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AXPZ20 KNHC 200704
TWDEP

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC SUN APR 20 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 0615 UTC.


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

THE MONSOON TROUGH EXTENDS 10N85W TO 08N90W. THE ITCZ EXTENDS FROM 08N90W TO 04N105W TO 05N110W TO 03N135W TO 05N140W. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS NOTED FROM 02N TO 06N W OF 135W.




...DISCUSSION... THE LAST REPORT AT 00 UTC FROM SALINA CRUZ ON THE PACIFIC END OF THE ISTHMUS OF TEHUANTEPEC INDICATED PEAK WINDS TO 31 KT...AN INDICATION THE STRONG GAP FLOW WILL POSSIBLY ONGOING INTO THE ADJACENT GULF OF TEHUANTEPEC AT THAT TIME. THIS WILL LIKELY BE ONGOING THROUGH A LITTLE AFTER SUNRISE THIS MORNING DUE TO DRAINAGE FLOW EFFECTS...THEN DIMINISH RAPIDLY. SEAS COULD REACH 10 FT IN FRESH NE SWELL AS FAR AS 120 NM DOWNSTREAM...DECAYING BELOW 8 FT BY LATE TODAY. NO SIGNIFICANT GAP WIND EVENTS ARE EXPECTED IN TEHUANTEPEC FOR THE REMAINDER OF THE WEEK.

FRESH GAP WIND FLOW IS ALSO POSSIBLE THROUGH THE GULF OF PAPAGAYO THIS MORNING AND AGAIN TONIGHT INTO EARLY MON MORNING.

ELSEWHERE AN UPPER TROUGH EXTENDING FROM THE SOUTHWEST UNITED STATES TO 20N130W WILL SHIFT EASTWARD ACROSS THE BAJA PENINSULA AND THE GULF OF CALIFORNIA THROUGH TONIGHT. UPPER FORCING ON THE SE SIDE OF THE TROUGH IS SUPPORTING A SURFACE TROUGH AND SCATTERED CONVECTION FROM 08N TO 15N BETWEEN 120W AND 125W.

1026 MB HIGH PRES IS CENTERED N OF THE AREA NEAR 36N130W...BEHIND A COLD FRONT ASSOCIATED WITH THE UPPER TROUGH. THE FRONT WILL STALL AND START TO DISSIPATE N OF THE AREA THROUGH TODAY...AS A WEAK SHORT WAVE RIDGE WILL FOLLOW BEHIND THE TROUGH N OF 20N THIS AFTERNOON.

FARTHER SOUTH...THE RIDGE IS SUPPORTING MAINLY 15 TO 20 KT TRADE WIND FLOW FROM 06N TO 20N W OF 130W...ALTHOUGH AN ASCAT SATELLITE PASS FROM 03 UTC INDICATED ISOLATED WINDS TO 25 KT NEAR 10N135W. A PAIR OF ALTIMETER SATELLITE PASSES FROM THE PREVIOUS 12 HOURS INDICATED SEAS TO 8 FT...CONFIRMING WAVE MODEL INITIALIZATIONS SHOWING A MIX OF SE AND NW SWELL IN ADDITION TO THE LOCAL TRADE WIND INFLUENCES. THE TRADE WIND CONVERGENCE IS SUPPORTING SCATTERED MODERATE TO ISOLATED STRONG CONVECTION ALONG THE ITCZ W OF 135W.

THE WEAK UPPER RIDGE WILL DAMPEN OUT TONIGHT AHEAD OF A MORE VIGOROUS NORTHERN STREAM DISTURBANCE AMPLIFYING N OF THE HAWAIIAN ISLANDS. THIS NEXT TROUGH WILL MOVE EAST THROUGH 140W TONIGHT. THE MAIN ENERGY WILL CROSS THE WEST COAST OF THE UNITED STATES LATE TOMORROW...WITH A TRAILING UPPER TROUGH SLOWLY MOVING EASTWARD N OF 20N AND NOT REACHING THE BAJA PENINSULA UNTIL LATE WED.

A REINFORCED SUBTROPICAL RIDGE WILL BUILD BEHIND THE SECOND UPPER TROUGH ALONG ROUGHLY 32N...ALLOWING AREAS OF 20 TO 25 KT WINDS IN THE TRADE WIND BELT FARTHER SOUTH. VARIOUS WAVE MODEL GUIDANCE INDICATES LONG PERIOD NW SWELL IN EXCESS OF 8 FT WILL MOVE SE OF 30N140W STARTING TONIGHT...EVENTUALLY COVERING THE AREA NW OF A LINE FROM 27N114W TO 07N140W BY LATE TUE.

NORTHERLY WINDS OFF THE PACIFIC COAST OF THE NORTHERN BAJA PENINSULA WILL INCREASE TO AT LEAST 20 KT BY LATE TUE INTO EARLY WED AS THE SUBTROPICAL RIDGE BUILDS TO THE WEST...AND LOW PRES DEEPENS OVER THE SW UNITED STATES AND NW MEXICO IN RESPONSE TO THE MOVEMENT OF THE UPPER TROUGH. THE LARGE AREA OF NW SWELL WILL DECAY BELOW 8 FT BY THIS TIME...ALTHOUGH 8 TO 11 FT SEAS WILL PERSIST N OF 25N E OF 125W BY MIDWEEK DUE TO THE ENHANCED FLOW OFF THE COAST OF THE NORTHERN BAJA PENINSULA.

THE GFS AND ECMWF HINT OF BRIEF PULSE OF FRESH WESTERLY FLOW INTO THE NORTHERN GULF OF CALIFORNIA ACROSS A GAP IN THE NORTHERN BAJA PENINSULA NEAR 30N LATE TUE INTO WED.

LOOKING AHEAD TO LATE IN THE WEEK...WAVE MODELS SUGGEST LONG PERIOD SW SWELL IN EXCESS OF 8 FT WILL PROPAGATE NORTHWARD ACROSS THE EQUATOR...REACHING AS FAR NORTH AS 15N AND WITHIN 200 NM OF THE CENTRAL AMERICAN AND SOUTHERN MEXICAN COASTLINES BY LATE FRI.

$$ CHRISTENSEN

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