000
AXPZ20 KNHC 171502
TWDEP 

TROPICAL WEATHER DISCUSSION                                     
NWS NATIONAL HURRICANE CENTER MIAMI FL                         
1605 UTC SUN MAY 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.
 
...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...              

THE MONSOON TROUGH WIND REGIME IS IN THE PROCESS OF BREAKING 
DOWN INTO SEVERAL LOWS. THE MONSOON TROUGH EXTENDS FROM 09N92W 
TO LOW PRES 1010 MB NEAR 05N101W TO 09N112W TO LOW PRES 1009 MB 
NEAR 09N116W. THE ITCZ EXTENDS FROM 06N132W TO 09N139W. 
SCATTERED MODERATE ISOLATED STRONG CONVECTION WAS NOTED WITHIN 
180 NM S OF THE TROUGH BETWEEN 92W AND 95W. SCATTERED MODERATE 
ISOLATED STRONG CONVECTION WAS NOTED WITHIN 150 NM S OF THE 
TROUGH BETWEEN 99W AND 102W. SCATTERED MODERATE ISOLATED STRONG 
CONVECTION WAS NOTED WITHIN 120 NM N OF THE TROUGH BETWEEN 104W 
AND 107W. 
 
...DISCUSSION...

A WEAK HIGH PRESSURE RIDGE EXTENDS OVER THE NORTHERN WATERS 
WHILE A COLD FRONT HAS JUST MOVED INTO THE NW WATERS. THE 
PRESSURE GRADIENT BETWEEN THE AREA OF HIGH PRESSURE AND LOWER 
PRESSURE TO THE SOUTH ASSOCIATED WITH LOW PRESSURE CIRCULATIONS 
NEAR 09N116W...09N125W...AND 09N139W IS MAINTAINING MODERATE TO 
FRESH TRADES BETWEEN 10N AND 20N AND W OF 120W. THE FRESH TRADES 
ARE HELPING TO MAINTAIN AN AREA OF SEAS TO 8 FT FROM 10N TO 15N 
W OF 130W. THE COLD FRONT WILL REACH FROM 30N128W TO 27N140W BY 
THIS EVENING THEN DISSIPATE THROUGH MONDAY AS IT SINKS SLOWLY 
SE. WEAK HIGH PRESSURE WILL REMAIN OVER THE NORTHERN WATERS 
WHICH WILL KEEP THE PRESSURE GRADIENT RELATIVELY CONSTANT AND 
MAINTAIN THE AREA OF MODERATE TO FRESH TRADES BETWEEN 10N AND 
20N W OF 120W.

AS MENTIONED ABOVE...THE MONSOON TROUGH WIND REGIME IS IN THE 
PROCESS OF BREAKING DOWN INTO SEVERAL CIRCULATION CENTERS. THE 
BREAKDOWN SHOULD BE COMPLETE BY LATER TONIGHT. THE SURFACE 
CIRCULATIONS WILL SPIN DOWN INTO TROUGHS THROUGH EARLY IN THE 
WEEK THEN DISSIPATE BY MIDWEEK WITH THE ITCZ WIND REGIME ONCE 
AGAIN TAKING CONTROL. 
 
THE PRESSURE GRADIENT BETWEEN THE SUBTROPICAL HIGH AND LOW 
PRESSURE ACROSS BAJA CALIFORNIA AND NW MEXICO IS PRODUCING 
NORTHWESTERLY WINDS AROUND 15-20 KT ALONG MOST OF THE PACIFIC 
COASTAL WATERS OF THE BAJA PENINSULA. THE GRADIENT WILL TIGHTEN 
SLIGHTLY BY MONDAY AFTERNOON OR EVENING TO PROMOTE 20 KT WINDS 
ALONG MUCH OF THE NEAR AND OFFSHORE COASTAL WATERS THERE THROUGH 
WED...WITH SEAS BRIEFLY BUILDING TO 7-8 FT N OF PUNTA 
EUGENIA...AND 6-7 FT ALONG THE SOUTHERN HALF.
 
GAP WINDS...                                                     
GULF OF PAPAGAYO...WINDS WILL CONTINUE TO PULSE OVER THE GULF OF 
PAPAGAYO THE NEXT COUPLE OF DAYS. WINDS WILL PEAK NEAR 25 KT 
DURING THE LATE NIGHT AND EARLY MORNING HOURS WITH THE ADDED 
COMPONENT OF NOCTURNAL DRAINAGE FLOW. WINDS WILL DIMINISH TO 20 
KT OR LESS DURING THE AFTERNOON AND EARLY EVENING HOURS. 

LOOKING AHEAD...ANOTHER STRONG SOUTHERN HEMISPHERIC SW SWELL 
WILL MOVE INTO THE REGIONAL WATERS LATE IN THE WEEK. SEAS WILL 
BUILD TO 8 FT AND GREATER ALONG THE EQUATORIAL WATERS BY 
THURSDAY MORNING. THIS PULSE OF LONG PERIOD SWELL IS EXPECTED TO
REACH THE COASTLINES OF CENTRAL AMERICA BY LATE FRIDAY.
 
$$
AL