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Eastern Pacific Tropical Weather Discussion (Text)



000
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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Page last modified: Sunday, 20-Apr-2014 07:04:16 UTC