[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT42 KNHC 082054
TCDAT2

HURRICANE KATIA DISCUSSION NUMBER  43
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL122011
500 PM AST THU SEP 08 2011


CONVECTION PERSISTS NEAR THE CENTER OF KATIA AND CLOUD BANDS HAVE
INCREASED IN ORGANIZATION...PARTICULARLY IN THE SOUTHWEST QUADRANT
THAT WAS PREVIOUSLY DEVOID OF CONVECTION. HOWEVER...A RECENT ASCAT
PASS AND TAFB/SAB SATELLITE ESTIMATES SUGGEST THAT THE MAXIMUM
WINDS HAVE DECREASED SLIGHTLY. THE TAFB/SAB ESTIMATES ARE THE BASIS
FOR A SLIGHT DECREASE IN THE INITIAL INTENSITY...TO 75 KT.

KATIA IS MOVING SLIGHTLY EAST OF NORTH...WITH AN INITIAL MOTION OF
005/14. RELIABLE NUMERICAL GUIDANCE SUGGESTS THAT KATIA WILL
CONTINUE TO TURN AND ACCELERATE NORTHEASTWARD OVER THE NEXT SEVERAL
DAYS...AND BECOME EXTRATROPICAL WITHIN TWO TO THREE DAYS. THE
EXTRATROPICAL STORM SHOULD PASS NEAR THE BRITISH ISLES IN ABOUT
FIVE DAYS. GUIDANCE HAS BEEN CONSISTENT AND IN GOOD AGREEMENT ON
THE TRACK OF KATIA...AND THE TRACK FORECAST IS VERY CLOSE TO THE
PREVIOUS ADVISORY.

RELIABLE INTENSITY GUIDANCE SUGGESTS THAT KATIA WILL WEAKEN RATHER
SLOWLY DURING THE NEXT SEVERAL DAYS...AND THE GLOBAL MODELS SUGGEST
THAT THE CYCLONE WILL REMAIN LARGE AND POWERFUL AFTER EXTRATROPICAL
TRANSITION AS IT TRAVERSES THE NORTH ATLANTIC. INITIAL WIND RADII
ARE ADJUSTED OUTWARD IN THE SOUTHWEST QUADRANT BASED ON THE RECENT
ASCAT PASS.


FORECAST POSITIONS AND MAX WINDS

INIT  08/2100Z 34.9N  69.6W   75 KT  85 MPH
 12H  09/0600Z 36.9N  68.4W   75 KT  85 MPH
 24H  09/1800Z 39.3N  64.6W   75 KT  85 MPH
 36H  10/0600Z 41.6N  57.7W   70 KT  80 MPH
 48H  10/1800Z 44.2N  47.7W   65 KT  75 MPH...POST-TROP/EXTRATROP
 72H  11/1800Z 52.2N  23.8W   60 KT  70 MPH...POST-TROP/EXTRATROP
 96H  12/1800Z 59.4N   6.9W   55 KT  65 MPH...POST-TROP/EXTRATROP
120H  13/1800Z 62.2N   2.2E   50 KT  60 MPH...POST-TROP/EXTRATROP

$$
FORECASTER HOGSETT/FRANKLIN


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