000
AXPZ20 KNHC 050907
TWDEP 

TROPICAL WEATHER DISCUSSION    
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC THU APR 05 2012

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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0645 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...

THE MONSOON TROUGH AXIS EXTENDS FROM 08N83W TO 04N95W TO 
05N108W. ITCZ AXIS EXTENDS FROM 05N108W TO 03N140W. SCATTERED 
MODERATE TO STRONG CONVECTION LIES WITHIN 420 NM NW AND 180 NM 
SE OF THE AXIS E OF 85W. SCATTERED MODERATE CONVECTION LIES 
WITHIN 150 NM N OF THE AXIS BETWEEN 97W AND 104W. 

...DISCUSSION...

THE 1034 MB SUBTROPICAL HIGH LIES WELL NORTH OF THE FORECAST 
AREA NEAR 40N141W. FRESH NE TRADE WINDS ARE CONFINED TO WESTERN 
WATERS FROM 13N TO 23N W OF 134W. THE BUILDING SUBTROPICAL RIDGE 
IS BEGINNING TO OVERTAKE A DISSIPATING COLD FRONT THAT LIES FROM 
30N115W TO 26N120W TO 26N130W. THE 0502 UTC ASCAT PASS CAPTURED 
THE FRESH N TO NE WINDS N OF THE FRONT W OF 121W...WITH STRONG 
NW TO N WINDS BELIEVED TO LIE BETWEEN 121W AND THE FRONT. A GALE 
WARNING IS IN EFFECT OFFSHORE OF SOUTHERN CALIFORNIA...JUST N OF 
THE FORECAST AREA. THE 0310 UTC JASON2 PASS MEASURED SEAS TO 12 
FT BEHIND THE FRONT. MEANWHILE...NW SWELL FROM THE PREVIOUS COLD 
FRONT HAS REACHED THE EQUATOR AND CONTINUES TO SUPPORT SEAS IN 
THE 8 TO 10 FT RANGE GENERALLY SPANNING THE AREA W OF 115W. THIS 
SWELL WILL GRADUALLY SUBSIDE THROUGH FRI. WINDS BEHIND THE FRONT 
INDUCED BY THE PRES GRADIENT BETWEEN THE SUBTROPICAL RIDGE AND 
TROUGHING OVER MEXICO WILL GRADUALLY SHIFT EASTWARD AS THEY 
SHRINK IN AREAL COVERAGE. LOOK FOR FRESH NW TO N WINDS TO BE 
CONFINED TO THE AREA OFF THE BAJA CALIFORNIA COAST AND IN THE 
NORTHERN GULF OF CALIFORNIA BY EARLY SAT.

THE UPPER TROUGH SUPPORTING THE AFOREMENTIONED COLD FRONT IS IN 
THE PROCESS OF TURNING NEGATIVE TILT AS IT MOVES INTO THE 
WESTERN U.S. THE NEXT NORTHERN STREAM TROUGH IN ITS WAKE LIES N 
OF HAWAII AND IS ALSO IN THE PROCESS OF TURNING NEGATIVE TILT. 
ITS ASSOCIATED COLD FRONT WILL WEAKEN AS IT APPROACHES NW WATERS 
EARLY SAT. 

FARTHER S...AN UPPER TROUGH LIES ALONG 114W FROM 07N TO 22N AND 
ANOTHER TROUGH LIES JUST W OF THE AREA ALONG 144W FROM 07N TO 
22N. WATER VAPOR IMAGERY SUGGESTS THAT THERE IS STRONG 
SUBSIDENCE OVER MUCH OF THE FORECAST AREA BETWEEN THESE TWO 
TROUGHS. THE SOUTHWESTERLY WINDS ALOFT ON THE SE SIDE OF THE 
EASTERN TROUGH ARE TRANSPORTING TROPICAL MOSITURE FROM THE ITCZ 
NORTHEASTWARD. PRECIPITABLE WATER IMAGERY SHOWS THAT THIS 
TROUGH ALOFT IS POOLING A MODEST AMOUNT OF LOW TO MID LEVEL 
MOISTURE AHEAD OF IT. A LARGE AREA OF SCATTERED SHOWERS AND 
THUNDERSTORMS LIES N OF THE ITCZ TO 22N BETWEEN 100W AND 114W 
AHEAD OF THIS TROUGH ALOFT. THIS TROUGH WILL CONTINUE TO WEAKEN 
AS IT MOVES TOWARD THE MAINLAND MEXICAN COAST EARLY FRI. SW 
WINDS ON THE SE SIDE OF THE WESTERN TROUGH ARE TRANSPORTING MID 
TO UPPER LEVEL MOSITURE INTO THE FORECAST AREA RESULTING IN AN 
AREA OF SCATTERED CIRRUS FROM 13N TO 22N W OF 130W. THIS BROAD 
TROUGH WILL MOVE EASTWARD INTO THE AREA TODAY.

THE MONSOON TROUGH OVER SE WATERS LIES IN THE REGION OF HIGHEST 
PRECIPITABLE WATER VALUES OVER THE FORECAST AREA. THE 
CONVERGENCE OF LOW LEVEL MOSITURE NEAR THE TROUGH COUPLED WITH 
DIFFLUENCE ALOFT ASSOCIATED WITH THE BROAD RIDGE AXIS CENTERED 
ALONG 07N E OF 97W IS YIELDING DEEP CONVECTION OVER AND OFFSHORE 
OF PORTIONS OF THE COLOMBIAN COAST AND CENTRAL AMERICA S OF 14N. 
MUCH OF THIS CONVECTION IS DESCRIBED IN THE SECTION ABOVE. THIS 
AREA SHOULD REMAIN CONVECTIVELY ACTIVE FOR THE NEXT DAY OR SO.

$$
SCHAUER