523
WTPZ44 KNHC 300249
TCDEP4
TROPICAL STORM PILAR DISCUSSION NUMBER 6
NWS NATIONAL HURRICANE CENTER MIAMI FL EP192023
1000 PM CDT SUN OCT 29 2023
A SMALL BUT CONCENTRATED CONVECTIVE BURST HAS BEEN PERSISTING NEAR
THE ESTIMATED CENTER OF THE TROPICAL CYCLONE TONIGHT. AFTER THE
PRIOR ADVISORY, WE RECEIVED A FORTUITOUS GPM MICROWAVE PASS VALID
AT 2252 UTC THAT SUGGESTED THE LOW-LEVEL CIRCULATION MAY HAVE
TIGHTENED UP SOME BUT WAS LOCATED JUST SOUTH OF THE DEEPEST
CONVECTION. SUBJECTIVE DVORAK INTENSITY ESTIMATES WERE UP TO T2.5/35
KT FORM TAFB AND T2.0/30 KT FROM SAB. THE OBJECTIVE ESTIMATES FROM
ADT, SATCON, AND D-PRINT/MINT ARE ALL BETWEEN 34-36 KT, AND THUS THE
LATEST ADVISORY IS SET AT 35 KT THIS ADVISORY, UPGRADING TD19-E TO
TROPICAL STORM PILAR.
A MORE PRONOUNCED EAST-NORTHEASTWARD MOTION APPEARS TO BE STARTING,
ESTIMATED AT 060/4 KT. A CONTINUED MOTION TO THE EAST-NORTHWEST IS
ANTICIPATED OVER THE NEXT 24-48 HOURS AS PILAR'S PRIMARY STEERING
INFLUENCES ARE AN EQUATORIAL RIDGE SOUTH OF THE STORM PROVIDING
DEEP-LAYER WESTERLIES IN ADDITION TO A MID- TO UPPER-LEVEL CUTOFF
LOW OVER THE NORTHWESTERN CARIBBEAN THAT IS INTERRUPTING THE MORE
TYPICAL RIDGING THAT WOULD BE PRESENT TO THE NORTH OVER MEXICO. THE
GUIDANCE IS IN GENERAL AGREEMENT ON THIS SCENARIO, BUT HOW FAR EAST
THE TROPICAL STORM GETS IN THE NEXT 48 H REMAINS UNCERTAIN, WITH THE
LATEST HWRF AND HAFS-B RUNS FAR ENOUGH EAST TO AFFECT THE GULF OF
FONSECA WITH TROPICAL STORM CONDITIONS. FOR THIS REASON, THE
TROPICAL STORM WATCH HAS BEEN EXTENDED EASTWARD TO PORTIONS OF THE
PACIFIC COAST OF HONDURAS AND NICARAGUA THIS ADVISORY. ON TUESDAY,
PILAR IS EXPECTED TO STALL AND MOVE VERY SLOWLY AS LOW TO MID-LEVEL
RIDGING ATTEMPTS TO BUILD BACK IN TO THE NORTH OF THE TROPICAL
CYCLONE AND A STRONG COLD FRONT INDUCES A SIGNIFICANT GAP WIND FLOW
EVENT IN THE GULF OF TEHUANTEPEC. BY THE MIDDLE OF THIS WEEK, THE
ENHANCED LOW-LEVEL FLOW ASSOCIATED WITH THE RIDGE AND GAP WINDS ARE
FORECAST TO PUSH PILAR AWAY FROM CENTRAL AMERICA TO THE
WEST-SOUTHWEST AS A WEAKENING TROPICAL STORM. AS DISCUSSED
PREVIOUSLY, THE CONFIDENCE OF WHEN OR HOW SHARP THIS TURN AWAY FROM
CENTRAL AMERICA WILL BE IS LOW GIVEN THE INCONSISTENT MODEL GUIDANCE
OVER THE PAST DAY. THE NHC TRACK THIS CYCLE IS JUST A BIT CLOSER TO
THE COAST AND A TOUCH EAST OF THE PRIOR TRACK, BUT IS ROUGHLY IN
BETWEEN THE TVCE AND HCCA CONSENSUS AIDS.
