[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT41 KNHC 290256
TCDAT1
TROPICAL DEPRESSION ONE DISCUSSION NUMBER   3
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL012009
1100 PM AST THU MAY 28 2009

THE LAST FEW VISIBLE IMAGES INDICATED THAT THE LOW-LEVEL CENTER OF
THE DEPRESSION WAS BECOMING SOMEWHAT EXPOSED TO THE NORTHWEST OF
THE DEEP CONVECTION.  THE CONVECTION ITSELF HAS SHRUNK A BIT IN SIZE
OVER THE PAST FEW HOURS...AND DATA T-NUMBERS HAVE FALLEN TO 1.5
FROM SAB AND REMAIN 2.0 FROM TAFB.  A QUIKSCAT PASS AT 2330 UTC
SHOWED A FEW TROPICAL-STORM-FORCE VECTORS THAT APPEAR TO HAVE BEEN
AFFECTED BY RAIN.  THEREFORE...THE INITIAL INTENSITY IS BEING
HELD AT 30 KT.

SEA SURFACE TEMPERATURE DATA SHOW THAT THE DEPRESSION IS CURRENTLY
HUGGING THE NORTH WALL OF THE GULF STREAM...AND THE FORECAST TRACK
TAKES THE CENTER NORTHWARD ACROSS THE WALL OVER COLDER WATERS
WITHIN THE NEXT 12 HOURS. THE OFFICIAL FORECAST STILL ALLOWS FOR
THE POSSIBILITY THAT THE DEPRESSION COULD BECOME A TROPICAL STORM
BEFORE THIS HAPPENS...BUT IT WILL HAVE TO HAPPEN SOON. THE GLOBAL
MODEL GUIDANCE GENERALLY INDICATES THAT THE DEPRESSION WILL BE
TANGLED WITHIN A BAROCLINIC ZONE TO ITS NORTH WITHIN THE NEXT 24
HOURS...SO THE OFFICIAL FORECAST CALLS FOR IT TO BE EXTRATROPICAL
AT THAT POINT. DISSIPATION IS EXPECTED BY 48 HOURS AS THE SYSTEM IS
OVERTAKEN BY ANOTHER LOW PRESSURE SYSTEM CURRENTLY NEAR NEW
ENGLAND.

THE DEPRESSION HAS BEEN MOVING A LITTLE SOUTH OF THE PREVIOUS TRACK
AND THE BULK OF THE MODELS.  THE INITIAL MOTION IS 070/13 AS THE
SYSTEM IS BEING STEERED BETWEEN THE SUBTROPICAL RIDGE AND A LARGE
TROUGH OVER EASTERN NORTH AMERICA.  THE OFFICIAL FORECAST IS ON THE
SOUTH SIDE OF THE GUIDANCE ENVELOPE.


FORECAST POSITIONS AND MAX WINDS

INITIAL      29/0300Z 38.1N  67.8W    30 KT
 12HR VT     29/1200Z 39.1N  65.0W    35 KT
 24HR VT     30/0000Z 41.2N  60.5W    30 KT...EXTRATROPICAL
 36HR VT     30/1200Z 43.4N  55.4W    30 KT...EXTRATROPICAL
 48HR VT     31/0000Z...DISSIPATED

$$
FORECASTER BERG



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