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Eastern Pacific Tropical Weather Discussion (Text)



000
AXPZ20 KNHC 272214
TWDEP 

TROPICAL WEATHER DISCUSSION                                     
NWS NATIONAL HURRICANE CENTER MIAMI FL                         
2205 UTC FRI MAR 13 2015

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 
2130 UTC. 

...SPECIAL FEATURES...  

GULF OF TEHUANTEPEC GALE WARNING...A STRONG COLD FRONT HAS MOVED 
ACROSS THE W HALF OF THE GULF OF MEXICO FOLLOWED BY GALE FORCE 
WINDS IN THE WESTERN BAY OF CAMPECHE. THE FRONT IS FORECAST TO 
MOVE ACROSS THE E BAY OF CAMPECHE AND INTO THE YUCATAN PENINSULA 
TONIGHT. HIGH PRES BUILDING SOUTHWARD ALONG THE MEXICO COASTAL 
PLAINS IN THE WAKE OF THE FRONT WILL TIGHTEN THE PRESSURE 
GRADIENT ACROSS SOUTHERN MEXICO RESULTING IN STRONG NORTHERLY 
WINDS QUICKLY BLASTING ACROSS THE CHIVELAS PASS AND THROUGH THE 
GULF OF TEHUANTEPEC EARLY THIS AFTERNOON AND EVENING...AND 
INCREASE TO GALE FORCE BEFORE SUNSET. WINDS THERE ARE EXPECTED 
TO INCREASE TO 35-40 KT THIS EVENING WITH BUILDING SEAS TO 16-17 
FT BY TONIGHT. WINDS WILL LIKELY REMAIN NEAR GALE FORCE SAT 
NIGHT BEFORE SLOWLY DIMINISHING BELOW GALE FORCE SUNDAY 
MORNING...WITH WIND AND SEAS THEN SUBSIDING QUICKLY SUN 
AFTERNOON AND EVENING. 

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

A WEAK TROUGH EXTENDS FROM 05N97W TO 04.5N120W. THE ITCZ EXTENDS 
FROM 04.5N122W TO BEYOND 06N140W. SCATTERED MODERATE ISOLATED 
STRONG CONVECTION WAS NOTED FROM 03N TO 07N BETWEEN 98W AND 
116W. SCATTERED MODERATE ISOLATED STRONG CONVECTION WAS 
NOTED FROM 07N TO 13N W OF 125W.

DURING LATE WINTER TO EARLY SPRING SEASONS...FROM MARCH TO  
APRIL OF EACH YEAR...A DOUBLE ITCZ CAN BE PRESENT ACROSS THE 
EASTERN PACIFIC...ONE ON EACH SIDE OF THE EQUATOR. THIS MORNING 
AND AFTERNOON...AN ACTIVE ITCZ WAS NOTED ON SATELLITE IMAGERY 
ALONG 08.5S82W TO 07S89W TO 2.5S108W. CLUSTERS OF MODERATE TO 
STRONG CONVECTION ARE ALONG THE AXIS.

...DISCUSSION...                                                

A COLD FRONT IS WEAKENING ACROSS THE NW CORNER OF THE FORECAST 
AREA AND CURRENTLY EXTENDS FROM 30N133W TO 25N140W. AN UPPER-
LEVEL TROUGH STRETCHING FROM 32N134W TO BEYOND 12N145W SUPPORTS 
THE FRONT...BUT THE FRONT WILL GRADUALLY STALL SAT AND DISSIPATE 
IN ABOUT 12-24 HOURS. NW SWELL IN THE WAKE OF THE FRONT HAS 
RAISED SEAS TO AROUND 9 FT. AS THE FRONT DISSIPATES...SEAS WILL 
SUBSIDE TO LESS THAN 8 FT BY SAT MORNING ACROSS THE NW PART OF 
THE REGION. HIGH PRES BEHIND THE FRONT WILL MOVE NE TO A 
POSITION NEAR 35N135W IN ABOUT 24 HOURS WHILE STRENGTHENING. 
THIS WILL BRING AN INCREASE IN THE TRADE WIND FLOW ON SAT 
MORNING...PARTICULARLY FROM 14N TO 20N W OF 134W. THESE FRESH TO 
STRONG WINDS WILL ALLOW SEAS TO BUILD TO AROUND 9 FT. 

A SURFACE RIDGE COVERS THE AREA N OF 16N W OF 115W...CENTERED ON 
A COLLAPSING 1025 MB HIGH NEAR 30N132W...JUST AHEAD OF THE COLD 
FRONT. SOUTH OF THE RIDGE...THE PRES GRADIENT BETWEEN THE HIGH 
AND LOWER PRES ALONG THE ITCZ IS PROMOTING MODERATE TO LOCALLY 
FRESH NE TRADEWINDS S OF 20N W OF 115W...WHERE SEAS ARE 7-9 FT. 
ALTIMETER OBSERVATIONS FROM ACROSS THE REGION DURING THE PAST 24 
HOURS SHOW THAT COMPUTER MODEL WAVE FORECASTS HAVE BEEN A FEW 
FEET LOW...AND THAT SEAS OF 9-11 FT DOMINATE THE WATERS S OF A 
LINE FROM 11N91W TO 17N122W...ASSOCIATION WITH VERY LONG PERIOD 
SOUTHERN HEMI SWELL. THE PEAK IN THIS SWELL WILL REACH THE 
CENTRAL AMERICAN AND MEXICAN COASTLINES THROUGH BAJA CALIFORNIA 
ON SATURDAY TO GENERATE VERY LARGE AND POWERFUL WAVES...AND 
DANGEROUS CONDITIONS WITHIN THE SURF ZONE.  

GAP WINDS...

GULF OF PAPAGAYO...EXPECT INCREASING WINDS ACROSS THIS GAP WIND 
REGION BY EARLY SUN MORNING AS HIGH PRES BUILDS ACROSS THE NW 
CARIBBEAN AND NORTHERN CENTRAL AMERICA.  

$$ 
STRIPLING

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Page last modified: Friday, 27-Mar-2015 22:14:49 UTC