A SMALL CORE MAY BE STARTING TO TAKE SHAPE GIVEN THE EARLIER
MICROWAVE IMAGERY, AND THE PERSISTENT AREA OF CONVECTION THAT PILAR
HAS BEEN MAINTAINING OVER THE LAST 3-6 HOURS NEAR THE ESTIMATED
CENTER. MOST OF THE GUIDANCE MAINTAINS THIS SMALL CORE STRUCTURE
WITH INTENSIFICATION WHILE THE STORM REMAINS EMBEDDED IN MODERATE
(15-20 KT) EASTERLY VERTICAL WIND SHEAR BUT IS OVER WARM 28-29 C
SEA-SURFACE TEMPERATURES IN A MOIST MID-LEVEL AIR ENVIRONMENT. THE
LATEST NHC INTENSITY FORECAST STILL TAKES PILAR TO NEAR HURRICANE
INTENSITY IN 36 H, ON THE HIGHER END OF THE INTENSITY GUIDANCE BUT
NOT FAR OFF THE HURRICANE-REGIONAL GUIDANCE SOLUTIONS. AFTERWARDS,
IT SEEMS LIKELY A COMBINATION OF THE DRY MID-LATITUDE GAP-WIND FLOW
IN ADDITION TO POSSIBLE COOL UPWELLING OF THE SHALLOW WARM WATERS
DUE TO SLOW MOTION NEAR THE COAST OF CENTRAL AMERICA COULD BEGIN A
WEAKENING TREND. IF THE LATEST HWRF AND HAFS-B RUNS END UP BEING
CORRECT, LAND INTERACTION COULD ALSO RESULT IN WEAKENING. THE
INTENSITY FORECAST BEYOND 48 H IS A LITTLE LOWER THAN THE PRIOR
ADVISORY, AS IT IS LOOKING MORE LIKELY THAT A COMBINATION OF
MODERATE SHEAR AND ADDITIONAL DRY STABLE AIR COULD PREVENT THE STORM
FROM RE-INTENSIFYING EVEN AFTER IT BEGINS TO MOVE BACK OVER WARMER
OCEAN WATERS AWAY FROM ITS OWN COLD WAKE.
KEY MESSAGES:
1. HEAVY RAINS FROM THE TROPICAL DEPRESSION WILL PRODUCE FLASH AND
URBAN FLOODING, ALONG WITH MUDSLIDES IN AREAS OF HIGHER TERRAIN
ALONG THE PACIFIC COAST OF CENTRAL AMERICA, INCLUDING EL SALVADOR,
THROUGH WEDNESDAY.
2. TROPICAL STORM CONDITIONS ARE POSSIBLE BY EARLY TUESDAY INTO
WEDNESDAY ALONG PORTIONS OF THE PACIFIC COAST OF EL SALVADOR,
HONDURAS, AND NICARAGUA WHERE A TROPICAL STORM WATCH IS NOW IN
EFFECT. INTERESTS ELSEWHERE ALONG THE PACIFIC COAST OF GUATEMALA,
AND NICARAGUA SHOULD MONITOR THE PROGRESS OF THIS SYSTEM AS
ADDITIONAL WATCHES OR WARNINGS COULD BE NEEDED TOMORROW.
3. SWELLS GENERATED BY THE DEPRESSION WILL BEGIN TO AFFECT PORTIONS
OF THE PACIFIC COAST OF CENTRAL AMERICA, INCLUDING EL SALVADOR,
BEGINNING ON MONDAY. THESE SWELLS ARE LIKELY TO CAUSE
LIFE-THREATENING SURF AND RIP CURRENT CONDITIONS.
FORECAST POSITIONS AND MAX WINDS
INIT 30/0300Z 11.0N 92.0W 35 KT 40 MPH
12H 30/1200Z 11.2N 91.3W 45 KT 50 MPH
24H 31/0000Z 11.6N 90.2W 55 KT 65 MPH
36H 31/1200Z 12.0N 89.4W 60 KT 70 MPH
48H 01/0000Z 12.3N 88.9W 55 KT 65 MPH
60H 01/1200Z 12.0N 88.9W 45 KT 50 MPH
72H 02/0000Z 11.2N 89.7W 35 KT 40 MPH
96H 03/0000Z 9.9N 93.0W 35 KT 40 MPH
120H 04/0000Z 9.0N 97.5W 35 KT 40 MPH
FORECASTER PAPIN
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