000
AXPZ20 KNHC 221605
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC THU SEP 22 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 
1545 UTC.

...SPECIAL FEATURE...

RECENTLY UPGRADED HURRICANE HILARY NEAR 15.1N 98.9W 989 MB AT 
1500 UTC SEP 22 MOVING WNW OR 295 DEG AT 8 KT. MAXIMUM SUSTAINED 
WIND SPEED IS 65 KT WITH GUSTS TO 80 KT. FIRST EARLY MORNING
VISIBLE IMAGERY SHOW A RELATIVELY SMALL CYCLONE THAT HAS BECOME 
BETTER ORGANIZED DURING THE NIGHT AS NOTED IN THE SMALL EYE 
FEATURE SURROUNDED BY A 60 NM WIDE RING OF NUMEROUS STRONG 
CONVECTION. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS 
ELSEWHERE WITHIN 90 NM OF THE CENTER. A LARGE CLUSTER OF
NUMEROUS STRONG CONVECTION IS TO THE W OF HILARY N OF 14N TO
THE COAST OF MEXICO BETWEEN 101W-105W. HILARY IS UNDER A LARGE
ANTICYCLONE...AND OVER VERY WARM SEA SURFACE TEMPERATURES IN 
ADDITION TO BEING IN A LOW SHEAR ENVIRONMENT. SO THE LATEST NHC 
FORECAST HAS THE CYCLONE INTENSIFYING...POSSIBLY IN A RAPID 
FASHION...AS MOVES TO NEAR 16N100W EARLY TONIGHT...16N102W FRI 
MORNING...NEAR 17N140W EARLY FRI NIGHT AND TO NEAR 17N106W BY 
SAT MORNING. SEE LATEST NHC FORECAST ADVISORY UNDER AWIPS/WMO 
HEADERS MIATCMEP4/WTPZ24 KNHC FOR MORE DETAILS.
 
...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH AXIS EXTENDS FROM 8N82W TO 10N88W WHERE IT 
ENDS. IT THEN RESUMES AT 13N108W TO 12N122W TO 8N133W. SCATTERED
MODERATE/ISOLATED CONVECTION IS WITHIN 120 NM S OF THE TROUGH
BETWEEN 110W-117W...AND BETWEEN 120W-122W. SCATTERED MODERATE
CONVECTION IS WITHIN 120 NM S OF THE MONSOON TROUGH BETWEEN 
86W-88W.

...DISCUSSION... 

AN UPPER LEVEL SHARP NARROW TROUGH ENTERS THE REGION THROUGH
32N124W TO 27N135W TO A DEVELOPING UPPER LOW NEAR 25N140W. BROAD
MID/UPPER LEVEL RIDGING COVERS THE REMAINDER OF THE AREA. 
SATELLITE WATER VAPOR IMAGERY SHOWS MODERATE TO STRONG 
SUBSIDENCE OVER JUST ABOUT THE ENTIRE...EXCEPT OVER THE MONSOON 
TROUGH AND OVER HILARY WHERE THE UPPER LEVEL OUTFLOW IS 
CHANNELING MOISTURE IN THE FORM OF CIRRUS OUTWARDS FROM THE 
CYCLONE. AT THE SURFACE...A TROUGH EXTENDS FROM 15N124W TO 
12N128W...WHILE ANOTHER TROUGH IS ALONG 139W FROM 7N-12N. 
SCATTERED MODERATE CONVECTION IS 30 NM OF THE FIRST TROUGH
WHILE SCATTERED MODERATE/ISOLATED STRONG CONVECTION EXISTS
WITHIN 60 NM OF THE SECOND TROUGH. A WEAK RIDGE EXTENDS FROM 
32N135W SE TO NEAR 21N125W. AN AREA OF NE 20 KT WINDS EXISTS TO 
THE SE OF THE RIDGE FROM 14N-19N BETWEEN 120W-130W. THESE WINDS
ARE FORECAST TO DIMINISH TO LESS THAN 20 KT IN ABOUT 18 HRS.

DIVERGENCE ALOFT ASSOCIATED WITH A SHARP UPPER TROUGH OVER THE 
SOUTHERN CENTRAL AMERICA CONTINUES TO SUSTAIN THE SCATTERED
MODERATE CONVECTION WITHIN 120 NM S OF THE MONSOON TROUGH 
BETWEEN 86W-88W.

NW SWELLS WITH HEIGHTS TO 11 FT AND PERIODS TO 16 SECONDS 
CONTINUES TO PROPAGATE S OF 32N AND E OF 140W...AND WAVEWATCH 
III SHOWS IT WILL REACH AS FAR E AS 115W N OF 18N AND W TO 125W
WITHIN ABOUT 48 HOURS WITH SEAS TO 8 FT IN A NW SWELL.

$$
AGUIRRE