000
AXPZ20 KNHC 300231
TWDEP 

TROPICAL WEATHER DISCUSSION                                    
NWS NATIONAL HURRICANE CENTER MIAMI FL                         
0405 UTC THU APR 30 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0200 UTC. 

...SPECIAL FEATURES...

GULF OF TEHUANTEPEC GALE WARNING...A HIGH PRESSURE RIDGE NOSING 
S-SE ACROSS NE AND EASTERN MEXICO HAS BUILT THROUGH THE ISTHMUS 
OF TEHUANTEPEC OVERNIGHT AND THIS MORNING...INDUCING STRONG 
NORTHERLY WINDS ACROSS THE GULF OF TEHUANTEPEC THEN SOUTHWARD 
INTO THE EASTERN PACIFIC. WINDS HAVE INCREASED TO MINIMAL GALE 
FORCE N OF 14N95W THIS AFTERNOON...WHERE SEAS ARE RUNNING 9-11 
FT. THESE MINIMAL GALES ARE EXPECTED TO CONTINUE THIS EVENING 
AND TONIGHT BEFORE DIMINISHING TO AROUND 30 KT THURSDAY 
MORNING...THEN GRADUALLY FALLING TO NEAR 20 KT BY FRIDAY 
AFTERNOON.  

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

THE MONSOON TROUGH EXTENDS FROM NEAR 10N80W TO 07N86W TO 
11.5N112W TO 07N129W...WHERE IT TRANSITIONS TO ITCZ TO BEYOND 
07N140W. CLUSTERS OF SCATTERED TO NUMEROUS MODERATE TO STRONG 
CONVECTION NOTED FROM 02.5N TO 12N E OF 101W. SCATTERED MODERATE 
TO STRONG CONVECTION NOTED WITHIN 150 NM N AND 120 NM S OF AXIS 
W OF 118W. 

...DISCUSSION...    

A VERY ENERGETIC UPPER LEVEL PATTERN DOMINATES THE DISCUSSION 
AREA N OF THE ITCZ AND 14N THIS EVENING TO 100W AND MEXICO. A 
SERIES OF TROUGHS CAN BEEN SEEN IN WATER VAPOR IMAGERY MOVING 
EASTWARD...EMBEDDED IN THE GENERAL WESTERLY FLOW ALOFT. A 
VIGOROUS MIDDLE TO UPPER TROUGH IS ALONG 105-107W FROM N CENTRAL 
MEXICO TO 12N106W...AND SHIFTING EWD ACROSS MEXICO. THIS TROUGH 
WILL CONTINUE EASTWARD AND LIFT OVER THE DOWNSTREAM UPPER RIDGE 
CENTERED OVER THE W CARIBBEAN. THIS PATTERN IS PRODUCING A ZONE 
OF STRONG UPPER LEVEL DIVERGENCE ACROSS THE TROPICS E OF 100W 
WHERE VERY DEEP CONVECTION CONTINUES ABOUT THE MONSOON TROUGH 
THERE. COMPUTER MODELS SUGGEST THAT THIS AREA WILL REMAIN VERY 
UNSTABLE AND ACTIVE WITH CONVECTION THROUGH THURSDAY BEFORE 
SHIFTING SLOWLY EWD FRI AND SAT.

AT THE SURFACE...A BROAD RIDGE EXTENDS FROM 1035 MB HIGH PRES N 
OF THE HAWAIIAN ISLANDS ALONG 35N...EAST AND SOUTHEASTWARD INTO 
THE AREA TO NEAR 18N109W. A DRY AND BENIGN COLD FRONTAL BOUNDARY 
HAS SHIFTED S INTO N AND NW PORTIONS OF THE AREA TODAY...AND WAS 
DEPICTED BY AFTERNOON SCATTEROMETER PASSES AS A SHEARLINE FROM 
30N127W TO 26.5N140W...WHERE NE WINDS 20-25 KT AND SEAS 9-11 FT 
IN NW SWELL PREVAILED N OF THE FRONT. THIS BOUNDARY WILL SINK 
FARTHER S TO 20N ACROSS W PORTIONS BY FRI NIGHT...WHILE 
DISSIPATING ACROSS NE PORTIONS OF THE AREA AS WEAK LOW PRESSURE 
PREVAILS THERE. ANOTHER SURGE OF N-NW SWELL ASSOCIATED WITH 
STRONG N WINDS E OF THE RIDGE AND ALONG THE CALIFORNIA COAST 
WILL SWEEP S OF 30N INTO NE PORTION OF THE AREA TONIGHT THROUGH 
THU NIGHT.

E OF 100W...WINDS ACROSS THE TROPICS ARE LIGHT TO MODERATE AND 
VARYING AS THE EASTERN PACIFIC MONSOONAL CIRCULATION HAS BECOME 
WELL ESTABLISHED ACROSS THE AREA...AND IS CONTRIBUTING TO THE 
VERY ACTIVE CONVECTION DESCRIBED ABOVE.

LOOKING AHEAD...LARGE LONG PERIOD SW SWELL GENERATED FROM A VERY 
LARGE STORM SYSTEM ACROSS THE SE PACIFIC A FEW DAYS AGO WILL 
BEGIN TO MOVE N AND NE INTO THE REGIONAL WATERS THU AND THU 
NIGHT AND REACH THE CENTRAL AMERICAN AND MEXICAN COAST SAT TO 
PRODUCE VERY LARGE AND DANGEROUS WAVES ACROSS THE COASTAL 
ZONES...FROM PANAMA TO BAJA CALIFORNIA. A SMALLER PRE CURSOR 
PULSE OF THIS SW SWELL WILL ARRIVE ALONG THE COASTS FRI AND BE 
OVERTAKEN ON SAT.

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STRIPLING