ATL: KATIA - Post Tropical - Discussion

[clfenwi]

ob 28 didn't get out... plane is now on the ascent.

URNT15 KNHC 061929
AF304 0112A KATIA HDOB 29 20110906
191930 2604N 06458W 6360 03886 //// +045 //// 209057 058 /// /// 05
192000 2603N 06500W 6094 04234 //// +027 //// 211058 059 /// /// 05
192030 2602N 06501W 5843 04581 //// +002 //// 218060 061 /// /// 05
192100 2601N 06502W 5625 04886 //// -013 //// 219060 060 /// /// 05
192130 2601N 06503W 5435 05160 0207 -032 //// 218060 061 /// /// 05
192200 2600N 06504W 5252 05431 0223 -044 //// 215060 062 /// /// 05
192230 2559N 06506W 5075 05701 0238 -066 //// 210063 064 /// /// 05
192300 2558N 06507W 4917 05949 0254 -086 //// 208064 064 035 001 05
192330 2558N 06508W 4813 06114 0262 -098 //// 210063 064 037 000 01
192400 2557N 06509W 4674 06338 0273 -098 //// 224062 062 037 001 01
192430 2556N 06511W 4538 06568 0285 -102 //// 234059 060 037 000 01
192500 2555N 06512W 4423 06752 0285 -114 //// 234059 060 038 001 01
192530 2554N 06513W 4318 06938 0297 -123 //// 237056 056 038 000 01
192600 2553N 06515W 4221 07108 0308 -129 //// 237055 056 038 000 01
192630 2552N 06516W 4130 07282 0324 -139 //// 241055 056 038 001 01
192700 2551N 06518W 4040 07446 0334 -146 //// 243053 055 037 001 01
192730 2551N 06519W 3959 07600 0343 -153 //// 244051 052 037 000 01
192800 2550N 06521W 3923 07669 0348 -161 //// 241055 057 037 000 01
192830 2549N 06522W 3926 07663 0348 -162 //// 247056 057 037 001 01
192900 2548N 06524W 3931 07657 0350 -163 //// 246056 057 037 000 01
$$

[cpdaman]

http://tropic.ssec.wisc.edu/real-time/d ... oom=&time=

current steering show katia should be moving more WNW over the next day or so...possibly going further west than forecast...not sure if this effects NC ....but today is first recon perhaps they will sample the ridge strength and find out it's a tad stronger? that's no 310 degree heading she's on

[SEASON_CANCELED]

So we can write this one off or are models shoving it west?

[GCANE]

HURRICANE KATIA DISCUSSION NUMBER 35
NWS NATIONAL HURRICANE CENTER MIAMI FL AL122011
500 PM AST TUE SEP 06 2011

A 1509 UTC TRMM PASS INDICATES THAT THE INNER EYEWALL OF KATIA IS
DECAYING WITHIN A LARGER EYEWALL...SUGGESTING THAT THE HURRICANE IS
NEARING THE END OF ITS EYEWALL REPLACEMENT.

[crimi481]

Almost looks like Katia wants to go more S.W.?
http://www.ssd.noaa.gov/goes/east/tatl/flash-bd.html

[westwind]

HURRICANE KATIA DISCUSSION NUMBER 35
NWS NATIONAL HURRICANE CENTER MIAMI FL AL122011
500 PM AST TUE SEP 06 2011

A 1509 UTC TRMM PASS INDICATES THAT THE INNER EYEWALL OF KATIA IS
DECAYING WITHIN A LARGER EYEWALL...SUGGESTING THAT THE HURRICANE IS
NEARING THE END OF ITS EYEWALL REPLACEMENT.

Yeah I agree. looks like it is doing something similar to the EWRC that occured a couple of days ago and I am expecting a large eye to become apparent in the next 3 hours after having looked at recent IR imagery. If this occurs as rapidly as I am expecting then it should have an short opportunity to strengthen back to a cat 3 as the eye contracts before sea surface temps become unfavourable for intensification.

