000
AXPZ20 KNHC 292218
TWDEP 

AXPZ20 KNHC DDHHMM
TWDEP 

TROPICAL WEATHER DISCUSSION                                    
NWS NATIONAL HURRICANE CENTER MIAMI FL                         
2205 UTC WED APR 29 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 
2130 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 FROM NEAR 10N79W TO 07N86W TO 57N99W TO 
11N111W TO 07N129W...WHERE IT TRANSITIONS TO ITCZ TO BEYOND 
07N140W. SCATTERED STRONG WITHIN 90 NM OF 05.5N84W AND 07.5N95W. 
SCATTERED TO NUMEROUS MODERATE TO STRONG CONVECTION NOTED WITHIN 
390 NM N AND 360 NM S OF TROUGH E OF 103W. SCATTERED MODERATE TO 
STRONG CONVECTION NOTED WITHIN 150 NM N AND 120 NM S OF AXIS W 
OF 120W. 

...DISCUSSION...    

A VERY ENERGETIC UPPER LEVEL PATTERN DOMINATES THE DISCUSSION 
AREA N OF THE ITCZ AND 15N THIS AFTERNOON TO 100W AND MEXICO. A 
SERIES OF TROUGHS CAN BEEN SEEN IN WATER VAPOR IMAGERY MOVING 
GENERALLY EASTWARD...EMBEDDED IN THE WESTERLY FLOW ALOFT. A 
VIGOROUS MIDDLE TO UPPER TROUGH IS ALONG 108-110W FROM THE S END 
OF BAJA CALIFORNIA TO 12N108W...AND SHIFTING EWD INTO MEXICO. 
THIS TROUGH WILL CONTINUE EASTWARD AND LIFT OVER THE DOWNSTREAM 
UPPER RIDGE CENTERED OVER THE W CARIBBEAN. THIS 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 1036 MB HIGH PRES N 
OF THE HAWAIIAN ISLANDS ALONG 35N...EAST AND SOUTHEASTWARD INTO 
THE AREA TO NEAR 17N110W. 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. NW SWELL BEHIND THE FRONT WILL SUBSIDE THURSDAY 
MORNING. 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.

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.

$$
STRIPLING