000
AXPZ20 KNHC 181608
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC SUN SEP 18 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 
1500 UTC.

...ITCZ/MONSOON TROUGH...

MONSOON TROUGH EXTENDS FROM 08.5N84.5W TO LOW PRES 10N94W 1009 
MB THEN BREAKS AT 10N102W. THE TROUGH RESUMES FROM 20N111W TO 
13N119W TO 10N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION
N OF 04N E OF 85W. SCATTERED MODERATE TO STRONG CONVECTION N OF 
05N BETWEEN 89W AND 103W. SCATTERED MODERATE TO STRONG CONVECTION
WITHIN 150 NM N AND 240 NM S OF TROUGH BETWEEN 111W AND 137W.

...DISCUSSION... 

HIGH PRES RIDGE N OF AREA EXTENDS FROM 37N130W THROUGH 1024 MB 
HIGH NEAR 33N135W TO 1025 MB HIGH NEAR 33N 147W. THE RIDGE IS 
SUPPORTING 15-20 KT WINDS BETWEEN THE MONSOON TROUGH TO AROUND 
15N. SCATTEROMETER DATA INDICATES STRONG LOW LEVEL CONVERGENCE 
ALONG 10N BETWEEN 120W AND 140W ASSOCIATED WITH THE MONSOON 
TROUGH. FRESH S TO SW FLOW IS EVIDENT S OF THE TROUGH BETWEEN 
125W AND 135W. THE CONVERGENT FLOW IS CONTINUING TO GENERATE 
ACTIVE CONVECTION IN SCATTERED MODERATE SHOWERS AND TSTMS IN 
THIS AREA AS WELL ALONG THE MONSOON TROUGH.

A WEAK LOW PRES CENTER IS EVIDENT FROM SATELLITE DATA NEAR 10N94W
WITH AN ESTIMATED PRES OF 1009 MB. GLOBAL MODELS CONTINUE TO 
SHOW THIS LOW PRES AREA DEVELOPING OVER THE NEXT COUPLE OF DAYS 
IN THIS AREA AND DRIFTING W ALONG THE MONSOON TROUGH AXIS. THE 
MAIN IMPACT OF THIS WILL BE SW WINDS REACHING 20 KT WITHIN 180 
NM S OF THE MONSOON TROUGH MAINLY BETWEEN 110W AND 130W OVER THE 
NEXT SEVERAL DAYS...WITH SEAS TO 9 FT. EXPECTED DEVELOPMENT HAS 
BEEN VERY SLOW AND THE FORECAST TENDENCY WILL BE TO REMAIN BELOW 
GUIDANCE ON WINDS AND SEAS ASSOCIATED WITH THIS FEATURE. 

WIND REPORTS CONFIRM 20 KT N FLOW THROUGH THE TEHUANTEPEC AREA. 
AN EARLIER ASCAT PASS ALSO SHOWED 15 KT IN THIS AREA. THIS IS A 
LITTLE LESS THAN EXPECTED...BUT GIVEN THE DEVELOPMENT OF WEAK 
LOW PRES TO THE SOUTH...EXPECT 20 KT FLOW THROUGH TEHUANTEPEC 
THROUGH MON...WITH DIURNAL MAXIMUMS IN THE EARLY MORNING.

$$
MUNDELL