000
AXPZ20 KNHC 232143
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC SUN AUG 23 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 FEATURE...

AN AREA OF LOW PRESSURE ASSOCIATED WITH A TROPICAL WAVE IS 
LOCATED NEAR 16N112W WITH AN ESTIMATED MINIMUM PRESSURE OF 1008 
MB. VISIBLE SATELLITE IMAGES THROUGHOUT THE DAY HAVE INDICATED 
FAIRLY WELL DEFINED LOW LEVEL TURNING ASSOCIATED WITH THE LOW 
PRESSURE WITH SCATTERED TO NUMEROUS STRONG CONVECTION NOTED 
WITHIN 180 NM OF THE LOW MAINLY IN THE W SEMICIRCLE. ADDITIONAL 
SCATTERED MODERATE TO STRONG CONVECTION WAS NOTED ELSEWHERE FROM 
14N TO 19N BETWEEN 112W AND 119W. CONVECTION ALONG THE ITCZ IN 
THIS AREA HAS WEAKENED. THERE IS A MODERATE POTENTIAL FOR 
TROPICAL CYCLONE FORMATION WITH THIS SYSTEM OVER THE NEXT 48 
HOURS. SEVERAL OF THE NWP MODELS SHOW DEVELOPMENT OF THE SYSTEM 
AS WELL.   

...TROPICAL WAVES...
  
TROPICAL WAVE IS ALONG 125W FROM 09N TO 16N HAS BEEN RELOCATED 
BUT IS ESTIMATED TO BE MOVING W 10 KT OVER THE PAST SEVERAL 
HOURS. VISIBLE SATELLITE IMAGES DURING THE DAY SHOWED SOME LOW 
TO MID LEVEL CYCLONIC TURNING NEAR 13N...BUT DISPLACED TO THE E 
OF THE WAVE AXIS. CONVECTIVE ACTIVITY ASSOCIATED WITH THE WAVE 
AND THE AREA OF TURNING HAS DIMINISHED OVER THE PAST 6 HOURS. 

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE IS ALONG 04N77W TO 06N105W TO 
11N120W TO 08N130W TO 08N140W. SCATTERED MODERATE TO STRONG 
WITHIN 90 NM OF 06.5N79.5W.

...DISCUSSION...

N OF 20N...
A FAIRLY COMPLEX MID-UPPER PATTERN REMAINS IN PLACE ACROSS THE 
SUBTROPICS. A LARGE UPPER LEVEL HIGH IS SITUATED JUST S OF SRN 
BAJA NEAR 23N111W...A SHARP UPPER LEVEL TROUGH EXTENDING FROM 
CENTRAL CALIFORNIA THROUGH 32N117W BECOMES FRACTURED AND EXTENDS 
SW TO 20N127W. THIS TROUGH SPLITS THE UPPER HIGH NOTED ABOVE 
FROM ANOTHER UPPER LEVEL HIGH NEAR 20N139W. DESPITE THE 
AMPLIFIED PATTERN...THE ONLY SENSIBLE WEATHER IS ALONG THE 
MEXICAN COAST OF THE GULF OF CALIFORNIA FROM 24N TO 28N WHERE A 
COMBINATION OF UPPER DIFFLUENCE AND OROGRAPHIC LIFT ALONG THE 
SIERRA MADRE OCCIDENTAL IS PRODUCING SCATTERED STRONG TSTMS 
ALONG AND W OF THE MOUNTAIN RANGE WITH THE STORMS PROPAGATING 
NORTHWARD ALONG THE COAST OVER THE PAST 6 TO 9 HOURS. A WEAK LOW 
LEVEL TROUGH ASSOCIATED WITH THE UPPER LOW OFF THE NRN BAJA 
COAST...HAS WEAKENED THE SUBTROPICAL RIDGE AND HENCE THE TRADES. 
THIS TROUGH WILL PERSIST FOR ANOTHER DAY OR SO ALLOWING WINDS TO 
BE MAINLY LESS THAN 20 KT...EXCEPT FOR OVER THE FAR NW CORNER. A 
MIX OF N AND S SWELL WILL ELEVATE SEAS TO 6 TO 8 FT ACROSS MUCH 
OF THE AREA THROUGH TUE.

S OF 20N...
A DEEP MOIST ENVIRONMENT IS PRESENT ACROSS MUCH OF THE 
TROPICS...ENHANCED BY DIFFLUENT MID-UPPER FLOW. THE DIFFLUENT 
FLOW IS MOST PRONOUNCED IN THE VICINITY OF THE TROPICAL 
WAVE AND AREA OF LOW PRES...SPECIAL FEATURE...NEAR 111W. SEE 
ABOVE FOR MORE DETAILS. LONG PERIOD...14-16 SECOND...S TO SW 
SWELL IS PROPAGATING ACROSS MUCH OF THE AREA AND WILL CONTINUE 
FOR ANOTHER DAY OR TWO BEFORE SUBSIDING.
  
$$
COBB