ATL: KATIA - Post Tropical - Discussion

[HurricaneBelle]

Katia is as far north now as irene was when she was just north of hispanola...the level of concern over Katia should be much less right now than it was for Irene...and if there was no Irene, this wouldn't be getting nearly as much attention. Once an area has been impacted by a storm, it is natural to think every storm is going to follow the same track! Until the U.S. is in the 5-day cone, the concern level should be 'monitor'.

Actually in looking back at most of the big storms to affect the NE US, Irene was kind of an outlier in how far south she was compared to the others. Most were north of the islands and north of the Bahamas.

Also, it's not unheard of for multiple storms to impact the same area in the same season - Carol/Edna both hit the NE in 1954, Bertha/Fran NC 1996, Dennis/Floyd NC 1999, Frances/Jeanne EFL 2004, etc.

[cpdaman]

i would like ARIC's imput on this but to me it look's like

the EURO operational run looks pretty well centered among ensemble members which for the first 120 hrs seem to have little spread

[supercane]

000
WTNT42 KNHC 032052
TCDAT2

TROPICAL STORM KATIA DISCUSSION NUMBER 23
NWS NATIONAL HURRICANE CENTER MIAMI FL AL122011
500 PM AST SAT SEP 03 2011

DVORAK INTENSITY ESTIMATES HAVE FALLEN THROUGH THE DAY AND ARE NOW
T3.0/4.0 FROM TAFB AND T3.5/3.5 FROM SAB. BASED ON THE STRUCTURE
NOTED IN EARLIER MICROWAVE DATA...IT APPEARS THAT KATIA HAS
WEAKENED SOME AND AGAIN IS A TROPICAL STORM. FLUCTUATIONS IN
INTENSITY BY 5 TO 10 KT ARE POSSIBLE OVER THE NEXT DAY OR SO...BUT
THIS FACT WILL ONLY BE MORE APPARENT THAN USUAL SINCE THE INTENSITY
WOULD BE OSCILLATING AROUND THE 65-KT HURRICANE THRESHOLD.

IT CANNOT BE STRESSED ENOUGH THAT THERE IS CONSIDERABLE UNCERTAINTY
IN THE TRACK FORECAST...WHICH IS EXTREMELY SENSITIVE TO THE
EVOLUTION OF TROPICAL STORM LEE AND ITS INTERACTION WITH A MID-
TO UPPER-LEVEL LOW OVER THE EASTERN UNITED STATES. THE MODEL
GUIDANCE IS IN PRETTY GOOD AGREEMENT DURING THE FIRST 36 HOURS OR
SO...BUT THE DIVERGENCE ONLY GROWS FROM THERE. COMPARED TO THE
PREVIOUS FORECAST CYCLE...THE UKMET HAS SHIFTED TO THE NORTH AND
THE GFS HAS SLOWED DOWN...WHICH NORMALLY WOULD HAVE INCREASED
CONFIDENCE IN THE FORECAST. FURTHERMORE...THE ECMWF...WHICH IS
NORMALLY RELIABLE...SWUNG FROM THE NORTH AND EAST SIDE OF THE
GUIDANCE TO THE SOUTH AND WEST SIDE...SHOWING A MORE WESTWARD
MOTION BY DAY 5. THE OFFICIAL TRACK FORECAST HAS BEEN NUDGED A BIT
TO THE WEST TOWARDS THE VARIOUS CONSENSUS MODELS...BUT WE WOULD
RATHER SEE SOME STABILITY IN THE MODELS BEFORE MAKING A LARGER
SHIFT.

NEEDLESS TO SAY...THE INTENSITY FORECAST IS ALSO COMPLEX. KATIA HAS
NOT BEEN STRENGTHENING AS ANTICIPATED...AND UPPER-LEVEL WINDS DO
NOT APPEAR AS THOUGH THEY WILL BE CONDUCIVE FOR SIGNIFICANT
INTENSIFICATION FOR THE NEXT 24 TO 48 HOURS. THE UPPER-LEVEL
ENVIRONMENT AROUND KATIA BECOMES MORE UNCERTAIN AFTER
THAT TIME DEPENDING ON THE POSITIONING OF THE EASTERN U.S.
MID-/UPPER-LEVEL LOW. THE STATISTICAL SHIPS AND LGEM MODELS DO NOT
STRENGTHEN KATIA BEYOND CATEGORY 1 STATUS WHEREAS THE GFDL AND HWRF
STILL SHOW THE STORM REACHING MAJOR HURRICANE STRENGTH. THE
OFFICIAL INTENSITY FORECAST IS STILL NEAR OR JUST ABOVE THE
INTENSITY CONSENSUS...ESPECIALLY AT DAYS 4 AND 5.

