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000
AXPZ20 KNHC 270245
TWDEP

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0200 UTC.


...SPECIAL FEATURES...

A STRONG COLD FRONT IS MOVING SE ACROSS THE NW GULF OF MEXICO THIS EVENING AND WILL REACH THE BAY OF CAMPECHE EARLY FRIDAY. 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 AROUND NOON...THEN INCREASE TO GALE FORCE DURING THE LATE AFTERNOON. WINDS ARE EXPECTED TO INCREASE FURTHER TO AROUND 40 KT FRI EVENING WITH SEAS BUILDING TO 17 FT BY EARLY SAT. 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. SEE LATEST NWS HIGH SEAS FORECAST UNDER AWIPS/WMO HEADERS MIAHSFEP2/FZPN03 KNHC FOR MORE DETAILS.


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

A WEAK TROUGH EXTENDS FROM 06N90W TO 04.5N101W TO 04N107W. ITCZ EXTENDS FROM 03.5N110W TO 06.5N130W TO BEYOND 07N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION NOTED WITHIN 120 NM EITHER SIDE OF TROUGH BETWEEN 91W AND 102W. SCATTERED MODERATE TO STRONG CONVECTION NOTED WITHIN 360 NM N AND 120 NM S OF ITCZ BETWEEN 111W AND 140W.


...DISCUSSION...

AN UPPER TROUGH IS JUST W OF THE FAR NW PORTION OF THE DISCUSSION AREA...ALONG ABOUT 143W-144W...AND IS SUPPORTING A COLD FRONT THAT HAS ENTERED THE AREA FROM 30N137W TO 27N140W. 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...REACHING NEAR 30N133W TO 24N140W BY FRI EVENING.

A BROAD UPPER RIDGE IS GENERALLY S OF 24N AND BETWEEN 100W AND 130W...AND IS PART OF A LOW LATITUDE UPPER 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 27N120W.

AT THE SURFACE...A RIDGE COVERS THE AREA N OF 14N W OF 105W...CENTERED ON A WEAKENING 1024 MB HIGH NEAR 30N130W. THE PRES GRADIENT BETWEEN THE HIGH AND LOWER PRES ACROSS BAJA CALIFORNIA HAS WEAKENED IN THE PAST 24 HOURS...WITH NWLY WINDS ONLY 10-15 KT 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 6-8 FT THIS EVENING. 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 EVENING 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 CONTINUING THROUGH SAT MORNING.

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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