000
AXPZ20 KNHC 282123
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC THU MAY 28 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 
2100 UTC.

...TROPICAL WAVES...
TROPICAL WAVE ALONG 89W FROM 04N-13N MOVING W AT AROUND 15 KT. 
SCATTERED MODERATE CONVECTION IS WHERE THE WAVE AXIS MEETS THE 
ITCZ. THIS WAVE IS ASSOCIATED WITH A MAXIMUM IN DEEP LAYER 
MOISTURE BASED ON TOTAL PRECIPITABLE WATER PRODUCT FROM CIMSS. 
THE WAVE COULD ENCOUNTER MORE FAVORABLE UPPER-LEVEL CONDITIONS 
AS IT CONTINUES TO PROGRESS ACROSS THE E PACIFIC REGION DURING 
THE NEXT DAY OR SO.

...ITCZ...
THE ITCZ IS PRETTY ACTIVE THIS AFTERNOON. ITS AXIS IS ALONG 
06N78W TO 11N95W TO 08N110W TO 07N125W TO 02N140W. SCATTERED 
MODERATE TO ISOLATED STRONG CONVECTION IS NOTED N OF 04N E OF 
80W. SIMILAR CONVECTION IS FROM 06N TO 10N BETWEEN 90W AND 
97W...AND WITHIN 80 NM N OF AXIS BETWEEN 100W AND 104W. 
SCATTERED MODERATE CONVECTION IS FROM 06N TO 09N BETWEEN 118W 
AND 127W.

...DISCUSSION...
A WEAK SURFACE RIDGE EXTENDS SOUTHWARD INTO THE NORTHERN WATERS 
FROM A 1020 MB SURFACE HIGH LOCATED WELL N OF THE AREA NEAR 
38N131W. GENERALLY LIGHT WINDS DOMINATE THE AREA N OF 18N AND W 
OF 115W UNDER THE INFLUENCE OF THIS RIDGE. A WEAK HIGH PRES 
CENTER IS FORECAST BY THE COMPUTER MODEL TO FORM NEAR 24N130W IN 
ABOUT 24 HOURS. A COLD FRONT IS APPROACHING THE NW CORNER OF THE 
DISCUSSION AREA. S TO SW WINDS OF 20 KT WILL BE FOUND AHEAD OF 
THE FRONT WHICH IS EXPECTED TO ENTER THE NW PORTION AROUND 1200 
UTC FRI. LONG PERIOD SWELL FROM THE NW WILL FOLLOW THE FRONT... 
RAISING SEAS TO 12 FT SAT MORNING. A WEAKENING SURFACE TROUGH IS 
ANALYZED FROM 12N124W TO 03N131W.

ALOFT...AN UPPER-LEVEL LOW LOCATED NEAR 32N122W HAS A WEAK 
TROUGH EXTENDING SWD TO NEAR 11N118W. AN UPPER-LEVEL HIGH 
CENTERED NEAR 06N137W EXTENDS A RIDGE EWD AND IS HELPING TO 
INDUCE CONVECTION ALONG THE ITCZ. A SECOND UPPER-LEVEL 
ANTICYCLONE IS NEAR 11N92W WITH A RIDGE STRETCHING NWD ACROSS 
THE YUCATAN PENINSULA AND EWD OVER CENTRAL AMERICA TO THE COAST 
OF COLOMBIA. THIS RIDGE IS ALSO ENHANCING CONVECTION E OF 95W. 
 
$$
GR