000
AXPZ20 KNHC 200317
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC TUE MAR 20 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 ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0100 UTC.

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

THE ITCZ AXIS EXTENDS FROM 04N127W TO 04N140W. NO SIGNIFICANT 
CONVECTION IS NOTED ALONG THE AXIS.

...DISCUSSION...

A DEEP LAYER TROUGH LIES OVER THE WESTERN U.S. AND NW MEXICO. A 
STRONG COLD FRONT ASSOCIATED WITH THIS TROUGH LIES OVER N 
CENTRAL MEXICO WHILE A SECONDARY IMPULSE IS DIVING INTO THE BASE 
OF THE TROUGH FROM THE NORTHWEST...DRAGGING ANOTHER WEAKER COLD 
FRONT WITH IT. FRESH TO STRONG W TO NW WINDS NEAR THIS SECONDARY 
IMPULSE CAN BE FOUND AS FAR AS 360 NM W OF THE BAJA PENINSULA N 
OF 26N ACCORDING TO THE 1942 UTC OSCAT PASS. THE SAME OSCAT PASS 
REPORTED FRESH SW TO W WINDS AHEAD OF THE SECOND COLD FRONT IN 
THE NORTHERN GULF OF CALIFORNIA WITH LOCALLY STRONGER 
MEASUREMENTS WHERE WINDS HAVE FUNNELED THROUGH THE MOUNTAIN 
PASSES IN BAJA CALIFORNIA NORTE. AN AREA OF FRESH N TO NW WINDS 
LIES NEAR CABO SAN LUCAS WHERE THE SW EDGE OF THE LEADING COLD 
FRONT BUTTS UP AGAINST THE SUBTROPICAL RIDGE. THESE WINDS SHOULD 
SHIFT SOUTHEASTWARD TO OFF THE COAST OF MAINLAND MEXICO NEAR 
CABO CORRIENTES ON TUE AND WILL DISSIPATE WED WHEN THE LEAD 
FRONT PULLS WELL E OF THE AREA. NORTHWEST SWELL IN THE PACIFIC 
CONTINUES TO GENERATE SEAS AS HIGH AS 13 FEET OFF THE W COAST OF 
BAJA CALIFORNIA. THESE SEAS WILL GRADUALLY SUBSIDE TO 9 FEET OR 
LESS AS THEY TRAVEL SOUTH OF 15N AND WELL OFFSHORE OF MEXICO AND 
CENTRAL AMERICA BY WED EVENING.

THE SUBTROPICAL RIDGE STEMS FROM 1026 MB HIGH PRES NEAR 29N142W 
AND EXTENDS SOUTHEASTWARD TO 18N108W. THIS RIDGE CONTINUES TO 
SUPPORT A LARGE AREA OF FRESH TRADE WINDS TO ITS SOUTH FROM 06N 
TO 19N W OF 125W AND FROM 10N TO 15N BETWEEN 120W AND 125W 
ACCORDING TO THE 1946 UTC AND 2124 ASCAT PASSES. THE SUBTROPICAL 
HIGH WILL BE WEAKENED AND PUSHED EASTWARD BY AN ENCROACHING COLD 
FRONT OVER THE NEXT FEW DAYS. THE AREA OF FRESH TRADES WILL THIN 
OUT FROM NORTH TO SOUTH TUE AND THEN SHRINK WESTWARD THROUGH WED 
EVENING IN RESPONSE TO CHANGES IN THE SUBTROPICAL HIGH.

GAP WINDS...
GULF OF PAPAGAYO...THE PRES GRADIENT BETWEEN RIDGING OVER THE NW 
CARIBBEAN AND A TROUGH FROM 10N86W TO 07N88W TO 04N94W HAS 
RELAXED ENOUGH FOR WINDS IN THE GULF OF PAPAGAYO TO DIMINISH 
BELOW 20 KT. WINDS MAY PULSE TO 20 KT IN THE EARLY MORNING HOURS 
WHEN DRAINAGE FLOW OFF THE LAND IS AT A MAXIMUM. 

$$
SCHAUER