ATL: KATIA - Post Tropical - Discussion

[Dave]

I live in southeast Indiana and a line of storms from the first outer band of Lee are moving through my area right now. The cold front in Minnesota is scheduled to be here tomorrow afternoon which will take us from the high 90's to the low 70's but it will hopefully help push Katia further out to sea.

[ozonepete]

Here's a side by side of KATIA from 2PM EDT today and 9:15PM this evening. Note the improvement in symmetry (getting much more circular). That's best illustrated by how the southern end was sheared and now it's building out nicely.



Note also the high white cirrus clouds feathering out all around the outer edges. That's a sign of good outflow at the top (around jet stream level) which allows the storm to vent all of that warm moist air it's pulling in at the surface.

[supercane]

Latest microwave image from ~2hr ago:

[ozonepete]

Thanks, supercane. Wow, look at this improvement on microwave over the last several hours. Convection wrapping nicely around the center.

[RL3AO]

Looks like a storm thats in a better environment.

[supercane]

000
WTNT22 KNHC 040249
TCMAT2

TROPICAL STORM KATIA FORECAST/ADVISORY NUMBER 24
NWS NATIONAL HURRICANE CENTER MIAMI FL AL122011
0300 UTC SUN SEP 04 2011

THERE ARE NO COASTAL WATCHES OR WARNINGS IN EFFECT.

TROPICAL STORM CENTER LOCATED NEAR 20.3N 57.4W AT 04/0300Z
POSITION ACCURATE WITHIN 20 NM

PRESENT MOVEMENT TOWARD THE NORTHWEST OR 305 DEGREES AT 9 KT

ESTIMATED MINIMUM CENTRAL PRESSURE 992 MB
MAX SUSTAINED WINDS 60 KT WITH GUSTS TO 75 KT.
50 KT....... 60NE 40SE 30SW 50NW.
34 KT.......120NE 105SE 75SW 105NW.
12 FT SEAS..270NE 180SE 180SW 270NW.
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 20.3N 57.4W AT 04/0300Z
AT 04/0000Z CENTER WAS LOCATED NEAR 20.0N 57.0W

FORECAST VALID 04/1200Z 21.0N 58.6W
MAX WIND 65 KT...GUSTS 80 KT.
64 KT... 30NE 0SE 0SW 0NW.
50 KT... 60NE 40SE 30SW 50NW.
34 KT...120NE 105SE 75SW 105NW.

FORECAST VALID 05/0000Z 22.3N 60.3W
MAX WIND 65 KT...GUSTS 80 KT.
64 KT... 30NE 0SE 0SW 0NW.
50 KT... 60NE 40SE 30SW 50NW.
34 KT...120NE 105SE 75SW 105NW.

FORECAST VALID 05/1200Z 23.5N 62.0W
MAX WIND 70 KT...GUSTS 85 KT.
64 KT... 35NE 30SE 0SW 30NW.
50 KT... 70NE 50SE 40SW 60NW.
34 KT...135NE 105SE 90SW 120NW.

FORECAST VALID 06/0000Z 24.5N 63.5W
MAX WIND 75 KT...GUSTS 90 KT.
50 KT... 70NE 50SE 50SW 60NW.
34 KT...135NE 105SE 90SW 120NW.

FORECAST VALID 07/0000Z 27.0N 67.0W
MAX WIND 85 KT...GUSTS 105 KT.
50 KT... 90NE 70SE 60SW 80NW.
34 KT...150NE 135SE 120SW 135NW.

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 08/0000Z 29.1N 70.0W
MAX WIND 90 KT...GUSTS 110 KT.

OUTLOOK VALID 09/0000Z 32.0N 71.0W
MAX WIND 85 KT...GUSTS 105 KT.

REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 20.3N 57.4W

NEXT ADVISORY AT 04/0900Z

$$
FORECASTER AVILA

[cycloneye]

TTAA00 KNHC DDHHMM

TROPICAL STORM KATIA DISCUSSION NUMBER 24
NWS NATIONAL HURRICANE CENTER MIAMI FL AL122011
1100 PM AST SAT SEP 03 2011

ONCE AGAIN TONIGHT...THERE IS AN INCREASE IN ORGANIZATION OF THE
CLOUD PATTERN WITH THE FORMATION OF A ROUND CENTRAL DENSE OVERCAST
AND A BETTER DEFINED OUTFLOW IN CONVENTIONAL IR IMAGES. I HAVE BEEN
LUCKY ENOUGH TO HAVE SEVERAL MICROWAVE PASSES OVER KATIA TONIGHT.
THESE DATA SHOW A MUCH BETTER ORGANIZED INNER CORE STRUCTURE THAN
IN EARLIER PASSES...BUT THE CIRCULAR RING OF CONVECTION
REPRESENTING THE MID-LEVEL EYE FEATURE CONTINUES TO BE DISPLACED TO
THE NORTH OF THE LOW-LEVEL CENTER DUE TO SHEAR. THIS SUGGESTS THAT
THE CYCLONE MIGHT NOT BE AS WELL ORGANIZED AS IT SEEMS IN
CONVENTIONAL IMAGERY. HAVING SAID THAT...THE INITIAL INTENSITY HAS
BEEN KEPT AT 60 KNOTS BASED ON A BLEND OF THE LATEST DVORAK
T-NUMBERS. AS STATED IN THE PREVIOUS ADVISORY...KATIA COULD REACH
HURRICANE STATUS AGAIN AT ANY TIME...AND SINCE THE SHEAR SHOULD
BEGIN TO RELAX IN ABOUT 12 TO 24 HOURS ACCORDING TO THE SHIPS
MODEL...A GRADUAL INTENSIFICATION IS INDICATED IN THE OFFICIAL
FORECAST.

