102
WTPZ44 KNHC 020232
TCDEP4
TROPICAL STORM PILAR DISCUSSION NUMBER 18
NWS NATIONAL HURRICANE CENTER MIAMI FL EP192023
1000 PM CDT WED NOV 01 2023
DEEP CONVECTION NEAR THE CENTER OF PILAR HAS DIMINISHED
SIGNIFICANTLY THIS EVENING. CLOUD TOPS ASSOCIATED WITH THE CYCLONE
ARE NOW GENERALLY WARMER THAN -50 DEG C. THIS DEGRADATION IN THE
CLOUD STRUCTURE COULD BE AT LEAST PARTIALLY BE CAUSED BY THE
SYSTEM'S PASSAGE OVER UPWELLED OCEAN WATERS NEAR THE COAST. ANOTHER
FACTOR COULD BE SOME DISRUPTION DUE TO THE INFLUENCE OF A NEARBY
TEHUANTEPEC GAP WIND EVENT. GIVEN THE DECREASE IN CONVECTION, IT IS
ASSUMED THAT SOME WEAKENING HAS OCCURRED AND THE CURRENT INTENSITY
IS SET AT 40 KT FOR THIS ADVISORY. THIS IS CLOSE TO THE MEAN OF
FINAL T-NUMBERS AND CI NUMBERS FROM TAFB AND SAB.
CENTER FIXES INDICATE THAT THE WESTWARD TRACK IS CONTINUING WITH A
MOTION ESTIMATE OF 270/10 KT. A PROMINENT MID-LEVEL SUBTROPICAL
RIDGE IS EXPECTED TO REMAIN NORTH OF PILAR, AND STRENGTHEN FURTHER,
DURING THE NEXT FEW DAYS. THIS SHOULD FORCE A WESTWARD TO
WEST-SOUTHWESTWARD MOTION WITH SOME INCREASE IN FORWARD SPEED. THE
OFFICIAL TRACK FORECAST IS AGAIN A LITTLE FASTER THAN THE PREVIOUS
ONE AND IS A BLEND OF THE SIMPLE AND CORRECTED DYNAMICAL MODEL
CONSENSUS PREDICTIONS.
THE GAP WIND EVENT AND EASTERLY VERTICAL WIND SHEAR COULD CAUSE
SOME ADDITIONAL WEAKENING DURING THE NEXT DAY OR SO. LATER IN THE
FORECAST PERIOD, MODERATE SHEAR AND MARGINAL THERMODYNAMIC
CONDITIONS ARE LIKELY TO INHIBIT STRENGTHENING. THE NHC FORECAST
SHOWS VERY SLOW WEAKENING THROUGH THE PERIOD. HOWEVER, THERE IS A
POSSIBILITY THAT THE SYSTEM WILL DEGENERATE INTO A REMNANT LOW OR A
TROUGH WITHIN THE NEXT 5 DAYS.
KEY MESSAGES:
1. THE COMBINATION OF PREVIOUS HEAVY RAINFALL AND ANY ADDITIONAL
RAINFALL FROM PILAR MAY PRODUCE FLASH AND URBAN FLOODING, ALONG WITH
MUDSLIDES IN AREAS OF HIGHER TERRAIN OF THE PACIFIC COAST FROM EL
SALVADOR INTO SOUTHERN GUATEMALA OVERNIGHT.
2. SWELLS GENERATED BY PILAR AND STRONG WINDS NEAR THE GULF OF
TEHUANTEPEC ARE EXPECTED TO CONTINUE AFFECTING THE PACIFIC COAST OF
CENTRAL AMERICA DURING THE NEXT DAY OR TWO. THESE SWELLS ARE
LIKELY TO CAUSE LIFE-THREATENING SURF AND RIP CURRENT CONDITIONS.
FORECAST POSITIONS AND MAX WINDS
INIT 02/0300Z 12.4N 92.6W 40 KT 45 MPH
12H 02/1200Z 11.7N 94.8W 40 KT 45 MPH
24H 03/0000Z 10.8N 97.8W 40 KT 45 MPH
36H 03/1200Z 9.9N 101.0W 35 KT 40 MPH
48H 04/0000Z 9.4N 104.1W 35 KT 40 MPH
60H 04/1200Z 9.5N 106.8W 35 KT 40 MPH
72H 05/0000Z 9.7N 109.2W 35 KT 40 MPH
96H 06/0000Z 10.5N 113.1W 30 KT 35 MPH
120H 07/0000Z 11.3N 116.0W 30 KT 35 MPH
FORECASTER PASCH
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