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Eastern Pacific Tropical Weather Discussion



000
AXPZ20 KNHC 201557
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC THU NOV 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1530 UTC.                       

...SPECIAL FEATURES... 

GULF OF TEHUANTEPEC...A TIGHT PRES GRADIENT CONTINUES TO PRODUCE 
GALE FORCE WINDS OF 30-35 KT AS CONFIRMED BY SCATTEROMETER 
PASSES FROM LATE LAST NIGHT. SEAS THERE HAVE SUBSIDE SLIGHTLY TO 
THE RANGE OF 10-14 FT. THE GALE FORCE WINDS ARE ON TRACK... 
ACCORDING TO MODEL GUIDANCE...TO DIMINISH TO LESS THAN GALE 
FORCE RANGE BY ABOUT 18Z THIS AFTERNOON AS THE PRES WEAKENS. 
THESE WINDS WILL FURTHER DIMINISH TO 20 KT OR LESS WITH 
RESULTANT SEAS SUBSIDING TO LESS THAN 8 FT BY FRI NIGHT.

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

THE MONSOON TROUGH AXIS EXTENDS FROM 09N84W TO 08N95W TO 09N105W 
TO LOW PRES NEAR 13N111W. ITCZ EXTENDS FROM 13N111W TO 10N125W 
TO 08N135W TO 07N140W. SCATTERED MODERATE/ISOLATED STRONG 
CONVECTION IS WITHIN 240 NM S OF THE TROUGH BETWEEN 90W-94W... 
WITHIN 120 NM OF THE TROUGH BETWEEN 98W-102W...ALSO WITHIN 60 NM 
N OF THE TROUGH BETWEEN 90W-94W...BETWEEN 98W-102W AND WITHIN 
120 NM S OF ITCZ W OF 137W. SCATTERED MODERATE CONVECTION IS  
WITHIN 120 NM S OF THE TROUGH BETWEEN 110W-12W...AND WITHIN 120 
NM N OF ITCZ BETWEEN 125W-132W. 

ALSO...SCATTERED MODERATE/ISOLATED STRONG CONVECTION OBSERVED 
FROM 08N-12N AND BETWEEN 91W-94W IS SUPPORTED BY UPPER LEVEL 
DIFFLUENCE OVER THAT VICINITY OF THE AREA. 

...DISCUSSION... 

IN THE UPPER LEVELS...A TROUGH SHIFTING EASTWARD EXTENDS FROM 
CENTRAL BAJA CALIFORNIA SE 20N110.5W TO NEAR 11N108W. AN 
ELONGATED TROUGH IS OVER THE FAR NW PORTION OF THE AREA 
STRETCHING FROM 32N125W SW TO 28N135W TO SW OF THE AREA AT 
26N140W. AMPLE SUBSIDENCE AS INFERRED FROM WATER VAPOR IMAGERY 
CONTINUES TO KEEP A CAP ON MOISTURE NEAR AND ALONG THESE 
TROUGHS. THE SUBSIDENCE IS ALLOWING FOR RATHER DRY AND STABLE 
CONDITIONS TO PREVAIL N OF 19N WHERE SCATTERED TO BROKEN 
STRATOCUMLUS CLOUDS MOVING SW ARE SEEN. S OF 19N...THE 
ATMOSPHERE REMAINS VERY MOIST AS NOTED BY THE ACTIVE CONVECTION 
ALONG AND NEAR THE ITCZ AND MONSOON TROUGH AS NOTED ABOVE. 
LITTLE CHANGE IS EXPECTED WITH THE CURRENT ATMOSPHERIC STATE 
OVER THE NEXT 24-48 HRS.

AT THE SURFACE...THE SOUTHERN SEGMENT OF A COLD FRONT ASSOCIATED 
WITH THE UPPER TROUGH OVER THE FAR NW PORTION EXTENDS SW TO 
31N138W. THIS FRONT IS FORECAST TO STAY JUST N OF THE AREA AS IT 
QUICKLY MOVES EASTWARD OVER THE NEXT 24-48 HRS. A RIDGE EXTENDS 
FROM A 1026 MB HIGH LOCATED AT 30N142W ESE TO 27N128W AND TO 
NEAR 24N119W. THE PRES GRADIENT BETWEEN THE RIDGE AND A TROUGH 
JUST W OF 140W IS INDUCING AN AREA OF FRESH TO STRONG E WINDS 
FROM 08N-18N W OF 137W. THESE WINDS WILL EXPAND NORTHWARD TO 
NEAR 24N AND EASTWARD TO NEAR 128W BY 48 HRS WITH RESULTANT SEAS 
OF 8-10 FT AS THE HIGH PRES BUILDS SOME TO THE SE. 

BROAD 1010 MB LOW PRES IS CENTERED NEAR 13N111W MOVING WNW 
AROUND 10 KT. LATEST SATELLITE IMAGERY SHOWS SCATTERED 
MODERATE/ISOLATED STRONG CONVECTION WITHIN 60 NM OF THE LOW IN 
THE SE QUADRANT...AND 120 NM OF THE LOW IN THE SW QUADRANT. THE 
LOW IS FORECAST TO GRADUALLY WEAKEN TO A TROUGH IN ABOUT 48 HRS 
OR SHORTLY THEREAFTER. A COMBINATION OF SW AND NW SWELLS WILL 
BRING SEAS TO 8 FT WITHIN 360 NM OF THE LOW IN THE NW QUADRANT 
THROUGH 24 HRS...AND TO INCLUDE 120 NM OF THE LOW IN THE NE 
QUADRANT AT 48 HRS.

WAVEWATCH GUIDANCE SUGGESTS THAT A NEW SET OF NW SWELLS...IN THE 
WAKE OF THE COLD FRONT THAT PASSES JUST TO THE N OF THE AREA... 
WILL PROPAGATE SEWD ACROSS THE FAR NW AND N CENTRAL WATERS BY 24 
HOURS WITH SEAS TO 9 FT IN MIXED SW AND NW SWELLS N OF ABOUT 28N 
AND W OF 132W...AND BY 48 HRS N OF A LINE FROM 30N116W TO 
24N130W TO 24N140W.

IN ADDITION TO THE ONGOING GULF OF TEHUANTEPEC WIND EVENT 
...STRONG NE-E WINDS WILL CONTINUE THROUGH THE GULF OF PAPAGAYO 
THROUGH EARLY THIS EVENING BEFORE DIMINISHING. SEAS CURRENTLY UP 
TO 8 FT ARE FORECAST TO SUBSIDE TO LESS THAN 8 FT AS THESE WINDS 
DIMINISH.

$$
AGUIRRE



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Page last modified: Thursday, 20-Nov-2014 15:57:41 UTC