000
AXPZ20 KNHC 252154
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC TUE AUG 25 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 
2145 UTC.

...SPECIAL FEATURE...

TROPICAL STORM IGNACIO WAS CENTERED NEAR 19.4N 120.3W OR ABOUT 
615 NM SOUTHWEST OF THE SOUTHERN TIP OF BAJA CALIFORNIA AT 
25/1500 UTC...MOVING WEST-NORTHWEST OR 300 DEGREES AT 11 KT. 
MAXIMUM SUSTAINED WINDS WERE 45 KT WITH GUSTS TO 55 KT AND THE 
ESTIMATED MINIMUM PRESSURE WAS 1000 MB. SATELLITE IMAGERY 
INDICATED A FAIRLY WELL ORGANIZED SYSTEM CONSISTING OF 
SCATTERED TO NUMEROUS MODERATE TO STRONG CONVECTION WITHIN 180 
NM IN THE SE AND 75 NM IN THE NW SEMICIRCLES AND THE APPEARANCE 
OF A CENTRAL DENSE OVERCAST. THE SYSTEM REMAINS IN AN 
ENVIRONMENT OF LIGHT SHEAR...HOWEVER THE WINDOW OF OPPORTUNITY 
FOR STRENGTHENING WILL BE CLOSING SOON SINCE IGNACIO SHOULD BE 
CROSSING OVER COOLER WATERS WITHIN 12 HOURS. ADDITIONAL 
INFORMATION CAN BE FOUND UNDER AWIPS/WMO HEADERS 
MIATCMEP3/WTPZ23 KNHC.
  
...TROPICAL WAVES...
A TROPICAL WAVE IS ALONG 85W/86W N OF 05N MOVING W NEAR 15 KT 
OVER THE PAST 24 HOURS. SATELLITE IMAGERY INDICATES WELL DEFINED 
TURNING IN THE LOW AND MID LEVEL CLOUDS ALONG THE WEST COAST OF
NICARAGUA. THE BULK OF THE STRONG THUNDERSTORMS ASSOCIATED WITH 
THE WAVE ARE OVER PORTIONS OF NORTHERN NICARAGUA AND HONDURAS. 
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 08N80W TO 08N100W TO 
06N108W TO 14N124W TO 10N134W TO 11N140W. SCATTERED MODERATE 
ISOLATED STRONG WITHIN 90 NM LINE 07N82W TO 07N93W...AND FROM 
05N TO 15N BETWEEN 100W AND 111W...AND FROM 07N TO 12N BETWEEN 
122W AND 138W.

...DISCUSSION...

N OF 20N...
THE MID TO UPPER PATTERN CONSISTS OF A RIDGE THAT EXTENDS FROM 
AN ANTICYCLONE NEAR 19N140W NE THROUGH 30N124W...A DOWNSTREAM 
TROUGH FROM AN UPPER LOW OVER THE GREAT BASIN TO THE THE NRN 
GULF OF CALIFORNIA...AND ANOTHER TROUGH ALONG 137W 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 WITH THE EXCEPTION OF A
FAIRLY BROAD AREA OF 20 TO 25 KT ON THE PERIPHERY OF TROPICAL 
STORM IGNACIO PER A 1416 UTC HIGH RESOLUTION QUIKSCAT PASS. 

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 TONIGHT OR TOMORROW.

GULF OF TEHUANTEPEC...A 1236 UTC HIGH RESOLUTION QUIKSCAT PASS 
AND A SUBSEQUENT 1628 UTC ASCAT PASS BOTH CONFIRMED 20 TO 25 KT 
WINDS IN THE GULF OF TEHUANTEPEC. THE WINDS HAVE BEEN ELEVATED 
IN THE EARLY MORNING HOURS AS A RESULT OF ENHANCED NOCTURNAL 
DRAINAGE FLOW IN THE CHIVELA PASS. LITTLE CHANGE IS ANTICIPATED 
IN THE HIGH SEAS FORECAST AS N FLOW WILL LIKELY CONTINUE TO BE 
ENHANCED AS THE TROPICAL WAVE OVER CENTRAL AMERICA APPROACHES 
THE REGION.

$$
COBB