SINCE THE OVERALL STEERING PATTERN HAS NOT CHANGED...THERE IS NOT
TOO MUCH TO ADD TO THE DISCUSSION. KATIA CONTINUES TO MOVE TOWARD
THE NORTHWEST OR 305 DEGREES AT 9 KNOTS AROUND THE SOUTHERN EDGE OF
THE SUBTROPICAL RIDGE. GUIDANCE HAS BEEN SHIFTING SLIGHTLY EASTWARD
OR WESTWARD DEPENDING ON HOW EACH MODEL REPRESENTS THE MID-LEVEL
TROUGH OVER THE EASTERN UNITED STATES IN EACH RUN. IT INTERESTING
TO NOTE THAT TONIGHT...THE GFS DEFINES THE EASTERN SIDE OF THE
GUIDANCE ENVELOPE AND THE ECMWF THE WESTERN EDGE. THE OFFICIAL
FORECAST IS A THE MIDDLE OF THESE TWO EXTREME SOLUTIONS. IN
GENERAL...MODEL SOLUTIONS ARE TO KEEP KATIA ON A TRACK BETWEEN THE
WEST-NORTHWEST AND NORTHWEST FOR THE NEXT 3 TO 4 DAYS AND THEN TURN
THE CYCLONE MORE TO THE NORTH THEREAFTER.

NOAA BUOY 41044...LOCATED A LITTLE MORE THAN 100 N MI TO THE
NORTHWEST OF KATIA RECENTLY REPORTED WINDS OF 33 KNOTS AND 18-FOOT
WAVES.


FORECAST POSITIONS AND MAX WINDS

INIT 04/0300Z 20.3N 57.4W 60 KT 70 MPH
12H 04/1200Z 21.0N 58.6W 65 KT 75 MPH
24H 05/0000Z 22.3N 60.3W 65 KT 75 MPH
36H 05/1200Z 23.5N 62.0W 70 KT 80 MPH
48H 06/0000Z 24.5N 63.5W 75 KT 85 MPH
72H 07/0000Z 27.0N 67.0W 85 KT 100 MPH
96H 08/0000Z 29.1N 70.0W 90 KT 105 MPH
120H 09/0000Z 32.0N 71.0W 85 KT 100 MPH

$$
FORECASTER AVILA

NNNN

[supercane]

Still a TS at 03Z:
BULLETIN
TROPICAL STORM KATIA ADVISORY NUMBER 24
NWS NATIONAL HURRICANE CENTER MIAMI FL AL122011
1100 PM AST SAT SEP 03 2011

...KATIA COULD REGAIN HURRICANE STATUS ON SUNDAY AS IT MOVES WELL
NORTH OF THE LEEWARD ISLANDS...


SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...20.3N 57.4W
ABOUT 400 MI...640 KM ENE OF THE NORTHERN LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...70 MPH...110 KM/H
PRESENT MOVEMENT...NW OR 305 DEGREES AT 10 MPH...17 KM/H
MINIMUM CENTRAL PRESSURE...992 MB...29.29 INCHES

[Macrocane]

Still a tropical storm, but Avila wrote the discussion so I know why it wasn't upgraded although he gave good reason to keep is as a TS.

[ozonepete]

The NHC 11PM discussion is very interesting. First of all, it points out the once again changing situation as Katia shows signs of strengthening again:

