[Tropical] Tropical Cyclone Discussion

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WTNT42 KNHC 301432
TCDAT2

TROPICAL STORM KATIA DISCUSSION NUMBER   6
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL122011
1100 AM AST TUE AUG 30 2011

EAST-NORTHEASTERLY SHEAR OVER KATIA HAS DECREASED AND THE STORM
CONTINUES TO GRADUALLY BECOME BETTER ORGANIZED.  THE BANDING
FEATURES ARE BETTER DEFINED AND THE LOW-LEVEL CENTER HAS BECOME
EMBEDDED WITHIN A SMALL CENTRAL CONVECTIVE OVERCAST.  UPPER-LEVEL
OUTFLOW IS ALSO BECOMING MORE PROMINENT.  DVORAK INTENSITY
ESTIMATES RANGE FROM 35 TO 45 KT SO THE CURRENT WIND SPEED IS SET
AT 40 KT.  WITH WEAKENING SHEAR AND SEA SURFACE TEMPERATURES JUST
BELOW 28 DEG C...KATIA SHOULD CONTINUE TO STRENGTHEN AND WILL
LIKELY BECOME A HURRICANE IN 36 HOURS OR SO.  THE OFFICIAL
INTENSITY FORECAST IS CLOSE TO THE HFIP MODEL CONSENSUS...WHICH
SHOWS KATIA NEARING MAJOR HURRICANE STATUS BY THE END OF THE
FORECAST PERIOD.

THE INITIAL MOTION IS A SLIGHTLY FASTER 285/16. NOT MUCH CHANGE HAS
BEEN MADE TO THE TRACK FORECAST.  KATIA IS EXPECTED TO CONTINUE
MOVING WEST-NORTHWESTWARD ON THE SOUTH SIDE OF THE SUBTROPICAL
RIDGE FOR THE NEXT COUPLE OF DAYS.  LATER IN THE FORECAST
PERIOD...THE TROPICAL CYCLONE IS EXPECTED TO BE APPROACHING A
WEAKNESS IN THE RIDGE CREATED BY A TROUGH OVER THE WESTERN
ATLANTIC.  THIS SHOULD CAUSE KATIA TO BEGIN TO TURN TOWARD THE
NORTHWEST WITH A DECREASE IN FORWARD SPEED.  THE OFFICIAL FORECAST
LIES A LITTLE NORTH OF THE DYNAMICAL MODEL CONSENSUS THROUGH 48
HOURS AND IS VERY CLOSE TO THE CONSENSUS FOR THE REMAINDER OF THE
FORECAST PERIOD.

FORECAST POSITIONS AND MAX WINDS

INIT  30/1500Z 12.3N  33.4W   40 KT  45 MPH
 12H  31/0000Z 13.0N  35.7W   50 KT  60 MPH
 24H  31/1200Z 13.8N  39.0W   55 KT  65 MPH
 36H  01/0000Z 14.6N  42.4W   65 KT  75 MPH
 48H  01/1200Z 15.4N  45.7W   75 KT  85 MPH
 72H  02/1200Z 17.0N  51.5W   85 KT 100 MPH
 96H  03/1200Z 19.0N  55.5W   95 KT 110 MPH
120H  04/1200Z 21.5N  59.5W  100 KT 115 MPH

$$
FORECASTER PASCH


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