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AXPZ20 KNHC 052154
TWDEP

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC TUE MAY 05 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.


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

SCATTEROMETER WINDS INDICATE THAT THE MONSOON TROUGH FORMS NEAR 06N90W AND EXTEND S SW TO AN EMBEDDED 1010 MB LOW PRESSURE AT 05N98W...AND THEN CONTINUES W TO 05N107W WHERE SCATTEROMETER WINDS INDICATE A TRANSITION TO AN ITCZ. THE ITCZ EXTENDS NW TO AN EMBEDDED TROUGH AT 10N121W...THEN TURNS SW TO BEYOND 04.5N140W. THE ITCZ EMBEDDED TROUGH IS ANALYZED FROM 07N121W TO 13N120W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS NOTED NEAR THE EASTERN PORTION OF THE MONSOON TROUGH...WITHIN 240 NM OF 04N89W. SIMILAR CONVECTION IS OBSERVED S OF THE EMBEDDED LOW PRESSURE...WITHIN 120 NM EITHER SIDE OF A LINE FROM 01N95W TO 05N108W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS FLARING N OF THE ITCZ AND EXTENDS SW ALONG THE EMBEDDED TROUGH WITHIN 90 NM EITHER SIDE OF A LINE FROM 11N111W TO 11N119W TO 07N125W. ISOLATED CELLS OF MODERATE CONVECTION ARE NOTED ELSEWHERE FROM 02S-10N BETWEEN 84-137W.

A 1009 MB LOW PRESSURE CENTER IS ANALYZED ALONG THE CARIBBEAN COAST OF COLOMBIA NEAR 11N75.5W WITH A TROUGH EXTENDING SW ACROSS THE COLOMBIA/PANAMA BORDER TO A BASE OVER THE TROPICAL PACIFIC NEAR 06N79W. SCATTERED MODERATE CONVECTION OCCASIONALLY FLARES WITHIN 45 NM EITHER SIDE OF THIS TROUGH.


...DISCUSSION...

AN UPPER CYCLONE IS OBSERVED AT 35N124W WITH AN UPPER TROUGH EXTENDING SSW TO BASE AT 23N127W. AN UPPER ANTICYCLONE IS CENTERED NEAR 11N114W WITH AN UPPER RIDGE EXTENDING W ACROSS THE TROPICAL PACIFIC TO BEYOND 08N140W. AN UPPER RIDGE ALSO EXTENDS E FROM THE ANTICYCLONE TO A FAIRLY SHARP CREST OVER COASTAL NORTHERN COSTA RICA. SOME UPPER MOISTURE IS ROTATING CYCLONICALLY AROUND THE UPPER CYCLONE AND WILL PASS NE ACROSS SOUTHERN CALIFORNIA TONIGHT. OTHERWISE VERY DRY UPPER AIR IS INDICATED OVER THE NORTHERN PORTION OF THE DISCUSSION AREA INCLUDING NORTHERN MEXICO...ROUGHLY N OF A LINE FROM 28N110W TO 21N140W. UPPER DIFFLUENCE ALONG THE PREVIOUSLY DESCRIBED WESTERN TROPICAL RIDGE IS ENHANCING CONVECTION ALONG THE ITCZ AND ITS EMBEDDED TROUGH ALSO PREVIOUSLY DESCRIBED. THE RESULTANT DEBRIS MOISTURE IS ADVECTED N FROM THE ITCZ BETWEEN 110W AND 120W. THIS MOISTURE MERGES AT 20N110W WITH A TROPICAL PLUME ORIGINATING IN THE CENTRAL PACIFIC THAT STREAMS ENE ACROSS THE DISCUSSION AREA WITHIN 150 NM EITHER SIDE OF A LINE FROM 17N140W TO ACROSS SOUTHERN BAJA AND CENTRAL MEXICO. UPPER DIFFLUENCE ALONG THE EASTERN TROPICAL RIDGE IS ENHANCING CONVECTION OVER AND TO THE S OF THE MONSOON TROUGH AS PREVIOUSLY DESCRIBED...WITH THE UPPER DEBRIS MOISTURE ADVECTED S ACROSS THE EQUATOR BETWEEN 85-118W.

ELSEWHERE AT THE LOW LEVELS A SURFACE RIDGE EXTENDS FROM 32N137W TO 16N104W. A SURFACE TROUGH EMBEDDED IN THE ITCZ FROM 07N121W TO 13N120W IS FORECAST TO SHIFT W FROM 05N131W TO 14N126W ON WED AND FROM 04N134W TO 13N129W ON THU. THE GRADIENT IS EXPECTED TO TIGHTEN SW OF THE RIDGE AXIS OVER THE NEXT FEW DAYS INCREASING THE NE TRADES TO 20-25 KT BETWEEN THE TROUGH AND THE RIDGE WITH SEAS BUILDING 7-10 FT IN THE NE WINDS WAVES THAT WILL MIX WITH LONG PERIOD SW AND NW SWELL. ALTHOUGH THE TROUGH WILL MOVE W OF 140W ON FRI...EXPECT THE FRESH NE TRADES TO CONTINUE THROUGH THE UPCOMING WEEKEND ACROSS THE TROPICAL WATERS BETWEEN 08-19W WITH EMBEDDED PATCHES OF STRONG TRADES. FRESH NW-N WINDS ARE EXPECTED ACROSS THE SUBTROPICAL WATERS NE OF THE RIDGE INTO THE UPCOMING WEEKEND. LONG PERIOD NW SWELL WILL PROPAGATE S INTO THE DISCUSSION AREA AND MIX WITH LONG PERIOD SOUTHERLY SWELL DRIVING THE COMBINED SEAS TO 7-10 FT ACROSS THE WATERS N OF 28N BETWEEN 116-128W THROUGH THU NIGHT...THEN GRADUALLY SUBSIDING THEREAFTER.

ANOTHER BATCH OF LONG PERIOD SW SWELL WILL CROSS THE EQUATOR BETWEEN 92-120W ON SUN NIGHT REACHING ALONG 03N ON MON.

GULF OF CALIFORNIA...A SURFACE LOW WILL MOVE E OVER THE FAR NORTHERN GULF OF CALIFORNIA TONIGHT WHERE IT WILL MEANDER THROUGH FRI. THE GRADIENT WILL SUPPORT S-SW 20-25 KT PULSES WITHIN ABOUT 90 NM S OF THE CENTER. AS THE LOW MOVES E ON THU NIGHT THE GRADIENT MAY BRIEFLY SUPPORT NW-N 20-25 KT WINDS OVER THE NW QUADRANT AS WELL. THE BRIEF STRONG PULSES WITH LIMITED FETCH SHOULD ONLY ALLOW SEAS TO BUILD TO 7 FT.

$$ NELSON

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