000
AXPZ20 KNHC 210917
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC MON FEB 21 2011

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

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0700 UTC.

...ITCZ...
THE INTERTROPICAL CONVERGENCE ZONE WAS ANALYZED FROM 04N77W TO 
01N85W TO 02N91W THEN CONTINUES FROM 01N113W TO 03N130W TO 
01N140W. ISOLATED MODERATE CONVECTION WAS WITHIN 75 NM N OF THE 
ITCZ AXIS BETWEEN 113W AND 115W AS WELL AS BETWEEN 90 NM AND 210 
NM N OF THE ITCZ AXIS BETWEEN 121W AND 128W.

...DISCUSSION...
THE LONGWAVE UPPER PATTERN IS EXPECTED TO CHANGE LITTLE OVER THE 
NEXT TWO DAYS WITH THE TROUGH AXIS GENERALLY EXTENDING ALONG 
125W AND BOOKENDED BY RIDGING WITH THE EASTERN RIDGE LYING OVER 
THE FORECAST AREA ALONG 95W. CONVECTION ALONG THE ITCZ IS 
FOCUSED IN THE AREA OF UPPER LEVEL DIFFLUENCE ON THE SE SIDE OF 
THE TROUGH AXIS BETWEEN THE TROUGH AND ANTICYCLONE. VERTICAL 
LIFT IN THIS AREA HAS INCREASED LOW LEVEL CONVERGENCE AND 
ALLOWED MOSITURE TO POOL. HOWEVER...A 20-40 KT UPPER JET LIES 
OVER THIS REGION AND IS INHIBITING THE DEVELOPMENT OF DEEP 
CONVECTION. THE HIGHEST PRECIPITABLE WATER VALUES ARE FOUND OVER 
THE GALAPAGOS ISLANDS...BUT SUBSIDENCE IS PREVENTING DEEP 
CONVECTION FROM OCCURRING N OF THE EQUATOR DESPITE LOW LEVEL 
CONVERGENCE AROUND A SURFACE TROUGH FROM 07N89W TO 01N94W.

FARTHER N...HIGH PRES DOMINATES THE SURFACE. 20 KT NW WINDS HUG 
THE W COAST OF BAJA CALIFORNIA ON THE E EDGE OF THIS RIDGING 
ACCORDING TO SHIPS DGTX AND C6FR3 AT 06Z AS WELL AS THE 0422Z 
ASCAT PASS. MULTILAYERED CLOUDINESS LIES N OF 23N W OF 125W 
WHERE MID LEVEL MOISTURE IS BEING TRANSPORTED NORTHEASTWARD BY 
THE UPPER JET ON THE LEADING EDGE OF THE SHORTWAVE TROUGH OVER 
THE SW CONUS. THAT SHORTWAVE TROUGH WILL BE REPLACED BY A NEW 
DEEP LAYER LOW EXPECTED TO MOVE INTO THE LONGWAVE TROUGH OVER NE 
WATERS BY TUE MORNING. WINDS WILL INCREASE TO 20 KT AHEAD OF THE 
COLD FRONT ASSOCIATED WITH THIS SYSTEM BY EARLY TUE MORNING 
AND QUICKLY INCREASE TO NEAR GALE FORCE AS THE LOW PRES SYSTEM 
MOVES INTO THE AREA. THE 00Z GEFS HAS UP TO A 20 PERCENT CHANCE 
OF GALE FORCE WINDS BEHIND THE FRONT TUE MORNING OVER FORECAST 
WATERS N OF 30N...BUT SHOWS NO CHANCE FOR GALES S OF 30N. THE 
PRES GRADIENT BETWEEN THE ANOMALOUSLY S ITCZ AND HIGH PRES TO 
THE N IS MAINTAINING FRESH TRADE WINDS AS FAR S AS 05N. THIS 
AREA OF TRADES IS EXPECTED TO GRADUALLY RETREAT WESTWARD 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 E PAC...WITH WINDS MOST 
LIKELY TO REACH ADVISORY CRITERIA IN 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.

$$
SCHAUER