000
AXPZ20 KNHC 201525
TWDEP 

TROPICAL WEATHER DISCUSSION                                      
NWS NATIONAL HURRICANE CENTER MIAMI FL                           
1605 UTC MON MAY 20 2013

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...

MONSOON TROUGH AXIS EXTENDS FROM 09N78W TO 11N95W TO 07N115W TO 
09N122W...THEN RESUMES AT 10N126W TO 07N132W. THE ITCZ AXIS 
CONTINUES FROM 07N132W TO 08N140W. CLUSTER OF MODERATE TO STRONG 
CONVECTION IS FROM 04N TO 08N E OF 80W TO THE COAST OF COLOMBIA. 
SCATTERED MODERATE ISOLATED STRONG CONVECTION IS NOTED FROM 05N 
TO 08N BETWEEN 80W AND 84W...FROM 06N TO 12N BETWEEN 100W AND 
109W...FROM 06N TO 10N BETWEEN 117W AND 127W AND FROM 05N TO 11N 
W OF 135W. 

...DISCUSSION... 

THE 1009 MB REMNANTS OF ALVIN ARE CENTERED NEAR 12.5N123W ALONG 
A NORTH-SOUTH ORIENTATED TROUGH THAT EXTENDS FROM 9N123W TO 
15N123W. AN EARLIER HIGH RESOLUTION ASCAT PASS PROVIDED 
OBSERVATIONS OF 20-30 KT WINDS WITHIN 150 NM N SEMICIRCLE OF LOW 
CENTER. THIS SYSTEM IS GENERATING MAXIMUM SEAS OF 11 FT. A BROAD 
MIX OF SWELL IS MAINTAINING SEAS OF 7-10 FT ELSEWHERE WITHIN THE 
AREA BOUNDED BY 11N-17N BETWEEN 120W-130W. FARTHER WEST...AN 
AREA OF ENHANCED NE TRADES AT 15-20 KT IS NOTED WITH SEAS TO 9 
FT...ACROSS THE TROPICS FROM 10N-15N W OF 136W. MARINE GUIDANCE 
SUGGESTS THAT THE REMNANT LOW OF ALVIN WILL CONTINUE TO MOVE 
MAINLY WESTWARD DURING THE NEXT COUPLE OF DAYS WITH AN AREA OF 
FRESH TO STRONG WINDS WITHIN ABOUT 150 NM TO THE N OF THE LOW 
CENTER.  

A 1033 MB HIGH PRES LOCATED N OF AREA NEAR 38N136W EXTENDS A 
RIDGE SE TO NEAR 18N112W. PRES GRADIENT TIGHTENS ON THE EAST 
SIDE OF THE RIDGE PRODUCING NW WINDS OF 10-15 KT ALONG THE 
ENTIRE W SHORE OF THE BAJA CALIFORNIA PENINSULA WITH SEAS OF 4-6 
FT. IN ADDITION...A SURGE OF NORTHERLY WINDS AT 15-20 KT 
CONTINUES ACROSS THE N-CENTRAL PACIFIC WATERS...ROUGHLY N OF 28N 
BETWEEN 119W AND 126W WITH SEAS TO 9 FT PRIMARILY IN N SWELL. 
THESE NORTHERLY WINDS WILL INCREASE TO 20-25 KT TUE NIGHT INTO WED AS 
HIGH PRES N OF AREA INTENSIFIES. 

LOW PRESSURE IS EXPECTED TO DEVELOP OVER THE SW CARIBBEAN ON WED 
AS A TROPICAL WAVE CURRENTLY OVER THE E CARIBBEAN MOVES INTO THE 
AREA. THE LOW PRESSURE WILL MOVE ACROSS CENTRAL AMERICA INTO THE 
E PACIFIC NEAR 09N87W LATE IN THE WEEK. 

ALOFT...A RIDGE/TROUGH/RIDGE PATTERN IS OBSERVED ACROSS THE 
FORECAST WATERS. A TROPICAL MOISTURE PLUME...ORIGINATING FROM 
THE CONVECTIVE DEBRIS MOISTURE FROM FORMER TROPICAL CYCLONE 
ALVIN...EXTENDS ALL THE WAY NE BETWEEN 110W AND 120W TO SOUTHERN 
BAJA CALIFORNIA INTO MAINLAND MEXICO. UPPER DIFFLUENCE IS 
HELPING TO INDUCE THE STRONG CONVECTION NEAR THE COAST OF 
COLOMBIA. 

$$
GR