000
AXPZ20 KNHC 120231
TWDEP 

TROPICAL WEATHER DISCUSSION                                      
NWS NATIONAL HURRICANE CENTER MIAMI FL                           
0405 UTC SUN MAY 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0230 UTC.

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

THE MONSOON TROUGH EXTENDS FROM 09N84W TO 08N93W TO 12N102W 
WHERE LOW LEVEL WINDS SUGGEST A TRANSITION TO ITCZ WHICH EXTENDS 
TO 09N115W TO BEYOND 07N140W. SCATTERED MODERATE CONVECTION WAS 
NOTED WITHIN 180 NM S OF THE MONSOON TROUGH BETWEEN 85W AND 90W. 
SCATTERED MODERATE TO ISOLATED STRONG CONVECTION WAS NOTED 
WITHIN 60 NM N AND 90 NM S OF THE ITCZ AXIS BETWEEN 110W AND 
130W. SCATTERED MODERATE CONVECTION WAS NOTED WITHIN 60 NM OF 
THE ITCZ AXIS W OF 135W.

...DISCUSSION... 

A 1027 MB HIGH PRESSURE CENTER IS LOCATED NEAR 31N128W WITH 
RIDGE EXTENDING SW TO BEYOND 26N140W AND SE TO NEAR 16N107W. THE 
PRESSURE GRADIENT BETWEEN THE AREA OF HIGH PRESSURE AND LOWER 
PRESSURE IN THE VICINITY OF THE ITCZ IS MAINTAINING MODERATE TO 
FRESH TRADES N OF THE ITCZ TO NEAR 20N AND W OF 115W AS DEPICTED 
BY THE LATEST SCATTEROMETER PASSES. THESE WINDS ARE PRODUCING 
ENOUGH CONVERGENCE INTO THE ITCZ TO PRODUCE ACTIVE CONVECTION 
ALONG THE ITCZ AS MENTIONED IN THE SECTION ABOVE. THE LARGE AREA 
OF FRESH WINDS IS RESULTING IN SEAS TO 8 FT FROM 10N TO 13N W OF 
129W AS CONFIRMED BY RECENT ALTIMETER PASS. 

A COLD FRONT IS IN THE FAR NW PART OF THE FORECAST AREA...AND IS 
IN THE PROCESS OF STALLING AND BECOMING DIFFUSE WITH THE 
SUPPORTING UPPER LOW OVER THE N CENTRAL PACIFIC LIFTING OUT TO 
THE NE THROUGH SUN. HIGH PRES BEHIND THE DYING FRONT WILL BUILD 
E ON SUN AND MERGE WITH THE HIGH PRES NEAR 128W. THIS WILL 
MAINTAIN THE AREA OF MODERATE TO FRESH TRADES AND SEAS TO 8 FT 
MENTIONED ABOVE. 

LATEST SATELLITE OBSERVATIONS ALONG WITH SATELLITE HOVMOLLERS 
INDICATES THE TROUGH IN THE THAT WAS IN THE SW CARIBBEAN HAS  
MOVED INTO THE FAR EASTERN NORTH PACIFIC WITH A WEAK LOW WITHIN 
THE MONSOON TROUGH JUST OFF THE WEST COAST OF COSTA RICA. THE 
TROUGH AND ASSOCIATED LOW ARE EXPECTED TO DRIFT WESTWARD ACROSS 
THE TROPICAL E PACIFIC THROUGH MID WEEK. ASIDE FROM ENHANCED 
CONVECTION ALONG THE MONSOON TROUGH...THE MAIN IMPACT WILL BE 
INCREASED EARLY MORNING DRAINAGE FLOW THROUGH THE GULF OF 
PAPAGAYO SUN MORNING AND MON MORNING TO AT LEAST TO 20 KT...AND 
PERHAPS EVEN REACHING 25 KT. BY EARLY MON...THE TROUGH AND LOW 
PRESSURE WILL SHIFT FAR ENOUGH TO THE WEST TO INDUCE GAP WINDS 
TO 30 KT THROUGH THE GULF OF TEHUNATEPEC. 
  
$$
AL