000
AXPZ20 KNHC 241544
TWDEP 

TROPICAL WEATHER DISCUSSION    
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC TUE FEB 24 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 
151 UTC.

...ITCZ...
THE INTERTROPICAL CONVERGENCE ZONE...THE AXIS EXTENDS ALONG 
07N78W TO 07N78W TO 01N105W TO 01N115W TO 05N140W. SCATTERED 
MODERATE CONVECTION IS NOTED WITHIN 30 NM EITHER SIDE OF LINE 
FROM 05N79W TO 06N85W TO 04N94W AND ALSO FROM 05.5N122W TO 
06N128W.

...DISCUSSION...
A LONG WAVE TROUGH LIES OFF THE WESTERN UNITED STATES WITH A 
SHORTWAVE TROUGH EXTENDING S ALONG 32N142W TO 24N135W. A BAND OF 
DRY UPPER AIR IS NOTED WITHIN 150 NM EITHER SIDE OF LINE 32N129W 
TO 24N142W. AT THE LOW LEVELS...A SERIES OF WEAK SURFACE FRONTS 
ARE ALSO ROTATING THROUGH THE PATTERN INTO THE NW PORTION 
PORTION OF THE DISCUSSION AREA...BUT THEIR EASTWARD ADVANCE IS
BLOCKED BY A QUASI STATIONARY SURFACE HIGH NEAR 29N129W 1023 MB. 
ALTHOUGH THE FRONTS CONTINUE TO WASH OUT OVER THE NW PORTION... 
REINFORCING NW SWELLS TO A MAX OF ABOUT 11 FT CONTINUE TO 
PROPAGATE SE INTO THE AREA. BRIEF SHIFTING WINDS...BUT ONLY TO 
MAX OF 20 KT...ALSO ACCOMPANY THE FRONTS.

A LONG WAVE UPPER TROUGH OVER THE EASTERN UNITED STATES EXTENDS 
SW ACROSS THE SOUTHERN GULF OF MEXICO AND DISSECTS THE CENTRAL 
PORTION OF THE DISCUSSION AREA FROM THE BAY OF CAMPECHE TO THE 
EQUATOR AT 120W. EMBEDDED UPPER CYCLONES AT NOTED NEAR 14N108W 
AND 06N119W WHERE THE ASSOCIATED UPPER DIFFLUENCE IS ENHANCING 
CONVECTION ALONG THE ITCZ BETWEEN 120W AND 132W. 

W OF THIS DISSECTING UPPER TROUGH...AN UPPER ANTICYCLONE NEAR 
THE EQUATOR AT 146W HAS A RIDGE EXTENDING NE INTO THE DISCUSSION 
AREA ALONG 17N135W TO BEYOND THE EQUATOR AT 129W. ANOTHER UPPER 
ANTICYCLONE...MORE DOMINATE...IS CENTERED NEAR 18N115W WITH A 
LONGWAVE RIDGE EXTENDING NE ACROSS CENTRAL N AMERICA. UPPER 
DEBRIS MOISTURE CENTRAL PACIFIC TROPICAL CONVECTION IS SPREADING 
NE ALONG THE W PERIPHERY OF THIS LONGWAVE UPPER RIDGE...ROUGHLY
WITHIN 300 NM EITHER SIDE OF LINE 16N140W TO 27N120W TO BEYOND 
32N94W.  

E OF THE DISSECTING AN UPPER LEVEL TROUGH...AN UPPER ANTICYCLONE 
IS OVER COLOMBIA HAS A RIDGE EXTENDING NW TO 12N102W. UPPER 
DIFFLUENCE IS ENHANCING ITCZ CONVECTION...DESCRIBED ABOVE...WITH 
THE DEBRIS MOISTURE SPREADING NE...BUT EVAPORATING BEFORE THE 
UPPER LEVELS OVER REACHING CENTRAL AMERICA. OTHERWISE THE UPPER 
LEVELS APPEAR VERY DRY S OF 20N E OF 122W.

CENTRAL AMERICAN GAPS...A GALE WARNING IS IN EFFECT FOR THE GULF 
OF TEHUANTEPEC AND IS EXPECTED TO WEAKEN BELOW GALE LATE TODAY. 
NE TO E WINDS IN AND DOWNSTREAM OF THE GULF OF PAPAGAYO OF 20 TO 
25 KNOTS WILL CONTINUE FOR SEVERAL MORE DAYS BUT DIMINISH N OF 
12N WED. NORTHERLY WINDS ARE SURGING TO 20 KT DOWNSTREAM OF THE 
GULF PANAMA. 

$$
NELSON