ATL: KATIA - Post Tropical - Discussion

[Parungo]

Best, TD

BEGIN
NHC_ATCF
invest_al122011.invest
AL, 12, 2011082906, , BEST, 0, 93N, 257W, 25, 1009, TD

[southerngale]

000
WTNT32 KNHC 290841
TCPAT2

BULLETIN
TROPICAL DEPRESSION TWELVE ADVISORY NUMBER 1
NWS NATIONAL HURRICANE CENTER MIAMI FL AL122011
500 AM AST MON AUG 29 2011

...NEW TROPICAL DEPRESSION FORMS SOUTH OF THE CAPE VERDE ISLANDS...


SUMMARY OF 500 AM AST...0900 UTC...INFORMATION
----------------------------------------------
LOCATION...9.4N 26.3W
ABOUT 395 MI...635 KM SSW OF THE SOUTHERNMOST CAPE VERDE ISLANDS
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H
PRESENT MOVEMENT...W OR 270 DEGREES AT 15 MPH...24 KM/H
MINIMUM CENTRAL PRESSURE...1009 MB...29.80 INCHES


WATCHES AND WARNINGS
--------------------
THERE ARE NO COASTAL WATCHES OR WARNINGS IN EFFECT.


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
AT 500 AM AST...0900 UTC...THE CENTER OF TROPICAL DEPRESSION TWELVE
WAS LOCATED NEAR LATITUDE 9.4 NORTH...LONGITUDE 26.3 WEST. THE
DEPRESSION IS MOVING TOWARD THE WEST NEAR 15 MPH...24 KM/H. A TURN
TOWARD THE WEST-NORTHWEST IS EXPECTED DURING THE NEXT COUPLE OF DAYS
WITH LITTLE CHANGE IN FORWARD SPEED.

MAXIMUM SUSTAINED WINDS ARE NEAR 35 MPH...55 KM/H...WITH HIGHER
GUSTS. SOME STRENGTHENING IS FORECAST DURING THE NEXT 48 HOURS...AND
THE DEPRESSION COULD BECOME A TROPICAL STORM LATER TODAY.

ESTIMATED MINIMUM CENTRAL PRESSURE IS 1009 MB...29.80 INCHES.


HAZARDS AFFECTING LAND
----------------------
NONE


NEXT ADVISORY
-------------
NEXT COMPLETE ADVISORY...1100 AM AST.

$$
FORECASTER BRENNAN




----------------------------




000
WTNT22 KNHC 290841
TCMAT2

TROPICAL DEPRESSION TWELVE FORECAST/ADVISORY NUMBER 1
NWS NATIONAL HURRICANE CENTER MIAMI FL AL122011
0900 UTC MON AUG 29 2011

THERE ARE NO COASTAL WATCHES OR WARNINGS IN EFFECT.

TROPICAL DEPRESSION CENTER LOCATED NEAR 9.4N 26.3W AT 29/0900Z
POSITION ACCURATE WITHIN 30 NM

PRESENT MOVEMENT TOWARD THE WEST OR 270 DEGREES AT 13 KT

ESTIMATED MINIMUM CENTRAL PRESSURE 1009 MB
MAX SUSTAINED WINDS 30 KT WITH GUSTS TO 40 KT.
WINDS AND SEAS VARY GREATLY IN EACH QUADRANT. RADII IN NAUTICAL
MILES ARE THE LARGEST RADII EXPECTED ANYWHERE IN THAT QUADRANT.

REPEAT...CENTER LOCATED NEAR 9.4N 26.3W AT 29/0900Z
AT 29/0600Z CENTER WAS LOCATED NEAR 9.3N 25.7W

FORECAST VALID 29/1800Z 9.8N 28.3W
MAX WIND 35 KT...GUSTS 45 KT.
34 KT... 30NE 0SE 0SW 30NW.

FORECAST VALID 30/0600Z 10.7N 30.9W
MAX WIND 40 KT...GUSTS 50 KT.
34 KT... 45NE 30SE 15SW 30NW.

FORECAST VALID 30/1800Z 11.9N 33.5W
MAX WIND 45 KT...GUSTS 55 KT.
34 KT... 60NE 30SE 30SW 60NW.

FORECAST VALID 31/0600Z 13.1N 36.3W
MAX WIND 50 KT...GUSTS 60 KT.
50 KT... 30NE 0SE 0SW 30NW.
34 KT... 75NE 45SE 30SW 75NW.

FORECAST VALID 01/0600Z 15.0N 42.5W
MAX WIND 65 KT...GUSTS 80 KT.
50 KT... 45NE 30SE 30SW 45NW.
34 KT...100NE 60SE 60SW 90NW.

EXTENDED OUTLOOK. NOTE...ERRORS FOR TRACK HAVE AVERAGED NEAR 175 NM
ON DAY 4 AND 225 NM ON DAY 5...AND FOR INTENSITY NEAR 20 KT EACH DAY

OUTLOOK VALID 02/0600Z 16.5N 48.0W
MAX WIND 75 KT...GUSTS 90 KT.

