ATL: TROPICAL DEPRESSION ANA (02L)

[HURAKAN]

392
WTNT32 KNHC 122033
TCPAT2
BULLETIN
TROPICAL DEPRESSION TWO ADVISORY NUMBER 7
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL022009
500 PM AST WED AUG 12 2009

...DEPRESSION HAS NOT YET BECOME A TROPICAL STORM...

AT 500 PM AST...2100 UTC...THE CENTER OF TROPICAL DEPRESSION TWO WAS
LOCATED NEAR LATITUDE 14.3 NORTH...LONGITUDE 35.0 WEST OR ABOUT 710
MILES...1140 KM...WEST OF THE SOUTHERNMOST CAPE VERDE ISLANDS.

THE DEPRESSION IS MOVING TOWARD THE WEST NEAR 14 MPH...23 KM/HR. A
GENERAL MOTION TOWARD THE WEST IS EXPECTED TO CONTINUE FOR THE NEXT
48 HOURS.

MAXIMUM SUSTAINED WINDS ARE NEAR 35 MPH...55 KM/HR...WITH HIGHER
GUSTS. SLOW STRENGTHENING IS POSSIBLE...AND THE DEPRESSION COULD
BECOME A TROPICAL STORM DURING THE NEXT DAY OR TWO.

ESTIMATED MINIMUM CENTRAL PRESSURE IS 1006 MB...29.71 INCHES.

...SUMMARY OF 500 PM AST INFORMATION...
LOCATION...14.3N 35.0W
MAXIMUM SUSTAINED WINDS...35 MPH
PRESENT MOVEMENT...WEST OR 265 DEGREES AT 14 MPH
MINIMUM CENTRAL PRESSURE...1006 MB

THE NEXT ADVISORY WILL BE ISSUED BY THE NATIONAL HURRICANE CENTER AT
1100 PM AST.

$$
FORECASTER BEVEN

386
WTNT42 KNHC 122034
TCDAT2
TROPICAL DEPRESSION TWO DISCUSSION NUMBER 7
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL022009
500 PM AST WED AUG 12 2009

THE DEPRESSION APPEARED TO BE ON THE VERGE OF BECOMING A TROPICAL
STORM A FEW HOURS AGO...WITH SATELLITE INTENSITY ESTIMATES OF 35 KT
FROM TAFB AND SAB. HOWEVER...SINCE ABOUT 18Z THE CONVECTION HAS
DECREASED SIGNIFICANTLY AND HAS MOVED FARTHER AWAY FROM THE EXPOSED
LOW-LEVEL CENTER. BASED ON THIS...THE CYCLONE WILL REMAIN A 30 KT
DEPRESSION FOR THIS ADVISORY. THE CURRENT DOWNWARD TREND IN THE
CONVECTION MAY BE DUE TO AN INCREASE IN EASTERLY VERTICAL WIND
SHEAR...AND TO A DRY SLOT WRAPPING AROUND THE CIRCULATION NOTED IN
AMSR-E VAPOR IMAGERY NEAR 1534Z. ALSO...AS SEEN EARLIER...MOST OF
THE LOW-LEVEL INFLOW INTO THE DEPRESSION SEEMS TO BE COMING FROM
THE NORTH...REPRESENTING POSSIBLY MORE STABLE AIR PASSING OVER
COOLER WATERS. THE FLOW ON THE SOUTH SIDE OF THE DEPRESSION IS
FEEDING INTO A LARGE DISTURBANCE BETWEEN THE CAPE VERDE ISLANDS AND
AFRICA.

THE INITIAL MOTION IS 265/12. THE DEPRESSION IS ON THE SOUTH
SIDE OF A LARGE LOW/MID-LEVEL RIDGE...AND THE LARGE-SCALE MODELS
FORECAST THIS TO CONTINUE FOR THE NEXT TWO DAYS OR SO. AFTER THAT
TIME...THE MODELS FORECAST A WEAKNESS IN THE RIDGE THAT WOULD STEER
THE CYCLONE WEST-NORTHWESTWARD. THE TRACK MODEL GUIDANCE GENERALLY
AGREES WITH THIS SCENARIO...AND WHILE THE MODEL CLUSTERS SEEN
EARLIER HAVE MERGED THERE IS STILL A SIGNIFICANT SPREAD BY 120 HR.
THE GFS AND UKMET ARE ON THE SOUTH SIDE OF THE GUIDANCE ENVELOPE
SHOWING A MORE WESTERLY MOTION...WHILE THE HWRF AND BAMD ARE ON THE
NORTH SIDE SHOWING A NORTHWESTWARD MOTION BY 120 HR. OVERALL...THE
GUIDANCE ENVELOPE HAS AGAIN SHIFTED A LITTLE SOUTHWARD...AND SO HAS
THE NEW OFFICIAL FORECAST. THE NEW TRACK IS IN THE CENTER OF THE
GUIDANCE ENVELOPE IN BEST AGREEMENT WITH THE TVCN AND TVCC
CONSENSUS MODELS.

