000
AXPZ20 KNHC 270939
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC THU OCT 27 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0900 UTC.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH IS ALONG 10N86W TO 08N99W. THE INTERTROPICAL 
CONVERGENCE ZONE AXIS EXTENDS FROM 08N99W TO 110N110W TO 11N120W 
TO 07N136W TO 08N140W. ISOLATED TO SCATTERED MODERATE 
CONVECTION IS FROM 10N TO 15N BETWEEN 119W AND 124W. SCATTERED 
MODERATE AND ISOLATED STRONG CONVECTION IS WITHIN 90-120 NM 
EITHER SIDE OF THE ITCZ BETWEEN 124W AND 130W.

...DISCUSSION...

A SHARP UPPER LEVEL TROUGH REACHES FROM NEAR POINT CONCEPTION 
CALIFORNIA TO 32N130W TO AN UPPER CYCLONE NEAR 28N133W TO 
15N136W THEN SE TO A BASE OVER THE DEEP TROPICAL PACIFIC AT 
07N126W. AN UPPER ANTICYCLONE IS OVER THE E PACIFIC NEAR 14N110W 
WITH RIDGING EXTENDING NW TO NEAR 30N124W AND ALSO SE TO THE 
ECUADOR/COLOMBIA BORDER NEAR 01N79W. CONVECTION REMAINS ACTIVE 
IN THE REGION FROM E OF THE UPPER TROUGH TO ACROSS THE WESTERN 
UPPER RIDGING. 

ITCZ CONVECTION IS AS DESCRIBED ABOVE WITH ADDITIONAL SCATTERED 
MODERATE AND ISOLATED STRONG CONVECTION FROM 10N TO 20N BETWEEN 
130W AND 134W WITH A SURFACE TROUGH FROM 18N130W TO 10N135W. A 
RECENT 0236 UTC WINDSAT SCATTEROMETER PASS INDICATED FRESH NE-E 
WINDS FROM 12N TO 20N W OF THE TROUGH...AND N OF 20N W OF 130W 
WHERE A TIGHT PRES GRADIENT EXISTS...ALONG WITH 8-10 FT SEAS IN 
MIXED NE AND NW SWELL. THIS TROUGH WILL MOVE W OF THE AREA BY 48 
HOURS WITH THE AREA OF FRESH WINDS BECOMING CONFINED TO THE AREA 
FROM 15N TO 23N W OF 135W AT THAT TIME IN THE WAKE OF THE TROUGH.

ELSEWHERE AT THE SURFACE...A RIDGE EXTENDS FROM HIGH PRES N OF 
THE AREA NEAR 38N135W TO 32N133W TO 16N110W. A TIGHT PRES 
GRADIENT IS ALSO OVER THE BAJA CALIFORNIA REGION BETWEEN THIS
RIDGE AND DEEPENING SURFACE LOW PRES OVER CENTRAL MEXICO. AS A 
RESULT...FRESH NORTHERLY WINDS WILL GRADUALLY SPREAD SOUTHWARD 
IN THE GULF OF CALIFORNIA REACHING TO 24N WITHIN 24 HOURS...THEN 
WILL DIMINISH TO LESS THAN 20 KT BY 48 HOURS AS THE SURFACE LOW 
WEAKEN AND SHIFTS W TO THE MEXICAN COASTLINE. SEAS WILL REMAIN
LESS THAN 8 FT THROUGH 48 HOURS.

MODEL GUIDANCE DEPICTS FRESH SW FLOW S OF THE MONSOON TROUGH 
FROM 36-48 HOURS OVER THE FAR SE PORTION OF THE AREA WITH SEAS 
BUILDING TO 8 FT.
 
GAP WINDS...A STRONG COLD FRONT WILL MOVE THROUGH THE SW GULF OF 
MEXICO ON FRI RESULTING IN A STRONG SURGE OF NORTHERLY WINDS 
WHICH WILL FUNNEL THROUGH THE CHIVELA PASS BEHIND THE FRONT. 
WINDS WILL ARRIVE IN AND DOWNSTREAM OF THE GULF OF TEHUANTEPEC 
AROUND SUNSET FRI QUICKLY INCREASING TO GALE FORCE AROUND 
MIDNIGHT WHEN A GALE WARNING WILL COMMENCE. SEAS WILL RAPIDLY 
BUILD TO UP TO 12 FT IN THE AREA OF GALE FORCE WINDS.
 
$$
LEWITSKY