[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT43 KNHC 230832
TCDAT3

TROPICAL STORM LORENZO DISCUSSION NUMBER   8
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL132013
500 AM AST WED OCT 23 2013

A TRMM PASS FROM 0247Z NICELY SHOWED THE SEPARATION OF THE LOW- AND
MID-LEVEL CLOUD FEATURES DUE TO NORTHWESTERLY SHEAR.  DESPITE THE
SHEAR...LORENZO IS MAINTAINING DEEP CONVECTION AND THE DVORAK
CLASSIFICATIONS FROM BOTH TAFB AND SAB WERE T3.0...45 KT.  AN ASCAT
PASS FROM 00Z MISSED THE CENTER BUT DID INDICATE THAT
TROPICAL-STORM-FORCE WINDS DO NOT EXTEND VERY FAR IN THE EASTERN
SEMICIRCLE.  BOTH THE GFS AND ECMWF INDICATE THAT THE SHEAR WILL
INCREASE OVER THE NEXT DAY OR SO BEFORE SHARPLY DECREASING...
HOWEVER BY THAT POINT LORENZO SHOULD BE MOVING OVER MUCH COOLER
WATERS.  CONSEQUENTLY...A STEADY WEAKENING TREND IS EXPECTED.
LORENZO SHOULD DEGENERATE INTO A REMNANT LOW BY 48 HOURS...AND WITH
ANY LUCK...SOONER THAN THAT.

THE TRACK FORECAST THINKING IS UNCHANGED.  THE CYCLONE IS MOVING
EASTWARD TO THE NORTH OF A MID-LEVEL RIDGE.  AS THE SHEAR INCREASES
AND THE DEEP CONVECTION SEPARATES OVER THE NEXT DAY OR SO...A TURN
TO THE NORTHEAST IN THE LOW-LEVEL FLOW IS EXPECTED AHEAD OF AN
APPROACHING COLD FRONT.  THE OFFICIAL FORECAST MAINLY BLENDS THE
GFS AND ECMWF GUIDANCE AND IS JUST A LITTLE SOUTH OF THE PREVIOUS
FORECAST.

FORECAST POSITIONS AND MAX WINDS

INIT  23/0900Z 29.6N  49.2W   45 KT  50 MPH
 12H  23/1800Z 30.0N  48.4W   40 KT  45 MPH
 24H  24/0600Z 30.6N  47.6W   35 KT  40 MPH
 36H  24/1800Z 31.6N  46.4W   30 KT  35 MPH
 48H  25/0600Z 32.7N  45.0W   25 KT  30 MPH...POST-TROP/REMNT LOW
 72H  26/0600Z...DISSIPATED

$$
FORECASTER FRANKLIN


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