000
AXPZ20 KNHC 271556
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC TUE SEP 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1430 UTC.

...SPECIAL FEATURE...

HURRICANE HILARY WAS LOCATED NEAR 16.8N 116.4W AT 1500 UTC  
MOVING W OR 270 DEG AT 9 KT. ESTIMATED MINIMUM CENTRAL PRESSURE 
IS 961 MB. MAXIMUM SUSTAINED WINDS ARE 100 KT WITH GUSTS TO 125 
KT. A TURN TOWARD THE WEST-NORTHWEST AND A DECREASE IN FORWARD 
SPEED ARE EXPECTED TODAY...FOLLOWED BY A TURN TOWARD THE NORTH 
ON WEDNESDAY. GRADUAL WEAKENING IS EXPECTED OVER THE NEXT 24 
HOURS...FOLLOWED BY ADDITIONAL WEAKENING ON WEDNESDAY. NUMEROUS 
STRONG CONVECTION WITHIN 90 NM OF CENTER. SCATTERED MODERATE 
ISOLATED STRONG CONVECTION ELSEWHERE WITHIN 120 NM OF CENTER. 
SWELLS GENERATED BY HILARY ARE AFFECTING THE SOUTHERN HALF OF 
BAJA CALIFORNIA AND THE GULF OF CALIFORNIA S OF 25N...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 EXTENDS FROM 12N88W TO 10N96W TO 13N104W... THEN 
RESUMES SW OF HURRICANE HILARY FROM 14N119W TO LOW PRES 10N129W 
1009 MB TO 10N140W. SCATTERED MODERATE ISOLATED STRONG 
CONVECTION WITHIN 90 NM OF LOW NEAR 10N129W.

...DISCUSSION... 

NEARLY STATIONARY 1022 MB HIGH PRES NEAR 28N135W ANCHORS SURFACE 
RIDGE THAT EXTENDS E-SE TO N OF HURRICANE HILARY INTO S PORTIONS 
OF BAJA CALIFORNIA NEAR 26N113W. THE PRES GRADIENT BETWEEN THE 
HIGH AND NW MEXICO WAS PRODUCING A NARROW ZONE OF FRESH NW WINDS 
WITHIN 150 NM OF THE W COAST OF BAJA N OF 25N. THE PRES GRADIENT 
IS ALSO INFLUENCING FAR NW PORTIONS OF HILARY...WHERE N-NE WINDS 
20 TO 25 KT EXTENDED OUTWARD TO 480 NM IN THE NW QUADRANT. S OF 
THE HIGH...NE TRADE WINDS NEAR 20 KT WERE OCCURRING FROM 11N TO 
20N W OF 126W...WITH SEAS TO 8 FT. THE HIGH WILL WEAKEN OVER THE 
NEXT FEW DAYS AS A SERIES OF COLD FRONTS APPROACH THE NW CORNER 
OF THE AREA...THEN STALL AND DISSIPATE. THIS COMBINED WITH THE 
BEGINNING OF A NORTHWARD MOTION OF HILARY WILL WEAKEN THE PRES 
GRADIENT AND WINDS ALONG THE BAJA PENINSULA...AND ALSO DECREASE 
THE AREA OF FRESH NE TRADE WINDS TO JUST N OF THE ITCZ. 

A 1009 MB LOW PRES CENTER EMBEDDED WITHIN THE MONSOON TROUGH NEAR
10N129W IS DRIFTING W AND GENERATING ACTIVE CONVECTION AND FRESH 
TO STRONG WINDS WITHIN 150 NM OF THE CENTER. THE LOW WILL DRIFT 
W THROUGH 36 HOURS BEFORE STALLING...THEN MOVE NE AS THE ENTIRE 
MONSOON TROUGH LIFTS NORTHWARD IN RESPONSE TO THE NORTHWARD TURN 
OF HILARY. LIGHT TO MODERATE S-SW WINDS WILL CONTINUE TO PREVAIL 
S OF THE MONSOON TROUGH ACROSS THE AREA THROUGH THU. MERGING SW 
CROSS-EQUATORIAL SWELL AND EXTRATROPICAL NW SWELL...ALONG WITH 
SWELL GENERATED BY HURRICANE HILARY...ARE CAUSING A CONFUSED SEA
STATE...A BROAD MIX OF SWELL FROM 10N-25N BETWEEN 110 AND 125W.

$$
MUNDELL