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AXPZ20 KNHC 311524
TWDEP

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC FRI OCT 31 2014

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. THE FOLLOWING INFORMATION IS BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL ANALYSIS.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1500 UTC.


...SPECIAL FEATURES... TROPICAL STORM VANCE IS THE 20TH NAMED STORM OF THE EASTERN NORTH PACIFIC HURRICANE SEASON. VANCE IS CENTERED NEAR 10.1N 100.8W OR ABOUT 475 NM S OF ACAPULCO MEXICO AT 31/1500 UTC MOVING TOWARD THE SOUTH-SOUTHWEST OR 195 DEGREES AT 3 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1004 MB. MAXIMUM SUSTAINED WIND SPEED IS 40 KT WITH GUSTS TO 50 KT. NUMEROUS MODERATE TO STRONG FROM 09N TO 13N BETWEEN 97W AND 102W. GRADUAL STRENGTHENING IS FORECAST OVER THE NEXT TWO DAYS AS VANCE MOVES TO THE W. SEE THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP1/WTPZ21 KNHC FOR MORE DETAILS.

THE PRESSURE GRADIENT BETWEEN HIGH PRES BUILDING BEHIND A COLD FRONT IN THE GULF OF MEXICO AND TROPICAL STORM VANCE TO THE S IS FUNNELING NORTHERLY WINDS THROUGH CHIVELA PASS. THESE WINDS ARE FORECAST TO INCREASE TO GALE FORCE LATER THIS MORNING AS DRAINAGE FLOW REACHES A MAXIMUM. STRONG VERTICAL MIXING OF THE WINDS ALOFT IS EXPECTED AS THE COLD...DRY AIR BEHIND THE FRONT MOVES OVER THE WARM WATER IN PLACE IN THE GULF OF TEHUANTEPEC. WINDS WILL INCREASE TO 40 KT AS THE COLD FRONT PASSES THROUGH SOUTHERN MEXICO THIS EVENING.


...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...

MONSOON TROUGH FROM 9N83W TO 10N94W...THEN RESUMES FROM 9N108W TO 12N125W TO 12N131W. ITCZ FROM 12N131W TO 10N140W. SCATTERED MODERATE TO STRONG CONVECTION N OF 3N BETWEEN 78-82W AND WITHIN 60 NM S OF AXIS FROM 121W-123W.


...DISCUSSION... A COLD FRONT IS OVER THE NW CORNER OF THE AREA AND EXTENDS FROM 30N128W TO 25N140W. NW SWELL 8 TO 11 FT NW OF THE FRONT. THIS SWELL IS FORECAST TO CONTINUE SE ACROSS THE FORECAST AREA...WITH SEAS EXPECTED TO BUILD AS HIGH AS 12 FT. AS THE COLD FRONT BEGINS TO DISSIPATE EARLY SAT...HIGH PRES IS EXPECTED TO BUILD OVER N WATERS. THIS WILL INCREASE THE PRES GRADIENT BETWEEN THE SUBTROPICAL HIGH AND THE MONSOON TROUGH...WITH TRADEWINDS INCREASING TO A FRESH TO STRONG BREEZE OVER WATERS N OF THE MONSOON TROUGH/ITCZ TO 21N AND W OF 130W.

$$ DGS

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