000
AXPZ20 KNHC 060910
TWDEP 

TROPICAL WEATHER DISCUSSION    
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC SUN MAY 06 2007

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W. THE FOLLOWING INFORMATION IS 
BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND 
METEOROLOGICAL ANALYSIS.

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0845 UTC.

...ITCZ...
AXIS IS CENTERED ALONG 7N78W 11N90W 12N98W 10N114W 5N140W. 
SCATTERED MODERATE TO STRONG CONVECTION WITHIN 45 NM EITHER SIDE 
OF A LINE FROM 3N78W TO 8N94W TO 11N109W TO 9N122W TO 5N140W. 

...DISCUSSION...

TWO LARGE UPPER FEATURES DOMINATE THE REGION TONIGHT. ONE IS A 
STRONG TROUGH OVER THE SW CONUS AND THE OTHER A BLOCKING RIDGE 
BETWEEN 130W AND 140W. BOTH HAVE STATIONARY THE PAST SEVERAL 
HOURS. THE TROUGH EXTENDS TO 20N WITH WEAK IMPULSES ROTATING 
AROUND IT'S PERIMETER. A SUBTROPIC JET IS NOTED IN WATER VAPOR 
IMAGERY FROM 14N140W ENE TO 20N110W AND ACROSS S CENTRAL MEXICO. 
ON THE SURFACE TONIGHT A MODERATE PACIFIC RIDGE BENEATH THE 
UPPER RIDGE CONTINUES TO PRODUCE BRISK NE TRADES W OF 125W AND 
MODERATE NW WINDS ALONG THE BAJA COAST ACCORDING TO THE LATEST 
SSMI AND QUIKSCAT IMAGERY. GAP WINDS ALONG THE CENTRAL AMERICAN 
COAST REMAIN LIGHT. 

LATER DAY 1 THE STRONG UPPER TROUGH OVER THE SW CONUS REMAINS IN 
PLACE N OF 20N BETWEEN 100W AND 125W. THE BLOCKING RIDGE SHOWS 
SIGNS OF WEAKENING BUT REMAINS NEARLY STATIONARY. ON THE SURFACE 
LATER DAY 1 THE PRESSURE GRADIENT E OF 120W TO THE BAJA COAST 
WEAKENS AND WINDS DIMINISH TO 10 TO 15 KT. NW SWELL CONTINUES 
ALONG THE BAJA COAST 8 TO 12 FT. THE PACIFIC RIDGE WEAKENS 
SLIGHTLY WITH NE TRADES MAINLY N OF 10N W OF 125W WITH SWELL TO 
11 FT. GAP WINDS REMAIN LIGHT.

FOR DAY 2 A NEW SURGE OF COLD AIR ALOFT DRIVES SWD OFF THE SRN 
CA COAST MAINTAINING THE TROUGH BETWEEN 100W AND 120W. THE 
BLOCKING RIDGE CENTER SHIFTS SLOWLY EWD TO 130W WHILE THE SRN 
BRANCH OF THE WESTERLIES CONTINUES TO SLIDE EWD ALONG 20N WITH 
WEAK IMPULSES EMBEDDED IN THE FLOW. ON THE SURFACE DAY 2 NE 
TRADES DECREASE SOME TO 15 TO 20 KT W OF 130W WITH NE SWELL 
DIMINISHING TO 8 TO 10 FT. WINDS ALONG THE BAJA COAST REMAIN 
LIGHT WITH WEAK PRESSURE GRADIENT CONTINUING. SOME SLIGHT 
INCREASE IN GAP WINDS TO 20 KT W OF NRN COSTA RICA AND NICARAGUA 
AS HIGH PRES BUILDS OVER THE NW CARIBBEAN. CONVECTION ALONG THE 
ITCZ BEGINNING TO GET A LITTLE MORE ACTIVE AS THE SUMMER SEASON 
APPROACHES.

$$
RRG