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AXPZ20 KNHC 132153
TWDEP

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC SAT FEB 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 2145 UTC.


...SPECIAL FEATURES...

GULF OF TEHUANTEPEC GALE WARNING...STRONG GALE FORCE NORTHERLY WINDS...WITH SEAS TO 18 FT...ARE EXPECTED TO PERSIST THROUGH SUN MORNING. THE N WINDS WILL QUICKLY DIMINISH TO 20 KT OR LESS BY SUNRISE ON MON. THE RESULTANT SWELL CONTINUES TO PROPAGATE SE THROUGH SW...MERGING WITH ENE SWELL GENERATED FROM PULSING STRONG WINDS IN GULFS OF FONSECA AND PAPAGAYO...MERGING WITH LONG PERIOD CROSS-EQUATORIAL SW SWELL...AND ALSO MERGING WITH LONG PERIOD NW SWELL. SEAS 12 FT OR GREATER ARE EXPECTED TO CONTINUE TO SPREAD SW REACHING NEAR 07N103W ON SUN...WITH SEAS 8 FT OR GREATER REACHING THE EQUATOR BETWEEN 100-110W...WITH SEAS THEN SUBSIDING AS THE PRESSURE GRADIENT RELAXES. SEE THE LATEST NWS HIGH SEAS FORECAST UNDER AWIPS/WMO HEADERS MIAHSFEP2/FZPN03 KNHC FOR MORE DETAILS.

EPAC GALE WARNING....TWO SURFACE TROUGHS ARE ANALYZED IN THE TROPICAL PACIFIC. THE EASTERNMOST TROUGH EXTENDS FROM 12N121W TO 06N122W WITH SCATTERED MODERATE CONVECTION FLARING INTERMITTENTLY TO THE N OF 10N WITHIN 90 NM E OF THE TROUGH. THE WESTERNMOST TROUGH EXTENDS FROM 16N128W TO 06N132W AND IS CONTRIBUTING TO SCATTERED MODERATE ISOLATED STRONG CONVECTION FROM 10-17N BETWEEN 121-133W. STRONG NORTHEASTERLY WINDS ARE OBSERVED TO THE N OF 12N WITHIN 480 NM E AND WITHIN 360 NM W OF TROUGH WITH 10-13 FT SEAS. THE GRADIENT IS EXPECTED TO STRENGTHEN OVER THE NEXT FEW HOURS WITH MINIMAL GALE FORCE NE WINDS DEVELOPING TO THE N OF 12N WITHIN 240 NM W OF TROUGH AND STILL SURROUNDED BY STRONG NE WINDS ELSEWHERE FROM 11-27N BETWEEN 123-140W. GALE CONDITIONS OF 30-40 KT ARE EXPECTED WITHIN 150 NM OF 12N132W LATE TONIGHT...WITH THE GRADIENT THEN RELAXING ON SUN MORNING WITH WINDS BELOW GALE BY SUN AFTERNOON. SEE THE LATEST NWS HIGH SEAS FORECAST UNDER AWIPS/WMO HEADERS MIAHSFEP2/FZPN03 KNHC FOR MORE DETAILS.


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

SEE SPECIAL FEATURES ABOVE FOR CONVECTION ASSOCIATED WITH 2 LOW LEVEL TROUGHS. SCATTEROMETER WINDS INDICATE THAT THE ITCZ FORMS NEAR 04N85W AND WIGGLES W THROUGH 05N105W TO 04N120W WHERE THE LOW LEVEL FLOW IS INTERRUPTED BY THE EASTERNMOST TROUGH PREVIOUSLY DESCRIBED. THE ITCZ RESUMES W OF THE TROUGH NEAR 06N123W...AND EXTENDS SW TO BEYOND 02N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS OBSERVED OVER AND TO THE N OF THE ITCZ WITHIN 120 NM EITHER SIDE OF A LINE FROM 04N92W TO 04N104W TO 08N114W.


...DISCUSSION...

