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000
AXPZ20 KNHC 262218
TWDEP

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC THU MAR 12 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...

A STRONG COLD FRONT HAS MOVED INTO THE NW GULF OF MEXICO THIS AFTERNOON AND WILL MOVE SE AND REACH THE BAY OF CAMPECHE TONIGHT. GALE FORCE WINDS ARE EXPECTED BEHIND THE FRONT ALONG THE MEXICAN COAST STARTING FRI MORNING. THIS 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 BY EARLY FRI AFTERNOON..THEN INCREASE TO GALE FORCE BY FRI AFTERNOON. WINDS ARE EXPECTED TO INCREASE FURTHER TO AROUND 40 KT FRI NIGHT WITH SEAS BUILDING TO 17 FT BY EARLY SAT. WINDS WILL LIKELY REMAIN NEAR GALE FORCE SAT NIGHT BEFORE SLOWLY DIMINISHING BELOW GALE FORCE MONDAY MORNING...WITH WIND AND SEAS THEN SUBSIDING QUICKLY SUN AFTERNOON.


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

A WEAK TROUGH EXTENDS FROM 06N90W TO 05N102W TO 05N113W...WHERE SCATTERED MODERATE ISOLATED STRONG CONVECTION WAS NOTED WITHIN 120 NM EITHER SIDE OF TROUGH FROM 06N90W TO 05N102W. THE ITCZ EXTENDS FROM 05N113W TO 08N135W TO 07N140W. SCATTERED MODERATE TO STRONG CONVECTION WAS NOTED FROM 05N TO 12N BETWEEN 116W AND 129W.


...DISCUSSION...

AN UPPER TROUGH IS JUST W OF THE FAR NW PORTION OF THE DISCUSSION AREA...ALONG ABOUT 144W...AND IS SUPPORTING A COLD FRONT THAT HAS JUST ENTERED THE AREA NEAR 29N139W THIS AFTERNOON. NW SWELL BEHIND THE FRONT HAS RAISED SEAS 8 TO 9 FT...AND WILL GENERALLY STAY IN SYNCH WITH THE FRONT AS IT MOVES SE AND WEAKENS OVER THE NEXT 24 HOURS.

A BROAD UPPER RIDGE IS GENERALLY S OF 24N AND BETWEEN 100W AND 130W...AND IS PART OF A LOW LATITUDE BLOCKING PATTERN OF RIDGE- TROUGH-RIDGE S OF 20N SPANNING BETWEEN THE CENTRAL CARIBBEAN AND 100W. THIS UPPER TROUGH IS SUPPORTING CONVECTION ASSOCIATED WITH THE WEAK TROUGH ACROSS E PORTIONS DESCRIBED ABOVE. N OF THE BROAD UPPER RIDGE...A DEEP LAYERED UPPER TROUGH EXTENDS FROM THE CENTRAL U.S. SW ACROSS W TEXAS AND NW MEXICO TO 26N120W.

AT THE SURFACE...A RIDGE COVERS THE AREA N OF 14N W OF 105W...CENTERED ON A WEAKENING 1024 MB HIGH NEAR 33N128W. THE PRES GRADIENT BETWEEN THE HIGH AND LOWER PRES ACROSS BAJA CALIFORNIA HAS WEAKENED IN THE PAST 24 HOURS...WITH NWLY WINDS DIMINISHING THERE. THIS IS ALLOWING FOR A SLOW SUBSIDING TREND IN THE NW SWELL MOVING FROM OFFSHORE OF CALIFORNIA SOUTHWARD ACROSS THE WATERS OFFSHORE OF BAJA CALIFORNIA...WHERE SEAS WERE 7-8 FT THIS AFTERNOON. THIS NW SWELL WILL CONTINUE TO SUBSIDE TONIGHT...WITH SEAS EXPECTED 6-7 FT BY FRI MORNING. 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 7-10 FT THIS AFTERNOON IN MIXED NE WIND SWELL AND BUILDING S SWELL. THE HIGH IS EXPECTED TO COLLAPSE OVERNIGHT AS THE COLD FRONT APPROACHES 135W...WITH STRONGER HIGH PRES BUILDING ACROSS THE NW HALF OF THE AREA OVER THE WEEKEND. THIS WILL STRENGTHEN THE TRADEWINDS MODESTLY...WITH AN AREA OF 20-25 KT TRADES EXPECTED FROM 13N TO 20N W OF 136W BY FRI AFTERNOON AND GENERALLY CONTINUING THROUGH SAT.

ELSEWHERE E OF 115W...WINDS AND LIGHT TO MODERATE...WITH NO SIGNIFICANT GAP WINDS OCCURRING. A STRONG PULSE OF CROSS EQUATORIAL S SWELL HAS REACHED THE COASTS OF CENTRAL AMERICA AND MEXICO TODAY...AND WILL BUILD DURING THE NEXT 24 HRS TO GENERATE STRONG AND DANGEROUS SURF ALONG THE LOCAL COASTLINES AND REEFS. SEAS TO 8 FT AND GREATER WILL REACH WITHIN 200 NM OF THE CENTRAL MEXICAN COAST ON FRIDAY...AND ALSO PASS BETWEEN THE GALAPAGOS AND ECUADOR. THIS SWELL EVENT WILL SLOWLY SUBSIDE OVER THE WEEKEND.

$$ STRIPLING

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