 8339
more W i see
Thanks! I don't know why they didn't teach me this stuff when I was studying accounting & taxes!
WHXX01 KWBC 160715
CHGHUR
TROPICAL CYCLONE GUIDANCE MESSAGE
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0715 UTC SUN AUG 16 2009
DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.
PLEASE REFER TO NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONE
AND SUBTROPICAL CYCLONE INFORMATION.
ATLANTIC OBJECTIVE AIDS FOR
TROPICAL CYCLONE ANA (AL022009) 20090816 0600 UTC
...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...
090816 0600 090816 1800 090817 0600 090817 1800
LAT LON LAT LON LAT LON LAT LON
BAMS 14.5N 52.9W 15.8N 57.2W 17.1N 61.7W 19.2N 66.2W
BAMD 14.5N 52.9W 15.2N 56.0W 15.8N 59.6W 16.5N 63.3W
BAMM 14.5N 52.9W 15.2N 56.5W 15.8N 60.4W 16.7N 64.5W
LBAR 14.5N 52.9W 15.0N 56.1W 15.8N 59.8W 16.7N 63.7W
SHIP 35KTS 36KTS 39KTS 45KTS
DSHP 35KTS 36KTS 39KTS 45KTS
...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...
090818 0600 090819 0600 090820 0600 090821 0600
LAT LON LAT LON LAT LON LAT LON
BAMS 20.8N 70.3W 23.9N 76.7W 26.2N 80.4W 27.6N 82.6W
BAMD 17.3N 67.0W 18.8N 74.1W 20.0N 79.8W 21.2N 85.1W
BAMM 17.5N 68.5W 18.8N 76.2W 20.1N 83.0W 21.6N 88.9W
LBAR 17.3N 67.5W 18.8N 74.7W .0N .0W .0N .0W
SHIP 49KTS 56KTS 63KTS 72KTS
DSHP 49KTS 36KTS 37KTS 45KTS
...INITIAL CONDITIONS...
LATCUR = 14.5N LONCUR = 52.9W DIRCUR = 270DEG SPDCUR = 17KT
LATM12 = 14.4N LONM12 = 49.2W DIRM12 = 272DEG SPDM12 = 15KT
LATM24 = 14.5N LONM24 = 46.1W
WNDCUR = 35KT RMAXWD = 40NM WNDM12 = 35KT
CENPRS = 1005MB OUTPRS = 1010MB OUTRAD = 150NM SDEPTH = M
RD34NE = 60NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0NM
$$
NNNN
No kiddin
Mmmmm THANX for popping in that link. Like I said before with the water vapor loop link, Anna looks like she is feeling the ULL. That visible defintely shows it..
can I get the loop of Bill with that satellite imagiry
I hate to say it...but this is why they always say - be prepared by June 1 - you NEVER know what will happen. I'm just afraid too many don't heed the warning
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