000
AXPZ20 KNHC 141508
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC WED SEP 14 2011

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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1500 UTC.

...ITCZ/MONSOON TROUGH...

MONSOON TROUGH EXTENDS ACROSS PANAMA AND COSTA RICA ENTERING THE 
PACIFIC WATERS AT 10N86W THEN TO 08N95W TO 11N105W TO A 1010 MB 
LOW NEAR 11N112W TO 11N121W. ITCZ AXIS EXTENDS FROM 11N121W TO 
09N140W.  SCATTERED MODERATE ISOLATED STRONG N OF 04N E OF 85W. 
SIMILAR CONVECTION IS NOTED FROM 12N TO 15N BETWEEN 97W AND 
102W...AND WITHIN 60 NM N OF ITCZ AXIS W OF 137W. 

...DISCUSSION...
SURFACE HIGH PRESSURE 1028 MB IS CENTERED NEAR 37N138W HAS RIDGE 
EXTENDING SE TO NEAR 23N112W. THE PRESSURE GRADIENT BETWEEN THE 
HIGH PRESSURE AND THE ITCZ IS SUPPORTING FRESH 20 KT TRADES FROM 
10N TO 17N W OF 135W AS DEPICTED BY THE LATEST ASCAT PASS. 
EXPECT LITTLE CHANGE OVER THE NEXT 48 HOURS.

GAP WINDS...CYCLONIC FLOW AROUND A TROPICAL WAVE OVER THE 
YUCATAN PENINSULA IS MAINTAINING NE WINDS OVER THE SW GULF OF 
MEXICO. THESE WINDS AREA FUNNELING THROUGH THE CHIVELA PASS 
MAINTAINING 20 KT WINDS OVER THE GULF OF TEHUANTEPEC. AS THE 
TROPICAL WAVE SHIFTS FURTHER WESTWARD...THESE WINDS ARE EXPECTED 
TO DIMINISH BELOW 20 KT WITHIN 12 HOURS. WITH THE MONSOON TROUGH 
SHIFTED FURTHER SOUTH...THE TROPICAL WAVE WILL CONTINUE TO 
PROPAGATE WESTWARD THROUGH THE FORECAST PERIOD. THE TROPICAL 
WAVE WILL START TO INTERACT WITH THE MONSOON TROUGH WITHIN THE 
NEXT 48 HOURS. THIS INTERACTION WILL INCREASE CONVECTION AND IN 
TURN WILL FRESHEN THE MONSOONAL FLOW FROM 05N TO 10N BETWEEN 95W 
AND 113W BY LATE THU NIGHT. 

SOUTHERLY CROSS EQUATORIAL SWELL RESULTING WITH COMBINED SEAS TO 
9 FT CONTINUE OVER THE TROPICAL WATERS S OF 09N W OF 110W. 

$$
AL/FORMOSA