I also think that the largest threat to land will be to the north west UK as an extra-tropical cyclone in about 7 days. As I live on the south coast in England I am watching this system closely. When will the data from the research mission be incorporated into the modal runs?

[KWT]

Cat 3 is relatively weak?

Well now its down to a category-2 however your point clearly stands, Katia is still a decent hurricane and we've just had our 2nd major before the peak of the season...

[leanne_uk]

I for one will be keeping an extra close eye on Katia as she takes her trip over the Atlantic. We could get ourselves a little action from her remenants in the UK

[cycloneye]

BULLETIN
HURRICANE KATIA INTERMEDIATE ADVISORY NUMBER 35A
NWS NATIONAL HURRICANE CENTER MIAMI FL AL122011
800 PM AST TUE SEP 06 2011

...KATIA EXPECTED TO PRODUCE LARGE WAVES AND GUSTY WINDS ON
BERMUDA...


SUMMARY OF 800 PM AST...0000 UTC...INFORMATION
----------------------------------------------
LOCATION...27.8N 66.9W
ABOUT 335 MI...540 KM SSW OF BERMUDA
MAXIMUM SUSTAINED WINDS...105 MPH...165 KM/H
PRESENT MOVEMENT...NW OR 310 DEGREES AT 10 MPH...17 KM/H
MINIMUM CENTRAL PRESSURE...963 MB...28.44 INCHES


WATCHES AND WARNINGS
--------------------
CHANGES IN WATCHES AND WARNINGS WITH THIS ADVISORY...

NONE.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT...

A TROPICAL STORM WATCH IS IN EFFECT FOR...
* BERMUDA

A TROPICAL STORM WATCH MEANS THAT TROPICAL STORM CONDITIONS ARE
POSSIBLE WITHIN THE WATCH AREA...GENERALLY WITHIN 48 HOURS.

FOR ADDITIONAL STORM INFORMATION...PLEASE MONITOR PRODUCTS ISSUED BY
THE BERMUDA WEATHER SERVICE.


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
AT 800 PM AST...0000 UTC...THE CENTER OF HURRICANE KATIA WAS LOCATED
NEAR LATITUDE 27.8 NORTH...LONGITUDE 66.9 WEST. KATIA IS MOVING
TOWARD THE NORTHWEST NEAR 10 MPH...17 KM/H...AND THIS GENERAL MOTION
IS EXPECTED TO CONTINUE THROUGH WEDNESDAY...FOLLOWED BY A TURN
TOWARD THE NORTH-NORTHWEST AND NORTH WEDNESDAY NIGHT AND THURSDAY.
ON THE FORECAST TRACK...THE CORE OF KATIA IS EXPECTED TO MOVE
BETWEEN THE EAST COAST OF THE UNITED STATES AND BERMUDA.

MAXIMUM SUSTAINED WINDS ARE NEAR 105 MPH...165 KM/H...WITH HIGHER
GUSTS. KATIA IS A CATEGORY TWO HURRICANE ON THE SAFFIR-SIMPSON
HURRICANE WIND SCALE. LITTLE CHANGE IN STRENGTH IS FORECAST THOUGH
WEDNESDAY...BUT GRADUAL WEAKENING COULD BEGIN BY THURSDAY.

HURRICANE FORCE WINDS EXTEND OUTWARD UP TO 80 MILES...130 KM...FROM
THE CENTER...AND TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 205
MILES...335 KM.

ESTIMATED MINIMUM CENTRAL PRESSURE IS 963 MB...28.44 INCHES.


HAZARDS AFFECTING LAND
----------------------
SURF...LARGE SWELLS GENERATED BY KATIA WILL CONTINUE TO AFFECT MOST
OF THE EAST COAST OF THE UNITED STATES...BERMUDA...THE GREATER
ANTILLES...AND EAST-FACING BEACHES OF THE BAHAMAS DURING THE NEXT
FEW DAYS. THESE SWELLS ARE LIKELY TO CAUSE LIFE-THREATENING SURF
AND RIP CURRENT CONDITIONS. PLEASE CONSULT PRODUCTS FROM YOUR LOCAL
WEATHER SERVICE OFFICE FOR ADDITIONAL INFORMATION.

