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Eastern Pacific Tropical Weather Discussion



000
AXPZ20 KNHC 220932
TWDEP 

TROPICAL WEATHER DISCUSSION                                    
NWS NATIONAL HURRICANE CENTER MIAMI FL                         
1005 UTC SAT NOV 22 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.                       

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

MONSOON TROUGH EXTENDS FROM 08N78W TO 10N88W TO LOW PRES 1010 MB 
NEAR 09N100W TO 10N114W. THE ITCZ CONTINUES FROM 10N114W TO LOW 
PRES 1008 MB LOW NEAR 11N118W TO 08N125W TO 09N135W TO 08N140W.  
ISOLATED MODERATE FROM 07N TO 11N BETWEEN 96W AND 105W. 
SCATTERED MODERATE ISOLATED STRONG FROM 10N TO 15N BETWEEN 107W 
AND 110W...FROM 08N TO 10N BETWEEN 114W AND 122W AND FROM 08N TO 
09N BETWEEN 136W AND 138W. 

...DISCUSSION...                                                 

ALOFT...AN UPPER-LEVEL TROUGH SHIFTING EASTWARD EXTENDS SW FROM 
NW MEXICO TO SOUTHERN BAJA CALIFORNIA NEAR 25N112W TO 22N126W 
THEN CONTINUES WESTWARD AS A SHEAR AXIS TO AN ELONGATED UPPER 
LEVEL LOW LOCATED JUST W OF THE AREA NEAR 23N144W. A RIDGE IS 
BEHIND THE TROUGH AXIS AND DOMINATES THE NW CORNER OF THE 
FORECAST REGION. SUBSIDENT CONDITIONS WITH RELATED DRY AND 
STABLE AIR MASS ARE NOTED ACROSS MOST OF THE AREA N OF 19N. S OF 
19N...THE ATMOSPHERE REMAINS VERY MOIST AS NOTED BY THE ACTIVE 
CONVECTION ALONG AND NEAR THE ITCZ AND MONSOON TROUGH AS 
DESCRIBED ABOVE. UPPER DIFFLUENCE IS HELPING TO SUSTAIN THE 
CONVECTIVE ACTIVITY E OF 125W.

AT THE SURFACE...A RIDGE EXTENDS FROM A 1026 MB HIGH PRES 
LOCATED NEAR 30N138W TO NEAR 22N115W. THE PRES GRADIENT BETWEEN 
THE RIDGE AND LOWER PRES IN THE VICINITY OF THE ITCZ IS INDUCING 
AN AREA OF FRESH TO STRONG TRADE WINDS FROM 10N-23N W OF 130W 
AND FROM 10N TO 20N BETWEEN 125W AND 130W. THESE WINDS WILL 
EXPAND SLIGHTLY NORTHWARD AND EASTWARD THROUGH LATE TODAY AS 
HIGH PRES LIFTS NE AND STRENGTHENS SOME WITH THE ASSOCIATED 
RIDGE BUILDING MORE FIRMLY OVER THE WATERS N OF 15N-16N. AT THE 
SAME TIME...EXPECT INCREASING WINDS OF 20-25 KT OVER THE NE PART 
OF THE AREA MAINLY N OF 28N BETWEEN 118W AND 123W WITH BUILDING 
SEAS OF 8-11 FT IN NW SWELL. BY LATE SUN...A RESIDUAL TIGHT PRES 
GRADIENT IS EXPECTED TO KEEP FRESH TO STRONG NE-E WINDS FROM 10N-
22N W OF 130W WITH SEAS OF 8-10 FT.

A SURFACE TROUGH IS ANALYZED FROM 15N116W TO A 1008 MB LOW PRES 
NEAR 11N118W TO 08N118W. THE LOW IS FORECAST TO GRADUALLY WEAKEN 
TO A TROUGH IN ABOUT 24-36 HRS. THE NIGHT CHANNEL VISIBLE IMAGES 
STILL SHOW A SWIRL OF LOW CLOUDS IN ASSOCIATION WITH THE LOW 
CENTER. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS 
NOTED MAINLY E OF THE TROUGH AXIS FROM 11N TO 14N TO 110W. 
SCATTEROMETER DATA PROVIDED OBSERVATIONS OF NE WINDS IN THE 20-
25 KT RANGE W OF THE TROUGH FROM 12N TO 16N TO 123W WHILE AN 
ALTIMETER PASS INDICATED SEAS OF 8-10 FT AHEAD OF THIS SYSTEM. 
THE TROUGH AND LOW WILL CONTINUE TO MOVE WESTWARD WITH AN AREA 
OF FRESH TO STRONG NE WINDS AHEAD OF IT...THAT IS FORECAST TO 
MERGE WITH THE AREA OF THE TRADE WINDS MENTIONED ABOVE IN ABOUT 
24 HOURS. 

LONG PERIOD NW SWELLS DOMINATE MUCH OF THE FORECAST WATERS W OF 
110W. THIS SWELL EVENT IS MIXING WITH SHORT PERIOD WIND WAVES 
RELATED TO THE TRADES. A NEW SET OF NW SWELLS WILL REACH THE FAR 
NW CORNER OF THE DISCUSSION AREA THIS MORNING. THIS SET OF 
SWELLS WILL THEN PROPAGATE SEWD ACROSS THE NW AND N CENTRAL 
WATERS WITHIN THE NEXT 48 HRS WITH SEAS OF 8-11 FT COVERING THE 
AREA N OF ABOUT 08N W OF ABOUT 118W. THE HIGHEST SEAS CAN BE 
FOUND AHEAD OF THE AFOREMENTIONED SURFACE TROUGH AND N OF 27N 
BETWEEN 118W AND 125W.

GAP WINDS...EXPECT GAP WINDS OF 20 KT ACROSS THE GULF OF 
TEHUANTEPEC AND GULF OF PAPAGAYO TODAY DURING THE EARLY MORNING 
HOURS WITH THE ASSISTANCE OF THE NOCTURNAL DRAINAGE FLOW WITH 
SEAS OF 6-7 FT. THESE CONDITIONS ARE FORECAST TO PERSIST ACROSS 
THE GULF OF PAPAGAYO ON EARLY SUN. 

LOOKING FURTHER AHEAD...THE NEXT GULF OF TEHUANTEPEC IS FORECAST 
TO BE THE STRONGEST ONE SO FAR THIS SEASON WITH MOST OF THE 
GLOBAL MODELS SUGGESTING NLY WINDS OF 50 KT BY WED MORNING. THE 
GEFS PROBABILITIES OF GALE FORCE WINDS HAVE INCREASED TO 90 
PERCENT WITH THE 22/0000 UTC RUN. WAVEWATCH GUIDANCE SUGGESTS 
BUILDING SEAS UP TO 23-25 FT WITH THIS EVENT. EDITS WILL BE MADE 
TO THE NDFD GRIDS AS NECESSARY PRIOR TO THIS UPCOMING EVENT.

$$
GR



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Page last modified: Saturday, 22-Nov-2014 09:32:23 UTC