000
AXPZ20 KNHC 022205
TWDEP 

TROPICAL WEATHER DISCUSSION    
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC MON APR 02 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2145 UTC.

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

THE ITCZ AXIS EXTENDS FROM 04N120W TO 03N132W TO BEYOND 02N140W. 
SCATTERED MODERATE CONVECTION IS N OF THE AXIS WITHIN 30 NM OF
08N119W.

...DISCUSSION...

NOW THAT THE LONGWAVE TROUGH THAT WAS THE MAIN FEATURE THE PAST
FEW DAYS OVER THE NE PACIFIC REGION AND FAR NE PART OF THE AREA
HAS MOVED INLAND...IN ITS WAKE A VERY EXPANSIVE MID/UPPER LEVEL
RIDGE HAS TAKEN PRECEDENCE ACROSS MUCH OF THE DISCUSSION AREA
STRETCHING FROM THE FAR NW U.S. SW TO THROUGH 32N130W AND TO 
SW OF THE AREA AT 23N140W. ITS SURFACE REFLECTION OF A 1026 MB
HIGH IS LOCATED AT 32N130W WITH A RIDGE SE TO NEAR 20N119W.
THE HIGH IS MOVING SW WHILE WEAKENING AS A COLD FRONT APPROACHES
THE NW PORTION OF THE DISCUSSION AREA. FURTHER EAST...A MID 
LEVEL SHORT WAVE TROUGH CONTINUES TO PUSH SE THROUGH THE 
SOUTHERN EXTENT OF THE BAJA CALIFORNIA PENINSULA AND GULF OF 
CALIFORNIA. THE ASSOCIATED SURFACE COLD FRONT HAS DISSIPATED.
ALTHOUGH THE AIR MASS BEHIND THE FRONT HAS MODIFIED AND THE 
FRONT HAS DISSIPATED...THE GRADIENT BETWEEN THE 1026 MB SURFACE 
HIGH AND VERY DEEP LOW PRES OVER THE ROCKIES IS RESULTING IN 
FRESH TO STRONG WINDS OFF THE COAST THE BAJA CALIFORNIA 
PENINSULA AS NOTED IN A PARTIAL ASCAT PASS FROM EARLIER TODAY
...AND BY A COUPLE OF SHIP OBSERVATIONS OVER THOSE WATERS.

THE ASCAT DATA ALSO REVEALED A BROAD AREA OF FRESH NE TRADE WINDS
FROM 06N TO 22N W OF 120W. SHIP AND ALTIMETER DATA REVEAL THAT
THE NW SWELL IS CONTINUING TO SUBSIDE....WITH MAXIMUM SEA HEIGHTS
NOW DOWN TO 14 FT NEAR 25N120W. SEAS TO 8 FT ARE NOTED AS FAR 
SOUTH AS 03N.

NWP MODELS INDICATE THAT THE NEXT APPROACHING COLD FRONT TO THE
AREA WILL JUST CROSS 32N140W OVERNIGHT TONIGHT...THEN GRADUALLY
WEAKEN AS IT REACHES FROM ABOUT 32N131W TO 29N140W BY TUE 
AFTERNOON AND WASH OUT OVER THAT SAME VICINITY LATE TUE NIGHT 
INTO WED AS A STRONG RIDGE BEHIND IT BRIDGES OVER IT WHILE 
BUILDING EWD. THIS WILL BRING NE TO E 20 KT WINDS TO THE NW PART 
OF THE AREA TUE THROUGH WED.

AS THE SURFACE HIGH NEAR 32N130W WEAKENS THROUGH TUE...THIS WILL
RESULT IN THE NE TRADES TO DIMINISH SOME IN AREAL COVERAGE LATE 
TONIGHT INTO TUE...BUT MATERIALIZE AGAIN LATER TUE INTO WED AS 
THE PRES GRADIENT OVER THE FAR WRN WATERS FROM 08N TO 20N W OF 
128W TIGHTENS UP AGAIN.

FURTHER SOUTH...A RATHER ELONGATED UPPER LOW NEAR 18N131W 
CONTINUES TO MOVE EAST. THE LOW IS FORECAST BY THE MODELS TO 
REACH NEAR 18N115W BY WED. TRADE WIND CONVERGENCE ALONG WITH 
UPPER FORCING ASSOCIATED WITH THE UPPER LOW IS PROVIDING ENOUGH 
LIFT TO INDUCE PERIODIC INSTANCES OF SCATTERED SHOWERS AND A FEW
TSTMS IN SMALL CLUSTERS N OF THE ITCZ FROM 04N TO 09N BETWEEN
120W AND 126W...AND ALSO W OF 132W. DESPITE PERSISTENT UPPER 
DIVERGENT FLOW SE OF THE LOW OVER THE NEXT COUPLE OF DAYS...THE 
DIMINISHED TRADE WINDS LATE TONIGHT INTO TUE SHOULD NOT PROVIDE 
ENOUGH LOW LEVEL CONVERGENCE TO ALLOW ANY SIGNIFICANT CONVECTION 
TO PERSIST IN THE DEEP TROPICS W OF 110W. 

OVER THE FAR ERN PORTION OF THE AREA...A NEGATIVELY TILTED UPPER 
TROUGH PERSISTS FROM ABOUT 12N95W SE TO 04N86W AND TO 02N79W. 
THIS LOCATION IS OVER THE SURFACE TROUGH...CAN ALMOST CALL IT
A CLIMATOLOGICAL FEATURE DUE TO IT BEING IN PLACE FOR SUCH A LONG
TIME...THAT EXTENDS FROM NRN COSTA RICA SW TO 06N90W. SURFACE 
WINDS CONTINUES TO BE LESS THAN 10 KT. HOWEVER ENOUGH UPPER 
FORCING REMAINS IN PLACE TO ALLOW FOR PERIODS OF DEEP CONVECTION
TO DEVELOP SE OF THE UPPER TROUGH. LATEST SATELLITE IMAGERY SHOWS
SCATTERED MODERATE CONVECTION N OF 03N BETWEEN 81W AND 85W.
GFS AND ECMWF GUIDANCE BOTH SHOW THE UPPER TROUGH SLOWLY 
MIGRATING NE THROUGH TUE...WITH THE GFS SLIGHTLY SLOWER. THE 
CONVECTION IN THIS AREA WILL LIKELY PERSIST AT LEAST ANOTHER 24 
HOURS...THEN SHOULD WEAKEN. 

GULF OF CALIFORNIA...A TIGHT PRES GRADIENT BETWEEN THE PACIFIC
RIDGE AND LOW PRES OVER NW MEXICO HAS INTIATED NW WINDS OF 20-25 
KT THROUGH THE GULF N OF 25N. A PARTIAL ASCAT PASS FROM EARLIER 
TODAY HINTED AT SUCH WINDS. THE GRADIENT WILL SLOWLY SLACKEN 
OVER THE NEXT 24-48 HRS ALLOWING FOR THE AREAL COVERAGE OF THESE 
WINDS TO DIMINISH FROM 24N TO 28N BY 18 HRS...WITH WINDS 
DIMINISHING TO LESS THAN 20 KT BY 24 HRS.

$$
AGUIRRE