000
AXPZ20 KNHC 192145
TWDEP 

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

...ITCZ/MONSOON TROUGH...

MONSOON TROUGH EXTENDS FROM 14N90W TO 13N103W TO 13N126W...THEN 
AS ITCZ TO 10N140W. SCATTERED MODERATE CONVECTION WITHIN 90 NM 
EITHER SIDE OF MONSOON TROUGH BETWEEN 99W AND 107W.

...DISCUSSION...

ANIMATED SATELLITE IMAGERY SHOWS COOL DRY AIR ASSOCIATED WITH A 
STRONG COLD FRONT IN THE SW GULF FUNNELING THROUGH THE CHIVELA 
PASS INTO THE GULF OF TEHUANTEPEC. GALE FORCE WINDS ARE EXPECTED 
THIS AFTERNOON...AND PERSISTING THROUGH THU. THE GFS REMAINS THE 
STRONGEST OF THE GLOBAL GUIDANCE SHOWING 30M WINDS TO 40 KT. THE 
REMAINING FORECAST MODELS SHOW WINDS BARELY TO GALE OR NOT QUITE 
TO GALE FORCE. FORECAST WILL MAINTAIN MAXIMUM WINDS TO 40 KT FOR 
THE NEXT 18-24 HOURS DECREASING TO 30-35 KT THU AFTERNOON. ASCAT 
AT 1545 UTC SHOWED WINDS TO 25 KT ALONG THE PASS EDGE OVER THE 
THE GULF OF TEHUANTEPEC...AFTER A WINDSAT PASS AT 1230 UTC ONLY 
INDICATED THE INITIAL WIND SHIFT TO N WINDS ALONG THE COAST.

A BROAD LOW/MID LEVEL CYCLONIC CIRCULATION IS EVIDENT NEAR 15N 
103W. MODELS SHOW A WEAK SURFACE LOW FORMING TONIGHT ASSOCIATED 
WITH THIS FEATURE...TRACKING W TO 110W. THIS WILL HELP MAINTAIN 
FRESH W TO SW WINDS S OF THE MONSOON TROUGH. MODEL GUIDANCE ALSO 
SUGGESTS A SECOND LOW WILL FORM STARTING FURTHER E NEAR 11N95W 
FROM THE ADDED VORTICITY OF THE STRONG NE TO E GAP WINDS TO THE 
NORTH...AND THE PERSISTENT FRESH SW MONSOONAL FLOW 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 N WINDS JUST W OF THE NORTHERN 
BAJA COAST. THESE WINDS WILL DIMINISH TONIGHT AS THE HIGH PRES 
SHIFTS N OF THE AREA AND WEAKENS. 

$$
MUNDELL