000
AXPZ20 KNHC 220348
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC WED APR 22 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 
0315 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 8N80W 4N88W 5N100W 5N100W 5N110W
5N120W 6N130W 6N140W. SCATTERED MODERATE ISOLATED/STRONG 
CONVECTION IS WITHIN 60 NM EITHER SIDE OF THE AXIS BETWEEN 
88W-92W...AND ALSO FROM 3N-5N BETWEEN 79W-82W. SCATTERED 
MODERATE CONVECTION EXISTS FROM 4N-9N W OF 137W.

...DISCUSSION...

THE VAST MAJORITY OF THE AREA IS UNDER BROAD MID TO UPPER LEVEL 
RIDGING...WITH THE EXCEPTION OF THE FAR NE PART WHERE A MID/UPPER
LEVEL TROUGH ASSOCIATED WITH A CYCLONIC VORTEX JUST N OF THE AREA
NEAR 33N123W ENTERS THE AREA THROUGH 32N121W AND EXTENDS TO 
26N121W...AND OVER THE FAR SW PART WHERE A MID/UPPER LEVEL TROUGH
EXTENDS FROM 17N140W SE TO 14N136W TO 10N131W TO 05N126W. THE 
TROUGH IS TRIGGERING OFF AN AREA OF WEAKENING SCATTERED MODERATE 
CONVECTION THAT IS WITHIN 45 NM OF 12N129W. AN UPPER LEVEL 
DIFFLUENT FLOW PATTERN JUST W OF THE AREA IS ENHANCING 
CONVECTION ALONG THE ITCZ W OF 140W...BUT UPPER LEVEL DEBRIS 
MOISTURE IN THE FORM OF SCATTERED TO BROKEN CIRRUS CLOUDS IS 
SPREADING NE INTO THE NW PORTION OF THE AREA. A SUBTROPICAL JET 
STREAM BRANCH WITH MAXIMUM WINDS OF 60-90 KT ROUNDS THE BASE OF 
THE TROUGH FROM 12N136W NE TO 18N131W TO 21N122W...THEN DIVES 
ESE TO ACROSS CENTRAL MEXICO.
 
THE JET IS ADVECTING BROKEN MID AND UPPER LEVEL CLOUDINESS FROM 
ITCZ CONVECTION NE AND EWD TOWARD SOUTHERN BAJA CALIFORNIA AND 
CENTRAL MEXICO. CONFLUENT FLOW OVER THE FAR EASTERN PORTION
OF THE AREA IN THE WAKE OF A DEPARTING BROAD UPPER LEVEL TROUGH 
IS RESULTING IN MODERATE TO STRONG SUBSIDENCE E OF ABOUT 100W
AND LIMITING CONVECTION THROUGHOUT THIS AREA N OF THE ITCZ.

AT THE SURFACE...A 1021 MB HIGH CENTERED NEAR 26N131W EXTENDS A 
RIDGE SE TO 20N111W. HIGH PRES COVERS THE AREA N OF 14N AND W OF
110W. A COLD FRONT JUST NW OF THE REGION WILL GRADUALLY WEAKEN
AS IT MOVES THROUGH THE NW WATERS THROUGH THU.

BROKEN TO OVERCAST STRATOCUMULUS CLOUDS BLANKET THE AREA N OF 
20N W OF 120W.

GAP WINDS...
A TIGHT PRES GRADIENT OVER SE MEXICO THAT HAS SETTLED IN BEHIND 
A GULF OF MEXICO COLD FRONT HAS RESULTED IN A LATE SEASON GALE 
EVENT THROUGH THE GULF OF TEHUANTEPEC THAT IS WINDING DOWN NOW. 
BOTH REGULAR AND HIGH RESOLUTION QUIKSCAT DATA FROM THIS MORNING 
SHOWED WINDS OF 30-40 KT WITH A FEW WIND BARBS OF 45 KT IN 
NARROW SWATH IN THE GULF. LATEST QUIKSCAT FROM 03Z SHOWS ONLY 30 
KT WINDS SO THE GALE HAS BEEN DROPPED. WINDS ARE FORECAST TO 
LESSEN TO LESS THAN 30 KT THROUGH WEDNESDAY AS THE PRES GRADIENT 
WEAKENS.

NE-E WINDS OF 20 KT IN THE GULF OF PAPAGAYO ARE FORECAST TO 
INCREASE TO 20-25 KT IN 24 HRS...THEN DIMINISH AGAIN TO 20 KT IN 
48 HRS.

$$
AGUIRRE/CHRISTENSEN