000
AXPZ20 KNHC 222204
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC WED APR 22 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 
2315 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 6N78W 6N90W 5N100W 5N110W 4N120W 
4N130W 5N140W. SCATTERED MODERATE TO STRONG CONVECTION EXISTS 
FROM 2N-6N BETWEEN 88W-91W. SCATTERED MODERATE/ISOLATED STRONG 
CONVECTION IS SEEN FROM 4N-8N BETWEEN 80W-85W. SCATTERED 
MODERATE CONVECTION IS OCCURRING FROM 4N-8N BETWEEN 
119W-122W...AND FROM 6N-9N W OF 136W.

...DISCUSSION...

BROAD MID/UPPER LEVEL RIDGING ENCOMPASSES JUST ABOUT THE ENTIRE
AREA WITH A MEAN RIDGE ALONG 32N130W THROUGH 24N130W TO 17N135W 
TO 13N138W. A LARGE UPPER LEVEL CYCLONIC VORTEX IN AN OMEGA TYPE
BLOCK PATTERN IS NW OF THE AREA TO THE W OF THE NRN EXTENSION OF
THE MID/UPPER LEVEL RIDGE. TO THE NE OF THE RIDGE...A SMALL UPPER
LEVEL CYCLONIC CIRCULATION OVER THE SW U.S. EXTENDS A TROUGH SSW
TO 32N115W TO 28N118W. THE MID/UPPER RIDGE IS FORECAST TO QUICKLY
MOVE E AND FLATTEN OUT OVER THE FAR NE PORTION OF THE AREA IN
ABOUT 48 HRS WHILE THE UPPER LEVEL CYCLONIC VORTEX SKIRTS JUST
N OF THE AREA WHILE BEGINNING TO SHEAR OUT. THE TROUGH ASSOCIATED
WITH THE LARGE UPPER LEVEL VORTEX IS FIRING UP SCATTERED MODERATE
CONVECTION ALONG THE FAR WRN BOUNDARY OF THE AREA FROM THE ITCZ
N TO 18N AND W OF 137W. EXTENSIVE UPPER LEVEL MOISTURE DERIVED 
FROM THIS CONVECTION IS RIDING EWD UP AND OVER THE RIDGE AND 
ADVANCING TO NEAR 127W.

A MID/UPPER LEVEL TROUGH EXTENDS FROM 16N128W SSW TO 7N129W. THE 
TROUGH IS AIDING ITCZ CONVECTION BETWEEN 119W-120W. UPPER LEVEL
ITCZ MOISTURE IS STREAMING EWD TOWARDS CENTRAL AND SE 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 1023 MB HIGH CENTERED NEAR 26N133W EXTENDS A 
RIDGE SE TO 19N110W. 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 HAS AGAIN RESULTED IN 
A LATE SEASON MINIMAL GALE EVENT THROUGH THE GULF OF TEHUANTEPEC 
THAT IS EXPECTED TO END IN ABOUT 6 HRS AS N TO NE WINDS DIMINISH 
TO 20 KT...AND TO LESS THAN 20 KT THU NIGHT.

NE WINDS OF 20-25 KT IN THE GULF OF PAPAGAYO ARE FORECAST TO 
CHANGE LITTLE THROUGH THE NEXT 48 HRS.

$$
AGUIRRE