000
AXPZ20 KNHC 040920
TWDEP 

TROPICAL WEATHER DISCUSSION    
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC WED APR 04 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 
0745 UTC.

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

THE MONSOON TROUGH AXIS EXTENDS FROM 08N83W TO 05N95W TO 
05N107W. THE ITCZ AXIS EXTENDS FROM 05N107W TO 06N121W TO 
03N140W. SCATTERED MODERATE CONVECTION LIES WITHIN 300 NM SE OF 
THE AXIS BETWEEN 83W AND 95W AS WELL AS WITHIN 270 NM S OF THE 
AXIS BETWEEN 98W AND 107W.

...DISCUSSION...

THE 1033 MB SUBTROPICAL HIGH LIES WELL NORTHWEST OF THE FORECAST 
AREA NEAR 40N150W. FRESH NE TRADE WINDS ARE CONFINED TO WESTERN 
WATERS FROM 13N TO 21N W OF 134W. A COLD FRONT HAS MOVED THROUGH 
THE NW CORNER OF THE FORECAST AREA WITH FRESH NE WINDS BEHIND IT 
AND SEAS TO 12 FT AS OBSERVED BY THE 0440 UTC JASON2 PASS. 
MEANWHILE...NW SWELL BEHIND THE PREVIOUS COLD FRONT CONTINUES TO 
MOVE SOUTHWARD THROUGH THE FORECAST AREA. THE JASON2 PASS AT 
0240 UTC MEASURED SEAS AT OR ABOVE 8 FT ALONG A LINE FROM 
26N113W TO 00N124W...WITH MAXIMUM SEAS TO 12 FT NEAR 23N115W. 
THIS SWELL WILL GRADUALLY SUBSIDE THROUGH EARLY FRI.

WATER VAPOR IMAGERY SHOWS MID TO UPPER LAYER MOISTURE CONFINED 
N OF 26N TO THE SOUTHERN EDGE OF THE BROAD UPPER TROUGH 
SUPPORTING THE COLD FRONT OVER NW WATERS. SOME WISPY CIRRUS 
CLOUDS CAN BE FOUND OVER NW WATERS AS A RESULT. THIS UPPER 
TROUGH WILL AMPLIFY AS IT MOVES INTO THE NW U.S. THU. GALE 
CONDITIONS ARE EXPECTED N OF THE FORECAST AREA OFFSHORE OF 
SOUTHERN CALIFORNIA AND SEAS WILL BUILD OVER NE WATERS OFF BAJA 
CALIFORNIA BEGINNING THU. 

FURTHER S...AN UPPER LOW LIES NEAR 18N120W. WATER VAPOR IMAGERY 
SUGGESTS THAT THERE IS STRONG SUBSIDENCE W OF THIS LOW. THE 
SOUTHWESTERLY WINDS ALOFT ON THE SE SIDE OF THIS SYSTEM ARE 
TRANSPORTING TROPICAL MOSITURE FROM THE ITCZ NORTHEASTWARD. 
PRECIPITABLE WATER IMAGERY SUGGESTS THAT THE LOW IS BEGINNING TO 
POOL A MODEST AMOUNT OF LOW TO MID LEVEL MOISTURE AHEAD OF IT AS 
WELL. A LARGE AREA OF SCATTERED SHOWERS AND THUNDERSTORMS LIES 
FROM 05N TO 20N BETWEEN 107W AND 120W AHEAD OF THE LOW ALOFT. 
THIS LOW WILL WEAKEN BEFORE IT REACHES THE MAINLAND MEXICAN 
COAST EARLY FRI. 

SE WATERS HAVE BECOME MORE CONVECTIVELY ACTIVE SINCE THIS TIME 
YESTERDAY. MUCH OF THIS CONVECTION IS DESCRIBED IN THE SECTION 
ABOVE. SCATTERED MODERATE TO STRONG CONVECTION ALSO LIES WITHIN 
180 NM W OF COLOMBIA FROM 02N TO 04N WHILE SCATTERED MODERATE 
CONVECTION CAN BE FOUND WITHIN 45 NM OF THE COAST FROM 12N TO 
13N. UPPER LEVEL DIFFLUENCE IS ENHANCING THE CONVECTION ALONG AN 
UPPER RIDGE AXIS FROM 06N77W TO 02N95W AND IN THE REAR RIGHT 
QUADRANT OF THE SOUTHERN STREAM UPPER JET OVER CENTRAL AMERICA. 
THE RIDGE AXIS IS EXPECTED TO SHIFT SLIGHTLY NORTHWARD OVER THE 
NEXT FEW DAYS. THIS PERSISTENT DIFFLUENCE ALOFT COUPLED WITH THE 
LOW LEVEL MOSITURE EXPECTED TO REMAIN CONVERGED ALONG THE 
MONSOON TROUGH AXIS WILL KEEP THIS AREA CONVECTIVELY ACTIVE INTO 
FRI MORNING.

$$
SCHAUER