000
AXPZ20 KNHC 211522
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC MON FEB 21 2011

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

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1500 UTC.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE AXIS WAS ANALYZED FROM 04N77W 
TO 00N90W THEN CONTINUES FROM 00N113W TO 04N131W THEN CONTINUES 
FROM 03N135W TO 02N140W. NO SIGNIFICANT CONVECTION WAS NOTED.

...DISCUSSION...

THE LONGWAVE UPPER PATTERN IS EXPECTED TO CHANGE LITTLE OVER THE 
NEXT TWO DAYS WITH AN UPPER TROUGH AXIS GENERALLY EXTENDING 
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. CONVECTION ASSOCIATED WITH THE ITCZ HAS 
DIMINISHED DURING THE EARLY MORNING HOURS WITH A 20 TO 40 KT 
UPPER JET LYING AHEAD OF THE TROUGH WHICH IS INHIBITING THE 
DEVELOPMENT OF DEEP CONVECTION. LOW TO MID LEVEL MOISTURE 
CONTINUES TO BE ADVECTED TO THE N AHEAD OF THE UPPER TROUGH AXIS 
MAINLY BETWEEN 110W AND 125W...ORIGINATING FROM THE ITCZ PORTION 
THAT IS S OF THE EQUATOR. 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 05N91W TO 00N94W.

FARTHER NW AND N...HIGH PRES DOMINATES AT THE SURFACE. RIDGING 
EXTENDS FROM 1026 MB HIGH PRES CENTERED NEAR 32N141W THROUGH 
23N123W TO 11N100W AND 20 KT NW WINDS CONTINUE TO HUG THE W 
COAST OF THE BAJA CALIFORNIA PENINSULA ON THE E EDGE OF THIS 
RIDGING ACCORDING TO SHIP ZCDG7 WHICH REPORTED AS RECENTLY AS 
12Z AND 13Z ALONG WITH SHIP 3FPR9 WHICH REPORTED 20 KT WINDS AT 
15Z. MULTILAYERED CLOUDINESS LIES N OF 20N AND W OF 110W WHERE 
MID LEVEL MOISTURE IS BEING TRANSPORTED NORTHEASTWARD BY AN 
UPPER JET ON THE LEADING EDGE OF THE SHORTWAVE TROUGH OVER THE 
SW CONUS. THAT SHORTWAVE TROUGH WILL BE REPLACED BY A NEW DEEP 
LAYERED LOW EXPECTED TO MOVE INTO THE ABOVE MENTIONED LONGWAVE 
TROUGH OVER THE NE WATERS BY TUE MORNING. WINDS WILL INCREASE TO 
20 KT AHEAD OF A SURFACE COLD FRONT ASSOCIATED WITH THIS SYSTEM 
BY LATE TONIGHT AND WILL QUICKLY INCREASE TO NEAR GALE FORCE 
BEHIND THE FRONT AS THE LOW PRES SYSTEM MOVES INTO THE AREA. THE 
06Z GEFS HAS BACKED OFF FROM EARLIER RUNS AND NOW HAS ONLY A 10 
PERCENT CHANCE OF GALE FORCE WINDS BEHIND THE FRONT N OF 
30N...WITH A 0 PERCENT CHANCE S 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 07N131W TO 01N134W 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.

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 WED MORNING.

$$
LEWITSKY