[Tropical] Tropical Cyclone Discussion

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WTNT43 KNHC 162154
TCDAT3

TROPICAL STORM GORDON DISCUSSION NUMBER   5...CORRECTED
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL082012
500 PM AST THU AUG 16 2012

...CORRECTED FOR INITIAL MOTION WHICH SHOULD BE 070/15 INSTEAD OF
055/15...

GORDON HAS BEEN STRENGTHENING OVER THE PAST 12 HOURS. VISIBLE
SATELLITE IMAGERY CONTINUES TO SHOW TIGHTLY COILED CONVECTIVE CLOUD
BANDS SPIRALING INTO A SMALL CENTRAL DENSE OVERCAST FEATURE.
SATELLITE INTENSITY ESTIMATES ARE T3.5/55 KT FROM TAFB...T3.0/45 KT
FROM SAB...AND T2.7/39 KT ADT FROM UW-CIMSS. AN 1143 UTC SSMIS
IMAGE INDICATED A CLOSED MID-LEVEL EYE FEATURE AND A 1311 UTC ASCAT
OVERPASS REVEALED 39-KT SURFACE WINDS...WHICH WHEN ADJUSTED FOR THE
KNOWN LOW BIAS OF THE SCATTEROMETER DATA YIELDS ABOUT 44 KT. GIVEN
THE MUCH IMPROVED BANDING STRUCTURE SINCE THOSE MICROWAVE DATA WERE
ACQUIRED...THE INITIAL INTENSITY HAS BEEN INCREASED TO 55 KT.

GORDON IS NOW MOVING TOWARD THE EAST-NORTHEAST...OR 070/15 KT...AND
IS ON THE PREVIOUS FORECAST TRACK. THE CYCLONE IS MOVING ALONG THE
NORTHERN PERIPHERY OF THE SUBTROPICAL RIDGE AND WILL BE MOVING INTO
THE MID-LATITUDE WESTERLIES DURING THE NEXT 12-18 HOURS. GORDON
SHOULD GRADUALLY TURN EASTWARD AND CONTINUE THAT MOTION THROUGH AT
LEAST THE 48-HOUR FORECAST PERIOD. BY 72 HOURS...THE CYCLONE IS
FORECAST TO BEGIN LIFTING OUT TOWARD THE NORTHEAST AHEAD OF A
SHORTWAVE TROUGH...AND BE NEAR THE AZORES ISLANDS BETWEEN DAYS 3
AND 4. THE NHC TRACK GUIDANCE REMAINS TIGHTLY PACKED AROUND THE
PREVIOUS FORECAST TRACK...SO NO SIGNIFICANT CHANGES WERE MADE TO
THIS FORECAST PACKAGE.

UPPER-LEVEL OUTFLOW REMAINS WELL ESTABLISHED IN ALL QUADRANTS...AND
DRY MID-LEVEL AIR HAS MANAGED THUS FAR TO REMAIN AWAY FROM THE
INNER CORE REGION. WEAK VERTICAL SHEAR COUPLED WITH SSTS GREATER
THAN 27C SHOULD ALLOW FOR SOME ADDITIONAL INTENSIFICATION TO OCCUR
DURING THE NEXT 24-36 HOURS. BY 48 HOURS...HOWEVER...ENTRAINMENT OF
DRY MID-LEVEL AIR FROM THE WEST ALONG WITH INCREASING VERTICAL WIND
SHEAR IN EXCESS OF 30 KT SHOULD INDUCE STEADY WEAKENING. AS GORDON
NEARS THE AZORES ISLANDS IN 3 TO 4 DAYS...THE CYCLONE IS FORECAST
BY MOST OF THE GLOBAL MODELS TO MERGE WITH A FRONTAL SYSTEM AND
BECOME A STRONG EXTRATROPICAL CYCLONE. THE INTENSITY FORECAST IS
ONLY SLIGHTLY HIGHER THAN THE PREVIOUS ADVISORY...AND REMAINS CLOSE
TO IV15 INTENSITY CONSENSUS MODEL.

FORECAST POSITIONS AND MAX WINDS

INIT  16/2100Z 34.2N  52.1W   55 KT  65 MPH
 12H  17/0600Z 34.7N  49.9W   60 KT  70 MPH
 24H  17/1800Z 34.9N  46.2W   65 KT  75 MPH
 36H  18/0600Z 34.7N  42.5W   70 KT  80 MPH
 48H  18/1800Z 34.7N  38.6W   60 KT  70 MPH
 72H  19/1800Z 36.1N  30.8W   55 KT  65 MPH
 96H  20/1800Z 38.8N  23.2W   45 KT  50 MPH...POST-TROP/EXTRATROP
120H  21/1800Z 41.2N  15.8W   40 KT  45 MPH...POST-TROP/EXTRATROP

$$
FORECASTER STEWART



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