000
AXPZ20 KNHC 011528
TWDEP 

TROPICAL WEATHER DISCUSSION   
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC SUN APR 01 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1500 UTC.

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

THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 05N125W TO 
03N140W. NO SIGNIFICANT CONVECTION NOTED NEAR THE ITCZ AXIS.

A SURFACE TROUGH EXTENDS FROM 07N81W TO 04N95W. SCATTERED 
MODERATE TO ISOLATED STRONG CONVECTION PERSISTS WITHIN 120 NM 
EITHER SIDE OF TROUGH AXIS BETWEEN 81W AND 83W...AND BETWEEN 86W 
AND 92W.

...DISCUSSION...

A FAIRLY AMPLIFIED AND PROGRESSIVE UPPER PATTERN REMAINS IN 
PLACE N OF 25N OVER THE NE PACIFIC. A MID TO UPPER LEVEL TROUGH 
IS MOVING ONSHORE FROM ALONG THE U.S. WEST COAST AND NORTHERN 
BAJA CALIFORNIA AHEAD OF A DEEP LAYER RIDGE MOVING E THROUGH 
150W. A MID/UPPER LEVEL SHORT WAVE TROUGH FROM CENTRAL BAJA TO 
20N120W IS SUPPORTING A WEAKENING COLD FRONT EXTENDING FROM THE 
NORTHERN COAST OF BAJA CALIFORNIA NEAR 31N116W TO 22N125W TO 
20N135W. A 1032 MB SURFACE HIGH PRES AREA CENTERED NEAR 33N141W 
WILL BUILD BEHIND THE FRONT THROUGH TODAY. 

OVERNIGHT SHIP OBSERVATIONS AND SCATTEROMETER PASSES SHOWED 
FRESH TO STRONG N TO NE SURFACE WINDS BEHIND THE FRONT...AS WELL 
AS NW TO N WINDS TO 20 KT OFF THE NORTHERN BAJA CALIFORNIA COAST 
AHEAD OF THE FRONT. A BROAD AREA OF FRESH TO STRONG TRADE WINDS 
IS ALSO NOTED GENERALLY FROM 06N TO 20N W OF 120W...TO THE SOUTH 
OF THE APPROACHING HIGH PRES. SHIP OBSERVATIONS AND ALTIMETER 
DATA ALSO CONFIRM 12 TO 20 FT NW SWELL INVADING THE WATERS N OF 
20N. COMBINED SEAS IN EXCESS OF 8 FT PERSIST S OF 20N IN MIXED 
SW AND NE SWELL.

THROUGH MONDAY...THE UPPER TROUGH STALLS AND CUTS OFF OVER THE 
SOUTHERN ROCKIES MON...ALLOWING THE COLD FRONT TO DISSIPATE FROM 
THE SOUTHERN GULF OF CALIFORNIA TO 18N120W. FURTHER WEST...A 
SHARP DEEP LAYER TROUGH CURRENTLY NW OF HAWAII AND WEST OF THE 
MID/UPPER RIDGE ALONG 150W WILL SHIFT EAST AND DISPLACE THE 
RIDGE TOWARD THE WEST COAST. AN ASSOCIATED COLD FRONT WILL PUSH 
THROUGH THE N CENTRAL PACIFIC...REACHING THE NW CORNER OF THE 
DISCUSSION AREA NEAR 30N140W BY LATE MON AND ERODING THE SURFACE 
HIGH PRES N OF THE AREA. THIS WILL ALLOW THE TRADE WINDS TO THE 
SOUTH AND THE MORE NORTHERLY FLOW CLOSER TO THE BAJA COAST TO 
DIMINISH. THE COLD FRONT WILL WEAKEN AS IT SHIFT EAST...REACHING 
FROM CENTRAL CALIFORNIA TO 28N140W BY LATE TUE. NW SWELL GREATER 
THAN 8 FT WILL PUSH AS FAR SOUTH AS 07N W OF 110W THROUGH LATE 
MON...WITH PEAK SWELL DECAYING TO 16 FT N OF 20N E OF 120W. 

FURTHER EAST...CLUSTERS OF SHOWERS AND THUNDERSTORMS PERSIST 
ALONG A STATIONARY EAST TO WEST ORIENTED TROUGH FROM WESTERN 
PANAMA TO 04N95W. THE TROUGH MAY ACTUALLY BE AN INCIPIENT WEAK 
MONSOON TROUGH...BUT SCATTEROMETER DATA CONTINUE TO SHOW ONLY 
VERY LIGHT AND OFTEN VARIABLE FLOW S OF THE AXIS. CONVECTIVE 
GROWTH CONTINUES TO BE AIDED BY A BROAD NEGATIVELY TILTED UPPER 
TROUGH GENERALLY PARALLELING THE CENTRAL AMERICAN COAST. 
STRONGER CONVECTION IS NOTED FURTHER EAST ALONG THE COAST OF 
COLOMBIA. THIS IS DUE IN PART TO NOCTURNAL DRAINAGE 
EFFECTS...BUT IS MAINLY DUE TO CONVERGENCE OF MODERATE NORTHERLY 
FLOW ACROSS THE PANAMANIAN ISTHMUS AND LIGHT TO MODERATE SW FLOW 
TO THE SOUTH.

GULF OF CALIFORNIA...A COLD FRONT IS STARTING TO MOVE INTO THE 
NORTHERN TIP OF THE GULF THIS MORNING...AND IS EXPECTED TO SWEEP 
THROUGH THE CENTRAL GULF BEFORE DISSIPATING OVER THE SOUTHERN 
GULF BY LATE MON. NW WINDS BEHIND THE FRONT WILL INCREASE TO 20 
TO 25 KT BY EARLY MON AS HIGH PRES BUILDS N OF THE AREA IN THE 
WAKE OF THE FRONT. WINDS DIMINISH BY LATE MON INTO TUE AS THE 
FRONT DISSIPATES AND THE HIGH PRES N OF THE AREA WEAKENS.

$$
CHRISTENSEN