000
AXPZ20 KNHC 171548
TWDEP 

TROPICAL WEATHER DISCUSSION                                    
NWS NATIONAL HURRICANE CENTER MIAMI FL                         
1605 UTC SAT JAN 17 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1500 UTC. 

...SPECIAL FEATURES...                                       

GULF OF TEHUANTEPEC GALE WARNING...WITHOUT SCATTEROMETER DATA 
AND SHIP OBS TO VERIFY BORDERLINE GALE WIND EVENT...AUTOMATED 
SURFACE OBS FROM SALINA CRUZ INDICATE GUSTS HAVE FALLEN BELOW 20 
KT. GFS MODEL GUIDANCE INDICATES MAX WINDS BELOW 35 KT AT 1200 
UTC...SO WILL ALLOW PREVIOUS GALE WARNING TO EXPIRE SIX HOURS 
EARLIER THAN INDICATED IN PREVIOUS FORECAST. WINDS AND SEAS IN 
TEHUANTEPEC WILL DIMINISH THROUGH TONIGHT AS THE PRES GRADIENT 
ACROSS SOUTHERN MEXICO RELAXES...THEN INCREASE IN ABOUT 24 HOURS 
AS HIGH PRES BUILDING INTO SOUTHERN TEXAS AND NE MEXICO TIGHTENS 
THE GRADIENT ONCE AGAIN...WITH WINDS EXPECTED TO REACH MINIMAL 
GALE AROUND 1500-1800 UTC SUN. PEAK WINDS ARE EXPECTED TO BE 35 
TO 40 KT SUN NIGHT...AND REMAIN GALE FORCE THROUGH MON MORNING.

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

THE MONSOON TROUGH EXTENDS FROM 05N77W TO 07N90W. ITCZ EXTENDS 
FROM 07N90W TO 10N116W...THEN RESUMES FROM 08N122W TO 06N140W. 
SCATTERED MODERATE ISOLATED STRONG CONVECTION WITHIN 60 NM OF 
AXIS E OF 87W. SCATTERED MODERATE CONVECTION FROM 08N TO 13N 
BETWEEN 116W AND 119W.

...DISCUSSION...                                                 

A 1011 MB LOW IS CENTERED NEAR 19N120W. RAPIDSCAT SCATTEROMETER 
PASS AT 0922 UTC SHOWED SMALL AREA OF 20-25 KT WINDS IN THE N 
SEMICIRCLE OF THE LOW WHILE AN ALTIMETER PASS BETWEEN 1000-1100 
UTC SHOWED AREA OF 9-11 FT SEAS NEAR THE LOW CENTER. BROAD AREA 
OF FRESH TRADE WINDS IS NOTED W OF THE LOW BASED ON RECENT ASCAT 
DATA...WITH SEAS TO 11 FT IN NW SWELL. THE LOW IS EXPECTED TO 
MOVE W-NW THROUGH MON AND GRADUALLY WEAKEN...THEN DISSIPATE INTO 
A SURFACE TROUGH AS IT DRIFTS WESTWARD. AN AREA OF ENHANCED SEAS 
TO 9-10 FT WILL ACCOMPANY THE LOW AS IT TRACKS ACROSS WATERS W 
OF 120W. A PRESSURE GRADIENT BETWEEN THE LOW AND THE SUBTROPICAL 
RIDGE TO THE N WILL SUPPORT MODERATE TO FRESH WINDS WITHIN THE 
NORTHERN SEMICIRCLE. SEAS WILL EVENTUALLY MERGE WITH LARGE AREA 
OF LONG PERIOD NW SWELL ACROSS NW CORNER OF DISCUSSION AREA.

THE SUBTROPICAL RIDGE EXTENDS SOUTHWARD FROM A 1024 MB HIGH NEAR 
32N128W SE TO 27N118W AND SW FROM THE HIGH TO 25N144W. THE PRES 
GRADIENT BETWEEN THE LOW CENTER MENTIONED ABOVE AND THE RIDGE IS 
PRODUCING A BROAD ZONE OF FRESH TRADE WINDS S OF 24N W OF 120W. 
ASSOCIATED WIND WAVES MERGING WITH FADING NW SWELL IS PRODUCING 
SEAS OF 8-10 FT ACROSS THIS AREA. TRADE WIND WAVES WILL DECAY 
SLIGHTLY AND PERSIST MAINLY W OF 125W SUN AND MON.

GULF OF PAPAGAYO...STRONG RIDGING ACROSS CENTRAL AMERICA IS 
SUPPORTING FRESH TO STRONG NE WINDS PULSING THROUGH PAPAGAYO. 
PEAK WINDS WILL CONTINUE TO PULSE IN EXCESS OF 25 KT DURING LATE 
NIGHT AND EARLY MORNING HOURS THROUGH MON...BRIEFLY REACHING 30 
KT DURING MAXIMUM NOCTURNAL DRAINAGE FLOW BEFORE SUNRISE...WITH 
A LULL EACH DAY DURING THE AFTERNOON WITH WINDS LESS THAN 20 KT. 
SEAS WILL REACH 8-9 FT DOWNWIND OF THE GULF EACH MORNING.

GULF OF PANAMA...FRESH TO LOCALLY STRONG N WINDS WILL PERSIST IN 
THE GULF OF PANAMA DUE TO THE PRESSURE GRADIENT ACROSS THE AREA. 
MAX SEAS TO 7 FT EXPECTED AT PEAK WINDS DURING THE EARLY MORNING.
 
$$ 
MUNDELL