000
AXPZ20 KNHC 030310
TWDEP 

TROPICAL WEATHER DISCUSSION    
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC TUE APR 03 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0315 UTC.

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

THE ITCZ AXIS EXTENDS FROM 03N119W TO 03N134W TO 03N140W. 
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 120 NM N 
OF AXIS BETWEEN 136W-139W.

...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 THROUGH 32N127W AND TO SW OF 
THE AREA AT 22N140W. ITS SURFACE REFLECTION OF A 1023 MB HIGH HAS
NOW SHIFTED S AND WEAKEN WITH A PSN AT 29N132W WITH A RIDGE SE 
TO NEAR 20N119W. THE WEAKENING HIGH WILL ALLOW FOR A COLD FRONT
TO APPROACH THE NW PORTION OF THE DISCUSSION AREA LATER TONIGHT. 
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. ALTHOUGH THE AIR MASS OVER
THIS PORTION OF THE AREA HAS MODIFIED WITH WITH THE PREVIOUS
COLD FRONT HAVING DISSIPATED...THE GRADIENT BETWEEN THE 1023 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 WAS NOTED IN AN OSCAT PASS FROM 
MON AFTERNOON...AND ALSO BY A COUPLE OF SHIP OBSERVATIONS OVER 
THOSE WATERS.

THE OSCAT PASS AND ASCAT DATA FROM EARLIER ON MON REVEALED A 
BROAD AREA OF FRESH NE TRADE WINDS FROM 06N TO 21N W OF 120W. 
SHIP AND ALTIMETER DATA REVEAL THAT THE NW SWELL IS CONTINUING 
TO SUBSIDE....WITH MAXIMUM SEA HEIGHTS NOW DOWN TO 15 FT IN THE 
FAR NE PORTION OF THE AREA. SEAS TO 8 FT ARE NOTED AS FAR SOUTH 
AS 03N.

NWP MODELS INDICATE THAT THE NEXT APPROACHING COLD FRONT AS
MENTIONED ABOVE WILL GRADUALLY WEAKEN AS IT REACHES FROM ABOUT 
32N132W TO 28N140W BY EARLY TUE EVENING...THEN BECOME QUASI-
STATIONARY FROM 32N129W TO 28N140W BY WED MORNING. THE FRONT
IS THEN FORECAST TO WASH OUT OVER THAT SAME VICINITY LATER ON
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 29N132W 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 MODERATE/ISOLATED
CONVECTION IN CLUSTERS N OF THE ITCZ FROM 04N TO 06N BETWEEN 
136W AND 139W. 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 12N93W SE TO 05N85W AND TO 02N79W. 
THIS LOCATION IS OVER THE SURFACE TROUGH...CAN ALMOST CALL IT A 
CLIMATOLOGICAL FEATURE DUE TO IT BEING IN THIS SAME VICINITY
OR 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 INITIATED NW WINDS OF 
20-25 KT THROUGH THE GULF N OF 25N. AN OSCAT PASS FROM YESTERDAY 
AFTERNOON REVEALED THESE WINDS AS WELL AS WAS HINTED AT IN A 
PARTIAL ASCAT PASS FROM MON. THE GRADIENT WILL DIMINISH THROUGH 
THE NEXT 12-18 HRS ALLOWING FOR THE AREAL COVERAGE OF THESE 
WINDS FROM 24N TO 28N BY EARLY WED...AND TO LESS THAN 20 KT BY 
18 HRS.

$$
AGUIRRE