438
WTPZ43 KNHC 231444
TCDEP3
TROPICAL STORM OTIS DISCUSSION NUMBER 5
NWS NATIONAL HURRICANE CENTER MIAMI FL EP182023
1000 AM CDT MON OCT 23 2023
OTIS HAS BEEN RELATIVELY STEADY IN STRENGTH THIS MORNING. SATELLITE
IMAGES INDICATE THAT DEEP CONVECTION HAS BEEN PULSING DURING THE
PAST SEVERAL HOURS. THE LOW-LEVEL CENTER REMAINS ON THE EAST SIDE
OF THE THUNDERSTORM ACTIVITY DUE TO EASTERLY WIND SHEAR. THE
SATELLITE INTENSITY ESTIMATES HAVE NOT CHANGED MUCH, THEREFORE, THE
INITIAL INTENSITY IS HELD AT 40 KT.
OTIS IS MOVING SLOWLY NORTH-NORTHWESTWARD AT 5 KT IN THE FLOW
BETWEEN A MID- TO UPPER-LEVEL TROUGH TO ITS NORTHWEST AND A RIDGE TO
ITS EAST. THERE CONTINUES TO BE SIGNIFICANT DISAGREEMENT AMONG THE
MODELS WITH THE ECMWF SHOWING OTIS MOVING INLAND IN ABOUT 48 HOURS
WHILE THE GFS, HWRF, AND HAFS MODELS KEEP THE SYSTEM OFFSHORE DURING
THE NEXT SEVERAL DAYS. A CLOSER INSPECTION OF THE GUIDANCE SUGGESTS
THAT THE DIFFERENCES IN THESE SOLUTIONS ARE RELATED TO THE VERTICAL
DEPTH AND CONVECTIVE ORGANIZATION OF OTIS IN THE SHORT TERM, WHICH
AFFECTS ITS FORWARD SPEED. SINCE IT APPEARS THAT THE ECMWF MODEL
HAS THE BEST HANDLE ON THE SHORT TERM CONVECTIVE TRENDS, THE NHC
TRACK FORECAST CONTINUES TO FAVOR THAT SOLUTION OVERALL. THIS
PREDICTION IS A LITTLE TO THE LEFT OF THE PREVIOUS ONE, MOSTLY BASED
ON THE INITIAL POSITION/MOTION.
ALTHOUGH OTIS IS EXPECTED TO REMAIN IN A MODERATE WIND SHEAR
ENVIRONMENT, ABUNDANT MOISTURE AND WARM SSTS SHOULD SUPPORT GRADUAL
STRENGTHENING AS LONG AS OTIS REMAINS OFFSHORE. THE NHC INTENSITY
FORECAST IS A LITTLE HIGHER THAN THE PREVIOUS ONE, FOLLOWING THE
IVCN AND HCCA CONSENSUS AIDS. RAPID WEAKENING IS EXPECTED AFTER
OTIS MOVES INLAND DUE TO THE RUGGED TERRAIN IN SOUTHERN AND
SOUTHWESTERN MEXICO.
KEY MESSAGES:
1. HEAVY RAINS FROM OTIS WILL BEGIN TO IMPACT AREAS OF SOUTHWEST
MEXICO EARLY THIS WEEK. THIS RAINFALL WILL PRODUCE FLASH AND URBAN
FLOODING, ALONG WITH MUDSLIDES IN AREAS OF HIGHER TERRAIN.
2. TROPICAL STORM CONDITIONS ARE POSSIBLE BY TUESDAY NIGHT ALONG
PORTIONS OF THE SOUTHERN COAST OF MEXICO, WHERE A TROPICAL STORM
WATCH IS IN EFFECT.
FORECAST POSITIONS AND MAX WINDS
INIT 23/1500Z 12.0N 97.5W 40 KT 45 MPH
12H 24/0000Z 12.6N 97.7W 45 KT 50 MPH
24H 24/1200Z 13.6N 98.0W 45 KT 50 MPH
36H 25/0000Z 14.6N 98.5W 50 KT 60 MPH
48H 25/1200Z 15.4N 99.0W 55 KT 65 MPH
60H 26/0000Z 16.2N 99.5W 55 KT 65 MPH
72H 26/1200Z 17.5N 100.5W 35 KT 40 MPH...INLAND
96H 27/1200Z...DISSIPATED
FORECASTER CANGIALOSI/DELGADO
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