OUTLOOK VALID 03/0600Z 18.0N 52.0W
MAX WIND 85 KT...GUSTS 105 KT.

REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 9.4N 26.3W

NEXT ADVISORY AT 29/1500Z

$$
FORECASTER BRENNAN





---------------------------------



000
WTNT42 KNHC 290850
TCDAT2

TROPICAL DEPRESSION TWELVE DISCUSSION NUMBER 1
NWS NATIONAL HURRICANE CENTER MIAMI FL AL122011
500 AM AST MON AUG 29 2011

THE AREA OF LOW PRESSURE IN THE FAR EASTERN ATLANTIC TO THE SOUTH OF
THE CAPE VERDE ISLANDS HAS GAINED SUFFICIENT CONVECTIVE
ORGANIZATION TO BE CLASSIFIED AS A TROPICAL DEPRESSION. A CURVED
CONVECTIVE BAND WRAPS AROUND THE WESTERN AND SOUTHERN SIDE OF THE
SYSTEM AND THE INITIAL INTENSITY IS SET TO 30 KT BASED ON THE 06Z
DVORAK CLASSIFICATION FROM TAFB. THE DEPRESSION IS CURRENTLY IN AN
EASTERLY SHEAR ENVIRONMENT SITUATED TO THE SOUTH OF AN UPPER-LEVEL
RIDGE OVER THE EASTERN ATLANTIC. SOME EASTERLY SHEAR IS EXPECTED TO
PERSIST...BUT OTHERWISE THE ENVIRONMENT SHOULD BE CONDUCIVE FOR
STRENGTHENING THROUGH THE PERIOD. THE OFFICIAL INTENSITY FORECAST
SHOWS SLOW STRENGTHENING IN GOOD AGREEMENT WITH THE SHIPS...GFDL...
AND HWRF MODELS THROUGH 48 HOURS. AFTER THAT TIME THE CYCLONE SHOULD
STRENGTHEN A LITTLE MORE QUICKLY AS IT MOVES OVER PROGRESSIVELY
HIGHER OCEAN HEAT CONTENT. AT DAYS 3 THROUGH 5 THE NHC FORECAST IS
CLOSEST TO BUT A LITTLE BELOW THE HWRF MODEL. THE SHIPS FORECAST
LATE IN THE PERIOD APPEARS TOO LOW DUE TO STRONG SOUTHERLY SHEAR
IMPARTED BY THE TROPICAL CYCLONE VORTEX IN THE GFS MODEL FIELDS...
WHICH IS DISPLACED TO THE SOUTH AND EAST OF THE OFFICIAL TRACK.

THE INITIAL MOTION ESTIMATE IS TOWARD THE WEST OR 270 DEGREES AT 13
KNOTS. THE DEPRESSION IS CURRENTLY SITUATED TO THE SOUTH OF THE
SUBTROPICAL RIDGE...BUT THE WESTERN EDGE OF THE RIDGE WILL WEAKEN
OVER THE NEXT DAY OR TWO AS A MID/UPPER-LEVEL LOW CUTS OFF AND
RETROGRADES ACROSS THE CENTRAL ATLANTIC. THIS WILL ALLOW THE
DEPRESSION TO TURN TOWARD THE WEST-NORTHWEST DURING THE NEXT DAY OR
SO. AFTER 48 HOURS...THE MID/UPPER-LEVEL-LOW WEAKENS AND THE RIDGE
RE-STRENGTHENS TO THE NORTHEAST OF THE CYCLONE...WHICH SHOULD
RESULT IN A CONTINUED WEST-NORTHWESTWARD MOTION THROUGH THE END OF
THE PERIOD. THE OFFICIAL NHC TRACK FORECAST IS SOUTH OF AND FASTER
THAN MOST OF THE GUIDANCE FOR THE FIRST 48 HOURS...AS MOST OF THE
DYNAMICAL MODELS SHOW A MORE POLEWARD AND SLOWER MOTION THAN IS
CURRENTLY OBSERVED. DURING THIS TIME THE NHC TRACK IS BETWEEN THE
DYNAMICAL MODEL CONSENSUS AND THE LBAR...WHICH TYPICALLY PERFORMS
WELL IN THE DEEP TROPICS. AT 72 HOURS AND BEYOND THE NHC FORECAST
IS CLOSE TO A BLEND OF THE HWRF...GFDL...AND ECMWF MODELS AND IS
MUCH FASTER THAN THE LATEST RUN OF THE GFS.

FORECAST POSITIONS AND MAX WINDS

INIT 29/0900Z 9.4N 26.3W 30 KT 35 MPH
12H 29/1800Z 9.8N 28.3W 35 KT 40 MPH
24H 30/0600Z 10.7N 30.9W 40 KT 45 MPH
36H 30/1800Z 11.9N 33.5W 45 KT 50 MPH
48H 31/0600Z 13.1N 36.3W 50 KT 60 MPH
72H 01/0600Z 15.0N 42.5W 65 KT 75 MPH
96H 02/0600Z 16.5N 48.0W 75 KT 85 MPH
120H 03/0600Z 18.0N 52.0W 85 KT 100 MPH

$$
FORECASTER BRENNAN

[southerngale]

[WeatherGuesser]

Faster it develops more likely to re-curve...Been the rule of thumb over the years...

