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Eastern Pacific Tropical Weather Discussion (Text)

000
AXPZ20 KNHC 252146
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL                         
2205 UTC SUN JAN 25 2015

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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2100 UTC. 

...SPECIAL FEATURES...                                          
A GALE WARNING REMAINS IN EFFECT FOR THE GULF OF TEHUANTEPEC. N 
TO NE WINDS OF 30-35 KT ARE OCCURRING ACROSS THE GULF AS COLD 
DENSE AIR CONTINUES TO FUNNEL THROUGH THE CHIVELA PASS AND INTO 
THE GULF. A RECENT ASCAT PASS CLEARLY REVEALED THESE WINDS. THE 
GALE WINDS ARE FORECAST TO DIMINISH TO JUST BELOW MINIMAL GALE 
FORCE BY THIS EVENING...THEN QUICKLY INCREASE TO GALE FORCE 
SPEEDS IN THE 30-40 KT RANGE OVERNIGHT TONIGHT AND INTO MON 
MORNING AS REINFORCING HIGH PRES ACROSS EASTERN MEXICO ALLOWS 
FOR ANOTHER SURGE OF COLD AIR TO SWEEP ACROSS THE GULF. THIS IS 
FORECAST TO BE A LONG DURATION GALE WIND EVENT LASTING WELL INTO 
THE UPCOMING WEEK.

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

THE MONSOON TROUGH EXTENDS FROM 06N77W TO 06N90W. THE ITCZ 
CONTINUES FROM 06N90W TO 08N114W TO 06N140W. NO SIGNIFICANT 
CONVECTION.

...DISCUSSION...                                                
ALOFT...A RIDGE/TROUGH/RIDGE PATTERN DOMINATES THE FORECAST AREA 
W OF 100W. A STRONG CUT-OFF LOW THAT YESTERDAY FORMED JUST W OF 
BAJA CALIFORNIA IS NOW CENTERED NEAR 27N118W...AND MOVING 
WESTWARD. A TROUGH EXTENDS FROM THE LOW SE TO NEAR 13N108W. 
ABUNDANT MIDDLE TO UPPER LEVEL MOISTURE IS STREAMING ENE AHEAD 
OF THE TROUGH AXIS FURTHER ENHANCED BY A VERY ACTIVE SUBTROPICAL 
JET STREAM BRANCH THAT EXTENDS NEWD TO ACROSS BAJA CALIFORNIA 
AND NW MEXICO. THE FLOW PATTERN TO THE SE OF THE LOW AND JET 
STREAM BRANCH IS IMPRESSIVELY DIFFLUENT THERE. AN ANTICYCLONE 
LOCATED OVER NORTHERN COLOMBIA AND WESTERN VENEZUELA EXTENDS A 
RIDGE WESTWARD ACROSS CENTRAL AMERICA AND SE MEXICO.

AT THE SURFACE...THE STRONG HIGH PRES THAT WAS LOCATED WELL N OF 
THE AREA DURING THE PREVIOUS DAYS CONTINUES TO WEAKEN AS A COLD 
FRONT APPROACHES FROM THE W. THIS HIGH PRES OF 1018 MB LOCATED 
NEAR 32N128W EXTENDS A RIDGE SW TO COVER MOST OF THE DISCUSSION 
AREA N OF 20N. A WEAK SURFACE TROUGH THAT DEVELOPED FROM A 
FORMER UPPER LOW IS ANALYZED FROM A 1009 MB LOW PRES NEAR 
20N115W TO 15N120W. SCATTERED SHOWERS AND ISOLATED TSTMS ARE E 
OF THE TROUGH MAINLY FROM 15N TO 20W BETWEEN THE TROUGH AXIS AND 
110W. THIS CONVECTIVE ACTIVITY ARE BEING ENHANCED BY THE 
AFOREMENTIONED DIFFLUENCE ALOFT. WINDS HAVE DIMINISHED ALONG THE 
THE SOUTHERN PERIPHERY OF THE RIDGE WITH RECENT SCATTEROMETER 
DATA SHOWING MAINLY GENTLE TO MODERATE NE WINDS FROM 15N TO 21N 
W OF 120W. 

AN AREA OF LARGE LONG PERIOD NW SWELLS...ASSOCIATED WITH A COLD 
FRONT THAT IS APPROACHING THE NW PORTION OF THE AREA IS 
PROPAGATING SEWD THROUGH OVER THE WESTERN WATERS. THESE SWELLS 
ARE RESULTING IN MAX COMBINED SEAS OF UP TO 11 FT WITH PERIODS 
OF 16-17 SECONDS. THE COLD FRONT WILL ENTER THE FAR NW PORTION 
OF THE AREA THIS EVENING...REACH FROM NEAR 30N136W TO 23N140W ON 
MON AT 1800 UTC...THEN BECOME STATIONARY INTO TUE AS WEAK LOW 
PRES FORMS ALONG THE FRONTAL BOUNDARY NEAR 24N136W BY TUE 
MORNING. THE PRES GRADIENT BETWEEN THE LOW AND HIGH PRES 
BUILDING EASTWARD JUST TO THE W OF 140W WILL BRING FRESH TO 
STRONG N-NE WINDS W OF THE LOW AND FRONT N OF 23N BY TUE WITH 
SEAS OF AROUND 9 FT. THE PRES GRADIENT WILL RELAX LATE ON TUE 
ALLOWING FOR THESE WINDS TO DIMINISH TO 15-20 KT WITH SEAS TO 8 
FT IN LINGERING NW SWELLS. 

GAP WINDS...                                                    
FRESH TO STRONG NE-E WINDS ARE EXPECTED ARE EXPECTED THROUGH THE 
GULF OF PAPAGAYO LATE TONIGHT AND INTO MON MORNING AS HIGH PRES 
BUILDS ACROSS THE WESTERN CARIBBEAN. THESE WINDS ARE FORECAST TO 
LAST THROUGH TUE EVENING.

FRESH TO STRONG N WINDS ARE ALSO EXPECTED THROUGH THE GULF OF 
PANAMA AND THESE WINDS WILL EXPAND S TO NEAR 04N AND BETWEEN 79W-
81W BY LATE MON NIGHT.

THE PRES GRADIENT WILL REMAIN STRONG ENOUGH ACROSS THE WESTERN 
CARIBBEAN THROUGH AT LEAST TUE TO SUPPORT THESE GAP WIND EVENTS. 

$$ 
GR