000
AXPZ20 KNHC 092139
TWDEP 

TROPICAL WEATHER DISCUSSION                                      
NWS NATIONAL HURRICANE CENTER MIAMI FL                           
2205 UTC THU MAY 09 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 AXIS EXTENDS FROM 09N78W TO 10N87W TO 9.5N91W 
WHERE LOW LEVEL WINDS SUGGEST A TRANSITION TO ITCZ WHICH EXTENDS 
TO 06N120W TO BEYOND 07N140W. NUMEROUS MODERATE TO SCATTERED 
STRONG CONVECTION WAS NOTED WITHIN 180 NM OFF COAST OF COLOMBIA 
FROM 04N TO 07N. SCATTERED MODERATE TO ISOLATED STRONG 
CONVECTION WAS NOTED WITHIN 60 NM N AND 90 NM S OF ITCZ BETWEEN 
99W AND 103W. SCATTERED MODERATE ISOLATED STRONG CONVECTION WAS 
NOTED WITHIN 60 NM N OF ITCZ BETWEEN 128W AND 132W.

...DISCUSSION...

HIGH PRESSURE IS CENTERED N OF THE AREA WITH SURFACE RIDGE 
EXTENDING SE TO NEAR 20N109W AND SW TO BEYOND 25N140W. LATEST 
SCATTEROMETER DATA INDICATE GENTLE TO MODERATE TRADE WIND FLOW 
GENERALLY S OF 20N W OF 110W. LATEST ASCAT PASS FROM 1630 UTC 
INDICATED NW TO N WINDS TO 20 KT JUST W OF THE BAJA CALIFORNIA 
PENINSULA WHERE THERE IS A LOCALLY TIGHTER PRESSURE GRADIENT 
BETWEEN THE RIDGE AND LOW PRESSURE OVER MAINLAND MEXICO. HIGH 
PRESSURE WILL BUILD SLIGHTLY OVER THE NEXT 24 HOURS...AND WILL 
FRESHEN TRADEWIND FLOW N OF THE ITCZ W OF 130W THROUGH SAT. THE 
FRESHENED WINDS WILL INCREASE SEAS TO 8 FT OVER THIS AREA FRI 
AND SAT. 
 
LOOKING AHEAD...FORECAST MODEL RUNS HAVE BEEN DEPICTING AN 
INTERESTING SCENARIO TO FOLLOW OVER THE NEXT WEEK. THE KEY 
FEATURE TO WATCH IS A CARIBBEAN WAVE/TROUGH AND ITS INTERACTION 
WITH THE MONSOON TROUGH IN THE E PACIFIC...PARTICULARLY FROM GAP 
WIND FLOW THROUGH THE TOPOGRAPHY OF CENTRAL AMERICA ACROSS THE 
GULFS OF PAPAGAYO AND TEHUANTEPEC. THE SCENARIO DEPICTED BY 
MODEL GUIDANCE HAS THE WAVE/TROUGH IN THE CARIBBEAN SHIFTING 
WESTWARD ACROSS CENTRAL AMERICA INTO THE FAR E PACIFIC THIS 
WEEKEND. GAP WINDS THROUGH THE GULF OF PAPAGAYO ASSOCIATED WITH 
THE WAVE/TROUGH WILL INTERACT WITH THE MONSOON TROUGH AND HELP 
TO INCREASE LOW LEVEL VORTICITY WITHIN THE MONSOON TROUGH LATE 
THIS WEEKEND. GAP WINDS THROUGH THE GULF OF TEHUANTEPEC WILL BE 
INDUCED EARLY NEXT WEEK BY THE WAVE/TROUGH AS IT SHIFTS WESTWARD 
ACROSS THE FAR E PORTION OF THE NE PACIFIC WATERS. THIS GAP WIND 
EVENT WILL HELP FURTHER INCREASE LOW LEVEL VORTICITY WITHIN THE 
MONSOON TROUGH EARLY NEXT WEEK. LATEST MODEL GUIDANCE SUGGESTS 
THAT THE BACKGROUND ENVIRONMENT WILL BECOME MORE FAVORABLE FOR 
BAROTROPIC GROWTH OF THE DISTURBANCE WITHIN THE MONSOON TROUGH 
EARLY NEXT WEEK. THIS SYNOPTIC SCENARIO HAS BEEN SHOWN TO 
OCCASIONALLY RESULT IN TROPICAL CYCLOGENESIS. DESPITE THAT 
FACT...THERE REMAINS A LOT OF UNCERTAINTY IN THIS CASE AS 
SUGGESTED BY THE SPREAD IN LATEST FORECAST GUIDANCE.  
  
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AL