000
AXPZ20 KNHC 261015
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC MON SEP 26 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 
0730 UTC.

...SPECIAL FEATURE...

HILARY REMAINS A POWERFUL HURRICANE. AT 0900 UTC...HILARY WAS 
CENTERED NEAR 16.9N 112.2W MOVING W OR 270 DEG AT 9 KT. 
ESTIMATED MINIMUM CENTRAL PRESSURE WAS 959 MB. MAXIMUM SUSTAINED 
WINDS ARE 105 KT GUSTS TO 130 KT. SOME MINOR FLUCTUATIONS IN 
INTENSITY ARE POSSIBLE DURING THE NEXT DAY OR SO...BUT THE 
OVERALL TREND SHOULD BE FOR HILARY TO SLOWLY WEAKEN DURING THE 
NEXT 48 HOURS BEFORE BEGINNING TO MAKE A TURN TOWARD THE 
NORTHWEST TUESDAY EVENING AND THEN A SHARP TURN TOWARDS THE 
NORTH WEDNESDAY. NUMEROUS STRONG CONVECTION WAS WITHIN 45 NM N 
AND 60 NM S OF THE CENTER OF HILARY WITH SCATTERED TO NUMEROUS 
MODERATE TO STRONG CONVECTION ELSEWHERE WITHIN 180 NM NE AND 150 
NM S QUADRANTS. SWELLS GENERATED BY HILARY ARE STILL AFFECTING 
PORTIONS OF THE COAST OF SOUTHWESTERN MEXICO AND THE S HALF OF 
BAJA CALIFORNIA...AND CONTINUE TO PROPAGATE NORTHWARD INTO THE 
GULF OF CALIFORNIA. THESE SWELLS ARE CAUSING HIGH SURF AND 
LIFE-THREATENING RIP CURRENT CONDITIONS. SEE LATEST NHC 
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP4/WTPZ24 KNHC 
FOR MORE DETAILS. 
 
...ITCZ/MONSOON TROUGH...

MONSOON TROUGH AXIS EXTENDS FROM EXTREME SW CARIBBEAN TO NEAR 
10N86W TO 09N97W TO 09N104W WHERE IT TERMINATES...THEN RESUMES W 
OF HURRICANE HILARY FROM NEAR 13N119W TO 11N126W TO 10N135W TO 
09N140W. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION NOTED 
FROM 06N TO 10N BETWEEN 87W AND 94W. SIMILAR CONVECTION WAS N OF 
10N E OF 94W. 

...DISCUSSION... 

HIGH PRES RIDGE EXTENDS SE FROM A 1021 MB HIGH CENTERED NEAR 
28N129W TO NEAR 25N112W. THE PRESSURE GRADIENT BETWEEN THE HIGH 
PRES AND A PERSISTENT TROUGH OVER WESTERN MEXICO IS SUPPORTING 
FRESH NW WINDS N OF 24N E OF 118W TO THE W COAST OF BAJA 
CALIFORNIA. LITTLE CHANGE IS EXPECTED IN THE GENERAL SYNOPTIC 
PATTERN DURING THE NEXT 24 HOURS AS REMAINS NEARLY STATIONARY 
AND CONTINUES TO PROMOTE FRESH NW WINDS OFF OF BAJA. HOWEVER 
AFTER 24 HOURS THE HIGH WILL BEGIN TO RETREAT SLOWLY TO THE NW 
AND ALLOW WINDS TO DIMINISH E OF 120W. THE PRES GRADIENT BETWEEN 
THE AFOREMENTIONED HIGH AND HURRICANE HILARY IS RESULTING IN AN 
AREA OF NELY WINDS TO 20 KT TO ALMOST 600 NM TO THE NW OF 
HILARY. AS THE HIGH RETREATS DURING THE WEEK...THIS PRESSURE 
GRADIENT WILL REMAIN INTACT...AND BEGIN TO FRESHEN THE NE 
TRADEWINDS S OF 20N AND W OF 125W...BUILDING SEAS TO AROUND 8 
FT. 

A STATIONARY FRONT CROSSES NEAR 30N140W. SW WINDS OF 15 KT ARE 
IN THE FAR NW PORTION WITH SEAS TO 8 FT IN NW SWELL AFFECTING 
THE FAR NW WATERS. SEAS ARE FORECAST TO SUBSIDE BELOW 8 FT LATE 
TODAY...BUT WILL INCREASE AGAIN TO 8 TO 10 FT TUE NIGHT AS A NEW 
PULSE OF NW SWELL MOVES INTO NW PORTIONS OF THE AREA. 

MODERATE SWLY WINDS OCCURRING S OF THE MONSOON TROUGH BETWEEN 
90W AND 103W WERE FUELING MODERATE TO ISOLATED STRONG CONVECTION 
ON BOTH SIDES OF THE TROUGH BETWEEN 83 AND 95W. 

LONG PERIOD NW SWELL IS MERGING WITH SW SWELL FROM THE SOUTHERN 
HEMISPHERE MAINLY S OF 05N.

$$
STRIPLING