WIND...TROPICAL-STORM-FORCE WINDS...ESPECIALLY IN GUSTS...ARE
POSSIBLE ON BERMUDA THROUGH THURSDAY.

RAINFALL...KATIA IS EXPECTED TO PRODUCE TOTAL RAIN ACCUMULATIONS OF
1 TO 2 INCHES ACROSS BERMUDA.


NEXT ADVISORY
-------------
NEXT COMPLETE ADVISORY...1100 PM AST.

$$
FORECASTER CANGIALOSI/BRENNAN

[clfenwi]

When will the data from the research mission be incorporated into the modal runs?

9 of the dropsondes got into the 12Z GFS, while another 18 were in the 18Z run. Mission started earlier in the day than the traditional surveillance ones.

[cycloneye]

HURRICANE KATIA DISCUSSION NUMBER 36
NWS NATIONAL HURRICANE CENTER MIAMI FL AL122011
1100 PM AST TUE SEP 06 2011

SINCE THE AIRCRAFT DEPARTED KATIA THIS AFTERNOON THE SATELLITE
PRESENTATION HAS IMPROVED SLIGHTLY. ALTHOUGH THE CONVECTIVE PATTERN
HAS GAINED CURVATURE...THUNDERSTORM ACTIVITY IS QUITE THIN OVER THE
WESTERN SEMICIRCLE...AS SEEN IN THE LAST FEW MICROWAVE OVERPASSES.
THIS ASYMMETRIC PATTERN IS LIKELY DUE TO SOME WESTERLY SHEAR AND
DRY AIR ENTRAINMENT. THE INITIAL WIND SPEED IS HELD AT 90 KT FOR
THIS ADVISORY...WHICH IS IN AGREEMENT WITH AN AVERAGE OF THE DVORAK
T AND CI NUMBERS.

KATIA IS STILL MOVING NORTHWESTWARD AT ABOUT 8 KT...BUT IS EXPECTED
TO TURN TOWARD THE NORTH WITH AN INCREASE IN FORWARD SPEED DURING
THE NEXT 24 TO 36 HOURS AS THE HURRICANE BECOMES EMBEDDED IN THE
FLOW BETWEEN THE SUBTROPICAL RIDGE AND A LARGE UPPER-LEVEL CUTOFF
LOW OVER THE OHIO VALLEY OF THE UNITED STATES. KATIA IS EXPECTED TO
ACCELERATE TO THE NORTHEAST AND EAST-NORTHEAST IN TWO TO THREE DAYS
AS THE CYCLONE GETS SWEPT UP IN THE STRONG MID-LATITUDE FLOW. THE
MODELS REMAIN IN GOOD AGREEMENT ON THE FUTURE TRACK OF KATIA...AND
THE OFFICIAL FORECAST IS SIMILAR TO THE PREVIOUS ONE. THE 96- AND
120-HOUR FORECAST POINTS ARE LARGELY BASED ON GUIDANCE FROM THE
OCEAN PREDICTION CENTER.

LITTLE CHANGE IN STRENGTH OR GRADUAL WEAKENING IS LIKELY DURING THE
NEXT 24 TO 48 HOURS. BEYOND THAT TIME...KATIA WILL BE MOVING OVER
COOLER WATERS AND IS EXPECTED TO ENCOUNTER STRONGER SOUTHWESTERLY
SHEAR. THESE FACTORS SHOULD LEAD TO EXTRATROPICAL TRANSITION...
WHICH IS LIKELY TO OCCUR IN THREE TO FOUR DAYS. ALL OF THE GLOBAL
MODELS SHOW KATIA BECOMING A LARGE AND POWERFUL POST-TROPICAL
CYCLONE OVER THE NORTH ATLANTIC.

