000
AXPZ20 KNHC 212200
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC MON FEB 21 2011

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2145 UTC.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE AXIS WAS ANALYZED FROM 03N78W 
TO 00N90W THEN CONTINUES FROM 03N108W TO 04N130W THEN CONTINUES 
FROM 03N135W TO 02N140W. NO SIGNIFICANT CONVECTION.

...DISCUSSION...

THE LONGWAVE UPPER PATTERN IS EXPECTED TO CHANGE LITTLE OVER THE 
NEXT TWO DAYS WITH AN UPPER TROUGH WITH MEAN AXIS ALONG 125W 
BOOKENDED BY RIDGING WITH THE EASTERN RIDGE LYING OVER THE 
FORECAST AREA ALONG 95W...AND THE WESTERN RIDGE W OF THE AREA 
ALONG 150W. A SHORTWAVE TROUGH WAS NOTED IN THE TROPICS 
EXTENDING FROM 15N122W TO 05N117W WITH AN AREA OF MAINLY MID 
LEVEL MOISTURE BEING ADVECTED TO THE N AHEAD OF THE UPPER 
TROUGH AXIS. THE HIGHEST PRECIPITABLE WATER VALUES IN THE 
DISCUSSION AREA CAN BE FOUND OVER AND E OF THE GALAPAGOS 
ISLANDS...BUT SUBSIDENCE THERE IS PREVENTING DEEP CONVECTION 
FROM OCCURRING N OF THE EQUATOR DESPITE LOW LEVEL CONVERGENCE 
AROUND A SURFACE TROUGH WHICH EXTENDS FROM 07N85W TO 02N94W.

FARTHER NW AND N...HIGH PRES DOMINATES AT THE SURFACE. RIDGING 
EXTENDS FROM 1027 MB HIGH PRES CENTERED NEAR 31N141W THROUGH 
26N125W TO 16N105W AND NW WINDS OF UP TO 20 KT CONTINUE TO HUG 
THE W COAST OF THE BAJA CALIFORNIA PENINSULA ON THE E EDGE OF 
THIS RIDGING ACCORDING TO SHIP ZCDG7 WHICH REPORTED 16 KT WINDS 
AND 8 FT SEAS AT 19Z. A VIGOROUS UPPER LEVEL LOW AND ASSOCIATED 
SHORTWAVE TROUGH NOW LOCATED OFF THE CALIFORNIA COAST NEAR 
39N127W IS DROPPING SWD AT 20 KT AND IS EXPECTED TO PROVIDE 
SUPPORT FOR A COLD FRONT WHICH WILL SWEEP INTO THE FAR N 
PORTIONS OF THE DISCUSSION AREA JUST BEFORE SUNRISE TUE AND 
EXTEND FROM 28N120W TO TO 26N135W BY LATE TUE. THIS FRONT WILL 
USHER IN N WINDS OF NEAR GALE FORCE ALONG 30N WITH SEAS BUILDING 
8 TO 15 FT. THE LATEST GFS ENSEMBLE FORECASTS DEPICT A SLIM 
PROBABILITY OF GALE FORCE WINDS BEHIND THE FRONT N OF 30N.

THE PRES GRADIENT BETWEEN THE ANOMALOUSLY SOUTHERN ITCZ AND THE 
RIDGING N OF IT IS MAINTAINING FRESH TRADE WINDS AS FAR S AS 
06N. A SURFACE TROUGH IS EMBEDDED IN THE ITCZ EXTENDING FROM 
NEAR 08N129W TO 03N132W AND IS HELPING TO ENHANCE THE TRADES. 
THIS AREA OF TRADES IS EXPECTED TO GRADUALLY RETREAT WESTWARD 
THROUGH WED MORNING AS THE SURFACE RIDGING IS COMPROMISED BY THE 
APPROACHING DEEP LAYERED LOW AND COLD FRONT. 

GAP WINDS...
GULF OF PAPAGAYO...FRESH NE TRADE WINDS WILL CONTINUE TO SPILL 
FROM THE WESTERN CARIBBEAN INTO THE GULF OF PAPAGAYO WITH 20 KT 
WINDS MOST PREVALENT DURING THE EARLY MORNING HOURS WHEN THE 
NIGHTTIME MOUNTAIN DRAINAGE FLOW IS AT A MAXIMUM.

GULF OF PANAMA...THE PRES GRADIENT OVER NW COLOMBIA WILL 
CONTINUE TO BE TIGHT ENOUGH TO SUPPORT FRESH NORTHERLY WINDS 
THROUGH TUE NIGHT...POSSIBLY INTO WED MORNING. 

$$
COBB