000
AXPZ20 KNHC 282119
TWDEP 

TROPICAL WEATHER DISCUSSION                                    
NWS NATIONAL HURRICANE CENTER MIAMI FL                         
2205 UTC TUE APR 28 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 
2145 UTC. 

...SPECIAL FEATURES...

GULF OF TEHUANTEPEC GALE WARNING...MODEL GUIDANCE IS IN GOOD 
AGREEMENT SHOWING WEAK LOW PRES DEVELOPMENT SE OF TEHUANTEPEC 
AND HIGH PRES BUILDING OVER EASTERN MEXICO WED NIGHT. THIS WILL 
RESULT IN THE TIGHTENING OF THE PRES GRADIENT ACROSS THE ISTHMUS 
TO SUPPORT MINIMAL GALE CONDITIONS IN THE GULF OF TEHUANTEPEC 
THROUGH THU MORNING. SEAS DURING THIS PERIOD WILL BUILD UP TO 13 
FT. GFS MODEL GUIDANCE SHOWS POSSIBILITY OF ANOTHER BRIEF SHOT 
OF GALE FORCE WINDS N OF 15N THU NIGHT.

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

MONSOON TROUGH EXTENDS FROM 05N80W TO 05N93W TO 1011 MB LOW AT 
08N103W. ITCZ EXTENDS FROM 08N120W TO 06N130W TO 05N140W. 
SCATTERED MODERATE ISOLATED STRONG CONVECTION IS FROM 02N TO 08N 
BETWEEN 77W AND 106W. SCATTERED MODERATE CONVECTION IS FROM 03N 
TO 10N BETWEEN 113W AND 140W. 

...DISCUSSION...    

WATER VAPOR IMAGERY SHOWS A MID-UPPER LEVEL TROUGH EXTENDING W 
FROM TEXAS-OKLAHOMA BORDER ACROSS NW MEXICO AND THE CENTRAL BAJA 
PENINSULA TO 26N126W THEN S-SW TO 13N127W. DRY STABLE AIR ALOFT 
IS W OF THE TROUGH AND A SWATH OF TROPICAL MOISTURE IS BEING 
ADVECTED SE OF THE TROUGH FROM ACTIVE CONVECTION OCCURRING E OF 
A LOW PRESSURE CENTER BETWEEN 99W-112W. THE SUBTROPICAL HIGH 
CONTINUES TO WEAKEN AN ADVANCING COLD FRONT THAT EXTENDS FROM 
THE CALIFORNIA COAST AT 37N127W TO 29N140W. NW SWELL BEHIND THE 
COLD FRONT HAS REACHED THE NW PORTION OF THE AREA. THE SWELL 
WILL SUBSIDE WED AS THE DISSIPATING COLD FRONT WEAKENS TONIGHT. 
ANOTHER SURGE OF N-NW SWELL ASSOCIATED WITH STRONG N WINDS ALONG 
THE CALIFORNIA COAST WILL SWEEP S OF 30N INTO NE PORTION OF THE 
AREA WED NIGHT THROUGH THU MORNING.

LOOKING AHEAD...VERY LARGE AREA OF CROSS-EQUATORIAL LONG PERIOD 
SW SWELL WILL BEGIN TO AFFECT S AND SE PORTIONS THU NIGHT AND 
FRI WITH SEAS 9-10 FT AND 19-20 SEC PERIOD. THIS SWELL WILL 
REACH THE WEST COAST OF CENTRAL AMERICA THIS WEEKEND...WITH 
LARGE SURF LIKELY FROM PANAMA TO CENTRAL MEXICO.

$$
FORMOSA