000
AXPZ20 KNHC 191536
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC WED OCT 19 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 
1515 UTC.

...ITCZ/MONSOON TROUGH...

MONSOON TROUGH AXIS FROM THE COAST OF CENTRAL AMERICA NEAR 
14N90W TO 14N103W TO 09N121W TO 10N135W. THE ITCZ EXTENDS FROM 
THERE TO 09N140W. SCATTERED MODERATE ISOLATED STRONG WITHIN 
WITHIN 240 NM OF TROUGH AXIS BETWEEN 97W AND 107W.

...DISCUSSION...

COOLER AND DRIER AIR RELATED TO A COLD FRONT IN THE SW GULF OF 
MEXICO IS STARTING TO FUNNEL THROUGH THE CHIVELA PASS AND WILL 
BRING GALE FORCE WINDS TO THE GULF OF TEHUANTEPEC THIS AFTERNOON 
AND PERSISTING THROUGH THU. THE GFS REMAINS THE STRONGEST OF THE 
GLOBAL GUIDANCE SHOWING 30M WINDS TO 40 KT. THE REMAIN GUIDANCE 
SHOW WINDS BARELY TO GALE OR NOT QUITE TO GALE FORCE. FORECAST 
WILL MAINTAIN MAXIMUM WINDS TO 40 KT FOR LATE TODAY. MEANWHILE 
ASCAT AND SHIP DATA SHOW 15 TO 20 KT SW WINDS WITHIN 250 NM S OF 
THE MONSOON TROUGH AXIS BETWEEN 90W AND 105W. 

FURTHER WEST...A MID LEVEL CYCLONIC SHOWS UP WELL NEAR 13N1041W. 
GLOBAL MODELS SHOW A BROAD SURFACE LOW FORMING TODAY ASSOCIATED 
WITH THIS FEATURE...AND TRACKING W TO 110W. THIS WILL MAINTAIN 
THE CURRENT FRESH SW WINDS S OF THE MONSOON TROUGH...BUT 
OTHERWISE NOT PRESENT MUCH SENSIBLE WEATHER. GLOBAL MODELS 
SUGGEST A SECOND LOW WILL FORM STARTING LATE TODAY FURTHER E 
NEAR 11N95W...DUE TO THE ADDED VORTICITY OF THE STRONG NE TO E 
GAP WINDS TO THE NORTH...AND THE PERSISTENT FRESH SW TO THE 
SOUTH. THE GFS DEEPENS THIS LOW BY EARLY SAT...BUT THIS MAY BE 
DUE TO SOME CONVECTIVE FEEDBACK. CONSIDERING THAT THE GAP WINDS 
WILL BRING LESS FAVORABLE DRY AIR INTO THE DEVELOPING 
CIRCULATION...THE FORECAST WILL FAVOR THE LESS AGGRESSIVE ECMWF 
SHOWING A SOMEWHAT WEAKER LOW FORMING. 

SHIP OBSERVATIONS INDICATE 20 KT NORTHERLY FLOW BETWEEN A 1020 
MB HIGH PRES CENTERED NEAR 29N129W AND THE NORTHERN BAJA COAST. 
THESE WINDS WILL DIMINISH THROUGH LATE TODAY AS THE HIGH PRES 
SHIFTS N OF THE AREA. 

$$
CHRISTENSEN