000
AXPZ20 KNHC 250926
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC TUE AUG 25 2009

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

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0900 UTC.

...SPECIAL FEATURE...

TROPICAL STORM IGNACIO WAS CENTERED NEAR 18.1N 118.5W OR ABOUT 
560 NM SOUTHWEST OF THE SOUTHERN TIP OF BAJA CALIFORNIA AT 
25/0900 UTC...MOVING WEST-NORTHWEST OR 290 DEGREES AT 9 KT. 
MAXIMUM SUSTAINED WINDS WERE 35 KT WITH GUSTS TO 45 KT AND THE 
ESTIMATED MINIMUM PRESSURE WAS 1004 MB. SATELLITE IMAGERY 
CONTINUES TO SHOW INCREASING ORGANIZATION IN THE CLOUD PATTERN 
WITH THE STRONGEST CONVECTION OVER THE SOUTHERN SEMICIRCLE 
...THOUGH DEEP CONVECTION HAS RECENTLY FORMED NEAR THE CENTER. 
SCATTERED MODERATE TO STRONG CONVECTION IS WITHIN 90 NM N AND 
360 NM S SEMICIRCLES. STRENGTHENING IS FORECAST IN THE SHORT 
TERM AS VERTICAL WIND SHEAR REMAINS LIGHT AND THE TROPICAL STORM 
IS OVER WARM WATERS. BEYOND 36 HOURS...IGNACIO IS FORECAST TO 
MOVE OVER COOLER WATERS CAUSING THE SYSTEM TO LOSE VERTICAL 
DEPTH AND WEAKEN. ADDITIONAL INFORMATION CAN BE FOUND UNDER 
AWIPS/WMO HEADERS MIATCMEP3/WTPZ23 KNHC.
  
...TROPICAL WAVES...
A TROPICAL WAVE IS ALONG 82W/83W N OF 05N MOVING W NEAR 20 KT. A 
VORTICITY MAXIMUM HAS BEEN EVIDENT ALONG THE WAVE NEAR 12N. 
SCATTERED MODERATE TO STRONG CONVECTION IS OVER PORTIONS OF NRN 
COSTA RICA AND NICARAGUA FROM 11N-14N BETWEEN 82W-86W. FURTHER 
DEVELOPMENT...IF ANY...WOULD BE SLOW TO OCCUR ONCE THE ENTIRE 
WAVE MOVES INTO THE EAST PACIFIC.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE IS ALONG 08N83W TO 08N107W TO 
14N121W TO 10N140W. SCATTERED MODERATE CONVECTION IS FROM 05N TO 
12N BETWEEN 100W AND 110W. SCATTERED MODERATE CONVECTION IS FROM 
06N TO 12N BETWEEN 133W AND 138W.

...DISCUSSION...

N OF 20N...
THE MID TO UPPER PATTERN CONSISTS OF A RIDGE THAT EXTENDS FROM 
AN ANTICYCLONE NEAR 21N140W NE THROUGH 30N125W...A DOWNSTREAM 
TROUGH FROM AN UPPER LOW OVER THE GREAT BASIN TO THE THE NRN 
GULF OF CALIFORNIA...AND ANOTHER TROUGH ALONG 138W N OF 25N. A 
VAST AREA OF DRY AIR ALOFT IS ASSOCIATED WITH THESE FEATURES... 
RESULTING IN GENERALLY FAIR WEATHER CONDITIONS. TROUGHING IS 
EXPECTED TO DEEPEN OVER THE N PACIFIC BY THE END OF THE WEEK 
DRAGGING A COLD FRONT TO THE NW CORNER BY LATE THU.

AT THE SURFACE...HIGH PRES IS CENTERED N OF THE AREA NEAR 
35N136W. NE 15-20 KT TRADES EXIST ACROSS THE NW CORNER WITH 
GENERALLY LIGHTER WINDS ELSEWHERE...EXCEPT NEAR IGNACIO.

S OF 20N...
A DEEP MOIST ENVIRONMENT IS PRESENT ACROSS MUCH OF THE 
TROPICS...THOUGH ORGANIZED DEEP CONVECTION IS MAINLY CONFINED TO 
IGNACIO AND THE TROPICAL WAVE OVER CENTRAL AMERICA. LONG 
PERIOD...14-16 SECOND...S TO SW SWELL PROPAGATING ACROSS MUCH OF 
THE AREA WILL BEGIN TO SUBSIDE LATE TODAY OR TOMORROW.

GULF OF TEHUANTEPEC...N WINDS ARE LIKELY NEAR OR SLIGHTLY HIGHER 
THAN 20 KT ENHANCED BY NOCTURNAL DRAINAGE FLOW. KEPT LITTLE 
CHANGE IN THE FORECAST AS N FLOW WILL LIKELY CONTINUE TO BE 
ENHANCED AS THE TROPICAL WAVE OVER CENTRAL AMERICA APPROACHES 
THE REGION.

$$
CANGIALOSI