000 WTNT41 KNHC 010841 TCDAT1 TROPICAL STORM JERRY DISCUSSION NUMBER 10 NWS NATIONAL HURRICANE CENTER MIAMI FL AL112013 500 AM AST TUE OCT 01 2013 SINCE THE PREVIOUS ADVISORY...STRONG NORTHWESTERLY VERTICAL WIND SHEAR HAS COMPLETELY SQUASHED THE CONVECTIVE STRUCTURE OF JERRY. A SHARP MID-/UPPER-LEVEL TROUGH TO THE NORTH OF JERRY IS DROPPING SOUTHWARD AND IS INCREASING THE SHEAR ACROSS THE CYCLONE...AND ALSO LIKELY ADVECTING DRY AIR INTO THE SYSTEM. A 0042Z PARTIAL ASCAT-B SCATTEROMETER OVERPASS...WHICH WAS UNAVAILABLE FOR THE PREVIOUS ADVISORY...INDICATED A COUPLE OF 38-KT SURFACE WIND VECTORS IN THE WESTERN QUADRANT. IT IS ASSUMED THAT SLIGHTLY STRONGER WINDS EXIST EAST OF THE CENTER WHERE VIGOROUS CONVECTION PREVIOUSLY EXISTED... SO THE INTENSITY IS LOWERED TO 40 KT FOR THIS ADVISORY...WHICH IS CONSISTENT WITH A BLEND OF SUBJECTIVE DVORAK SATELLITE INTENSITY ESTIMATES FROM TAFB AND SAB. IT IS DIFFICULT TO ASCERTAIN THE MOTION OF JERRY DUE TO THE LACK OF CONTINUITY IN THE CONVECTIVE CLOUD PATTERN. HOWEVER...0559Z ATMS AND 0608Z AMSU OVERPASSES SUGGEST THAT JERRY IS MOVING LITTLE. THE GLOBAL AND REGIONAL MODELS ARE ALL IN FAIRLY GOOD AGREEMENT ON THE CYCLONE REMAINING IN WEAK STEERING CONDITIONS FOR THE NEXT 24-36 HOURS...WHICH SHOULD RESULT IN SOME ERRATIC MOTION. BY 48 HOURS... HOWEVER...THE NEXT MID-UPPER-LEVEL TROUGH THAT HAS JUST MOVED OFF THE U.S. EAST COAST IS FORECAST TO BEGIN LIFTING OUT JERRY TO THE NORTHEAST...AND THAT MOTION IS EXPECTED TO CONTINUE THROUGH 120 HOURS. THE NEW NHC FORECAST TRACK HAS AGAIN BEEN SHIFTED TO THE EAST OF THE PREVIOUS ADVISORY TRACK...BUT IT REMAINS WEST OF THE MULTI-MODEL CONSENSUS TVCA. WATER VAPOR IMAGERY INDICATES THE SMALL UPPER-LEVEL LOW THAT THE JERRY BRIEFLY BECAME ENTANGLED WITH DURING THE AFTERNOON OF 30 SEP IS NOW EXITING THE SYSTEM TO THE SOUTHEAST. THE STRONG SHEAR ACROSS THE CYCLONE CREATED BY THAT LOW AND THE UPPER-TROUGH TO THE NORTH COULD CAUSE SOME ADDITIONAL WEAKENING TODAY. HOWEVER...BY 36-48 HOURS...AN UPPER-LEVEL SHORTWAVE RIDGE AHEAD OF THE U.S. EAST COAST TROUGH IS EXPECTED TO PASS OVER THE CYCLONE...WHICH COULD ALLOW FOR SOME SLIGHT RE-STRENGTHENING TO OCCUR. AFTER THAT...INCREASING SOUTHWESTERLY VERTICAL SHEAR SHOULD CAUSE THE INTENSITY TO LEVEL OFF...AND POSSIBLY INDUCE SOME WEAKENING BY DAY 5. THERE REMAINS A LARGE SPREAD IN THE INTENSITY GUIDANCE RANGING FROM A WEAK TROPICAL STORM IN THE HWRF AND ECMWF MODELS TO A HURRICANE IN THE LGEM STATISTICAL-DYNAMICAL MODEL OUTPUT. GIVEN THE PROXIMITY OF DRY MID-LEVEL AIR AND EXPECTED MODERATE SHEAR FOR MOST OF THE FORECAST PERIOD...THE INTENSITY FORECAST WILL REMAIN ON THE CONSERVATIVE SIDE AND IS SLIGHTLY LOWER THAN THE CONSENSUS MODEL ICON. FORECAST POSITIONS AND MAX WINDS INIT 01/0900Z 27.2N 43.7W 40 KT 45 MPH 12H 01/1800Z 27.2N 43.9W 40 KT 45 MPH 24H 02/0600Z 27.5N 44.2W 40 KT 45 MPH 36H 02/1800Z 28.2N 44.4W 45 KT 50 MPH 48H 03/0600Z 29.0N 44.2W 45 KT 50 MPH 72H 04/0600Z 30.7N 41.4W 45 KT 50 MPH 96H 05/0600Z 32.0N 37.9W 40 KT 45 MPH 120H 06/0600Z 33.5N 33.5W 35 KT 40 MPH $$ FORECASTER STEWART