FORECAST POSITIONS AND MAX WINDS

INIT 03/2100Z 19.9N 56.8W 60 KT 70 MPH
12H 04/0600Z 20.7N 58.1W 65 KT 75 MPH
24H 04/1800Z 21.8N 59.8W 65 KT 75 MPH
36H 05/0600Z 23.1N 61.5W 70 KT 80 MPH
48H 05/1800Z 24.3N 63.2W 75 KT 85 MPH
72H 06/1800Z 27.0N 66.0W 85 KT 100 MPH
96H 07/1800Z 29.5N 69.0W 90 KT 105 MPH
120H 08/1800Z 31.5N 70.5W 85 KT 100 MPH

$$
FORECASTER BERG

[Aric Dunn]

hardly a consensus after just 36 to 48 hours

[gatorcane]

Some strong wording on the 5pmEST NHC discussion:

Just shows how much they respect the ECMWF because it made a big shift west though nearly all of the other models still go NW following the GFS operational.

IT CANNOT BE STRESSED ENOUGH THAT THERE IS CONSIDERABLE UNCERTAINTY
IN THE TRACK FORECAST...WHICH IS EXTREMELY SENSITIVE TO THE
EVOLUTION OF TROPICAL STORM LEE AND ITS INTERACTION WITH A MID-
TO UPPER-LEVEL LOW OVER THE EASTERN UNITED STATES.

http://www.nhc.noaa.gov/text/refresh/MI ... 2052.shtml?

[cycloneye]

SUMMARY OF 500 PM AST...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...19.9N 56.8W
ABOUT 430 MI...690 KM ENE OF THE NORTHERN LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...70 MPH...110 KM/H
PRESENT MOVEMENT...WNW OR 300 DEGREES AT 10 MPH...17 KM/H
MINIMUM CENTRAL PRESSURE...993 MB...29.32 INCHES

[Aric Dunn]

18z nam showing more ridging early on an more late as well... with the trough off the east coast starting to lift and weaken in 24 hours.. so thats what we need to watch as see what happens with that trough

http://mag.ncep.noaa.gov/NCOMAGWEB/appc ... mageSize=M

[Aric Dunn]

Some strong wording on the 5pmEST NHC discussion:

Just shows how much they respect the ECMWF because it made a big shift west though nearly all of the other models still go NW following the GFS operational.

IT CANNOT BE STRESSED ENOUGH THAT THERE IS CONSIDERABLE UNCERTAINTY
IN THE TRACK FORECAST...WHICH IS EXTREMELY SENSITIVE TO THE
EVOLUTION OF TROPICAL STORM LEE AND ITS INTERACTION WITH A MID-
TO UPPER-LEVEL LOW OVER THE EASTERN UNITED STATES.

http://www.nhc.noaa.gov/text/refresh/MI ... 2052.shtml?

yeah its very very uncertain still basically from the bahamas to nova scotia need to watch still

[gatorcane]

18z nam showing more ridging early on an more late as well... with the trough off the east coast starting to lift and weaken in 24 hours.. so thats what we need to watch as see what happens with that trough

http://mag.ncep.noaa.gov/NCOMAGWEB/appc ... mageSize=M

Yeah Aric, I see that. The trough is also lifting out pretty quickly there and it didn't scoop it up. Could even bend a bit more due west if we went farther out, maybe going into the Bahamas.

[cycloneye]

5 PM Track. Saved image.

[WeatherGuesser]

Although I don't really have anything to base it on, I've been saying from early on in this thread that the east coast should not be taken out of play just yet.