ELSEWHERE N OF 15N E OF 120W...A SURFACE RIDGE EXTENDS SE FROM 24N120W TO 20N108W. THE PRESSURE GRADIENT IS TIGHTENING AND EXPECT MODERATE TO FRESH NW WINDS ACROSS THE OPEN PACIFIC WATERS N OF 26N E OF 120W TO THE BAJA CALIFORNIA PENINSULA TONIGHT. MODERATE N TO NE WINDS ARE EXPECTED ELSEWHERE AROUND THE RIDGE THROUGH MON MORNING. THE GRADIENT WILL RELAX ON TUE WITH WEAK SURFACE HIGHS DEVELOPING ALONG THE RIDGE NEAR 27N120W AND 21N111W SURROUNDED BY LIGHT ANTICYCLONIC FLOW THROUGH WED. A WEAK TROUGH WILL PASS E ACROSS THE WATERS N OF 24N ON WED NIGHT THROUGH THU NIGHT. COMBINED SEAS OF 7-10 FT CURRENTLY ACROSS THE PAC WATERS BETWEEN 107-120W WILL BEGIN TO SUBSIDE FROM THE N ON MON WITH 4-6 FT SEAS EXPECTED BY TUE...AND 3-5 FT SEAS ON THU. LIGHT AND VARIABLE WINDS ARE OBSERVED BETWEEN 97-108W WITH THE PREVIOUSLY DESCRIBED GALE EVENT OCCURRING ACROSS THE WATERS TO THE E OF 97W. MODERATE NW WINDS ARE EXPECTED ACROSS THE GULF OF CALIFORNIA THROUGH SUN MORNING...INCREASING TO FRESH ON SUN AFTERNOON ACROSS THE CENTRAL GULF WATERS...AND SPREADING N ACROSS THE WATERS N OF 30N ON SUN NIGHT. STRONG NW WINDS EXPECTED ACROSS THE GULF OF CALIFORNIA N OF 30N ON MON AFTERNOON. THE NW FLOW WILL GRADUALLY DIMINISH ACROSS THE GULF WATERS ON MON NIGHT AND TUE.

S OF 15N E OF 110W...ONE LAST PULSE OF STRONG NE WINDS WILL SURGE ACROSS THE GULF OF FONSECA TONIGHT...WITH SEAS BUILDING TO ONLY 8 FT IN THE LIMITED FETCH. NE 20-30 KT SURGES WILL CONTINUE ACROSS AND DOWNSTREAM OF THE GULF OF PAPAGAYO THROUGH SUN MORNING AND EXTEND AS FAR SW AS 07N96W. EXPECT THE NE FLOW TO DIMINISH TO 15-20 KT DURING THE AFTERNOONS BEGINNING ON SUN...THEN INCREASE TO 20-25 KT AGAIN EACH NIGHT THROUGH WED NIGHT...WITH GUIDANCE SUGGESTING A STRONGER 20-30 EVENT ON THU NIGHT. PULSES OF FRESH TO STRONG NORTHERLY WINDS WILL SPREAD S FROM THE GULF OF PANAMA TO ALONG ABOUT 04N EACH NIGHT THROUGH THROUGH MON NIGHT WITH SEAS BUILDING TO ABOUT 10 FT NEAR 06N81W.

ELSEWHERE FROM THE EQUATOR TO 32N E OF 140W...A SURFACE HIGH IS CENTERED N OF THE AREA NEAR 36N133W WITH ITS ENVELOPE OF ANTICYCLONIC FLOW DOMINATING THE AREA W OF 110W. THE ITCZ HAS SHIFTED S ACROSS THE AREA W OF 120W...AND MAY EVEN DIP S OF THE EQUATOR...WITH MODERATE TO FRESH NE WINDS OBSERVED ACROSS THE DEEP TROPICS S OF 10N W OF 130W. THE PRESSURE GRADIENT WILL TIGHTEN TONIGHT RESULTING IN THE PREVIOUSLY MENTIONED GALE WITH FRESH TO STRONG NE-E WINDS DEVELOPING ELSEWHERE W OF 125W THROUGH SUN WHEN THE GRADIENT WILL BEGIN TO RELAX AGAIN. EXPECT A W TO E ORIENTATED RIDGE FROM 25N140W TO 25N120W ON TUE NIGHT WITH A COLD FRONT SWEEPING E ACROSS THE WATERS N OF THE RIDGE ACCOMPANIED BY STRONG NW FLOW N OF 30N W OF THE FRONT LATE TUE NIGHT.

$$ NELSON

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