[Tropical] Tropical Cyclone Discussion

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WTNT42 KNHC 302040
TCDAT2

TROPICAL STORM KATIA DISCUSSION NUMBER   7
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL122011
500 PM AST TUE AUG 30 2011

KATIA CONTINUES TO LOOK MORE IMPRESSIVE ON SATELLITE IMAGES...WITH
INCREASING CENTRAL DEEP CONVECTION AND WELL-DEFINED BANDING
FEATURES.  UPPER-LEVEL OUTFLOW IS BECOMING WELL ESTABLISHED TO THE
NORTH...WEST...AND SOUTH OF THE STORM.  DVORAK INTENSITY ESTIMATES
HAVE INCREASED TO 45 KT AND 55 KT FROM SAB AND TAFB RESPECTIVELY...
AND THE ADVISORY INTENSITY IS SET AT 50 KT.  KATIA WILL BE MOVING
OVER SEA SURFACE TEMPERATURES NEAR 28 DEG C AND IN A LOW SHEAR
ENVIRONMENT FOR THE NEXT FEW DAYS...SO STEADY STRENGTHENING APPEARS
TO BE LIKELY.  THE OFFICIAL INTENSITY FORECAST IS A BLEND OF THE
STATISTICAL AND DYNAMICAL MODEL GUIDANCE.

THE INITIAL MOTION...285/17...IS ONLY A LITTLE FASTER THAN IN THE
PREVIOUS PACKAGE.  THE TRACK FORECAST AND FORECAST PHILOSOPHY ARE
BASICALLY UNCHANGED.  KATIA SHOULD CONTINUE TO MOVE
WEST-NORTHWESTWARD TO THE SOUTH OF THE SUBTROPICAL RIDGE FOR THE
NEXT SEVERAL DAYS.  NEAR THE END OF THE FORECAST PERIOD...A WEAKNESS
IN THE RIDGE PRODUCED BY A TROUGH OVER THE WESTERN ATLANTIC IS
EXPECTED TO INDUCE A GRADUAL TURN TO THE RIGHT WITH A DECREASE IN
FORWARD SPEED.  THE OFFICIAL TRACK FORECAST IS CLOSE TO THE
MULTI-MODEL CONSENSUS AND SOUTH OF THE LATEST ECMWF SOLUTION.

THE WIND RADII HAVE BEEN EXPANDED ON THE BASIS OF AN ASCAT PASS FROM
EARLIER TODAY.

FORECAST POSITIONS AND MAX WINDS

INIT  30/2100Z 12.7N  35.4W   50 KT  60 MPH
 12H  31/0600Z 13.3N  37.9W   60 KT  70 MPH
 24H  31/1800Z 14.1N  41.1W   65 KT  75 MPH
 36H  01/0600Z 14.9N  44.4W   70 KT  80 MPH
 48H  01/1800Z 15.7N  47.5W   80 KT  90 MPH
 72H  02/1800Z 17.5N  52.5W   90 KT 105 MPH
 96H  03/1800Z 19.5N  56.5W  100 KT 115 MPH
120H  04/1800Z 21.5N  60.5W  105 KT 120 MPH

$$
FORECASTER PASCH

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