I really wish people wouldn't make statements like that. If we've learned anything from the last two or three years, it's that there really aren't any normals any more. The past is no guarantee of the present or the future.

And I'm REEAALLYY tired of hearing about JB whoever and so-and-so Masters like they're some kind of Gods of knowing everything possible about everything. They're just people like all the rest of us.

[KWT]

Pretty much no chance of a US landfall if the ECM synoptics are correct, huge upper trough over the E.coast of the US.

Set-up is a possdible threat to Bermuda and E.Canada though I'd have thought, and the 00z ECM backs up that idea with a hit.

Ne Caribbean isn't totally out of the question either...

[KWT]

Looking at the set-up aloft it looks like a big risk down the line to Bermuda...I suspect anywhere else other then maybe E.Canada should be *ok*.

As I said in the model thread, its a track that probably the NE Caribbean needs to keep a close eye on, I think it should clear the islands to the north but then again the models thought the same with Earl last year and that had a mighty close call.

I expect a slightly further west version of Danielle from last year.

[Florida1118]

Faster it develops more likely to re-curve...Been the rule of thumb over the years...

I really wish people wouldn't make statements like that. If we've learned anything from the last two or three years, it's that there really aren't any normals any more. The past is no guarantee of the present or the future.

And I'm REEAALLYY tired of hearing about JB whoever and so-and-so Masters like they're some kind of Gods of knowing everything possible about everything. They're just people like all the rest of us.

Well that rule of thumb is generally correct. They didnt say itwas 100%, just somewhat likely. And yeah your going to hear about JB, a met who likes to hype, and Dr.Jeff Masters, a well respected met. And yes they are normal people like us, but they have degrees

[KWT]

Yeah to be fair more often then not if they form this far east they recurve, there are probably aren't that many that have struck the US from this position, maybe something between 10-15%?

Thats without considering the Perma trough we've had for the last few years.

[Thunder44]

I do think given that's already developed and the how far east ridge is positioned in the Atlantic. I think chances are greater than not for a recurve, into the open Atlantic. But given how much the models underestimated the strength of the ridge in the West Atlantic with Irene and the usual problems with models, in long range, I'm not going to write off a threat to the East Coast US or even the NE Leeward Islands, down the road, yet.

This the 0z Euro ensemble mean at 216hrs:

[KWT]

You could easily argue the opposite though Thunder, given the models constantly shifted eastwards would suggest they under-eatimated the strength of the upper trough.

The ensembles show that big upper trough as well, I'd be very surprised if it ends up getting west of 65-70W, recurve would probably make it a threat to bermuda though IMO...

[Nightwatch]

it's already TS Katia

Wonder if this one is gonna curve or not. Gotta follow this. Thx for the updates.

[Thunder44]

You could easily argue the opposite though Thunder, given the models constantly shifted eastwards would suggest they under-eatimated the strength of the upper trough.

The ensembles show that big upper trough as well, I'd be very surprised if it ends up getting west of 65-70W, recurve would probably make it a threat to bermuda though IMO...

I don't think you will see models showing a Gulf coast or a FL east coast threat too much this time around. But I will also point out that the strong +PNA forecast at this time, by the GFS and ECMWF ensemble means also support a much deeper East Coast/West Atantic trough. And a +NAO that would not prevent this from recurving more out to sea, unlike Irene.

[KWT]

I think with Irejne is a combo of timing and the fact it stayed weak till 55-60W...this could be a major hurricane by that point and that is going to make a difference when it comes to the probable track.

[cycloneye]

06z GFS slightly closer to NE Caribbean at 168 hours. After that it does the same,going north close to Bermuda to it's east and making landfall at Nova Scotia.



Saved image.

[WeatherGuesser]

it's already TS Katia

Says who?

[KWT]

I think if you look at where Jose is you'll get a good general area as to where TD12 will likely head in 10-12 days time...

[KWT]

Very interesting run, goes east of Bermuda by a reasonable distance bur ends up bending back decently to the NW into E.Canada.

Doesn't seem all that realisitic IMO...esp with the predicted set-up aloft.

[Thunder44]

I think with Irejne is a combo of timing and the fact it stayed weak till 55-60W...this could be a major hurricane by that point and that is going to make a difference when it comes to the probable track.

Yeah, it important to watch how much this develops as well. So far the models have been overdoing development with waves farther in the Atlantic, because of the SAL. It doesn't seem to be as much of problem with this system, right now. But need to wait and see, before writing off landfall threats. It's also pretty far south, right now.

[KWT]

It is very far south, still the models are very agressive when it comes to making a hurricane, they've not been bad when it comes to that side of things this season it has to be said, even if they have somewhat under-estimated systems sometimes.

[Blown Away]

Looks like a giant hole off the EC that will allow any system reaching @60W to turn N. Almost September and any system after TD12 will be 2 weeks from the EC, it seems the chances of an EC strike from the SE are lessoning.