660
WTPZ45 KNHC 260240
TCDEP5
TROPICAL STORM RAMON DISCUSSION NUMBER 11
NWS NATIONAL HURRICANE CENTER MIAMI FL EP202023
700 PM PST SAT NOV 25 2023
ON GEOSTATIONARY SATELLITE IMAGERY, RAMON HAS TAKEN ON THE
APPEARANCE OF A HIGHLY SHEARED TROPICAL CYCLONE, WITH BURSTS OF DEEP
CONVECTION FORMING NEAR THE CENTER THAT HAVE CONTINUALLY BEEN
STRIPPED AWAY. DESPITE THIS PATTERN, THERE IS EVIDENCE THAT
UPPER-LEVEL DIVERGENCE HAS AIDED IN CONVECTIVE GENERATION TODAY,
WITH THE GOES-18 MESOSCALE SECTOR DERIVED MOTIONS WINDS SHOWING
250-350 MB FLOW FANNING OFF IN A V-SHAPE PATTERN ALONG THE EASTERN
FLANK OF THE CYCLONE. A LATE ARRIVING ASCAT-C PASS RECEIVED AFTER
THE PRIOR ADVISORY SUGGESTED THAT RAMON WAS A BIT STRONGER THAN
PREVIOUSLY ESTIMATED, WITH A FAIRLY LARGE SWATH OF GREATER THAN 35
KT WINDS OVER ITS NORTHERN SEMICIRCLE, THOUGH THE HIGHEST VALUES MAY
HAVE BEEN RAIN INFLATED. AN AMSR2 MICROWAVE PASS AT 2152 UTC ALSO
SHOWED A PROMINENT CURVED BAND ON THE 37 GHZ CHANNEL ALONG WHERE
THESE HIGHEST WINDS WERE OBSERVED EARLIER ON SCATTEROMETER. BASED ON
THIS INFORMATION, THE INITIAL INTENSITY IS ADJUSTED TO 40 KT FOR
THIS ADVISORY. THIS VALUE IS A LITTLE HIGHER THAN THE SUBJECTIVE
DVORAK ESTIMATES, BUT DOES MATCH THE MOST RECENT SATCON INTENSITY
ESTIMATE FROM UW-CIMSS.
RAMON IS ALREADY BATTLING SOME VERY HOSTILE WESTERLY VERTICAL WIND
SHEAR ABOVE 40 KT, AND THIS IS ONLY FORECAST TO INCREASE FURTHER
OVER THE NEXT 12-24 HOURS. THE DIVERGENT UPPER-LEVEL FLOW IS ALSO
FORECAST TO QUICKLY BYPASS THE STORM. THUS, THE ONGOING CONVECTION
IS EXPECTED TO FULLY DETACH FROM THE LOW-LEVEL CIRCULATION LATER
TONIGHT, AND WEAKENING SHOULD BEGIN SHORTLY. RAMON IS STILL EXPECTED
TO BECOME A REMNANT LOW IN A DAY OR TWO, WITH THE LOW OPENING UP
INTO A TROUGH NOT LONG BEYOND THAT. ASIDE FROM THE SHORT-TERM
INTENSITY, THE LATEST FORECAST IS CLOSE TO THE PREVIOUS ONE, AND IS
IN GOOD AGREEMENT WITH THE CONSENSUS AIDS.
THE ONGOING CONVECTIVE BURSTS MAY HAVE TEMPORARILY CAUSED RAMON TO
JOG EAST THIS EVENING, THOUGH AS THE LOW-LEVEL CIRCULATION STARTS TO
BECOME DETACHED, A SLOW WESTWARD DRIFT MAY BE STARTING, ESTIMATED AT
260/1 KT. WHILE THE CYCLONE MAY CONTINUE TO DRIFT SLOWLY TONIGHT, BY
TOMORROW, A BIT FASTER WESTWARD TO WEST-NORTHWESTWARD MOTION SHOULD
BEGIN AS THE CYCLONE IS STEERED BY A WEAK LOW-LEVEL RIDGE. THE NHC
TRACK FORECAST IS A BIT SOUTH AND EAST OF THE PREVIOUS ONE,
PARTIALLY DUE TO ADJUSTMENTS IN THE INITIAL POTION, BUT ENDS UP
CLOSE TO THE PRIOR TRACK FORECAST IN 36-48 H, CLOSE TO THE SIMPLE
AND CORRECTED CONSENSUS AIDS.
FORECAST POSITIONS AND MAX WINDS
INIT 26/0300Z 14.8N 122.7W 40 KT 45 MPH
12H 26/1200Z 14.8N 122.8W 35 KT 40 MPH
24H 27/0000Z 14.9N 123.1W 30 KT 35 MPH
36H 27/1200Z 15.0N 123.9W 25 KT 30 MPH...POST-TROP/REMNT LOW
48H 28/0000Z 15.7N 125.2W 20 KT 25 MPH...POST-TROP/REMNT LOW
60H 28/1200Z...DISSIPATED
FORECASTER PAPIN
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