000
AXPZ20 KNHC 242153
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC MON AUG 24 2009

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W. 

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2130 UTC.

...SPECIAL FEATURE...

THE AREA OF LOW PRESSURE CENTERED SEVERAL HUNDRED NM SW OF THE 
SRN TIP OF BAJA CALIFORNIA HAS BEEN UPGRADED TO TROPICAL 
DEPRESSION TWELVE-E. THE DEPRESSION WAS CENTERED NEAR LATITUDE 
16.3N...LONGITUDE 117.2W OR ABOUT 575 NM...1060 KM...SOUTHWEST 
OF THE SOUTHERN TIP OF BAJA CALIFORNIA AT 24/2100 UTC...MOVING 
WEST-NORTHWEST OR 285 DEGREES AT 9 KT. MAXIMUM SUSTAINED WINDS 
WERE 30 KT WITH GUSTS TO 40 KT AND THE ESTIMATED MINIMUM CENTRAL 
PRESSURE WAS 1005 MB. VISIBLE AND INFRARED SATELLITE IMAGERY 
CONTINUES TO SHOW INCREASING ORGANIZATION IN THE CLOUD PATTERN 
WITH A BAND OF STRONG CONVECTION IN THE NW SEMICIRCLE AND A 
DEVELOPING CENTRAL DENSE OVERCAST OVER THE LOW LEVEL CENTER. 
CLOUD TOP TEMPERATURES WERE -85C WITHIN THE CENTRAL DENSE 
OVERCAST. DESPITE THE RECENT TRENDS IN SATELLITE...THE SYSTEM 
REMAINS IN AN ENVIRONMENT OF MODERATE ELY SHEAR. A RECENT HIGH 
RESOLUTION ASCAT PASS AT 1648 UTC REVEALED 30 KT WINDS OVER THE 
E SEMICIRCLE OF THE SYSTEM VERIFYING THE CURRENT INTENSITY. THE 
SYSTEM IS FORECAST TO BECOME A TROPICAL STORM WITHIN THE NEXT 12 
HOURS. ADDITIONAL INFORMATION CAN BE FOUND UNDER AWIPS/WMO 
HEADERS MIATCMEP3/WTPZ23 KNHC.
  
...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE IS ALONG 08N78W TO 06N90W TO 
7N100W TO 12N110W THEN CONTINUE FROM 13N120W TO 09N130W TO 
13N140W. SCATTERED MODERATE ISOLATED STRONG 90 NM EITHER SIDE OF 
AXIS FROM 122W TO 136W.

...DISCUSSION...

N OF 20N...
THE MID-UPPER PATTERN HAS BECOME MORE ZONAL OVER THE PAST 24 
HOURS WITH A RIDGE/TROUGH/RIDGE PATTERN EVIDENT ACROSS THE 
REGION. THE RIDGE EXTENDS FROM AN ANTICYCLONE NEAR 21N144W NE 
THROUGH 23N135W TO 32N130W. DOWNSTREAM TROUGH EXTENDS FROM A 
CYCLONIC CIRCULATION OVER SE NEVADA ACROSS NORTHERN BAJA 
CALIFORNIA TO A COL NEAR 21N129W. A VAST AREA OF DRY AIR ALOFT 
IS ASSOCIATED WITH THESE FEATURES...RESULTING IN GENERALLY FAIR 
WEATHER CONDITIONS. A NARROW RIDGE AXIS EXTENDS FROM THE GREAT 
PLAINS OF THE U.S. ACROSS W MEXICO TO ANOTHER UPPER LEVEL HIGH 
SEVERAL HUNDRED MILES SW OF THE SOUTHERN TIP OF BAJA CALIFORNIA 
NEAR 22N115W. 

AT THE SURFACE...HIGH PRES IS CENTERED N OF THE AREA NEAR 
36N137W. NE 15-20 KT TRADES EXIST ACROSS THE NW CORNER AND N 
15-20 KT WINDS NEAR THE N BAJA COAST WITH GENERALLY LIGHTER 
WINDS IN BETWEEN. A MIX OF N AND S SWELL WILL MAINTAIN SEAS OF 6 
TO 8 FT ACROSS MUCH OF THE AREA THROUGH MID-WEEK.

S OF 20N...
A DEEP MOIST ENVIRONMENT IS PRESENT ACROSS MUCH OF THE 
TROPICS...ENHANCED BY DIFFLUENT MID-UPPER FLOW TO THE S OF THE 
ANTICYCLONE NEAR 22N115W. THIS DIFFLUENT FLOW TO THE SOUTH OF 
THE ANTICYCLONE IS ALSO PROVIDING EASTERLY SHEAR OVER TROPICAL 
DEPRESSION TWELVE-E. SEE SPECIAL FEATURES SECTION FOR ADDITIONAL 
DETAILS. LONG PERIOD...14-16 SECOND...S TO SW SWELL IS 
PROPAGATING ACROSS MUCH OF THE AREA AND WILL CONTINUE FOR 
ANOTHER DAY OR SO BEFORE SUBSIDING.

$$
COBB