000
AXPZ20 KNHC 201559
TWDEP 

TROPICAL WEATHER DISCUSSION    
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC FRI FEB 20 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...AXIS 6N77W TO 03N90W T0 
03N116W TO 06N140W. SCATTERED MODERATE ISOLATED STRONG 
CONVECTION NOTED WITHIN 150 NM EITHER SIDE OF LINE FROM 07N131W 
TO 09N138W. 

...DISCUSSION...
A LONG WAVE TROUGH LIES OFF THE WESTERN UNITED STATES WITH A 
UPPER LAYER CYCLONE CENTERED N OF THE DISCUSSION AREA NEAR 
34N148W. AN ASSOCIATED SURFACE LOW PRES IS AT 33N140W 1005 MB 
WITH A COLD FRONT S TO 27N145W. A SERIES OF FRONTS ARE EXPECTED 
TO ROTATE AROUND THE CYCLONE QUICKLY LOSING IDENTITY OVER THE NW 
PORTION OF THE DISCUSSION OVER THE NEXT FEW DAYS. SURFACE WINDS 
TO 25 KT ARE EXPECTED WITHIN 300 NM EITHER SIDE OF THIS FRONT... 
AND ALONG A SECOND FRONT WHICH WILL FOLLOW ON SAT...AND A THIRD 
FRONT ON SUN. CURRENTLY SCATTERED MODERATE CONVECTION IS 
ENHANCED ALONG THE FRONT...PRIMARILY FROM 30N TO 34N...WHILE 
MULTI LEVEL CLOUDS AND LIGHT SHOWERS ARE NOTED WITHIN 90 NM W OF 
THE FRONT TO THE S OF 30N. 

AN UPPER LEVEL ANTICYCLONE IS NEAR 12N106W WITH A RIDGE 
EXTENDING NW TO BEYOND 35N125W. ANOTHER UPPER ANTICYLONE IS S OF 
THE AREA AT 10S137W WITH ITS ENVELOPE OF ANTICYCLONIC FLOW 
EXPANDING N OVER THE DISCUSSION AREA TO THE S OF 23N W OF 125W. 
UPPER DEBRIS MOISTURE...ORIGINATING FROM ITCZ CONVECTION BETWEEN 
130W AND 140W AND ITCZ CONVECTION W OF THE AREA NEAR 155W...FANS 
OUT THE AREA N OF 10N W OF 120W...THEN CONCENTRATES INTO A PLUME 
ADVECTED E FROM 20N TO 27N BETWEEN 120W AND 105W. 

SOME DEBRIS MOISTURE IS NOTED ALONG THE PACIFIC COAST OF 
COLOMBIA. OTHERWISE THE UPPER LEVELS APPEAR VERY DRY S OF 23N 
BETWEEN 120W AND 80W. 

ELSEWHERE AT THE SURFACE...HIGH PRES NEAR 31N122W HAS A RIDGE 
EXTENDING SW TO 22N132W AND WILL BLOCK THE EASTWARD PROGRESSION 
OF THE SERIES OF COLD FRONTS PREVIOUSLY MENTIONED. E OF THE 
RIDGE...NW WINDS 20 TO 25 KT IN THE GULF OF CALIFORNIA WILL
DIMINISH BY SUNSET TODAY PER GUIDANCE.

CENTRAL AMERICAN GAPS...NE TO E WINDS IN AND DOWNSTREAM OF THE 
GULF OF PAPAGAYO OF 20 TO 25 KNOTS WILL INCREASE TO 20 TO 30 KT 
LATE TONIGHT THEN DIMINISH SOME ON SUN. NORTHERLY WINDS 20 TO 30
KT IN THE GULF OF TEHUANTEPEC EXPECTED TO DIMINISH SAT NIGHT. 

$$
NELSON