000
AXPZ20 KNHC 212145
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC WED SEP 21 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 
2130 UTC.

...SPECIAL FEATURE...

.TROPICAL STORM HILARY NEAR 14.0N 96.6W 1003 MB AT 2100 UTC SEP 
21 MOVING NW OR 305 DEG AT 5 KT. MAXIMUM SUSTAINED WINDS 40 KT 
GUSTS 50 KT. TROPICAL STORM FORCE WINDS WITHIN 45 NM NE AND 35 
NM NW QUADRANTS. SEAS 12 FT OR GREATER WITHIN 60 NM N SEMICIRCLE 
AND 90 NM SE QUADRANT WITH SEAS TO 12 FT. SEE LATEST NHC FORECAST
ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP4/WTPZ24 KNHC FOR MORE 
DETAILS. CONVECTIVE BANDS ASSOCIATED WITH HILARY ARE STARTING 
TO WRAP TIGHTLY AROUND THE CYCLONE CENTER UNDER A SMALL AREA OF 
DENSE OVERCAST.
 
...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH AXIS EXTENDS FROM PANAMA AT 08N78W TO 09N83W 
TO 12N90W TO T.S. HILARY...THEN RESUMES AT 11N104W TO A 1011 MB 
LOW NEAR 12N116W TO SECOND 1011 MB LOW NEAR 10N129W TO 11N136W. 
SCATTERED MODERATE CONVECTION FROM 05N TO 08N BETWEEN 83W AND 
88W. SCATTERED MODERATE ISOLATED STRONG CONVECTION FROM 09N TO 
17N BETWEEN 92W AND 107W.

...DISCUSSION... 

A RIDGE EXTENDS SW FROM 1022 MB HIGH PRES NEAR 32N140W TO 
23N121W...SUPPORTING LIGHT N-NE WINDS N OF 20N...AND LIGHT TO 
MODERATE NE TRADE WINDS N OF THE MONSOON TROUGH...W OF 115W. 
SCATTEROMETER DATA SHOWS WINDS LESS THAN 20 KT AROUND SURFACE 
LOWS EMBEDDED WITHIN THE MONSOON TROUGH NEAR 12N117W AND 11N129W.
A LACK OF DEEP LAYER MOISTURE IS INHIBITING CONVECTION ALONG THE 
MONSOON TROUGH W OF 110W.

TROPICAL STORM HILARY IS ANCHORING A BROAD CYCLONIC CIRCULATION 
IN THE MONSOON TROUGH E OF 105W. CONVECTION REMAINS VERY ACTIVE 
OVER A LARGE PORTION OF THE AREA FROM 11N TO 17N BETWEEN 92W AND 
102W. MODEL GUIDANCE IS IN GOOD AGREEMENT...MOVING HILARY WNW TO 
NW S OF MEXICO THROUGH THE WEEKEND. LITTLE CHANGE IN THE OVERALL 
PATTERN IS EXPECTED ELSEWHERE...WITH MODERATE N-NE TRADE WINDS N 
OF THE MONSOON TROUGH AXIS...WHICH WILL EXTEND ACROSS THE ENTIRE 
BASIN ALONG 11-12N W OF HILARY.

THE GFS MODEL BUILDS SEAS TO 10 FT S OF A LOW EMBEDDED IN THE 
TROUGH NEAR 12N114W BY FRI...BUT THIS FORECAST IS NOT SUPPORTED 
BY EITHER ECMWF OR UKMET MODELS...SO DOWNPLAYING ANY SIGNIFICANT 
IMPACT FOR THIS FEATURE IN HIGH SEAS FCST. OTHERWISE EXPECT SEAS 
TO BUILD TO 11 FT IN LONG PERIOD SWELL EXTREME NW PORTION THU.

$$
MUNDELL/FORMOSA