ONCE AGAIN TONIGHT...THERE IS AN INCREASE IN ORGANIZATION OF THE CLOUD PATTERN WITH THE FORMATION OF A ROUND CENTRAL DENSE OVERCAST AND A BETTER DEFINED OUTFLOW IN CONVENTIONAL IR IMAGES. I HAVE BEEN LUCKY ENOUGH TO HAVE SEVERAL MICROWAVE PASSES OVER KATIA TONIGHT. THESE DATA SHOW A MUCH BETTER ORGANIZED INNER CORE STRUCTURE THAN IN EARLIER PASSES...BUT THE CIRCULAR RING OF CONVECTION REPRESENTING THE MID-LEVEL EYE FEATURE CONTINUES TO BE DISPLACED TO THE NORTH OF THE LOW-LEVEL CENTER DUE TO SHEAR. THIS SUGGESTS THAT THE CYCLONE MIGHT NOT BE AS WELL ORGANIZED AS IT SEEMS IN CONVENTIONAL IMAGERY. HAVING SAID THAT...THE INITIAL INTENSITY HAS BEEN KEPT AT 60 KNOTS BASED ON A BLEND OF THE LATEST DVORAK T-NUMBERS. AS STATED IN THE PREVIOUS ADVISORY...KATIA COULD REACH HURRICANE STATUS AGAIN AT ANY TIME...AND SINCE THE SHEAR SHOULD BEGIN TO RELAX IN ABOUT 12 TO 24 HOURS ACCORDING TO THE SHIPS MODEL...A GRADUAL INTENSIFICATION IS INDICATED IN THE OFFICIAL FORECAST.

One very interesting comment our great forecaster Lixion Avila added to the discussion:

IT INTERESTING TO NOTE THAT TONIGHT...THE GFS DEFINES THE EASTERN SIDE OF THE GUIDANCE ENVELOPE AND THE ECMWF THE WESTERN EDGE. THE OFFICIAL FORECAST IS A THE MIDDLE OF THESE TWO EXTREME SOLUTIONS.

Why so interesting, and why did he say that? Well, that’s what happened with Irene. The ECMWF went west and the GFS went right for quite a while and then the GFS finally moved into agreement with the Euro model. This could get interesting…

[Jevo]

0z GFS Initialized (24 hour plots)



0z GFS +24

[Jevo]

0z GFS +48



0z GFS +72

[Time_Zone]

So if it were to make it to Nova Scotia it would be weakened quite a bit, correct?

Still looks like its gonna go straight out to sea anyways.

[Jevo]

18z GFS +96



18z GFS +120

[maxintensity]

Looks like yet another safe recurve on this run of the GFS. To be fair, the gfs and euro have never showed this hitting the USA.

[Jevo]

0z GFS +144



0z GFS +171 (Heading to the Flemish Cap)

Another home brew coming together in the gulf

[floridasun78]

is their error with 11pm avd one part say nw other say wnw here what i talking about LOCATION...20.3N 57.4W
ABOUT 400 MI...640 KM ENE OF THE NORTHERN LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...70 MPH...110 KM/H
PRESENT MOVEMENT...NW OR 305 DEGREES AT 10 MPH...17 KM/H
MINIMUM CENTRAL PRESSURE...992 MB...29.29 INCHES here were say wnw DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
AT 1100 PM AST...0300 UTC...THE CENTER OF TROPICAL STORM KATIA WAS
LOCATED NEAR LATITUDE 20.3 NORTH...LONGITUDE 57.4 WEST. KATIA IS
MOVING TOWARD THE WEST-NORTHWEST NEAR 10 MPH...17 KM/H...AND THIS
GENERAL MOTION IS EXPECTED TO CONTINUE THROUGH MONDAY.

[WeatherEmperor]

Just in case nobody noticed yet, I present to you the 00Z NOGAPS. I know it is just the NOGAPS but don't shoot the messenger.....



Uploaded with ImageShack.us

[Blown Away]

Nogaps still is and the ukmet had been showing SE CONUS solutions, but with the GFS/ECMWF/TVCN continued recurve it's a very low probability anything else but recurve from US was gonna happen.

[WeatherEmperor]

The 00Z UKMET is at it again. Shows a big westward bend heading towards FL





GLOBAL MODEL DATA TIME 00UTC 04.09.2011



TROPICAL STORM KATIA ANALYSED POSITION : 20.1N 57.1W



ATCF IDENTIFIER : AL122011



VERIFYING TIME POSITION STRENGTH TENDENCY

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

00UTC 04.09.2011 20.1N 57.1W MODERATE

12UTC 04.09.2011 21.0N 58.7W MODERATE LITTLE CHANGE

00UTC 05.09.2011 22.1N 60.3W STRONG INTENSIFYING SLIGHTLY

12UTC 05.09.2011 22.8N 62.3W STRONG LITTLE CHANGE

00UTC 06.09.2011 23.6N 63.7W STRONG LITTLE CHANGE

12UTC 06.09.2011 24.0N 65.5W STRONG LITTLE CHANGE

00UTC 07.09.2011 24.4N 67.3W INTENSE INTENSIFYING SLIGHTLY

12UTC 07.09.2011 24.7N 69.2W STRONG LITTLE CHANGE

00UTC 08.09.2011 24.8N 70.9W INTENSE LITTLE CHANGE

12UTC 08.09.2011 25.0N 72.7W INTENSE LITTLE CHANGE

00UTC 09.09.2011 25.2N 74.0W INTENSE LITTLE CHANGE

12UTC 09.09.2011 25.7N 75.0W INTENSE LITTLE CHANGE

00UTC 10.09.2011 26.3N 75.4W INTENSE LITTLE CHANGE