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#152162 (Received by flhurricane at: 10:31 AM 23.Sep.2007) TCDAT1 SUBTROPICAL STORM JERRY DISCUSSION NUMBER 2 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL112007 1100 AM EDT SUN SEP 23 2007 AN 0807 UTC QUIKSCAT PASS INDICATED THAT THE MAXIMUM WINDS IN THE CIRCULATION ARE AT LEAST 35 KT AND SATELLITE CLASSIFICATIONS GIVE A SUBTROPICAL T-NUMBER OF 2.5 USING THE HEBERT-POTEAT METHOD. THE SYSTEM IS THEREFORE UPGRADED TO SUBTROPICAL STORM JERRY. THE CYCLONE LACKS A WELL-DEFINED INNER CORE WITH MULTIPLE LOW-CLOUD SWIRLS NEAR THE ESTIMATED CENTER. THERE IS A NARROW WINDOW OF OPPORTUNITY FOR THE SYSTEM TO ACQUIRE TROPICAL CHARACTERISTICS AND TO STRENGTHEN FURTHER. HOWEVER...COOLING SEA SURFACE TEMPERATURES AND INCREASING SHEAR WILL PROBABLY LIMIT THE INTENSIFICATION PROCESS. GLOBAL MODELS SHOW A LARGE AND VIGOROUS EXTRATROPICAL CYCLONE OVERTAKING JERRY WITHIN 48 HOURS...SO THE SYSTEM IS LIKELY TO BECOME ABSORBED BY THIS LARGER SYSTEM IN A COUPLE OF DAYS. THERE HAS BEEN LITTLE NET MOTION OVER THE PAST SEVERAL HOURS AS JERRY IS STILL EMBEDDED WITHIN A BROADER CYCLONIC CIRCULATION. HOWEVER...AS A STRONG 500 MB TROUGH MOVES OFF THE CANADIAN MARITIMES TONIGHT AND EARLY MONDAY...THE SOUTH-SOUTHWESTERLY STEERING CURRENT WILL GRADUALLY INCREASE. THIS SHOULD PULL JERRY TOWARD HIGHER LATITUDES BEFORE IT BECOMES ABSORBED. THIS IS SIMILAR TO THE PREVIOUS NHC FORECAST...AND ABOUT IN THE MIDDLE OF THE TRACK GUIDANCE SUITE. FORECAST POSITIONS AND MAX WINDS INITIAL 23/1500Z 36.0N 46.3W 35 KT 12HR VT 24/0000Z 37.3N 45.8W 40 KT...TROPICAL 24HR VT 24/1200Z 39.7N 44.0W 45 KT...TROPICAL 36HR VT 25/0000Z 44.0N 40.5W 45 KT...BECOMING EXTRATROPICAL 48HR VT 25/1200Z...ABSORBED BY LARGER EXTRATROPICAL CYCLONE $$ FORECASTER PASCH |