THE DEPRESSION REMAINS OVER SEA SURFACE TEMPERATURES NEAR 27C...WITH
SSTS ALONG THE FORECAST TRACK INCREASING TO 28C AFTER 72 HR. THE
LARGE-SCALE MODELS FORECAST THE DEPRESSION TO ENCOUNTER MODERATE
VERTICAL WIND SHEAR DURING THE FORECAST PERIOD...FIRST FROM THE
EAST AND LATER FROM THE SOUTHWEST. ALSO...WATER VAPOR IMAGERY
SHOWS VERY DRY AIR AT THE MID/UPPER-LEVELS TO THE NORTHWEST OF THE
DEPRESSION. THE LATTER TWO FACTORS SUGGEST THE SYSTEM MAY BE SLOW
TO STRENGTHEN...AND NONE OF THE INTENSITY GUIDANCE CURRENTLY
FORECASTS AN INTENSITY GREATER THAN 55 KT DURING THE FORECAST
PERIOD. BASED ON THIS...THE NEW INTENSITY FORECAST IS AN UPDATE OF
THE PREVIOUS FORECAST IN BEST AGREEMENT WITH THE SHIPS MODEL. IT
IS POSSIBLE THAT THE SYSTEM COULD WEAKEN TO A TROPICAL WAVE DURING
THE FORECAST PERIOD...AS FORECAST BY THE ECMWF...UKMET...AND GFS
MODELS.

FORECAST POSITIONS AND MAX WINDS

INITIAL 12/2100Z 14.3N 35.0W 30 KT
12HR VT 13/0600Z 14.1N 36.7W 35 KT
24HR VT 13/1800Z 14.1N 38.9W 35 KT
36HR VT 14/0600Z 14.2N 41.3W 40 KT
48HR VT 14/1800Z 14.6N 43.7W 45 KT
72HR VT 15/1800Z 16.0N 49.5W 50 KT
96HR VT 16/1800Z 19.0N 56.0W 50 KT
120HR VT 17/1800Z 23.0N 62.0W 45 KT

$$
FORECASTER BEVEN

[Evil Jeremy]

Well, at least I did not loose in the Ana/90L poll yet lol!

[tolakram]

Good call in my opinion, because right now there's not much there and what is there is fading fast.

[fox13weather]

Nice call.

[Evil Jeremy]

From the discussion:

"THE DEPRESSION APPEARED TO BE ON THE VERGE OF BECOMING A TROPICAL
STORM A FEW HOURS AGO...WITH SATELLITE INTENSITY ESTIMATES OF 35 KT
FROM TAFB AND SAB. HOWEVER...SINCE ABOUT 18Z THE CONVECTION HAS
DECREASED SIGNIFICANTLY AND HAS MOVED FARTHER AWAY FROM THE EXPOSED
LOW-LEVEL CENTER. BASED ON THIS...THE CYCLONE WILL REMAIN A 30 KT
DEPRESSION FOR THIS ADVISORY."

That likely explains what has been going on. A couple of hours ago they were probably getting ready to upgrade it but decided not to later. Also, the cone has once again shifted south in the long term, and that is a trend that has been going on for a while now.

[HURAKAN]

There was a change of heart at the NHC.

I have a question, based on the ATCF numbers, could it have been a tropical storm between the 11 AM and 5 PM advisories?

[HURAKAN]

The models never had "Ana" though. Neither did NRL. I think when they don't give a name to these things, it means that they maybe hedging.

02LTWO.35kts-1005mb-143N-344W

NRL never had Ana but they did have 35 knots.

[cycloneye]

There was a change of heart at the NHC.

I have a question, based on the ATCF numbers, could it have been a tropical storm between the 11 AM and 5 PM advisories?

For sure after the season is over,they will look into it at ATCF best track in the post season reports.

[HurricaneRobert]

'Ana's' too ugly. I want to get a number for the one behind her so we can start the thread already.

[poof121]

There was a change of heart at the NHC.

I have a question, based on the ATCF numbers, could it have been a tropical storm between the 11 AM and 5 PM advisories?

For sure after the season is over,they will look into it at ATCF best track in the post season reports.

I'll bet this was one reason why they almost upgraded. 35 kt wind barbs, but they were rain flagged...

[MGC]

TD2 has hit a rough strech of road. Really looks like it is falling apart this evening....but, I've witnessed many a TC lose organization only to regain it down the road. If TD2 remains shallow I think it will track futher west than forecast.......MGC

[CrazyC83]

Aren't we in diurnal minimum though?

[HURAKAN]

I think the most important occurrence today was the dramatic increase in shear. This should keep the system weak and we will likely see the track being shifted more and more to the left. Interesting week ahead.

[HURAKAN]

Aren't we in diurnal minimum though?

yes

[Macrocane]

Too bad it wasn't upgraded, but I think we've learned our lesson well "wait for the advisory".

[KWT]

Yep looks like whilst I was at work we had some fun and games here!
Still it remains a tropical depression, seems like its the right call for now.

[Scorpion]

It will get its act together again overnight. We have seen this before.

[thequeenamom]

OK folks, help me out here... We are going on a once in a lifetime trip to Disney World in Orlando, FL 8/22-8/29, what are the odds of this hitting there (or even getting rain from it)??? Thanks for your help.

[RL3AO]

OK folks, help me out here... We are going on a once in a lifetime trip to Disney World in Orlando, FL 8/22-8/29, what are the odds of this hitting there (or even getting rain from it)??? Thanks for your help.

Too early.

[Derek Ortt]

this weakening today also means the CMC forecast for the one behind has very little chance of occurring. It showed this TD as large and intense enough to affect the track of the future system