FORECAST POSITIONS AND MAX WINDS

INIT 07/0300Z 28.1N 67.2W 90 KT 105 MPH
12H 07/1200Z 29.0N 68.3W 85 KT 100 MPH
24H 08/0000Z 30.6N 69.5W 85 KT 100 MPH
36H 08/1200Z 32.7N 69.9W 80 KT 90 MPH
48H 09/0000Z 35.2N 69.2W 80 KT 90 MPH
72H 10/0000Z 40.0N 62.5W 75 KT 85 MPH
96H 11/0000Z 45.0N 44.0W 70 KT 80 MPH...POST-TROP/EXTRATROP
120H 12/0000Z 55.0N 25.0W 70 KT 80 MPH...POST-TROP/EXTRATROP

$$
FORECASTER CANGIALOSI/BRENNAN

[magnusson_r]

I'm impressed with how accurate the ensemble model has turned out to be. This recurve was predicted last Friday. If all holds steady (as it appears to be doing) it will basically be near 100% accuracy for a 7-day forecast.

I don't think I've ever seen that before.

[SouthFloridawx]

what cha coin katia lol. Anyone notice that wave in the atlantic that has a high chance of becoming a td? Wonder where this one will head.

You mean this one?

2. A TROPICAL WAVE LOCATED ABOUT 300 MILES EAST OF THE LEEWARD ISLANDS
IS EXPECTED TO BRING CLOUDINESS AND SHOWERS OVER THESE ISLANDS
DURING THE NEXT DAY OR SO AS IT MOVES WESTWARD AT AROUND 20 MPH.
UPPER-LEVEL WINDS ARE NOT FAVORABLE FOR SIGNIFICANT DEVELOPMENT...
AND THIS SYSTEM HAS A LOW CHANCE...10 PERCENT...OF BECOMING A
TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

[WxGuy1]

I'm impressed with how accurate the ensemble model has turned out to be. This recurve was predicted last Friday. If all holds steady (as it appears to be doing) it will basically be near 100% accuracy for a 7-day forecast.

I don't think I've ever seen that before.

By and large, I think the GFS and ECMWF have performed well in regards to Katia forecasts. Sure, there have been shifts westward and eastward, but, except for a few very isolated runs, the GFS and ECMWF consistently have forecast that Katia will curve away from the U.S. and into the northern Atlantic for many days now. When the reliable models are this consistent and in pretty good agreement (again, you have to expect 100-300 mile variations from model to model and run to run sometimes when you're looking at a 5 day forecast), you typically can put greater confidence in their forecasts. The UKMET was in wonkeyland for days and days with its forecast of Katia near the Bahamas, but that model was a significant outlier.

[xironman]

Looks like there has been enough shear to drive the dry air into the circulation. This one may wind down faster than expected.



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[dwsqos2]

No, I don't think that the 2005 and especially not the unimpressive 2007 hurricane seasons warped my expectations. Every single non-positive ENSO season of the +AMO era had a hurricane to achieve and maintain major hurricane intensity for more than 18 hours. And most had a storm to remain at or above category 2 intensity above 30N. The unimpressive 2007 season was an exception. Katia's a category one; Katia pretty much has imploded.

[lester]

Two cat5s in the one year is unimpressive? ok

[dwsqos2]

A total of 72 units of ACE was generated that season well below the 1968-2010 mean. There was little significant activity in the MDR after September 5th; most of the storms that did exist were murdered by a powerful central Atlantic upper trough. Yes, I call that a pathetic season by +AMO standards.

[clfenwi]

Gulfstream IV is flying again this morning on a research mission. I haven't seen anything on the particulars of this mission. However, yesterday, I failed to link to the Hurricane Field Program writeup, which explained the research yesterday's flight supported. See pages 35-38.

Recon mission for today was cancelled

. REMARK: MISSION FOR HURRICANE KATIA AT 07/1700Z
CANCELED AT 07/1110Z.

[HurrMark]

A total of 72 units of ACE was generated that season well below the 1968-2010 mean. There was little significant activity in the MDR after September 5th; most of the storms that did exist were murdered by a powerful central Atlantic upper trough. Yes, I call that a pathetic season by +AMO standards.

72 is about average...not well below.