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AXPZ20 KNHC 220957
TWDEP

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC FRI MAY 22 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0945 UTC.


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

SCATTEROMETER WINDS INDICATE THAT THE ITCZ FORMS NEAR 08N86W AND CONTINUES SW TO 05N97W...THEN TURNS NW TO 10N115W. ISOLATED MODERATE TO STRONG CONVECTION IS OBSERVED WITHIN 120 NM EITHER SIDE OF A LINE FROM 06N93W TO 03N103W TO 04N115W. THE ITCZ IS INTERRUPTED W OF 115W BY THE BROAD CYCLONIC FLOW ASSOCIATED WITH TWO SURFACE LOWS. THE EASTERNMOST LOW IS CENTERED NEAR 08N122W ALONG A NE TO SW ORIENTATED TROUGH THAT EXTENDS FROM 13N117W TO 02N125W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS NOTED N OF 09N WITHIN 150 NM EITHER SIDE OF A LINE FROM 14N113W TO 10N125W...AND WITHIN 180 NM OF 04N126W.

A SECOND SURFACE LOW IS ESTIMATED NEAR 08N137W AT 1009 MB AND CURRENTLY LACKS SIGNIFICANT CONVECTION. ISOLATED MODERATE TO STRONG CONVECTION IS NOTED BETWEEN THE TWO LOW PRESSURE CENTERS FROM 02-12N BETWEEN 130-140W.


...DISCUSSION...

AN UPPER CYCLONE IS MOVING ACROSS THE CALIFORNIA COAST AT 34N WITH AN UPPER SHORTWAVE TROUGH EXTENDING SE ACROSS THE GULF OF CALIFORNIA. AN ASSOCIATED SURFACE TROUGH EXTENDS S ACROSS THE NORTHERN GULF OF CALIFORNIA WITH S-SW 20-25 KT WINDS OBSERVED ACROSS THE GULF WATERS N OF 30N E OF THE TROUGH. EXPECT THE GRADIENT TO RELAX EARLY TODAY WITH WINDS DIMINISHED TO 15-20 KT BY THIS AFTERNOON.

AN UPPER ANTICYCLONE IS CENTERED OVER THE TROPICS NEAR 11N113W WITH AN UPPER RIDGE EXTENDING W TO BEYOND 11N140W. ADDITIONALLY A KELVIN WAVE HAS MOVED E INTO THE WESTERN PORTION OF THE DISCUSSION AREA...AND COMBINES WITH THE UPPER DIFFLUENCE ALONG THE UPPER RIDGE TO ENHANCE THE CONVECTION NEAR THE TROPICAL SURFACE LOWS. GLOBAL MODELS SUGGEST SLOW DEVELOPMENT OF THE EASTERNMOST LOW PRES THAT IS EXPECTED TO REACH NEAR 10N127W TONIGHT WITH THE GRADIENT SUPPORTING NE 20-25 KT WINDS DEVELOPING WITHIN 360 NM NW-N OF THE LOW WITH SEAS BUILDING 7-11 FT. THE LOW SHOULD REACH NEAR 11N131W ON SAT NIGHT. TROPICAL CYCLONE DEVELOPMENT IS POSSIBLE AFTER 48 HOURS.

LONG PERIOD SOUTHERLY SWELL AT 14-18 SECONDS IS OBSERVED ACROSS THE TROPICS S OF 03N BETWEEN 85-120W WITH COMBINED SEAS OF 7-9 FT. THESE SOUTHERLY SWELLS WILL SPREAD N REACHING THE PACIFIC COAST OF MEXICO AND CENTRAL AMERICA TONIGHT WITH SEAS SUBSIDED TO 4-6 FT.

GULF OF PAPAGAYO...GUIDANCE INDICATES NE-E 20-25 KT WINDS WILL DEVELOP OVER AND JUST SW OF THE GULF OF PAPAGAYO LATE TONIGHT THROUGH THE EARLY MORNING ON SAT...AND AGAIN ON SAT NIGHT INTO EARLY SUN. SEAS ARE EXPECTED TO BUILD TO 8 FT WITH THE RESULTANT NE SWELL PROPAGATING W AND MIXING WITH LONG PERIOD CROSS- EQUATORIAL SWELL ACROSS THE PACIFIC WATERS FROM 09-11N BETWEEN 88W AND 93W ON SAT.

$$ NELSON

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