000
AXPZ20 KNHC 120932
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC TUE FEB 12 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 
0700 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
THE MONSOON TROUGH AXIS WAS ANALYZED FROM 01N79W TO 02N87W TO 
06N92W TO 06N100W. ITCZ AXIS WAS ANALYZED FROM 06N100W TO 
04N108W TO 07N123W TO 03N140W. NO SIGNIFICANT CONVECTION WAS 
NOTED.

...DISCUSSION...
THE 120-140 KT WESTERLY UPPER JET IN PLACE FROM 20N140W TO NW 
MEXICO WILL WEAKEN TODAY AND SHIFT NORTHWARD WED AS RIDGING 
BUILDS OVER THE NORTH CENTRAL PORTION OF THE FORECAST AREA. TO 
THE EAST...A STRONG AND ELONGATED SHORTWAVE SYSTEM LIES IN THE 
SOUTHWESTERN SIDE OF A MEAN UPPER TROUGH CENTERED OVER THE 
INTERIOR WESTERN UNITED STATES. THIS ENERGY WILL SLOWLY MAKE ITS 
WAY INTO NW MEXICO TONIGHT AS A NEW SHORTWAVE SYSTEM ON THE 
BACKSIDE OF THE MEAN TROUGH APPROACHES NE FORECAST WATERS FROM 
THE N. BOTH SYSTEM WILL MERGE WITH THE MEAN TROUGH BY THU. AS 
FIRST SHORTWAVE SYSTEM MOVES INLAND TONIGHT...WEAK SURFACE 
TROUGHING IN NE WATERS AND ALONG THE BAJA PENINSULA WILL 
STRENGTHEN AND MOVE INTO NW MAINLAND MEXICO AS THE SUBTROPICAL 
RIDGE BUILDS EASTWARD. THIS WILL INCREASE THE PRESSURE GRADIENT 
OVER THE GULF OF CALIFORNIA. FRESH TO STRONG N-NW WINDS ARE 
FORECAST TO OVERTAKE THE GULF OVERNIGHT TONIGHT THROUGH AT LEAST 
THU MORNING AS A RESULT. 

AN UPPER LOW LIES JUST W OF THE AREA NEAR 29N145W AND REFLECTS A 
1019 MB LOW AT THE SURFACE NEAR 28N143W WITH A TROUGH EXTENDING 
FROM 30N143W THROUGH THE LOW TO 23N146W. NW SWELL FROM THIS 
SYSTEM THAT MOVE INTO NW WATERS A FEW DAYS AGO IS MAKING ITS WAY 
SOUTHEASTWARD...WITH PERIODS ON THE LEADING EDGE OF THE SWELL IN 
THE 19-21 SECOND RANGE. THE LEADING EDGE OF THE SWELL IS 
CURRENTLY NEAR MANZANILLO MEXICO AND WILL LIE ALONG 95W S OF 13N 
BY WED MORNING BEFORE MIXING WITH LONG PERIOD SW SWELL E OF 95W. 
THE 0706 UTC ASCAT PASS SHOWS STRONG SE WINDS N OF 25N ALONG 
140W ON THE WESTERN EDGE OF THE SCATTEROMETER SWATH. THESE WINDS 
ARE BELIEVED TO EXTEND TO AT LEAST 138W IN THE NW CORNER OF THE 
FORECAST AREA. THE TROUGH WILL MOVE SW AND GRADUALLY 
DISSIPATE...BUT THE PRESSURE GRADIENT BETWEEN THE LINGERING 
TROUGHING AND THE SUBTROPICAL RIDGE WILL KEEP FRESH TO STRONG 
WINDS OVER THE NW CORNER OF THE FORECAST AREA INTO WED MORNING. 
SOME SCATTERED SHOWERS AND POSSIBLY AN ISOLATED THUNDERSTORM ARE 
CURRENTLY JUST W OF THE AREA AND E OF THE TROUGH N OF 27N. THESE 
CONDITIONS WILL HUG NW WATERS TODAY BEFORE SHIFTING SW AND 
DIMINISHING. 

THE 0524 UTC ASCAT PASS SHOWS FRESH TO STRONG TRADE WINDS HAVE 
RETURNED TO WATERS N OF THE ITCZ BETWEEN 120W AND 135W AS THE 
SUBTROPICAL RIDGE BUILT BETWEEN THE AFOREMENTIONED TROUGHING 
OVER THE BAJA PENINSULA AND TROUGHING OVER NW WATERS. LOOK FOR 
TRADES TO REMAIN UNCHANGED FOR THE NEXT 24 HOURS AND THEN SHIFT 
WEST-SOUTHWESTWARD BY EARLY THU.

GAP WINDS...
GULF OF PAPAGAYO...THE PRESSURE GRADIENT BETWEEN THE MONSOON 
TROUGH TO THE S AND RIDGING OVER THE NW CARIBBEAN HAS GENERATED 
FRESH TO STRONG NE TRADE WIND FLOW THROUGH CENTRAL AMERICA AND 
INTO THE GULF OF PAPAGAYO. THE 0340 UTC ASCAT PASS CAPTURED 
THESE WINDS WHICH ARE EXPECTED TO EXPAND WESTWARD TO 89W THIS 
MORNING. RIDGING IN THE CARIBBEAN WILL WEAKEN LATER 
TODAY...SLACKENING THE PRESSURE GRADIENT AND DIMINISHING WINDS 
IN THE GULF OF PAPAGAYO. 

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SCHAUER