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AXPZ20 KNHC 312128
TWDEP

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2100 UTC.


...SPECIAL FEATURES... TROPICAL STORM VANCE IS CENTERED NEAR 9.5N 101.4W OR ABOUT 450 NM...840 KM S OF ACAPULCO MEXICO AT 31/2100 UTC MOVING TOWARD THE WEST-SOUTHWEST OR 250 DEGREES AT 6 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1004 MB. MAXIMUM SUSTAINED WIND SPEED IS 40 KT WITH GUSTS TO 50 KT. GRADUAL STRENGTHENING IS FORECAST DURING THE NEXT COUPLE OF DAYS...AND VANCE COULD BECOME A HURRICANE ON SUNDAY. DEEP CONVECTION ASSOCIATED WITH VANCE HAS DIMINISHED SINCE YESTERDAY...WITH THE CENTER EXPOSED AT TIMES. SATELLITE IMAGES SHOW A CLUSTER OF MODERATE TO STRONG CONVECTION WITHIN 60 NM W OF CENTER. NUMEROUS MODERATE TO ISOLATED STRONG CONVECTION IS ALSO NOTED E OF CENTER FROM 09N TO 13N BETWEEN 97W AND 100W. SIMILAR CONVECTION CAN BE FOUND IN A BAND TO THE SW OF THE CENTER AND WITHIN 90 NM SW OF A LINE FROM 07N102W TO 08N105W TO 10N107W. SEE THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP1/WTPZ21 KNHC FOR MORE DETAILS.

LATEST SCATTEROMETER DATA SHOWED 20-30 KT NLY WINDS ACROSS THE TEHUANTEPEC REGION. 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 THIS EVENING. 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 TONIGHT INTO SAT MORNING. THIS GALE FORCE WIND EVENT IS FORECAST TO PERSIST AT LEAST THROUGH LATE SUN MORNING AND WILL LIKELY BE THE SECOND GALE FORCE EVENT OF THE COLD SEASON 2014- 2015.


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

MONSOON TROUGH EXTENDS FROM 09N83W TO 10N98W...THEN RESUMES W OF T.S. VANCE FROM 09N105W TO 08N110W TO 11N125W TO 08N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS NOTED N OF 06N E OF 83W...WITHIN 150 NM S OF TROUGH BETWEEN 85W AND 91W AND FROM 10N TO 13N BETWEEN 120W AND 123W.


...DISCUSSION... A COLD FRONT IS OVER THE NW CORNER OF THE AREA AND EXTENDS FROM 30N125W TO 23N140W. MODERATE TO FRESH NLY WINDS ARE NOTED BEHIND THE FRONT PER SCATTEROMETER DATA. A SET OF NW SWELL FOLLOWS THE FRONT BUILDING SEAS TO 11 FT. THIS SWELL EVENT 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 24N AND W OF 130W.

NE WINDS IN THE GULF OF PAPAGAYO ARE EXPECTED TO INCREASE TO A FRESH TO STRONG BREEZE EARLY SUN AS THE COLD FRONT CURRENTLY IN THE GULF OF MEXICO MOVES ACROSS THE WESTERN CARIBBEAN SEA.

$$ GR

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