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AXPZ20 KNHC 070230
TWDEP

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC THU MAY 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 0215 UTC.


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

SCATTEROMETER WINDS INDICATE THAT THE ITCZ FORMS NEAR 07N91W AND EXTENDS W TO AN NEWLY FORMED TROUGH EMBEDDED AT 08N112W... THEN THE ITCZ REFORMS SW OF THE TROUGH AT 04N116W AND EXTENDS NW TO A PERSISTENT TROUGH EMBEDDED AT AT 09N131W...THE CONTINUES SW TO BEYOND 05N140W.

SCATTERED MODERATE ISOLATED STRONG CONVECTION IS OBSERVED ALONG THE ITCZ WITHIN 120 NM EITHER SIDE OF A LINE FROM 06N95W TO 07N100W...NEAR THE EASTERNMOST EMBEDDED TROUGH WITHIN 150 NM EITHER SIDE OF A LINE FROM 08N110W TO 13N125W...ALONG THE ITCZ WITHIN 90 NM OF 04N115W...ALONG THE WESTERNMOST TROUGH WITHIN 150 NM OF 09N131W... AND S OF THE ITCZ WITHIN 60 NM OF 04.5N128W AND WITHIN 75 NM EITHER SIDE OF A LINE FROM 02N134W TO 04N138W.


...DISCUSSION...

AN UPPER TROUGH EXTENDS SW FROM SOUTHERN CALIFORNIA AT 34N119W TO 16N137W. AN UPPER ANTICYCLONE IS CENTERED OVER THE TROPICS NEAR 11N111W WITH AN UPPER RIDGE EXTENDING W TO A SHARP CREST AT 10N129W WITH SEVERAL MORE EMBEDDED SMALL ANTICYCLONIC CENTERS INDICATED ALONG THE RIDGE BY THE CLOUD MOTION VECTORS. AN UPPER RIDGE ALSO EXTENDS E FROM THE ANTICYCLONE TO ANOTHER FAIRLY SHARP CREST NEAR 10N91W. A SHORTWAVE RIDGE EXTENDS N ACROSS CENTRAL MEXICO TO A CREST OVER THE TEXAS COASTAL BEND. AN UPPER TROUGH EXTENDS S ACROSS THE WESTERN CARIBBEAN FROM CENTRAL CUBA TO ACROSS COSTA RICA TO A BASE OVER THE DEEP TROPICAL PACIFIC AT 05N87W.

A BAND OF UPPER MOISTURE IS MOVING ACROSS THE SHORTWAVE RIDGE FROM 20-24N FROM THE PACIFIC AT 111W ACROSS MEXICO TO OVER THE W GULF OF MEXICO ALONG 94W. THERE ARE EMBEDDED CLUSTERS OF CONVECTION WITHIN THIS AREA AND THESE WILL LIKELY CONTINUE TONIGHT. VERY DRY UPPER AIR IS INDICATED ELSEWHERE OVER THE NORTHERN PORTION OF THE DISCUSSION AREA INCLUDING NORTHERN MEXICO IN NEARLY ZONAL UPPER FLOW...ALL ROUGHLY N OF A LINE FROM 27N100W TO 10N140W.

UPPER DIFFLUENCE AROUND THE TROPICAL UPPER ANTICYCLONE AND ITS WESTERN RIDGE IS ENHANCING CONVECTION ALONG THE ITCZ AND ITS EMBEDDED LOW LEVEL TROUGH AS PREVIOUSLY DESCRIBED. THE RESULTANT DEBRIS MOISTURE IS ADVECTED NE TO NEAR 19N114W AND WILL RE- INFORCE THE PLUME PREVIOUSLY MENTIONED ACROSS CENTRAL MEXICO. A THIN TROPICAL MOISTURE PLUME ORIGINATING IN THE CENTRAL PACIFIC IS ALSO STREAMING ENE ACROSS THE DISCUSSION AREA WITHIN 120 NM EITHER SIDE OF A LINE FROM 16N140W TO JUST S OF THE SOUTHERN BAJA PENINSULA WHERE IT MERGES WITH THE DENSE PLUME ALREADY DESCRIBED. WEAK UPPER DIFFLUENCE BETWEEN THE PREVIOUSLY MENTIONED EASTERN TROPICAL RIDGE AND THE CARIBBEAN UPPER TROUGH IS ENHANCING THE CONVECTION OVER THE AREA S OF 10N BETWEEN 83- 100W...WITH THE UPPER DEBRIS MOISTURE EVAPORATING AS IT SPREADS SW ACROSS THE EQUATOR BETWEEN 94-113W.

ELSEWHERE AT THE LOW LEVELS A SURFACE RIDGE EXTENDS FROM 33N140W TO 16N103W. A SURFACE TROUGH IS EMBEDDED IN THE ITCZ FROM 08N127W TO 16N125W...AND IS FORECAST TO SHIFT W FROM 05N135W TO 12N130W ON THU AND NEARLY FILL FROM 04N139W TO 11N138W LATE FRI. THE GRADIENT SW OF THE RIDGE IS SUPPORTING 20-25 KT NE TRADES ACROSS THE WATERS FROM 10-18N BETWEEN 120-140W. THE NE WIND WAVES ARE MIXING WITH LONG PERIOD SW AND NW SWELL RESULTING IN COMBINED SEAS OF 7-10 FT. THE GRADIENT WILL GRADUALLY RELAX THROUGH SAT WITH THE WINDS DIMINISHED TO 15-20 KT ON SUN. THE AFFECTED AREA OF ENHANCED SEAS OF 7-9 FT WILL GRADUALLY SHRINK FROM 06-13N BETWEEN 130-140W ON TUE. 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 117-130W THROUGH FRI EVENING...THEN GRADUALLY SUBSIDING THEREAFTER.

ANOTHER BATCH OF LONG PERIOD SW SWELL WILL CROSS THE EQUATOR E OF 120W ON SUN NIGHT REACHING ALONG 06N ON TUE.

GULF OF CALIFORNIA...A SURFACE TROUGH WILL MEANDER OVER THE FAR NORTHERN GULF OF THROUGH FRI...AND MOVE E OVER EXTREME NW MEXICO ON FRI NIGHT. THE GRADIENT WILL SUPPORT S-SW 20-25 KT PULSES WITHIN ABOUT 90 NM E OF THE TROUGH AXIS. THE LIMITED FETCH SHOULD ONLY ALLOW SEAS TO BUILD TO A MAXIMUM OF 7 FT. GUIDANCE IS SUGGESTING THE GRADIENT NE OF THE PACIFIC RIDGE WILL SUPPORT NW WINDS OF 20-25 KT ALONG THE PACIFIC COAST OF THE BAJA PENINSULA ON FRI NIGHT THROUGH SAT NIGHT.

GULF OF PAPAGAYO...EXTENDED GUIDANCE INDICATES NE-E 20-25 KT WINDS OVER AND SW OF THE GULF OF PAPAGAYO ON MON NIGHT.

$$ NELSON

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