000
AXPZ20 KNHC 040337
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC SAT APR 04 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 
0330 UTC.

...ITCZ...
THE INTERTROPICAL CONVERGENCE ZONE LIES ALONG A LINE FROM 08N81W 
TO 04N100W TO 02N120W TO 03N140W. ISOLATED MODERATE WITHIN 120 
NM SOUTH OF AXIS BETWEEN 84W AND 87W. 

...DISCUSSION...
AT THE SURFACE...A 1027 MB HIGH PRES CENTERED NORTH OF AREA NEAR 
40N131W EXTENDS A RIDGE THROUGH THE REGION FROM 30N130W TO 
18N112W. THIS FEATURE IS STILL PRODUCING A BELT OF MODERATE TO 
FRESH TRADE WINDS FROM 07N TO 14N W OF 130W...AND ALSO NW TO N 
WINDS OF 20 KT N OF 25N BETWEEN 118W AND 125W AS THE RIDGE 
INTERACTS WITH A LOW PRES SYSTEM OVER THE SW CONUS. THE TRADES 
ARE EXPECTED TO DIMINISH BELOW 20 KT IN ABOUT 24 HOURS AS THE 
HIGH MOVES SE WHILE WEAKENING. N TO NW SWELL WILL CONTINUE TO 
PUSH INTO THE WATERS OFF THE NORTHERN BAJA PENINSULA...DRIVEN BY 
GALE FORCE WINDS N OF THE AREA. SEAS ARE CURRENTLY IN THE 8 TO 
11 FT RANGE...THEN SUBSIDE BELOW 8 FT SUN EVENING AS A COLD 
FRONT APPROACHES FROM THE W. SATELLITE IMAGERY REVEALS BROKEN TO 
OVERCAST STRATOCUMULUS CLOUDS COVERING MOST OF THE AREA N OF 
20N. S TO SW WINDS OF ABOUT 20 KT ARE BLOWING ALONG THE GULF OF 
CALIFORNIA...PARTICULARLY N 26N. THESE WINDS ARE ASSOCIATED WITH 
THE BROAD CIRCULATION OF STRONG LOW PRES SYSTEM OVER THE SW 
U.S...AND ARE FORECAST TO DIMINISH IN ABOUT 12 HOURS AS THE LOW 
PRES SYSTEM MOVES NE AND AWAY FROM THE SW CONUS. A WEAK SFC 
TROUGH IS ANALYZED ALONG 98W FROM 11N TO 15N BASED ON SATELLITE 
IMAGERY THAT SHOWS A SWIRL OF LOW CLOUDS IN THIS AREA.  

AN UPPER-LEVEL TROUGH PERSISTS OVER N WATERS EXTENDING FROM 
30N120W TO 27N138W. THIS TROUGH WILL BE REINFORCED BY A STRONG 
UPPER-LEVEL LOW MOVING EASTWARD N OF THE AREA ON SUN. THE 
ATTENDANT COLD FRONT WILL ENTER THE NW CORNER OF THE FORECAST 
REGION EARLY SUN. LONG PERIOD NW SWELL BEHIND THE FRONT IN THE 
10 TO 15 FT RANGE WILL INVADE THE FORECAST AREA DURING THE DAY. 
ALSO...EXPECT ISOLATED SHOWERS ALONG THE FRONT.  

GOES-W SATELLITE IMAGERY SHOWS A LARGE AREA OF MID/UPPER LEVEL 
MOISTURE...COINCIDENT WITH THE SUBTROPICAL JET EXTENDING FROM 
THE SOUTHERN BAJA CALIFORNIA PENINSULA TO 20N130W...THEN TURNING 
MORE W TO 20N140W. A BROAD UPPER-LEVEL RIDGE ANCHORED BY A HIGH 
OVER THE GULF OF TEHUANTEPEC DOMINATES THE AREA S OF 20N WEST OF 
105W...INCLUDING ALSO SE MEXICO...THE BAY OF CAMPECHE AND N 
CENTRAL AMERICA. MODERATE TO STRONG UPPER LEVEL SUBSIDENCE AND 
IMPLIED DRY AIR MASS IS NOTED WITHIN THE RIDGE AXIS. 

$$
GR