Tropical Storm SANDY
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TROPICAL STORM SANDY DISCUSSION NUMBER 4...CORRECTED
NWS NATIONAL HURRICANE CENTER MIAMI FL AL182012
500 AM EDT TUE OCT 23 2012
BANDS OF VERY DEEP CONVECTION HAVE DEVELOPED OVER THE EASTERN
PORTION OF THE CIRCULATION OVERNIGHT. HOWEVER...THERE APPEARS TO
BE VERY LITTLE OVERALL CHANGE IN THE INNER-CORE STRUCTURE DURING
THE PAST 12-18 HOURS...AS AN EARLIER ASCAT PASS INDICATED THAT
SANDY STILL HAS A LARGE AREA OF LIGHT WINDS NEAR THE CENTER.
SUBJECTIVE DVORAK T-NUMBERS ARE T2.5...AND THE INITIAL WIND
SPEED IS MAINTAINED AT 40 KT. AN AIR FORCE RESERVE HURRICANE
HUNTER AIRCRAFT IS CURRENTLY EN ROUTE TO THE CYCLONE AND SHOULD
PROVIDE A BETTER ASSESSMENT OF THE INTENSITY OF THE STORM.
SANDY APPEARS TO BE MOVING SLOWLY NORTHWARD. THE TRACK GUIDANCE IS
IN VERY GOOD AGREEMENT ON A FASTER NORTH TO NORTH-NORTHEASTWARD
MOTION BEGINNING TODAY AS A MID-LEVEL RIDGE TO THE NORTH OF SANDY
WEAKENS. THE CENTER OF SANDY SHOULD MOVE NEAR OR OVER
JAMAICA ON WEDNESDAY AND APPROACH EASTERN CUBA BY WEDNESDAY NIGHT.
THE MODEL GUIDANCE REMAINS IN GOOD AGREEMENT THROUGH 96 HOURS WITH
A TRACK ACROSS THE CENTRAL BAHAMAS. BY DAY 5...HOWEVER...THERE IS
SIGNIFICANT SPREAD IN THE GUIDANCE...WITH THE ECMWF ALONG THE
WESTERN EDGE OF THE GUIDANCE ENVELOPE AND THE HWRF ALONG THE
EASTERN SIDE. THE GFS IS CLOSER TO THE MIDDLE OF THE GUIDANCE
ENVELOPE AND THE NHC FORECAST IS BASED ON THE MULTI-MODEL CONSENSUS
AND THE FLORIDA STATE ENSEMBLE AT DAYS 4 AND 5.
ENVIRONMENTAL CONDITIONS CONSISTING OF LOW SHEAR...WARM WATERS...
AND A MOIST ATMOSPHERE...FAVOR STRENGTHENING DURING THE NEXT
COUPLE OF DAYS. IN FACT...ALL OF THE INTENSITY MODELS BRING
SANDY TO HURRICANE STRENGTH WITHIN 36 TO 48 HOURS AND SO DOES
THE NHC FORECAST. AFTER SANDY CROSSES EASTERN CUBA...THE
VERTICAL SHEAR IS FORECAST TO INCREASE SIGNIFICANTLY...HOWEVER THE
GLOBAL MODELS DEPICT A DEEPENING CYCLONE...POSSIBLY DUE TO SOME
BAROCLINIC FORCING. THE NHC FORECAST STILL INDICATES THE SYSTEM
BECOMING SUBTROPICAL LATE IN THE PERIOD...ALTHOUGH THERE ARE SOME
INDICATIONS IN THE GLOBAL MODELS THAT SANDY COULD BE TRANSITIONING
TO AN EXTRATROPICAL CYCLONE AROUND THAT TIME.
FORECAST POSITIONS AND MAX WINDS
INIT 23/0900Z 13.3N 78.6W 40 KT 45 MPH
12H 23/1800Z 14.1N 78.2W 50 KT 60 MPH
24H 24/0600Z 15.6N 77.8W 60 KT 70 MPH
36H 24/1800Z 17.6N 77.4W 70 KT 80 MPH
48H 25/0600Z 19.6N 77.0W 70 KT 80 MPH
72H 26/0600Z 24.0N 76.0W 60 KT 70 MPH
96H 27/0600Z 26.8N 74.8W 60 KT 70 MPH
120H 28/0600Z 30.0N 71.5W 60 KT 70 MPH...SUBTROPICAL
$$
FORECASTER BROWN
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