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AXPZ20 KNHC 281554
TWDEP

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC FRI NOV 28 2014

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 1530 UTC.


...SPECIAL FEATURE...

GULF OF TEHUANTEPEC STORM WARNING...THE VERY TIGHT PRES GRADIENT OVER SOUTHEASTERN MEXICO CONTINUES TO SUPPORT STRONG STORM FORCE N-NE WINDS OF 40-50 KT ACROSS THE GULF AS WELL AS JUST DOWNSTREAM OF THE GULF WITH MAXIMUM WAVEHEIGHTS TO 25 FT. NE-E WINDS OF 25-30 KT EXTEND AS FAR S AS 07N BETWEEN 94W-101W...AND EXTEND AS FAR W AS 11N109W. THE STORM FORM FORCE WINDS ARE FORECAST TO DIMINISH TO GALE FORCE WINDS OF ABOUT 30-45 KT EARLY THIS AFTERNOON AND SLOWLY DIMINISH INTO EARLY SAT...AND JUST BELOW GALE FORCE BY EARLY SAT AFTERNOON WITH SEAS SUBSIDING TO THE 9-12 FT RANGE. AS THE PRES GRADIENT WEAKENS FURTHER...THE WINDS WILL CONTINUE THE DIMINISHING TREND REACHING TO 20-25 KT ACROSS THE GULF BY EARLY SUN. MODEL GUIDANCE FOR BEYOND THE DISCUSSION RANGE SUGGESTS THAT NORTHERLY WINDS ACROSS THE GULF INCREASE AGAIN TO GALE FORCE MON NIGHT AND PERHAPS LAST THROUGH LATE WED.


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

THE MONSOON TROUGH AXIS EXTENDS WSW FROM THE COAST OF COLOMBIA AT 07N78W TO 07N91W WHERE LATEST SCATTEROMETER WINDS INDICATES A TRANSITION TO AN ITCZ WHICH CONTINUES W TO 07N101W TO 10N113W TO 09N125W...THEN TURNS SW TO BEYOND 08N140W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS OBSERVED WITHIN 60 NM EITHER SIDE OF THE ITCZ BETWEEN 108W-113W...WITHIN 60 NM N OF ITCZ BETWEEN 125W-128W...AND WITHIN 120 NM N OF ITCZ W OF 137W.


...DISCUSSION...

ALOFT...WATER VAPOR IMAGERY SHOWS ABUNDANT MODERATE SUBSIDENCE EXISTING N OF 20N SUGGESTING RATHER STABLE AND DRY CONDITIONS PREVAILING OVER THE NORTHERN CENTRAL SECTIONS OF THE AREA. S OF 20N...SUBTROPICAL JET STREAM ENERGY CONTINUES TO TRANSPORT ABUNDANT MOISTURE...IN THE FORM OF BROKEN HIGH CLOUDS...EASTWARD TOWARDS W CENTRAL MEXICO. SOME OF THIS UPPER LEVEL MOISTURE IS COMBINING WITH DEBRIS LEFTOVER MOISTURE ASSOCIATED WITH ITCZ CONVECTION AS DESCRIBED ABOVE.

AT THE SURFACE...THE 12 UTC SURFACE ANALYSIS HAS A WEAKENING STATIONARY FRONT EXTENDING FROM 32N133W TO 25N140W...WHILE A FAST MOVING COLD FRONT IS TO ITS NW ALONG A POSITION FROM 32N135W TO 28N140W. THE COLD FRONT IS FORECAST TO OVERTAKE THE STATIONARY FRONT THIS AFTERNOON OR EVENING WITH THE MERGED FRONT BECOMING STATIONARY BY EARLY ON SAT FROM NEAR 32N129W TO NEAR 25N136W...AND WEAKEN FURTHER TO A TROUGH BY EARLY ON MON.

LONG PERIOD PRIMARILY NW SWELLS ARE IDENTIFIED TO BE NW OF A LINE FROM 32N123W TO 16N129W TO 09N140W PRODUCING COMBINED WAVEHEIGHTS OF 8-10 FT. THE AREA AFFECTED BY THESE SWELLS IS FORECAST TO SHRINK TO NW OF A LINE FROM 32N135W TO 26N140W BY EARLY SAT. ANOTHER COLD FRONT WILL PUSH INTO THE NW WATERS SUN AFTERNOON ACCOMPANIED BY A 20-30 KT SW-W-NW WIND SHIFT AND BUILDING SEAS TO THE RANGE OF 8-12 FT. A NEW BATCH OF LONG PERIOD NW SWELLS WILL BEGIN TO PROPAGATE SEWD ACROSS THE NW PORTION OF THE AREA LATE SUN NIGHT INTO MON WITH COMBINED SEAS TO 21 FT EXPECTED NEAR 32N140W.

THE 12 UTC SURFACE ANALYSIS ALSO HAS A WEAK TROUGH ALONG 119N FROM 08N-14N MOVING W AT 15 KT. THIS FEATURE HAS A WEAK CYCLONIC CIRCULATION AT 10N119W BASED ON LATEST SATELLITE IMAGERY. WEAK ISOLATED CONVECTION IS NOTED WITHIN 60 NM OF THE CIRCULATION.

ANOTHER WEAK SURFACE TROUGH IS ANALYZED ALONG 138W/139W FROM 08N- 13N. THIS FEATURE IS HELPING TO ENHANCE CONVECTION SOME ALONG AND NEAR THE ITCZ W OF 137W. THE TROUGH IS FORECAST TO MOVE W OF THE AREA EARLY THIS EVENING.

OTHER GAP WINDS... GULF OF PAPAGAYO...THE PRES GRADIENT RELATED TO CARIBBEAN HIGH PRES WILL MAINTAIN NE 20-30 KT WINDS WITH SEAS OF 8-11 FT ACROSS AND DOWNSTREAM OF THE GULF OF PAPAGAYO DURING THE THE LATE NIGHT THROUGH EARLY MORNING HOURS THROUGH SAT...THEN THE NOCTURNAL MAX WILL REACH 25 KT ONLY SAT THROUGH TUE NIGHTS.

$$ AGUIRRE

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