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000
AXPZ20 KNHC 231528
TWDEP

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC SAT MAY 23 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1400 UTC.


...SPECIAL FEATURES...

BROAD CYCLONIC CIRCULATION IS ANALYZED AS A 1008 MB SURFACE LOW NEAR 12N127W. SCATTERED MODERATE CONVECTION WAS WITHIN 180 NM NE SEMICIRCLE OF THIS LOW. THE PRESSURE GRADIENT BETWEEN THIS LOW THE SUBTROPICAL RIDGE TO THE N IS MAINTAINING NE-E 20-25 KT WINDS WITHIN 240 NM NW QUADRANT OF THE LOW. THE LOW HAS THE POTENTIAL TO BECOME A TROPICAL CYCLONE AS IT MOVES N-NW TO NEAR 12N132W SUN MORNING AND NEAR 13N133W MON MORNING.

A 1008 MB LOW IS ANALYZED AT 05N137W WITH SCATTERED MODERATE TO STRONG CONVECTION OBSERVED WITHIN 75 NM NE AND 210 NM SW SEMICIRCLES. WINDS ARE BELIEVED TO BE A FRESH TO OCCASIONALLY STRONG BREEZE WITHIN 90 NM SE SEMICIRCLE OF THE CENTER. THERE IS SOME POTENTIAL FOR TROPICAL CYCLONE FORMATION AS THE LOW REACHES NEAR 08N140W SUN MORNING AND NEAR 09N140W MON MORNING. THEN THE NUMERICAL GUIDANCE SUGGESTS THIS LOW WILL WEAKEN AS THE LOW PRESSURE SYSTEM TO ITS EAST INTENSIFIES.


...TROPICAL WAVES...

A TROPICAL WAVE WAS ANALYZED ALONG 90W FROM THE EL SALVADOR S TO NEAR 03N. SCATTERED MODERATE CONVECTION WAS NEAR THE AXIS IN THE AREA S OF 06N BETWEEN 88W AND 92W. SCATTERED MODERATE WITH ISOLATED STRONG CONVECTION ALSO TRAILS THE WAVE FROM 05N TO 08N BETWEEN 81W AND 87W NEAR THE COAST OF WESTERN PANAMA. THIS WAVE IS FORECAST TO CONTINUE W AROUND 10-15 KT OVER THE NEXT FEW DAYS.


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

THE ITCZ WAS ANALYZED FROM 06N100W TO 07N109W TO 06N115W TO 11N123W. SCATTERED MODERATE WITH ISOLATED STRONG CONVECTION WAS WITHIN 300 NM N AND 180 NM S OF THE AXIS BETWEEN 105W-123W.


...DISCUSSION...

1029 MB HIGH PRESSURE CENTERED WELL N OF THE AREA NEAR 44N137W EXTENDS A RIDGE AXIS THROUGH 30N130W TO THE ISLAS REVILLAGIGEDO. THIS RIDGE IS EXPECTED TO REMAIN QUASISTATIONARY THROUGH THE END OF THE FORECAST PERIOD MON MORNING. ASIDE FROM THE TWO LOW PRESSURE SYSTEM MENTIONED ABOVE...PRIMARILY MODERATE TO FRESH TRADE WINDS LIE SW OF THE RIDGE AXIS. AN ASCAT PASS FROM 0648 UTC AND A RAPIDSCAT PASS FROM 0812 UTC CAPTURED FRESH TO STRONG E WINDS FROM 20N TO 24N BETWEEN 135W AND 139W ASSOCIATED WITH A WEAK MID-LEVEL SHORTWAVE TROUGH THAT IS MOVING INTO THE EASTERN SIDE OF A DEEP LAYERED LOW CENTERED NW OF THE AREA NEAR 33N150W. A COLD FRONT AT THE SURFACE W OF THE AREA ASSOCIATED WITH THIS LOW WAS ANALYZED FROM THE ALENUIHAHA CHANNEL BETWEEN MAUI AND THE BIG ISLAND OF HAWAII TO 32N147W. THIS FRONT WILL MOVE INTO FORECAST WATERS N OF 23N W OF 138W SUN INTO MON...WITH FRESH TO STRONG SE WINDS EXPECTED AHEAD OF THE FRONT AND SEAS BUILDING TO 10 FT.

THE PRESSURE GRADIENT BETWEEN TROUGHING OVER THE SW UNITED STATES AND THE SUBTROPICAL RIDGE WILL ALLOW NW WINDS TO INCREASE TO 20-25 KT IN THE LATE AFTERNOON AND EVENING HOURS TONIGHT IN THE PACIFIC OFFSHORE OF THE CENTRAL BAJA CALIFORNIA PENINSULA. THE PRESSURE GRADIENT WILL WEAKEN SUN AS DEEP LAYERED LOW PRESSURE OVER THE SW UNITED STATES SHIFTS EASTWARD. THIS WILL DIMINISH THE WINDS.

4-6 FT SEAS IN SOUTH-SOUTHWESTERLY SWELL OF 17-19 SECOND PERIOD HAS REACHED THE ENTIRE PACIFIC COAST S OF CABO LAZARO IN BAJA CALIFORNIA SUR. THESE LONG PERIOD SWELLS WILL SUBSIDE OVER THE NEXT TWO DAYS...BUT WILL STILL GENERATE LARGE AND DANGEROUS SURF CONDITIONS ALONG THE COASTLINE THROUGH THE WEEKEND. SEAS OVER 8 FT IN THE S-SW SWELL ARE CONFINED S OF A LINE FROM 00N84W TO 03N100W TO 00N110W AND WILL SUBSIDE N OF THE EQUATOR OVERNIGHT TONIGHT.

GAP WINDS... GULF OF PAPAGAYO...THE PRESSURE GRADIENT BETWEEN RIDGING OVER THE NW CARIBBEAN AND TROUGHING TO THE SW ENHANCED BY THE AFOREMENTIONED TROPICAL WAVE HAS GENERATED 20-25 KT WINDS IN THE GULF OF PAPAGAYO THIS MORNING WITH THE HELP OF NOCTURNAL DRAINAGE FLOW. SEAS HAVE BUILT TO 8 FT. ENHANCED SEAS WILL PROPAGATE W AND MIX WITH LONG PERIOD CROSS-EQUATORIAL SW SWELL ACROSS THE PACIFIC WATERS FROM 09-12N BETWEEN 90-96W TODAY AND SUBSIDE TO 5- 7 FT TONIGHT. ANOTHER WEAKER PULSE OF FRESH TO STRONG WINDS IS EXPECTED IN THE GULF OF PAPAGAYO SUN NIGHT DURING THE PERIOD OF PEAK NOCTURNAL DRAINAGE FLOW.

GULF OF TEHUANTEPEC...THE 0410 UTC ASCAT PASS CAPTURED THE ONSET OF THE FRESH TO STRONG N WINDS IN THE GULF OF TEHUANTEPEC. THESE WINDS SHOULD DIMINISH TODAY AFTER THE NOCTURNAL DRAINAGE FLOW ABATES. IN ADDITION...SCATTERED MODERATE CONVECTION WAS NEAR THE GULF OF TEHUANTEPEC FROM 12N-16N BETWEEN 92W-101W THIS MORNING.

$$ SCHAUER

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