000
AXPZ20 KNHC 251545
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC SUN SEP 25 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.

...SPECIAL FEATURE...

HILARY REMAINS A POWERFUL HURRICANE. AT 1500 UTC...HILARY WAS 
CENTERED NEAR 17.2N 109.2W MOVING W OR 275 DEG AT 8 KT. ESTIMATED
MINIMUM CENTRAL PRESSURE IS 953 MB. MAXIMUM SUSTAINED WINDS ARE 
110 KT GUSTS TO 135 KT. SOME MINOR FLUCTUATIONS IN INTENSITY ARE 
LIKELY IN THE SHORT TERM...BUT THE OVERALL TREND IS TO SLOWLY 
WEAKEN. HILARY IS EXPECTED TO MOVE WEST THE NEXT TWO DAYS THEN 
TURN NORTHWARD. NUMEROUS STRONG CONVECTION IS WITHIN 90 NM E AND 
45 NM W SEMICIRCLES. SCATTERED TO NUMEROUS MODERATE TO STRONG 
CONVECTION ELSEWHERE WITHIN 150 NM E AND 90 NM W SEMICIRCLES. 
SWELLS GENERATED BY HILARY ARE AFFECTING PORTIONS OF THE COAST 
OF SOUTHWESTERN MEXICO AND INTO THE SOUTHERN GULF OF CALIFORNIA. 
SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS 
MIATCMEP4/WTPZ24 KNHC FOR MORE DETAILS. 
 
...ITCZ/MONSOON TROUGH...

MONSOON TROUGH EXTENDS FROM 12N87W TO 11N90W TO 08N100W THEN 
RESUMES W OF HURRICANE HILARY NEAR 14N116W TO 12N130W TO 09N140W.
SCATTERED MODERATE TO STRONG CONVECTION WITHIN 180 NM S OF TROUGH
BETWEEN 84W AND 91W AND ELSEWHERE N OF 05N TO COAST OF PANAMA. 
SCATTERED MODERATE TO STRONG CONVECTION FROM 05N TO 10N BETWEEN 
98W AND 103W. SCATTERED MODERATE ISOLATED STRONG CONVECTION FROM 
10N TO 13N BETWEEN 123W AND 135W.

...DISCUSSION... 

WEAK RIDGE EXTENDS SE FROM A 1020 MB HIGH WAS CENTERED NEAR 
27N129W TO NEAR 22N116W. PRESSURE GRADIENT BETWEEN THE HIGH PRES 
AND LOWER PRES OVER MOJAVE DESERT IS SUPPORTING FRESH NW WINDS N 
OF 25N E OF 116W TO THE W COAST OF BAJA CALIFORNIA. LITTLE CHANGE
IS EXPECTED IN THE SYNOPTIC PATTERN AT LEAST THE NEXT TWO DAYS AS
THE HIGH REMAINS STATIONARY. A WEAKENING STATIONARY FRONT JUST 
NW OF THE FORECAST AREA CROSSING NEAR 30N140W. SW WINDS 15 TO 20 
KT ARE NOTED OVER THE FAR NW PORTION WITH SEAS TO 8 FT IN NW 
SWELL AFFECTING THE WATERS N OF 29N W OF 138W. LITTLE CHANGE IS 
EXPECTED NEXT 24 HOURS WITH SEAS SUBSIDING BELOW 8 FT MON. LIGHT 
TO MODERATE N-NE TRADE WINDS DOMINATE THE REGION N OF THE MONSOON
TROUGH W OF 115W...WITH A NARROW ZONE OF 15 TO 20 KT TRADE WINDS 
BETWEEN 13N AND 17N W OF 125W.

SEVERAL WEAK DISTURBANCES EMBEDDED WITHIN THE MONSOON TROUGH ARE 
PRODUCING SCATTERED SHOWERS AND ISOLATED TSTMS ALONG THE TROUGH 
AXIS W OF 122W. FRESH MONSOONAL FLOW PREVAILS S OF THE TROUGH 
AXIS E OF 95W. WEAK HIGH PRESSURE IN THE GULF OF MEXICO SUPPORTS
MODERATE TO FRESH WINDS IN THE GULF OF TEHUANTEPEC THIS MORNING. 

HURRICANE HILARY IS GENERATING LARGE LONG-PERIOD SWELL WITH SEAS 
GREATER THAN 8 FT UP TO 240 NM AWAY FROM THE CENTER. CONDITIONS 
ELSEWHERE REMAIN FAIRLY BENIGN ACROSS THE DISCUSSION AREA. LONG 
PERIOD NW SWELL ARE MERGING WITH SW SWELL FROM THE SOUTHERN 
HEMISPHERE MAINLY S OF 04N.

$$
MUNDELL/COBB