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AXPZ20 KNHC 250928
TWDEP

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC THU DEC 25 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0900 UTC.


...SPECIAL FEATURES... GULF OF TEHUANTEPEC GALE WARNING...A COLD FRONT HAS PASSED TO THE NE OF THE ISTHMUS OF TEHUANTEPEC REGION WITH COLD DENSE AIR FUNNELING THROUGH THE CHIVELA PASS GENERATING GALE FORCE WINDS IN THE GULF OF TEHUANTEPEC. A PAIR OF RECENT SCATTEROMETER SATELLITE PASSES VERIFY GALES ARE ONGOING IN THE GULF OF TEHUANTEPEC. SEAS ARE FORECAST TO BUILD UP TO 15 FT THROUGH THIS MORNING. HIGH PRES IN THE GULF OF MEXICO WILL QUICKLY SHIFT EAST FROM THIS MORNING LATE INTO THE AFTERNOON HOURS WHILE WEAKENING ACROSS THE WESTERN GULF OF MEXICO. THIS WILL ALLOW WINDS IN THE GULF OF TEHUANTEPEC TO QUICKLY DIMINISH BELOW GALE FORCE THIS AFTERNOON...AND BELOW 20 KT BY FRI. NE SWELL IN EXCESS OF 8 FT WILL PROPAGATE SOUTHWEST AWAY FROM THE GULF REGION AFTER THE ONSET OF THE GALE EVENT...AND REACH FROM 07N TO 14N BETWEEN 98W AND 105W FRI MORNING.


...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM 07N78W TO 06N90W TO 07N95W...WHERE IT TRANSITIONS TO AN ITCZ. THE ITCZ REACHES FROM 07N95W TO 07N100W TO BEYOND 07N140W. SCATTERED MODERATE CONVECTION IS NOTED WITHIN 60 NM EITHER SIDE OF ITCZ AXIS BETWEEN 105W AND 115W.


...DISCUSSION...

A DEEP LAYER RIDGE REMAINS ANCHORED ALONG ROUGHLY 140W...WITH AN ASSOCIATED 1035 MB CENTERED N OF THE AREA NEAR 42N140W. THE SURFACE HIGH PRES IS BEING DISPLACED FARTHER N OF THE AREA BY DEVELOPING LOW PRES NE OF HAWAII. AS A RESULT...TRADE WINDS OVER THE TROPICAL E PACIFIC W OF 120W REMAIN LIMITED TO 15 TO 20 KT OR LESS. MEANWHILE THE TIGHTENING GRADIENT BETWEEN THE DEVELOPING LOW PRES NE OF HAWAII AND THE RIDGE TO THE NORTH IS PROMOTING FRESH TO STRONG E TO SE WINDS OVER THE FAR NW PORTION OF THE DISCUSSION AREA...N OF 24N AND W OF 130W. THIS PATTERN WILL PERSIST THROUGH THE NEXT SEVERAL DAYS...WITH SOME POTENTIAL FOR WINDS TO NEAR GALE FORCE BY LATE SAT.

A VIGOROUS MID LEVEL SHORT WAVE TROUGH IS MOVING ACROSS THE WESTERN UNITED STATES ON THE WEST SIDE OF THE RIDGE...SUPPORTING THE APPROACH OF A COLD FRONT ACROSS SOUTHERN CALIFORNIA AND ADJACENT PACIFIC WATERS. THIS FRONT WILL PUSH INTO THE NORTHERN GULF OF CALIFORNIA AND BAJA CALIFORNIA NORTE LATE TODAY...THROUGH THE MIDDLE GULF OF CALIFORNIA AND INTO BAJA CALIFORNIA SUR BY LATE FRI BEFORE BECOMING DIFFUSE SAT. STRONG NW FLOW IS FOLLOWING THE FRONT ALONG THE CALIFORNIA COAST. N TO NE WINDS OF 20 TO 25 KT WILL PENETRATE SOUTH TO NEAR 28N BY LATE TODAY. ASSOCIATED SHORT PERIOD SWELL WITH HEIGHTS OF 12 TO 14 FT WILL FOLLOW IN THE WATERS N OF 28N BETWEEN 116W AND 125W BEFORE DECAYING TO 8 FT BY LATE FRI.

RECENT ALTIMETER SATELLITE PASSES INDICATE EVIDENCE OF LONG PERIOD NW SWELL WITH HEIGHTS OF 8 TO 10 FT FROM AN EARLIER EVENT LINGERING ACROSS THE WATERS W OF A LINE FROM 30N115W TO 20N112W TO 00N130W. THIS WILL DECAY BELOW 8 FT EXCEPT WHERE IT IS MIXED WITH WAVES GENERATED FROM TRADE WINDS AND WHERE REINFORCED FROM NORTHERLY SWELL N OF 25N.

A CUT OFF UPPER LOW PREVIOUSLY NEAR 16N105W IS NOW LIFTING NE AHEAD OF A SHARP UPPER TROUGH REACHING FROM N CENTRAL MEXICO TO 10N120W. ASSOCIATED DIVERGENCE OF THE UPPER LOW IS SUPPORTING A FEW SHOWERS AND THUNDERSTORMS ALONG THE COAST OF MEXICO FROM ACAPULCO TO MANZANILLO.

GULF OF PAPAGAYO...BUILDING HIGH PRES INTO THE NW CARIBBEAN WILL PROMOTE FRESH TO STRONG GAP WINDS INTO THE GULF OF PAPAGAYO STARTING LATE TODAY. AIDED BY LOCAL OVERNIGHT DRAINAGE EFFECTS...GAP WINDS WILL REACH NEAR GALE FORCE OVERNIGHT. THIS WILL GENERATE A PLUME OF 8 TO 11 FT SEAS OUT TO 350 NM INTO THE EASTERN PACIFIC DOWNSTREAM OF THE GULF OF PAPAGAYO BY FRI...WITH SHORT PERIOD 8 TO 9 FT SWELL REACHING AS FAR AS 100W BY LATE SAT. A WEAKER SECONDARY PULSE IS EXPECT FRI NIGHT/EARLY SAT MORNING.

$$ CHRISTENSEN

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