000
AXPZ20 KNHC 272136
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC THU AUG 27 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 
2115 UTC.

...SPECIAL FEATURES...

THE REMNANT LOW OF TROPICAL DEPRESSION IGNACIO WAS CENTERED NEAR 
27N128W WITH ESTIMATED WINDS OF 25-30 KT. THE SYSTEM CONSISTED 
OF ONLY A SWIRL OF LOW CLOUDS WITH NO DEEP CONVECTION. THE 
SYSTEM IS EXPECTED TO DEGENERATE INTO A SURFACE TROUGH WITHIN 
THE NEXT FEW DAYS. 

A BROAD AREA OF LOW PRESSURE IS CENTERED NEAR 09N115W MOVING W 
NEAR 10 KT. VISIBLE SATELLITE IMAGERY AND A HIGH RESOLUTION 
QUIKSCAT PASS FROM 1504 UTC INDICATED THAT THE CIRCULATION IS 
ELONGATED ALONG A SW-NE AXIS AND MAY CONSIST OF A COUPLE OF 
EMBEDDED VORTICES. THE ASSOCIATED CONVECTION ALSO APPEARS 
LOOSELY ORGANIZED IN BANDS WELL AWAY FROM THE CIRCULATION CENTER 
WITH SCATTERED MODERATE TO STRONG CONVECTION NOTED FROM 12N TO 
14N BETWEEN 112W AND 116W. THE NUMERICAL MODELS SHOW SOME 
DEVELOPMENT OF THIS SYSTEM OVER THE NEXT FEW DAYS AS IT TRACKS 
WEST-NORTHWESTWARD...AND THERE IS A MODERATE PROBABILITY OF 
TROPICAL CYCLONE FORMATION OVER THE NEXT 48 HOURS.

AN AREA OF CONVECTION IS BECOMING MORE ORGANIZED OFF THE COAST 
OF MEXICO NEAR ACAPULCO. THIS ACTIVITY IS ASSOCIATED A TROPICAL 
WAVE RELOCATED TO ALONG 96W WHICH IS INTERACTING WITH AN AREA OF 
UPPER LEVEL DIVERGENCE BETWEEN THE WESTERN EDGE OF AN UPPER 
ANTICYCLONE TO THE NE AND AN UPPER LOW TO THE NW. THE OVERALL 
CLOUD PATTERN HAS ACQUIRED MORE CYCLONIC CURVATURE WITH A BAND
OF SCATTERED STRONG CONVECTION EXTENDING FROM 14N98.5W TO THE 
MEXICAN COAST E OF ACAPULCO. THE ATTENDANT RAINFALL ASSOCIATED 
WITH THE CONVECTION POSES THE DANGER OF MUDSLIDES ALONG THE 
MEXICAN COAST ALONG THE COASTLINES OF OAXACA AND GUERRERO.
THE PROBABILITY OF THIS SYSTEM BECOMING A TROPICAL CYCLONE OVER 
THE NEXT 48 HOURS IS NOW CONSIDERED MODERATE. THE NUMERICAL 
MODELS SHOW SOME DEVELOPMENT OF THIS SYSTEM OVER THE NEXT FEW 
DAYS AS IT TRACKS WEST-NORTHWESTWARD.

...TROPICAL WAVES...
A RELOCATED TROPICAL WAVE IS ALONG 96W N OF 06N MOVING W NEAR 15 
KT OVER THE PAST 24 HOURS. SEE DETAILS IN SPECIAL FEATURES 
ABOVE. 

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE IS ALONG 06N77W TO 10N96W TO 
10N110W TO 07N120W TO 12N130W TO 10N140W. SCATTERED MODERATE 
ISOLATED STRONG WITHIN 120 NM LINE 05N77W TO 10N109W AND LINE 
06N117W TO 11N123W AND WITHIN 90 NM OF 13N133W AND 09N138W.

...DISCUSSION...

A STRONG COLD FRONT APPROACHING THE FAR NW CORNER OF THE 
DISCUSSION AREA IS BEING SUPPORTED BY A SHARP UPPER TROUGH OVER 
THE N PACIFIC ALONG 138W. THIS UPPER TROUGH IS PIVOTING NE WHICH 
WILL CAUSE THE FRONT TO WEAKEN AS IT CROSSES 30N140W LATER 
TONIGHT. WHILE WINDS SHOULD BE FAIRLY LIGHT ALONG THE FRONT AT 
THAT TIME...NW SWELL COMBINED WITH THE EFFECTS OF WEAKENING 
IGNACIO WILL PRODUCE 8-12 FT CONFUSED SEAS OVER THE NW PORTION 
OF THE SUBTROPICS.

ELSEWHERE AT THE MID AND UPPER LEVELS...AN ELONGATED ANTICYLONE
EXTENDS FROM NEAR 20N123W TO JUST OFF THE N BAJA CALIFORNIA 
COAST NEAR 30N120W. A NARROW TROUGH EXTENDS FROM 30N135W THROUGH 
23N140W. FURTHER TO THE EAST...AN UPPER TROUGH EXTENDS FROM AN 
UPPER LOW OVER CENTRAL MEXICO TO 11N115W. DIVERGENCE ALOFT 
ASSOCIATED WITH THIS UPPER TROUGH IS AIDING CONVECTION ALONG THE 
LOW PRES NEAR 09N115W. 

GULF OF TEHUANTEPEC...A HIGH RESOLUTION 1548 UTC ASCAT PASS 
INDICATED THAT WINDS HAVE SHIFTED NE TO E ACROSS THE GULF OF 
TEHUANTEPEC DUE TO THE PASSAGE OF THE STRONG TROPICAL WAVE SOUTH 
OF THE AREA. WHILE THIS FLOW WILL LIMIT FUNNELING THROUGH THE 
GAP...A BROAD AREA OF E 20 KT WINDS IS EXPECTED TO CONTINUE FOR 
ANOTHER DAY OR SO DUE TO THE PRESSURE GRADIENT BETWEEN THE WAVE 
AND RIDGING OVER THE GULF OF MEXICO/MEXICO.

$$
COBB