425
WTPZ43 KNHC 240848
TCDEP3
TROPICAL STORM OTIS DISCUSSION NUMBER 8
NWS NATIONAL HURRICANE CENTER MIAMI FL EP182023
400 AM CDT TUE OCT 24 2023
OTIS HAS STRENGTHENED OVERNIGHT. THERE HAS BEEN A SIGNIFICANT
INCREASE IN BANDING AND THE CENTER IS NOW WELL EMBEDDED WITHIN THE
DEEP CONVECTION. WHILE THERE HAS BEEN NO RECENT MICROWAVE IMAGERY
TO EVALUATE THE INNER CORE STRUCTURE, A COUPLE OF EARLIER ASCAT
OVERPASS INDICATED THAT THE CENTER HAD BECOME EMBEDDED WITHIN THE
COLD CLOUD TOPS. THE INITIAL INTENSITY HAS BEEN INCREASED TO 55 KT
FOR THIS ADVISORY, AND THAT IS IN AGREEMENT WITH SUBJECTIVE DVORAK
DATA T-NUMBERS OF 3.5 FROM BOTH SAB AND TAFB.
IT APPEARS THAT THE VERTICAL SHEAR OVER OTIS HAS DECREASED AS THERE
HAS BEEN AN EXPANSION OF THE CIRRUS OUTFLOW OVER THE EASTERN PORTION
OF THE STORM. THE SHEAR IS EXPECTED TO REMAIN LIGHT TO MODERATE
WHILE OTIS MOVES OVER SSTS OF 29-30 DEGREES C DURING THE NEXT DAY OR
SO. THESE CONDITIONS SHOULD ALLOW FOR CONTINUED STRENGTHENING AS
OTIS APPROACHES THE SOUTHERN COAST OF MEXICO. THE LATEST NHC
INTENSITY FORECAST CALLS FOR OTIS TO BECOME A HURRICANE TODAY, AND
IT SHOWS ADDITIONAL STRENGTHENING BEFORE OTIS REACHES SOUTHERN
MEXICO IN A DAY OR SO. BY 36 HOURS, OTIS IS FORECAST TO BE INLAND,
AND RAPID WEAKENING SHOULD OCCUR AS THE CYCLONE MOVES OVER
MOUNTAINOUS TERRAIN. THE NHC INTENSITY FORECAST IS AT THE HIGH END
OF THE GUIDANCE IN BEST AGREEMENT WITH THE HWRF AND HAFS-B MODELS.
THE SHIPS RAPID INTENSIFICATION INDEX NOW SHOWS ABOUT A 1 IN 4
CHANCE OF RAPID STRENGTHENING DURING THE NEXT 24 HOURS, WHICH
SUPPORTS BEING ON THE HIGHER SIDE OF THE GUIDANCE.
OTIS IS MOVING NORTH-NORTHWESTWARD AT ABOUT 7 KT. A NORTH-NORTHWEST
MOTION IS EXPECTED TO CONTINUE DURING THE NEXT COUPLE OF DAYS
BETWEEN A MID- TO UPPER-LEVEL TROUGH TO THE CYCLONE'S NORTHWEST AND
A RIDGE TO ITS EAST. THE GFS HAS FINALLY COME ONBOARD WITH THIS
SCENARIO AND THE TRACK GUIDANCE IS MUCH MORE TIGHTLY CLUSTERED THAN
BEFORE. THE MAIN DIFFERENCE IS IN THE FORWARD SPEED WITH THE ECMWF
BEING ON THE FASTER SIDE OF THE GUIDANCE ENVELOPE. THE NHC
FORECAST IS NEAR A BLEND OF THE LATEST GFS AND ECMWF MODELS, WHICH
IS A LITTLE FASTER THAN THE SIMPLE CONSENSUS AIDS.
BASED ON THE UPDATED TRACK AND INTENSITY FORECAST, THE GOVERNMENT
OF MEXICO HAS ISSUED A HURRICANE WARNING FOR A PORTION OF THE
SOUTHERN COAST OF MEXICO.
KEY MESSAGES:
1. OTIS IS FORECAST TO BECOME A HURRICANE BEFORE IT REACHES THE
SOUTHERN COAST OF MEXICO LATE TONIGHT OR WEDNESDAY, AND HURRICANE
AND TROPICAL STORM CONDITIONS ARE EXPECTED ALONG PORTIONS OF THE
SOUTHERN COAST OF MEXICO WHERE HURRICANE AND TROPICAL STORM
WARNINGS ARE IN EFFECT.
2. HEAVY RAINS FROM OTIS WILL BEGIN TO IMPACT AREAS OF SOUTHERN AND
SOUTHWESTERN MEXICO LATER TODAY. THIS RAINFALL WILL PRODUCE FLASH
AND URBAN FLOODING, ALONG WITH MUDSLIDES IN AREAS OF HIGHER TERRAIN.
3. A DANGEROUS STORM SURGE IS EXPECTED TO PRODUCE SIGNIFICANT
COASTAL FLOODING NEAR AND TO THE EAST OF WHERE THE CENTER MAKES
LANDFALL. NEAR THE COAST, THE SURGE WILL BE ACCOMPANIED BY LARGE
AND DESTRUCTIVE WAVES.
FORECAST POSITIONS AND MAX WINDS
INIT 24/0900Z 14.2N 98.5W 55 KT 65 MPH
12H 24/1800Z 15.0N 99.0W 65 KT 75 MPH
24H 25/0600Z 16.1N 99.7W 75 KT 85 MPH
36H 25/1800Z 17.1N 100.3W 70 KT 80 MPH...INLAND
48H 26/0600Z 17.9N 100.9W 35 KT 40 MPH...INLAND
60H 26/1800Z 18.6N 101.6W 25 KT 30 MPH...POST-TROP/REMNT LOW
72H 27/0600Z...DISSIPATED
FORECASTER BROWN
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