000
AXPZ20 KNHC 180949
TWDEP 

TROPICAL WEATHER DISCUSSION                                      
NWS NATIONAL HURRICANE CENTER MIAMI FL                           
1005 UTC SAT MAY 18 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0900 UTC.

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

THE MONSOON TROUGH AXIS EXTENDS NW FROM THE COAST OF COLOMBIA AT
07N78W TO 08N89W TO 09N111W WHERE IT LOSES IDENTITY IN THE BROAD
CYCLONIC CIRCULATION ASSOCIATED WITH THE REMNANT LOW PRESSURE OF
FORMER TROPICAL CYCLONE ALVIN NOW AT 12N115.5W. THE MONSOON TROUGH
RESUMES SW OF THE REMNANT LOW NEAR 10N118W AND CONTINUES SW TO
07N130W WHERE SCATTEROMETER WINDS INDICATE A TRANSITION TO AN 
ITCZ WHICH EXTENDS W TO BEYOND 05N140W. SMALL ISOLATED CLUSTERS
OF MODERATE TO STRONG CONVECTION IS OBSERVED WITHIN 75 NM OF THE
EASTERN SEGMENT OF THE MONSOON TROUGH TO THE E OF 85W. SCATTERED
MODERATE ISOLATED STRONG CONVECTION IS NOTED WITHIN 180 NM OVER
THE S QUADRANT OF THE REMNANT LOW OF ALVIN AND WITHIN 120 NM
EITHER SIDE OF LINES FROM 06N95W TO 07N103W...FROM 09N111W TO 
07N117W...AND FROM 11N118W TO 12N127W.

THE 1008 MB REMNANTS OF ALVIN ARE CENTERED NEAR 12N115.5W WITH
NE-E-SE WINDS AT 20-25 KT WITHIN 210 NM OF THE CENTER OVER THE
NE QUADRANT...WITH MAXIMUM SEAS OF 11 FT. A BROAD MIX OF SWELL 
IS MAINTAINING SEAS OF 7-10 FT ELSEWHERE WITHIN 300 NM OF THE 
CENTER. THE AREA OF SEAS TO 8 FT PRIMARILY DUE TO CROSS 
EQUATORIAL SW SWELL HAS SHRUNK TO THE DEEP TROPICAL WATERS S OF
03N BETWEEN 105W-118W. THE LOW IS EXPECTED TO MOVE NW TO NEAR 
12.5N117W TONIGHT...AND THEN MOVE WSW TO NEAR 12N122W ON SUN 
NIGHT WITH THE AREA OF ENHANCED WINDS AT 20-25 KT SHIFTING TO
WITHIN 330 NM OVER THE N SEMICIRCLE. THE GRADIENT SHOULD RELAX
SOME ON MON NIGHT WITH WINDS DIMINISHING TO 15-20 KT ON TUE.
DISSIPATING REMNANTS OF THE LOW MAY PERSIST WITHIN THE MONSOON
TROUGH WELL INTO THE MIDDLE OF NEXT WEEK.      
 
A 1026 MB SURFACE HIGH PRESSURE IS AT 32N140W WITH A RIDGE 
EXTENDING SE TO 20N111W. NW WINDS ARE AT 10-15 KT ALONG THE ENTIRE
W SHORE OF THE BAJA CALIFORNIA PENINSULA WITH SEAS OF 4-5 FT. THE
GRADIENT WILL TIGHTEN BRIEFLY LATE TODAY THROUGH MIDNIGHT TONIGHT
WITH THE NW FLOW INCREASING TO 15-20 KT N OF 27N ALONG THE PACIFIC
COAST OF WITH SEAS BUILDING TO 5-7 FT. THE GRADIENT WILL RELAX
AGAIN ON SUN SUPPORTING MOSTLY W-NW WINDS AT 10 KT WITH LITTLE 
CHANGE THEN EXPECTED THROUGH THU. LOOKING FURTHER W ACROSS 
THE N-CENTRAL PORTION OF THE DISCUSSION AREA...NORTHERLY WINDS WILL
INCREASE TO 15-20 KT ON SUN ACROSS THE WATERS N OF 29N BETWEEN 
118W-125W WITH SEAS MAXING AT 8 FT IN THE ASSOCIATED N SWELL. THESE
CONDITIONS WILL SHIFT A LITTLE W AND DISSIPATE THROUGH EARLY TUE.
A SECONDARY SURGE ON TUE NIGHT WILL INCREASE THE N WINDS TO 20 KT
WITH THESE CONDITIONS SPREADING S ACROSS THE PACIFIC WATERS N OF 25N
BETWEEN 116W-140W ON WED NIGHT...WITH SEAS BUILDING 8 TO 12 FT IN
LONG PERIOD N SWELL.     

ALOFT...A TROPICAL MOISTURE PLUME...ORIGINATING FROM THE CONVECTIVE 
DEBRIS MOISTURE FROM FORMER TROPICAL CYCLONE ALVIN AND OTHER 
CONVECTION ALONG THE MONSOON TROUGH BETWEEN 110W-125W...CONCENTRATES
INTO A 500 NM WIDE PLUME FROM 10N118W TO ACROSS CENTRAL MEXICO AT 
25N102W TO OVER W TEXAS.  

$$
NELSON