000
AXPZ20 KNHC 181540
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC TUE OCT 18 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 FROM 14N91W TO 1011 MB LOW PRES...REMNANTS OF 
IRWIN...NEAR 16N110W TO 09N131W. ITCZ FROM 09N131W TO 09N140W. 
SCATTERED MODERATE ISOLATED STRONG WITHIN 180 NM OF TROUGH 
BETWEEN 92W AND 102W.

...DISCUSSION...

E OF 110W...SW FLOW PERSISTS OVER EASTERN PACIFIC THIS MORNING 
WITH SHIP AND ASCAT DATA SHOWING 15 TO 20 KT FLOW INTO CENTRAL 
AMERICA SOUTH OF THE MONSOON TROUGH. THIS HAS DIMINISHED 
SOMEWHAT FROM PAST DAYS...BUT CONTINUES TO PUSH VERY MOIST AIR 
ONSHORE AND TO PROMOTE AREAS OF MODERATE TO OCCASIONALLY HEAVY 
RAINFALL ACROSS PORTIONS OF NORTHERN CENTRAL AMERICA AND 
SOUTHERN MEXICO. THE ENHANCED MONSOON FLOW HAS BEEN ASSOCIATED 
WITH A BROAD AREA OF LOW PRES OVER THE GULF OF HONDURAS AND 
YUCATAN PENINSULA THAT IS NOW DRIFTING NE THROUGH THE GULF OF 
MEXICO. AS THE LOW PRES MOVE FURTHER AWAY...THE SW FLOW WILL 
DIMINISH FURTHER. HOWEVER...AN ACTIVE MONSOON PATTERN THROUGH 
CENTRAL AMERICA WILL MEAN SOME POTENTIAL FOR PERIODIC HEAVY 
RAINFALL WILL PERSIST. MEANWHILE A COLD FRONT...THE FIRST STRONG 
COLD FRONT OF THE SEASON...WILL PUSH THROUGH THE WESTERN GULF OF 
MEXICO TODAY...AND INTO THE GULF OF TEHUANTEPEC OVERNIGHT. THE 
SURGE OF COOLER AND DRIER AIR WILL SUPPORT WINDS TO GALE FORCE 
IN THE GULF OF TEHUANTEPEC. THE GFS SHOWS WINDS TO 40 KT 
OVERNIGHT. THE FORECAST WILL FAVOR THE SLIGHTLY MORE 
CONSERVATIVE ECMWF SHOWING A MORE GRADUAL INCREASE TO 35 KT 
THROUGH EARLY WED. THE COMBINATION OF THE STRONG GAP WIND FLOW 
AND THE ALREADY PRESENT MODERATE TO FRESH SW MONSOON FLOW WILL 
SUPPORT DEVELOPMENT OF A WEAK LOW PRES AREA OFF GUATEMALA WED 
AND THU. SEAS WILL BUILD FROM 06N TO 14N BETWEEN 95W AND 105W 
THROUGH THU ASSOCIATED WITH THE STRONG GAP FLOW. 

W OF 110W...1019 MB SURFACE HIGH PRES IS CENTERED NEAR 30N127W. 
WINDS TO 20 KT ARE PLAUSIBLE BETWEEN THE HIGH PRES AND THE 
NORTHERN BAJA COAST INTO WED. FURTHER SOUTH...THE REMNANT LOW OF 
IRWIN IS STILL DISCERNIBLE ON VISIBLE SATELLITE IMAGERY NEAR 
15N110W. OTHER THAN ENHANCED SW MONSOON FLOW WELL S OF THE 
LOW...ASCAT DATA SHOWS MOSTLY LIGHT TO MODERATE FLOW IN THE 
VICINITY OF THE LOW. FURTHER WEST...ASCAT ALSO SHOWS MOSTLY 
MODERATE TRADES S OF THE HIGH PRES...WITH SOME AREAS OF 20 KT 
PERSISTING THAT WILL GRADUALLY DIMINISH THROUGH THE NEXT 24 TO 
48 HOURS.

$$
CHRISTENSEN