000
AXPZ20 KNHC 042155
TWDEP 

TROPICAL WEATHER DISCUSSION    
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC WED MAR 04 2009

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

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2145 UTC.

...ITCZ...
AXIS ALONG 03N77W TO 02N107W TO 03N140W. SCATTERED MODERATE 
ISOLATED STRONG CONVECTION IS OBSERVED WITHIN 60 NM EITHER SIDE 
OF LINE FROM 06N85W TO 04N91W AND ALSO WITHIN 30 NM OF 03N132W.

...DISCUSSION...

A LONGWAVE TROUGH DOMINATES WESTERN N AMERICA AND THE EASTERN N 
PACIFIC WITH ITS AXIS EXTENDING S INTO THE DISCUSSION AREA FROM 
32N130W TO 19N137W. A BAND OF DRY UPPER AIR IS OBSERVED NEAR THE 
BASE OF THE TROUGH...ROUGHLY FROM 21N TO 26N BETWEEN 130W AND 
145W. FURTHER N...UPPER MOISTURE IS SWEEPING CYCLONICALLY E 
THROUGH THE TROUGH EVENTUALLY REACHING THE UPPER LEVELS OVER 
CENTRAL CALIFORNIA. 

AN UPPER ANTICYCLONE IS CENTERED NEAR 19N105W WITH A RIDGE 
EXTENDING N TO WELL BEYOND 32N97W...AND DOMINATING THE UPPER 
LEVELS OF THE CONUS. UPPER DEBRIS MOISTURE...ORIGINATING FROM 
CONVECTION IN THE TROPICAL CENTRAL PACIFIC...CONCENTRATES INTO A 
PLUME SPREADING NE AROUND THE W PERIPHERY OF THE UPPER 
RIDGE...ROUGHLY WITHIN 180 NM EITHER SIDE OF POINTS 15N140W TO 
BEYOND 32N112W THEN SPILLING EASTWARD ACROSS THE RIDGE OVER THE 
CENTRAL CONUS. SOME OF THIS DEBRIS MOISTURE IS NOW PLUNGING SE 
OVER THE NE GULF OF MEXICO AND N FLORIDA. 

A LONGWAVE TROUGH OVER THE WESTERN N ATLC HAS AN UPPER TROUGH 
EXTENDING SW ALONG 20N74W TO 11N84W TO A SMALL UPPER CYCLONE AT 
06N98W. CONVECTION ALONG THE PACIFIC ITCZ WAS ENHANCED BETWEEN 
83W AND 93W...WITH THE DEBRIS MOISTURE ADVECTED NE ACROSS COSTA 
RICA. OTHERWISE THE UPPER LEVELS APPEAR VERY DRY E OF 115W.

AT THE LOW LEVELS...A WEAK COLD FRONT IS LOSING IDENTITY FROM 
SOUTHERN CALIFORNIA TO NEAR 28N127W. A RIDGE IS BUILDING E 
ACROSS THE AREA ALONG 27N140W TO 17N112W. NW SWELLS ARE 
PROPAGATING SE ACROSS THE WATERS W OF 110W. 

GAP WINDS...N WINDS IN AND DOWNSTREAM OF THE GULF OF TEHUANTEPEC 
WILL CONTINUE TO WEAKEN TO LESS THAN 20 KT THU AND CONTINUE 
THROUGH FRI. NE WINDS IN THE GULF OF FONSECA AND THE GULF OF 
PAPAGAYO CONTINUE AT 20 TO 30 KT...AND EXPECTED TO DIMINISH TO 
20 TO 25 KT THU AND FRI DOWNSTREAM OF PAPAGAYO. THESE GAP WINDS 
ARE GENERATING A SWATH OF NE SWELL THAT PROPAGATES W TO AROUND 
115W MIXING WITH THE TRAIN OF NW SWELLS MENTIONED ABOVE. 
CARIBBEAN TRADES ARE SURGING THROUGH THE ISTHMUS OF PANAMA 
MAINTAINING A 20 KT NORTHERLY FLOW THROUGH THE GULF OF PANAMA 
WELL INTO FRI.  

$$
NELSON