[meriland23]

From the NHC
(bold interet parts)
000
WTNT42 KNHC 032052
TCDAT2

TROPICAL STORM KATIA DISCUSSION NUMBER 23
NWS NATIONAL HURRICANE CENTER MIAMI FL AL122011
500 PM AST SAT SEP 03 2011

DVORAK INTENSITY ESTIMATES HAVE FALLEN THROUGH THE DAY AND ARE NOW
T3.0/4.0 FROM TAFB AND T3.5/3.5 FROM SAB. BASED ON THE STRUCTURE
NOTED IN EARLIER MICROWAVE DATA...IT APPEARS THAT KATIA HAS
WEAKENED SOME AND AGAIN IS A TROPICAL STORM. FLUCTUATIONS IN
INTENSITY BY 5 TO 10 KT ARE POSSIBLE OVER THE NEXT DAY OR SO...BUT
THIS FACT WILL ONLY BE MORE APPARENT THAN USUAL SINCE THE INTENSITY
WOULD BE OSCILLATING AROUND THE 65-KT HURRICANE THRESHOLD.

IT CANNOT BE STRESSED ENOUGH THAT THERE IS CONSIDERABLE UNCERTAINTY
IN THE TRACK FORECAST...WHICH IS EXTREMELY SENSITIVE TO THE
EVOLUTION OF TROPICAL STORM LEE AND ITS INTERACTION WITH A MID-
TO UPPER-LEVEL LOW OVER THE EASTERN UNITED STATES. THE MODEL
GUIDANCE IS IN PRETTY GOOD AGREEMENT DURING THE FIRST 36 HOURS OR
SO...BUT THE DIVERGENCE ONLY GROWS FROM THERE. COMPARED TO THE
PREVIOUS FORECAST CYCLE...THE UKMET HAS SHIFTED TO THE NORTH AND
THE GFS HAS SLOWED DOWN...WHICH NORMALLY WOULD HAVE INCREASED
CONFIDENCE IN THE FORECAST. FURTHERMORE...THE ECMWF...WHICH IS
NORMALLY RELIABLE...SWUNG FROM THE NORTH AND EAST SIDE OF THE
GUIDANCE TO THE SOUTH AND WEST SIDE...SHOWING A MORE WESTWARD
MOTION BY DAY 5. THE OFFICIAL TRACK FORECAST HAS BEEN NUDGED A BIT
TO THE WEST TOWARDS THE VARIOUS CONSENSUS MODELS...BUT WE WOULD
RATHER SEE SOME STABILITY IN THE MODELS BEFORE MAKING A LARGER
SHIFT.

NEEDLESS TO SAY...THE INTENSITY FORECAST IS ALSO COMPLEX. KATIA HAS
NOT BEEN STRENGTHENING AS ANTICIPATED...AND UPPER-LEVEL WINDS DO
NOT APPEAR AS THOUGH THEY WILL BE CONDUCIVE FOR SIGNIFICANT
INTENSIFICATION FOR THE NEXT 24 TO 48 HOURS. THE UPPER-LEVEL
ENVIRONMENT AROUND KATIA BECOMES MORE UNCERTAIN AFTER
THAT TIME DEPENDING ON THE POSITIONING OF THE EASTERN U.S.
MID-/UPPER-LEVEL LOW. THE STATISTICAL SHIPS AND LGEM MODELS DO NOT
STRENGTHEN KATIA BEYOND CATEGORY 1 STATUS WHEREAS THE GFDL AND HWRF
STILL SHOW THE STORM REACHING MAJOR HURRICANE STRENGTH. THE
OFFICIAL INTENSITY FORECAST IS STILL NEAR OR JUST ABOVE THE
INTENSITY CONSENSUS...ESPECIALLY AT DAYS 4 AND 5.

[GCANE]

18z nam showing more ridging early on an more late as well... with the trough off the east coast starting to lift and weaken in 24 hours.. so thats what we need to watch as see what happens with that trough

http://mag.ncep.noaa.gov/NCOMAGWEB/appc ... mageSize=M

Yeah Aric, I see that. The trough is also lifting out pretty quickly there and it didn't scoop it up. Could even bend a bit more due west if we went farther out, maybe going into the Bahamas.

That would starting bringing it close to some very warm water.

