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AXPZ20 KNHC 070334
TWDEP

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC SAT MAR 07 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 0300 UTC.


...SPECIAL FEATURE...

A STORM WARNING REMAINS IN EFFECT FOR THE GULF OF TEHUANTEPEC. PERSISTENT STRONG HIGH PRESSURE EXTENDING SOUTHWARD ALONG THE MEXICO COASTAL PLAINS TO SOUTH CENTRAL MEXICO CONTINUES TO MAINTAIN A TIGHT PRESSURE GRADIENT INTO THE GULF OF TEHUANTEPEC. THIS IS SUPPORTING MINIMAL STORM FORCE WINDS FLUCTUATING 40-50 KT THROUGH THE GULF OF TEHUANTEPEC...WITH GALE FORCE WINDS EXTENDING DOWNWIND SOME 220-240 NM. IZTEPEC IN THE NORTHERN END OF THIS GULF HAS REPORTED GUSTY WINDS OF AROUND 40 KT FOR SEVERAL HOURS. SEAS WILL BUILD TO 22-23 FT WITH THE STRONGEST WINDS. THE PRESSURE GRADIENT SHOULD BEGIN TO RELAX BY SAT MORNING WITH THE NORTHERLY FLOW DIMINISHING TO A STRONG GALE AROUND 1800 UTC...THEN CONTINUE TO WEAKEN THROUGHOUT THE DAY SAT INTO SAT NIGHT WITH ONLY MINIMAL GALE CONDITIONS EXPECTED EARLY SUN MORNING...AND BELOW GALE FORCE WINDS BY SUN AFTERNOON. THIS WILL BE THE THIRD STORM EVENT TO OCCUR ACROSS THE GULF OF TEHUANTEPEC DURING THIS COLD SEASON. THE NEXT TEHUANTEPEC EVENT IS EXPECTED TO BEGIN WITH 20-25 KT NORTHERLY WINDS ON TUE NIGHT...GRADUALLY INCREASING TO A MINIMAL GALE ON WED EVENING THROUGH SUNRISE ON THU.

A GALE WARNING IS IN EFFECT FOR THE GULF OF PAPAGAYO. THIS SAME STRONG PRESSURE GRADIENT IS COMBINING WITH STRONG TRADE WINDS ACROSS THE CENTRAL AND SW CARIBBEAN TO SUPPORT STRONG GAP WINDS ACROSS THE GULF OF PAPAGAYO. WINDS ARE EXPECTED TO PULSE TO MINIMAL GALE FORCE WITH THE ASSISTANCE OF THE NOCTURNAL DRAINAGE FLOW TONIGHT THROUGH THE EARLY MORNING HOURS SAT...AND AGAIN SAT NIGHT INTO EARLY SUN MORNING...WITH WINDS OF 20-30 KT EXTENDING DOWNWIND TO NEAR 93W. EXPECT BUILDING SEAS TO AROUND 12 FT WITH THE STRONGEST WINDS.


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

THE ITCZ EXTENDS FROM 03N87W TO 02N100W TO 03N107W THEN RESUMES AT 03N110W TO 01N125W TO BEYOND 02N140W. A SECOND ITCZ AXIS IS NOTED SOUTH OF THE EQUATOR AND EXTENDS FROM 07S90W TO 06S120W. DURING MARCH AND APRIL...IT IS USUAL TO OBSERVE A DOUBLE ITCZ AXES. NO SIGNIFICANT CONVECTION WITH THESE FEATURES.


...DISCUSSION...

A SURFACE RIDGE EXTENDS SE FROM A 1026 MB HIGH PRESSURE LOCATED N OF AREA NEAR 41N127W TO 20N110W. THE TRADE WINDS SW OF THE RIDGE ARE AT 15-20 KT WITH COMBINED SEAS OF 7-9 FT IN MIXING NE TRADES...ALONG WITH LONG PERIOD SW AND NW SWELL. THE GRADIENT IS EXPECTED TO INCREASE SW OF THE RIDGE OVER THE WEEKEND...WITH EMBEDDED PATCHES OF 20-25 KT WINDS AND SEAS BUILDING TO 10 FT. REINFORCING NE SWELL...ORIGINATING FROM A STORM EVENT IN THE GULF OF TEHUANTEPEC AND A GALE EVENT IN THE GULF OF PAPAGAYO... WILL PROPAGATE WSW INTO THE TROPICAL WATERS TO THE S OF 13N... AND SPREAD W ACROSS THE WATERS BETWEEN 110-120W WELL INTO NEXT WEEK MIXING WITH THE NE TRADE WIND SWELL.

A COLD FRONT IS FORECAST TO APPROACH THE FAR NW CORNER OF THE AREA EARLY SAT MORNING. AT THIS TIME...SOUTHERLY WINDS AHEAD OF THE FRONT WILL INCREASE TO 20-30 KT WITH BUILDING SEAS TO AROUND 12 FT DUE TO THE PRES GRADIENT BETWEEN THE ABOVE MENTIONED RIDGE AND THE FRONT. IT WILL BE NEAR 30N140W BY SAT AFTERNOON...THEN WILL BECOME NEARLY STATIONARY OVER THE NW CORNER OF THE FORECAST AREA ON SUN BEFORE DISSIPATING. ADDITIONAL PULSES OF NW SWELL WILL FOLLOW THE FRONT.

GAP WINDS...

THE ENHANCED NE WINDS ACROSS THE GULF OF PAPAGAYO WILL ALSO SPREAD N ALONG THE COAST OF NICARAGUA TO THE GULF OF FONSECA MAINLY DURING THE OVERNIGHT AND EARLY MORNING HOURS LIKELY THROUGH MON MORNING.

GULF PANAMA...NORTHERLY WINDS ARE EXPECTED TO INCREASE TO 20-25 KT THIS EVENING...AND SPREAD AS FAR S AS 05N81W TONIGHT INTO EARLY SAT MORNING...AND AS FAR SW AS 04N82W ON EARLY SUN MORNING WITH MAX SEAS OF 9 FT EACH NIGHT DOWNSTREAM OF THE GULF PANAMA.

$$ GR

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