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AXPZ20 KNHC 240951
TWDEP

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC SUN MAY 24 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.


...SPECIAL FEATURES...

BROAD CYCLONIC CIRCULATION IS ANALYZED AS A 1008 MB SURFACE LOW NEAR 12N130W. SCATTERED MODERATE ISOLATED STRONG CONVECTION REMAINS UNORGANIZED WITHIN 300 NM NE OF THE CENTER. THE GRADIENT N OF THE LOW AND S OF A SUBTROPICAL RIDGE IS MAINTAINING NE-E 20- 25 KT WINDS ACROSS THE WATERS FROM 12-17N BETWEEN 128-133W WITH SEAS OF 9-11 FT. THE LOW HAS THE POTENTIAL TO BECOME A TROPICAL CYCLONE AS IT REACHES NEAR 14N133W LATE TONIGHT AND NEAR 16N135W ON MON NIGHT. THE LOW...OR POSSIBLE TROPICAL CYCLONE...IS EXPECTED TO MOVE WNW THROUGH MOST OF NEXT WEEK WITH THE STRONG EASTERLY WINDS OVER THE N SEMICIRCLE.

A 1008 MB LOW IS ANALYZED AT 05.5N140W WITH SCATTERED MODERATE CONVECTION OBSERVED WELL N OF THE CENTER WITHIN 90 NM OF 08N137W. THE GRADIENT SUPPORTS CYCLONIC 20-25 KT WINDS WITH 30- 45 NM OF THE CENTER WITH SEAS OF 5-8 FT. THE SYSTEM IS VERY DISORGANIZED SO INITIAL MOTION IS UNCERTAIN. THERE REMAINS SOME POTENTIAL FOR ORGANIZATION AND EVEN TROPICAL CYCLONE FORMATION AS THE LOW DRIFTS SLOWLY W OVER THE NEXT COUPLE OF DAYS.


...TROPICAL WAVE...

A TROPICAL WAVE WAS ANALYZED 04N96W TO 12.5N96W AND IS MOVING W AT ABOUT 12 KT. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS OBSERVED TO THE S OF 10N WITHIN 240 NM E OF THE WAVE AXIS.


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

A TROUGH EXTENDS W OFF THE COAST OF COLOMBIA FROM 05N78W TO 04N83W AND IS ACCOMPANIED BY SCATTERED MODERATE ISOLATED STRONG WITHIN 30 NM OF TROUGH. A LOW LEVEL TROUGH EXTENDS SW FROM THE PACIFIC COAST OF COSTA RICA AT 09.5N TO 08N93W AND IS ACCOMPANIED BY SCATTERED MODERATE ISOLATED STRONG CONVECTION WITHIN 30 NM OF TROUGH AXIS. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS NOTED BETWEEN THESE TWO SURFACE TROUGHS...WITHIN 60 NM OF COAST OF CENTRAL AMERICA FROM 79-86W.

SCATTEROMETER WINDS INDICATE THAT THE ITCZ FORMS W OF THE TROPICAL WAVE AT 09N98W...AND EXTENDS NW TO AN EMBEDDED TROUGH AT 12N110W...THE ITCZ RESUMES NEAR 06N119W AND EXTENDS NW TO 11N129W WHERE THE ITCZ IS INTERRUPTED BY THE BROAD CYCLONIC FLOW ASSOCIATED WITH TWO SURFACE LOWS PREVIOUSLY MENTIONED. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS OBSERVED WITHIN 90 NM EITHER SIDE OF A LINE FROM 03N96W TO 05N120W. SIMILAR CONVECTION IS OBSERVED WITHIN 180 NM OF 06N116W AND IS ASSOCIATED WITH A LOW LEVEL TROUGH ANALYZED FROM 07N117W TO 12N112W. LOW PRESSURE IS EXPECTED TO SOON DEVELOP ALONG THIS TROUGH NEAR 10N115W AND MOVE SLOWLY WESTWARD OVER THE NEXT FEW DAYS.


...DISCUSSION...

AN UPPER CYCLONE IS W OF THE AREA NEAR 31N149W WITH AN UPPER TROUGH EXTENDING SE IN THE DISCUSSION AREA NEAR 25N139W. ALTHOUGH AN ASSOCIATED FRONTAL TROUGH WILL DISSIPATE W OF 140W...THE GRADIENT IS SUPPORTING SE 20-25 KT WINDS AND 7-9 FT SEAS ACROSS THE DISCUSSION WATERS FROM 23-28N W OF 137W. THE GRADIENT WILL RELAX TONIGHT WITH WINDS DIMINISHING TO SE AT 15- 20 KT...AND THE ASSOCIATED SEAS ARE EXPECTED TO SUBSIDE TO 5-7 FT BY SUNRISE ON TUE. ADDITIONALLY...THE MID LEVEL SOUTHERLY FLOW IS PARTIALLY PROVIDING THE WNW STEERING FOR THE TROPICAL LOW CURRENTLY NEAR 12N130W.

AN UPPER CYCLONE OVER SOUTHERN NEW MEXICO TRAILS AN UPPER TROUGH SSE ACROSS NORTHERN MEXICO AND THE SOUTHERN GULF OF CALIFORNIA TO A BASE NEAR 20N108W...AND IS ADVECTING VERY DRY UPPER AIR SE ACROSS THE SUBTROPICS BETWEEN 120-103W.

AN UPPER ANTICYCLONE IS CENTERED OVER THE TROPICS NEAR 11N112W WITH AN UPPER RIDGE EXTENDING W TO BEYOND 11N140W. AN UPPER RIDGE ALSO EXTENDS NW TO BEYOND 32N130W AND SEPARATES THE UPPER CYCLONIC FLOW PREVIOUSLY DESCRIBED. UPPER MOISTURE IS ADVECTED ACROSS THE RIDGE CREST NEAR 32N129W...AND MAY REACH THE NORTHER BAJA PENINSULA LATE TONIGHT. A KELVIN WAVE IS SHIFTING E ACROSS THE DEEP TROPICS WITH ITS EASTERN EXTENT CURRENTLY NEAR 118W... AND COMBINES WITH THE UPPER DIFFLUENCE ALONG THE UPPER RIDGE TO ENHANCE THE CONVECTION NEAR THE TROPICAL SURFACE LOWS AND ITCZ ALL PREVIOUSLY DESCRIBED. ALTHOUGH THE DEBRIS MOISTURE FROM THIS CONVECTION IS ADVECTED N UNDER THE UPPER RIDGE...IT SEEMS TO EVAPORATE NEAR 20N107W IN THE DRY UPPER AIR PREVIOUSLY MENTIONED.

A SURFACE RIDGE EXTENDS FROM 32N132W TO 17N107W. TO THE NE OF THE RIDGE ARE NW WINDS AT 15-20 KT WITHIN ABOUT 180 NM W OF THE PACIFIC COAST OF THE BAJA PENINSULA WITH COMBINED SEAS OF 4-6 FT. THE GRADIENT WILL RELAX TODAY SUPPORTING 10-15 KT CONDITIONS BY LATE TONIGHT AND CONTINUING THROUGH EARLY FRI.

GULF OF PAPAGAYO...EXPECT NOCTURNAL 15-20 KT PULSES THIS WEEK.

$$ NELSON

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