000
AXPZ20 KNHC 272130
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2100 UTC.

...SPECIAL FEATURE...

HURRICANE HILARY WAS LOCATED NEAR 17.1N 117.1W AT 2100 UTC  
MOVING WNW OR 290 DEG AT 6 KT. ESTIMATED MINIMUM CENTRAL PRESSURE
IS 964 MB. MAXIMUM SUSTAINED WINDS ARE 95 KT WITH GUSTS TO 115 
KT. A TURN TOWARD THE NORTH AND A DECREASE IN FORWARD SPEED ARE 
EXPECTED BY WEDNESDAY NIGHT. WEAKENING IS FORECAST DURING THE 
NEXT 48 HOURS...AND HILARY IS EXPECTED TO WEAKEN TO A TROPICAL 
STORM ON THURSDAY. NUMEROUS STRONG CONVECTION WITHIN 60 NM OF 
CENTER. SCATTERED MODERATE ISOLATED STRONG CONVECTION ELSEWHERE 
WITHIN 120 NM NW OF CENTER. SWELLS GENERATED BY HILARY ARE 
AFFECTING THE WEST COAST OF BAJA CALIFORNIA AND THE SOUTHERN 
GULF OF CALIFORNIA...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 13N87W TO 10N96W TO 09N106W... THEN 
RESUMES SW OF HURRICANE HILARY FROM 14N120W TO LOW PRES 10N130W 
1009 MB TO 09N140W. SCATTERED MODERATE CONVECTION WITHIN 60 NM 
OF LOW NEAR 10N130W.

...DISCUSSION... 

NEARLY STATIONARY 1022 MB HIGH PRES NEAR 29N135W ANCHORS SURFACE 
RIDGE THAT EXTENDS E-SE TO N OF HURRICANE HILARY INTO S PORTIONS 
OF BAJA CALIFORNIA NEAR 26N117W. THE PRES GRADIENT BETWEEN THE 
HIGH AND HILARY IS PRODUCING FRESH TO STRONG N-NE WINDS WELL FROM
THE CENTER...EXTENDING OUTWARD TO 480 NM IN THE NW QUADRANT. S OF
THE HIGH...NE TRADE WINDS NEAR 20 KT WERE OCCURRING FROM 10N TO 
20N W OF 128W 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...DECREASING 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 BURSTS OF ACTIVE CONVECTION 
AND FRESH WINDS WITHIN 120 NM OF THE CENTER. THE LOW WILL DRIFT 
W THROUGH 36 HOURS BEFORE STALLING...THEN MOVE SLOWLY N AS THE 
MONSOON TROUGH LIFTS POLEWARD 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