000
AXPZ20 KNHC 030948
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC SUN MAY 03 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 
0915 UTC.

...ITCZ...

ITCZ AXIS IS ALONG 09N80W TO 07N110W TO 09N123W TO 06N140W. 
SCATTERED MODERATE ISOLATED STRONG CONVECTION IS CONFIRMED BY 
LIGHTNING DATA WITHIN 120 NM EITHER SIDE OF A LINE FROM 08N78W 
TO 07N107W. ISOLATED MODERATE AND STRONG CONVECTION IS OBSERVED 
FROM 05N TO 10N BETWEEN 107W AND 138W.

...DISCUSSION...

ALOFT...AN UPPER TROUGH OVER CENTRAL N AMERICA EXTENDS SW INTO 
THE DISCUSSION AREA ALONG 32N98W TO 25N112W TO 27N120W TO 
21N130W TO 10N140W...AND IS DEFINED BY A BAND OF DRY UPPER AIR 
WITHIN 120 NM OF THE AXIS. AN UPPER ANTICYCLONE NEAR HAWAII HAS 
A RIDGE EXTENDING E TO NEAR 23N138W. A QUASI STATIONARY UPPER 
ANTICYCLONE IS CENTERED AT 14N118W WITH A RIDGE EXTENDING N TO 
25N123W WITH THE UPPER TROUGH ERODING THE TOP OF THE RIDGE. 
UPPER DIFFLUENCE UNDER THE RIDGE HAS BEEN ENHANCING CONVECTION 
ALONG THE ITCZ BETWEEN 120W AND 150W...WITH THE DEBRIS MOISTURE 
ADVECTED NE WITHIN 180 NM EITHER SIDE OF LINE FROM 11N130W TO 
21N122W THEN NARROWS ALONG 22N105W TO BEYOND 32N91W. 

AN UPPER TROUGH DISSECTS THE GULF OF MEXICO FROM 24N80W TO 
20N95W AND CONTINUES S INTO A MID TO UPPER CYCLONE AT 10N106W 
AND FURTHER S INTO ANOTHER UPPER CYCLONE AT 06N106W...WITH THE 
TROUGH CONTINUING S ACROSS THE EQUATOR AT 108W. A STATIONARY 
UPPER RIDGE EXTENDS NW OFF COLOMBIA ACROSS CENTRAL AMERICA 
CRESTING OVER THE YUCATAN PENINSULA. UPPER DIFFLUENCE E OF THE 
UPPER TROUGH ENHANCED CONVECTION ALONG THE PACIFIC ITCZ BETWEEN 
100W AND 110W. UPPER DIFFLUENCE UNDER THE RIDGE HAS ENHANCED 
CONVECTION ALONG THE PACIFIC ITCZ E OF 100W WITH THE COMBINED 
UPPER DEBRIS MOISTURE CONCENTRATED TO THE N OF A LONE FROM THE 
EQUATOR AT 85W TO 08N100W AND EXTENDING NE ACROSS ALL OF CENTRAL 
AMERICA AND THE W CARIBBEAN EVENTUALLY EVAPORATING OVER THE N 
CENTRAL CARIBBEAN.

AT THE SURFACE...A 1024 MB HIGH PRES IS QUASI STATIONARY NEAR 
26N132W WITH A RIDGE EXTENDING SW TO BEYOND 25N140W...AND A 
RIDGE EXTENDING SE TO NEAR 13N107W. THE RIDGE IS BLOCKING THE 
SOUTHEAST PROGRESSION OF A SERIES OF COLD FRONTS TO N OF 
30N...HOWEVER NW SWELLS TO 10 FT WILL SPREAD SE INTO THE NW 
WATERS IN ABOUT 24 HOURS AND BUILD TO 12 FT IN 72 HOURS. TO THE 
E OF THE RIDGE...NORTHERLY WINDS AT 20 KT ARE OBSERVED ALONG THE 
PACIFIC COAST OF NORTHERN BAJA AND EXPECTED TO CHANGE LITTLE 
OVER THE NEXT COUPLE OF DAYS. EASTERLY TRADES S OF THE RIDGE AND 
N OF THE ITCZ ARE MOSTLY IN THE 15 TO 20 KT RANGE AND NOT 
EXPECTED TO CHANGE MUCH FOR A COUPLE OF DAYS.

$$
NELSON