Tropical Depression One Discussion No. 4

AFTER AN INCREASE IN DEEP CONVECTION THAT BEGAN AROUND 0400

UTC...SATELLITE IMAGERY INDICATES THAT THE CONVECTION HAS BEGUN TO

DECREASE AND MOVE EASTWARD AWAY FROM THE LOW LEVEL CIRCULATION

CENTER. DVORAK T-NUMBERS AT 0600 UTC WERE 2.5 AND 1.5 FROM TAFB

AND SAB...RESPECTIVELY...AND THE CURRENT INTENSITY IS HELD AT 30 KT

BASED ON A BLEND OF THESE ESTIMATES. THIS INTENSITY IS ALSO

SUPPORTED BY AN ASCAT PASS OVER THE SYSTEM AT 0102 UTC THAT SHOWED

MAXIMUM WINDS OF AROUND 30 KT.

THE CENTER OF THE DEPRESSION IS VERY CLOSE TO THE NORTHERN WALL OF

THE GULF STREAM...AND THE FORECAST TRACK TAKES THE CYCLONE OVER

COLDER WATER TODAY. THEREFORE...IT APPEARS THAT THE OPPORTUNITY FOR

THIS SYSTEM TO REACH TROPICAL STORM STRENGTH HAS PASSED. MOST OF

THE GLOBAL MODEL GUIDANCE SHOWS THE CYCLONE BECOMING EXTRATROPICAL

WITHIN 24 HOURS AS IT BECOMES ENTANGLED WITH A FRONTAL BOUNDARY TO

THE NORTH. THESE MODELS ALSO SHOW THE CYCLONE DISSIPATING BY 36

HOURS...HOWEVER THIS COULD OCCUR SOONER IF THE CIRCULATION BECOMES

POORLY DEFINED AS IT INTERACTS WITH THE FRONT.

THE DEPRESSION APPEARS TO BE MOVING AROUND 070/13. THE CYCLONE IS

BEING STEERED BY DEEP LAYER SOUTHWESTERLY FLOW BETWEEN THE

SUBTROPICAL RIDGE AND A TROUGH OVER EASTERN NORTH AMERICA. MOST OF

THE MODEL GUIDANCE...WITH THE EXCEPTION OF THE GFS AND CANADIAN...

ARE TO THE LEFT OF THE PREVIOUS TRACK. THE OFFICIAL FORECAST HAS

BEEN ADJUSTED TOWARD THIS MULTI-MODEL CONSENSUS.

FORECAST POSITIONS AND MAX WINDS

INITIAL 29/0900Z 38.9N 66.3W 30 KT

12HR VT 29/1800Z 40.2N 63.7W 30 KT

24HR VT 30/0600Z 42.5N 59.1W 25 KT...EXTRATROPICAL

36HR VT 30/1800Z...DISSIPATED

$$

FORECASTER BRENNAN/BROWN