000
AXPZ20 KNHC 211607
TWDEP 

TROPICAL WEATHER DISCUSSION    
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC SAT FEB 21 2009

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 
1545 UTC.

...ITCZ...
THE INTERTROPICAL CONVERGENCE ZONE...THE AXIS MEANDERS FROM 05N 
TO 07N BETWEEN E OF 140W TO THE COAST OF COLOMBIA. SCATTERED
MODERATE AND ISOLATED STRONG CONVECTION IS FLARING WITHIN 30 NM 
OF 03N78W. A SMALL CLUSTER IS NOTED NEAR 07N122W.

...DISCUSSION...
A LONG WAVE TROUGH LIES OFF THE WESTERN UNITED STATES WITH A 
UPPER LAYER CYCLONE CENTERED N OF THE DISCUSSION AREA NEAR 
35N141W. AN ASSOCIATED SURFACE LOW PRES IS AT 34N140W 1005 MB 
AND MOVING ESE. A SERIES OF COLD FRONTS ARE ROTATING AROUND THE 
CYCLONE BUT QUICKLY LOSE IDENTITY OVER THE NW PORTION OF THE 
DISCUSSION AREA. SURFACE WINDS ARE EXPECTED TO MAX AT 25 KT WITH 
THESE FRONTS. CURRENTLY MODERATE CONVECTION IS ENHANCED E OF THE 
SURFACE LOW...PRIMARILY FROM 32N TO 35N.

AN UPPER LEVEL ANTICYCLONE IS NEAR 15N118W WITH A RIDGE 
EXTENDING N TO BEYOND 36N123W. ANOTHER UPPER ANTICYLONE IS S OF 
THE AREA AT 04S140W WITH ITS ENVELOPE OF ANTICYCLONIC FLOW 
EXPANDING N OVER THE DISCUSSION AREA TO THE S OF 18N W OF 130W 
MERGING WITH THE UPPER FLOW FROM THE LARGE UPPER RIDGE. UPPER 
DEBRIS MOISTURE...ORIGINATING FROM ITCZ CONVECTION BETWEEN 130W 
AND 148W...IS SPREADING NE ALONG THE W PERIPHERY OF THE UPPER 
RIDGE...BASICALLY COVERING THE UPPER LEVELS NW OF LINE 10N130W 
TO 20N105W. 

SOME DEBRIS MOISTURE IS NOTED ALONG THE PACIFIC COAST OF 
COLOMBIA ORIGINATING FROM ITCZ CONVECTION DESCRIBED ABOVE.
OTHERWISE THE UPPER LEVELS APPEAR VERY DRY S OF 20N E OF 
122W.

ELSEWHERE AT THE SURFACE...HIGH PRES NEAR 31N122W HAS A RIDGE 
EXTENDING SW TO 20N134W AND BLOCKS THE EASTWARD PROGRESSION OF 
THE SERIES OF COLD FRONTS PREVIOUSLY MENTIONED.

CENTRAL AMERICAN GAPS...NORTHERLY WINDS 20 TO 30 KT IN THE GULF 
OF TEHUANTEPEC EXPECTED INCREASE TO GALE FORCE SUN AND MINIMUM 
STORM FORCE MON. NE TO E WINDS IN AND DOWNSTREAM OF THE GULF OF 
PAPAGAYO OF 20 TO 25 KNOTS WILL DIMINISH SOME SUN THEN INCREASE 
AGAIN MON. 

$$
NELSON