000
AXPZ20 KNHC 260318
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC SUN APR 26 2009

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

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0300 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 6N77W 4N84W 4N92W 3N98W 3N110W
2N123W 6N140W. SCATTERED MODERATE TO STRONG CONVECTION EXISTS 
FROM 4N-14N W OF 133W

...DISCUSSION...

MOSTLY MID/UPPER LEVEL RIDGE COVERS THE REGION WITH A MEAN RIDGE
AXIS STRETCHING FROM NRN MEXICO SW TO 17N105W TO 13N108. A 
TROUGH OVER THE ERN PORTION OF THE AREA EXTENDS FROM SE MEXICO 
SW TO NEAR 09N103W. THE TROUGH IS SLIGHTLY ENHANCING ITCZ 
CONVECTION BETWEEN 90W-100W WHERE SMALL CLUSTERS OF ISOLATED
TO WIDELY SCATTERED MODERATE CONVECTION IS NOTED DUE TO MODERATE 
SUBSIDENCE AND STABLE ENVIRONMENTAL CONDITIONS FOUND THERE. THE 
COMBINATION BETWEEN THIS TROUGH AND BROAD MID/UPPER LEVEL RIDGING
TO ITS E FROM COLOMBIA NW ACROSS MUCH OF CENTRAL AMERICA IS 
ALLOWING FOR HIGH DEBRIS CLOUDINESS FROM ITCZ CONVECTION TO 
ADVECT NNE TOWARDS CENTRAL AMERICA. 

A STRONG SHORTWAVE TROUGH W OF THE REGION ALONG 150W IS 
GRADUALLY LIFTING NE...AND IS CREATING A DIFFLUENT PATTERN 
OBSERVED TO ITS ESE IS ENHANCING CONVECTION WITHIN 300 NM SE OF 
THE TROUGH. DUE TO THE CURRENT PLACEMENT OF THE TROUGH AND 
RIDGE...THE RESULTANT MODERATE TO STRONG UPPER FLOW BETWEEN 
THESE TWO FEATURES IS ADVECTING ABUNDANT MID AND UPPER LEVEL 
CLOUDINESS IN THE FORM OF BROKEN TO OVERCAST MID AND HIGH 
CLOUDS ORIGINATING TO CONVECTION W OF THE AREA SUSTAINED UNDER
DIFFLUENT FLOW ENE INTO THE DISCUSSION AREA N OF 16N W OF 135W.  

SURFACE LOW PRES ASSOCIATED WITH THE TROUGH W OF THE AREA IS
FORECAST TO TRACK N OVER THE NEXT 48 HRS AS THE SHORTWAVE TROUGH
LIFTS NE. HIGH PRES RIDGING EXTENDING SE INTO THE AREA THROUGH
32N130W TO 26N125W TO 20N112W WILL REINFORCE ITSELF THROUGH
THE NEXT 48 HRS WHILE THE LOW MOVES N. THIS SETUP WILL ACT
TO INTENSIFY THE PRES GRADIENT OVER THE NW CORNER OF THE AREA 
BRINGING SE WINDS OF 20 KT THERE THROUGH AT LEAST EARLY MON.

AS THE RIDGE STRENGTHENS OVER THE NEXT 48 HRS...THE RESULTANT
PRES GRADIENT WILL KEEP NW 20 KT OVER THE NE WATERS N OF 23N E OF
118W TO THE COAST OF BAJA CALIFORNIA COAST...BUT WEAKEN LATE SUN 
NIGHT AND EARLY ON MON TO WITHIN 60 NM OF THE COAST BY MON NIGHT.

LATEST SATELLITE IMAGERY SHOWERS PATCHES OF SCATTERED TO BROKEN 
STRATOCUMULUS CLOUDS N OF 19N W OF 112W...AND IS ERODING FROM THE
E WITH TIME. THE LEADING EDGE OF A COOLER AND DRIER AIR 
ADVANCING SWD INTO THE NE PORTION OF THE AREA IS MARKED BY A 
BROKEN STRATOCUMULUS CLOUD FIELD N OF 29N E OF 128W.

GAP WINDS...
NE-E WINDS OF 20 KT IN THE GULF OF PAPAGAYO ARE FORECAST TO 
DIMINISH IN AREAL COVERAGE AND PULSATE ON AND OFF OVER THE NEXT 
48 HRS WITH SEAS UP TO 8 FT.

$$
AGUIRRE