000
AXPZ20 KNHC 030959
TWDEP 

TROPICAL WEATHER DISCUSSION    
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC TUE FEB 03 2009

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 
0945 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG AXIS 04N77W TO 02N86W TO 06N140W.
ISOLATED THUNDERSTORMS CONTINUE TO FLARE WITHIN 90 NM OF THE 
PACIFIC COAST OF COLOMBIA. ISOLATED SHOWERS RECENTLY DEVELOPED 
WITHIN 15 NM EITHER SIDE OF LINE 08N131W TO 05.5N140W. 
OTHERWISE...LOCALLY OVERCAST LOW CLOUDS WITH EMBEDDED WEAK 
SHOWERS WERE NOTED FROM 06N TO EQUATOR BETWEEN 80W AND 109W. 

...DISCUSSION...

A QUASI STATIONARY UPPER ANTICYCLONE IS CENTERED OVER THE 
TROPICS NEAR 10N103W WITH A RIDGE EXTENDING NW TO CREST ALONG 
21N123W TO 25N109W TO 20N100W. THERE IS SOME DEBRIS MOISTURE 
FROM THE ISOLATED CONVECTION ALONG THE PACIFIC COAST OF 
COLOMBIA. A NARROW BAND OF MOISTURE LIES ALONG THE N PERIPHERY 
OF THIS RIDGE EVAPORATING NEAR 23N96W. OTHERWISE...THE UPPER 
LEVELS ARE VERY DRY OVER THE DISCUSSION AREA S OF 18N E OF 130W 
AND SUPPRESSING CONVECTION.

TO THE N OF THIS RIDGE...AN UPPER TROUGH HAS SWUNG S OVER THE 
GULF OF MEXICO CONTINUING W ALONG 28N ACROSS OLD MEXICO AND THE 
GULF OF CALIFORNIA INTO AN UPPER CYCLONE AT 29N125W. A TROUGH 
EXTENDS SW FROM THIS CYCLONE TO 15N135W AND NOW SEPARATES THE 
PERSISTENT DEEP TROPICAL RIDGE OVER THE E PORTION OF THE 
DISCUSSION AREA FROM ANOTHER TROPICAL RIDGE OVER THE CENTRAL 
PACIFIC NOW SPREADING E INTO THE AREA S OF 20N W OF 135W. THIS 
NEW RIDGE IS WELL DEFINED BY DEBRIS MOISTURE TRAPPED WITHIN ITS 
ENVELOPE OF ANTICYCLONIC UPPER FLOW. N OF THIS WESTERN RIDGE... 
AN UPPER TROUGH IS NOTED N OF 23N ALONG 145W AND SHIFTING E 
TOWARDS THE NW CORNER OF THE AREA ALSO ACCOMPANIED BY UPPER 
MOISTURE. DRY UPPER AIR IS INDICATED WITHIN 300 NM SW SEMICIRCLE 
OF THE CYCLONE AT 29N125W.   

AT THE LOW LEVELS WEAK RIDGING HAS SHIFTED E OVER THE 
SUBTROPICAL WATERS E OF 130W. WINDS NE OF THE RIDGE CONTINUE AT 
NW 15 TO OCCASIONALLY KT OVER THE N GULF OF CALIFORNIA...BUT 
EXPECTED TO FINALLY DIMINISH TO LESS THAN 20 KT LATE TODAY. A 
COLD FRONT HAS JUST MOVED INTO THE EXTREME NW PORTION OF THE 
AREA. HOWEVER...MOST OF THE UPPER SUPPORT WILL LIFT NE AND THIS 
FRONT...AND AT LEAST ONE SECONDARY FRONT...ARE EXPECTED TO WASH 
OUT OVER THE SUBTROPICS ALONG 128W OVER THE NEXT FEW DAYS. BUT 
LARGE NW SWELLS WILL PROPAGATE SE OVER MOST OF THE AREA IN THE 
WAKE OF THE DECAYING FRONTS.   

CENTRAL AMERICAN GAPS...N WINDS ARE CURRENTLY INCREASING IN THE 
GULF OF TEHUANTEPEC AND EXPECTED TO REACH TO GALE FORCE BY 
SUNRISE THIS MORNING...AND FURTHER INCREASE TO STORM FORCE THIS 
AFTERNOON. THE STORM CONDITIONS SHOULD CONTINUE INTO FRI 
MORNING. LATEST GUIDANCE NO LONGER SUGGESTS WINDS WILL BRIEFLY 
DIMINISH BELOW GALE. WILL CONTINUE TREND OF BUILDING ASSOCIATED 
SEAS A LITTLE SLOWER THAN NORMAL AS COLD WATER UPWELLING FROM 
LAST STORM EVENT MODIFIED THE MARINE LAYER. NE WINDS IN AND 
DOWNSTREAM OF THE GULF OF PAPAGAYO HAVE ALSO BEEN SURGING AT 20 
KT. EXPECT NE WINDS TO SURGE THROUGH ALL THE GAPS N OF 09N E OF 
91W TONIGHT AND GRADUALLY INCREASE TO GALE FORCE WED NIGHT. NE 
WINDS ALSO EXPECTED TO INCREASE TO 20 KT OVER THE PACIFIC 
COASTAL WATERS OF COSTA RICA WED AFTERNOON...WITH THESE 
CONDITIONS SPREADING E TO THE PANAMA WATERS THU. EXPECT N WINDS 
TO INCREASE TO MINIMAL GALE NEAR 07N79.5W FRI MORNING. THUS  AND 
POSTED A LABEL FOR POSSIBLE GALE AT 06 HRS ON 72 HOUR 
GRAPHICS...ALL ASSOCIATED WITH GALE CONDITIONS EXPECTED BEGGING 
THU NIGHT OVER THE SW CARIBBEAN.       

$$
NELSON