000
AXPZ20 KNHC 230342
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC THU APR 23 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 6N78W 5N91W 4N100W 5N110W 5N120W
4N130W 5N140W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION
IS N OF 4N BETWEEN 84W-86W...AND ALSO FROM 2N-8N BETWEEN 89W-91W.

...DISCUSSION...

BROAD MID/UPPER LEVEL RIDGING COVERS JUST ABOUT THE ENTIRE AREA 
WITH A MEAN RIDGE AXIS ALONG 32N127W THROUGH 24N128W TO 17N133W
TO 13N136W. 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 26N134W EXTENDS A 
RIDGE SE TO 19N110W. HIGH PRES COVERS THE AREA N OF 14N AND W OF 
110W. A COLD FRONT ENTERING THE FAR NW PART OF THE REGION WILL 
GRADUALLY WEAKEN AS IT MOVES THROUGH THE NW WATERS THROUGH FRI.

BROKEN TO OVERCAST STRATOCUMULUS CLOUDS ARE NOTED N OF 15N NW
OF LINE FROM 27N114W TO 19N121W TO 16N132W.

GAP WINDS...
A LATE SEASON GULF OF TEHUANTEPEC GALE EVENT IS JUST ENDING WITH
WINDS THERE FORECAST TO DIMINISH TO 20 KT IN 12 HRS...AND TO 
LESS THAN 20 KT IN 48 HRS.

NE WINDS OF 20-25 KT IN THE GULF OF PAPAGAYO ARE FORECAST TO 
DIMINISH TO 20 KT IN 48 HRS.

$$
AGUIRRE