[meriland23]

From the NHC
(bold interet parts)
000
WTNT42 KNHC 032052
TCDAT2

TROPICAL STORM KATIA DISCUSSION NUMBER 23
NWS NATIONAL HURRICANE CENTER MIAMI FL AL122011
500 PM AST SAT SEP 03 2011

DVORAK INTENSITY ESTIMATES HAVE FALLEN THROUGH THE DAY AND ARE NOW
T3.0/4.0 FROM TAFB AND T3.5/3.5 FROM SAB. BASED ON THE STRUCTURE
NOTED IN EARLIER MICROWAVE DATA...IT APPEARS THAT KATIA HAS
WEAKENED SOME AND AGAIN IS A TROPICAL STORM. FLUCTUATIONS IN
INTENSITY BY 5 TO 10 KT ARE POSSIBLE OVER THE NEXT DAY OR SO...BUT
THIS FACT WILL ONLY BE MORE APPARENT THAN USUAL SINCE THE INTENSITY
WOULD BE OSCILLATING AROUND THE 65-KT HURRICANE THRESHOLD.

IT CANNOT BE STRESSED ENOUGH THAT THERE IS CONSIDERABLE UNCERTAINTY
IN THE TRACK FORECAST...WHICH IS EXTREMELY SENSITIVE TO THE
EVOLUTION OF TROPICAL STORM LEE AND ITS INTERACTION WITH A MID-
TO UPPER-LEVEL LOW OVER THE EASTERN UNITED STATES. THE MODEL
GUIDANCE IS IN PRETTY GOOD AGREEMENT DURING THE FIRST 36 HOURS OR
SO...BUT THE DIVERGENCE ONLY GROWS FROM THERE. COMPARED TO THE
PREVIOUS FORECAST CYCLE...THE UKMET HAS SHIFTED TO THE NORTH AND
THE GFS HAS SLOWED DOWN...WHICH NORMALLY WOULD HAVE INCREASED
CONFIDENCE IN THE FORECAST. FURTHERMORE...THE ECMWF...WHICH IS
NORMALLY RELIABLE...SWUNG FROM THE NORTH AND EAST SIDE OF THE
GUIDANCE TO THE SOUTH AND WEST SIDE...SHOWING A MORE WESTWARD
MOTION BY DAY 5. THE OFFICIAL TRACK FORECAST HAS BEEN NUDGED A BIT
TO THE WEST TOWARDS THE VARIOUS CONSENSUS MODELS...BUT WE WOULD
RATHER SEE SOME STABILITY IN THE MODELS BEFORE MAKING A LARGER
SHIFT.

NEEDLESS TO SAY...THE INTENSITY FORECAST IS ALSO COMPLEX. KATIA HAS
NOT BEEN STRENGTHENING AS ANTICIPATED...AND UPPER-LEVEL WINDS DO
NOT APPEAR AS THOUGH THEY WILL BE CONDUCIVE FOR SIGNIFICANT
INTENSIFICATION FOR THE NEXT 24 TO 48 HOURS. THE UPPER-LEVEL
ENVIRONMENT AROUND KATIA BECOMES MORE UNCERTAIN AFTER
THAT TIME DEPENDING ON THE POSITIONING OF THE EASTERN U.S.
MID-/UPPER-LEVEL LOW. THE STATISTICAL SHIPS AND LGEM MODELS DO NOT
STRENGTHEN KATIA BEYOND CATEGORY 1 STATUS WHEREAS THE GFDL AND HWRF
STILL SHOW THE STORM REACHING MAJOR HURRICANE STRENGTH. THE
OFFICIAL INTENSITY FORECAST IS STILL NEAR OR JUST ABOVE THE
INTENSITY CONSENSUS...ESPECIALLY AT DAYS 4 AND 5.

[gatorcane]

18Z GFS runs shortly, it has been really reluctant to show any bend to the west.

It will be interesting if it bends west also. It might considering the GFS ensembles have shifted west.

[meriland23]

18Z GFS runs shortly, it has been really reluctant to show any bend to the west.

It will be interesting if it bends west also. It might considering the GFS ensembles have shifted west.

If the 12z euro influences gfs 18z, there might be serious concern on nhc.

[Aric Dunn]

just noticed the motion is back wnw..

[WeatherEmperor]

just noticed the motion is back wnw..

What was it before? Was it NW? So now that the motion is WNW does that mean that the models tonight could shift more west?

[ROCK]

18Z GFS runs shortly, it has been really reluctant to show any bend to the west.

It will be interesting if it bends west also. It might considering the GFS ensembles have shifted west.

ensembles I think give it away...I think the 18z GFS will bend west...

[WeatherEmperor]

How often do you see this? The HWRF is the LEFT outlier? I thought it always used to be the RIGHT outlier???



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