000
AXPZ20 KNHC 112111
TWDEP 

TROPICAL WEATHER DISCUSSION                                      
NWS NATIONAL HURRICANE CENTER MIAMI FL                           
2205 UTC SAT MAY 11 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2100 UTC.

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

THE MONSOON TROUGH EXTENDS FROM 10N84W TO 09N88W TO 11N100W 
WHERE LOW LEVEL WINDS SUGGEST A TRANSITION TO ITCZ WHICH EXTENDS 
TO 11N105W TO 10N115W TO 10N132W TO BEYOND 08N140W. SCATTERED 
MODERATE CONVECTION WAS NOTED WITHIN 120 NM S OF AXIS BETWEEN 
85W AND 88W. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION 
WAS NOTED WITHIN 60 NM N AND 90 NM S OF THE ITCZ AXIS BETWEEN 
110W AND 130W.

...DISCUSSION... 

A 1023 MB HIGH PRESSURE CENTER IS LOCATED NEAR 29N128W WITH 
RIDGE EXTENDING SW TO BEYOND 25N140W AND SE TO NEAR 17N108W. 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 
126W 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 LIFT 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 SW CARIBBEAN IS CROSSING CENTRAL 
AMERICA WITH A WEAK LOW FORMING WITHIN THE MONSOON TROUGH OVER 
FAR NW 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 AT 
LEAST TO 20 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