000
AXPZ20 KNHC 250912
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC MON MAY 25 2009

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

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0900 UTC.

...TROPICAL WAVES...
TROPICAL WAVE ALONG 99W FROM 03N-13N MOVING W AT 10-15 KT. NO 
DEEP CONVECTION IS ASSOCIATED WITH THE WAVE. ONLY A FEW SHOWERS 
ARE SEEN EITHER SIDE OF THE WAVE AXIS.   

...ITCZ...
THE ITCZ AXIS IS ALONG 08N84W TO 10N98W TO 12N115W TO 09N125W TO 
07N140W. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS 
NOTED WITHIN 100 NM OF AXIS BETWEEN 100W AND 108W...AND WITHIN 
120 NM S OF AXIS W OF 134W. 

.DISCUSSION...
NEARLY ZONAL FLOW CONTINUES TO DOMINATE THE FORECAST REGION N OF 
20N. A RIDGE WITH AXIS ALONG 10N/11N COVERS THE AREA S OF 20N 
AND E OF 125W. UPPER DIFFLUENCE RELATED TO THIS FEATURE IS 
SUPPORTING A CLUSTER OF MODERATE TO ISOLATED STRONG CONVECTION 
NEAR THE NICARAGUA/COSTA RICA BORDER. THE RIDGE WHICH IS 
ANCHORED ON AN UPPER-LEVEL HIGH NEAR 11N88W IS ALSO ENHANCING 
CONVECTION ALONG THE COAST OF COLOMBIA. ANOTHER RIDGE ENTERS THE 
SW PORTION OF THE DISCUSSION AREA AND IS HELPING TO INDUCE 
CONVECTION ALONG THE ITCZ W OF 134W.

AT THE SURFACE...A 1030 MB HIGH PRES CENTER LOCATED WELL N OF 
AREA EXTENDS A RIDGE SE TO 15N105W. A PAIR OF WEAK TROUGHS...
REMNANTS OF PREVIOUS LOW PRES CENTERS...ARE MOVING WWD ACROSS 
THE SOUTHERN PERIPHERY OF THE RIDGE. ONE IS ALONG 118W FROM 9N 
TO 17N. THE SECOND ONE EXTENDS FROM 05N135W TO 13N135W. PRES 
GRADIENT BETWEEN THE RIDGE AND THIS SECOND TROUGH IS PRODUCING A 
SWATH OF NE WINDS 20 KT WEST OF TROUGH TO 140W. A RECENT QSCAT 
PASS CONFIRMED THESE WIND SPEEDS. 

NORTHERLY SWELLS WILL CONTINUE TO PUSH INTO THE N WATERS THROUGH 
THE NEXT 48 HOURS PARTICULARLY N OF 28N AND W OF 120W. A SHIP IS 
REPORTING WAVE HEIGHT OF 9 FT IN THIS AREA.        

$$
GR