000
AXPZ20 KNHC 200330
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC THU OCT 20 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0300 UTC.

...ITCZ/MONSOON TROUGH...

MONSOON TROUGH EXTENDS FROM 13N89W TO 14N111W TO 13N127W...THEN 
AS ITCZ TO 10N140W. SCATTERED MODERATE CONVECTION WITHIN 150 NM 
S OF MONSOON TROUGH BETWEEN 100W AND 112W.

...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 
TO PERSIST THROUGH THU. GFS REMAINS THE STRONGEST OF THE GLOBAL 
GUIDANCE...SHOWING BOUNDARY LAYER WINDS TO 40 KT. THE REMAINING 
FORECAST MODELS SHOW WINDS NEAR GALE. FORECAST WILL MAINTAIN 
MAXIMUM WINDS TO 40 KT FOR THE NEXT 18 HOURS DECREASING TO 30 KT 
THU NIGHT. ASCAT AT 1545 UTC SHOWED WINDS TO 25 KT ALONG THE 
PASS EDGE OVER THE THE GULF OF TEHUANTEPEC. A WINDSAT PASS AT 
1230 UTC INDICATED INITIAL WIND SHIFT TO N WINDS ALONG THE COAST.

A BROAD MID LEVEL CYCLONIC CIRCULATION IS EVIDENT NEAR 15N104W 
AND MODERATE TO FRESH W-SW WINDS ARE INDICATED FROM SCATTEROMETER
DATA S OF THE MONSOON TROUGH BETWEEN 98W AND 116W. MODEL GUIDANCE
SUGGESTS A LOW WILL FORM NEAR 11N95W FROM THE ADDED VORTICITY OF 
STRONG NE TO E GAP WINDS TO THE NORTH AND THE PERSISTENT FRESH SW
MONSOONAL FLOW TO THE SOUTH. THE GFS DEEPENS THIS LOW SAT AND SUN
BUT THIS MAY BE DUE TO 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 
SOLUTION...SHOWING A SIGNIFICANTLY WEAKER LOW FORMING.

SHIP OBSERVATIONS AND SCATTEROMETER DATA SHOW 20 KT N WINDS W OF 
THE NORTHERN BAJA COAST TO AROUND 121W. THESE WINDS WILL DIMINISH
LATER TONIGHT AS HIGH PRES SHIFTS N OF THE AREA AND WEAKENS. 

$$
MUNDELL