000
AXPZ20 KNHC 120954
TWDEP 

TROPICAL WEATHER DISCUSSION    
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC THU MAR 12 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 
0930 UTC.

...ITCZ...
AXIS ALONG 08N82W TO 01N110W TO 02N125W TO 01N140W. SCATTERED 
MODERATE WITHIN 45-60 NM OF LINE 06N86W TO 04N95W. 

SCATTERED MODERATE CONVECTION FROM 14N TO 17N W OF 138W.

...DISCUSSION...

A PAIR OF CYCLONIC CIRCULATIONS JUST N OF THE AREA ARE THE MAIN 
FEATURES OF NOTE THAT ARE AFFECTING THE AREA. THE 
FIRST...ASSOCIATED WITH A WELL DEFINED SHORTWAVE IS APPROACHING 
THE CALIFORNIA COAST NEAR AT 32N120W IS ROUNDING THE BASE OF A 
LONG WAVE TROUGH LOCATED ALONG THE W COAST OF THE U.S. THIS 
SHORTWAVE IS FLATTENING THE CREST OF MID-UPPER LEVEL RIDGE ALONG 
125W. WINDS ALOFT BECOME QUASI-ZONAL WITH LARGE MOISTURE PLUME 
COVERING BASIN N OF 15N.  RIDGE MAINTAINS AREA OF MODERATE TO 
STRONG SUBSIDENCE OF 15N E OF 130W WHICH IS INHIBITING 
CONVECTION ALONG THE ITCZ.  ADVECTED MOISTURE REACHING CENTRAL 
TEXAS FEEDING DEVELOPING LOW PRES AND ASSOCIATED COLD FRONT 
THERE. 

THE OTHER CYCLONIC CIRCULATION IS LOCATED WELL TO THE NW OF THE 
DISCUSSION AREA NEAR 33N152W AND IS IN THE PROCESS OF CUTTING 
OFF. THIS SYSTEM IS EXPECTED TO FUEL A DEVELOPING STORM FORCE 
SYSTEM THAT IS EXPECTED TO REMAIN WELL W OF THE AREA. HOWEVER
SE WINDS ARE FORECAST TO INCREASE TO 20-25 KT...POSSIBLY 30 KT 
OVER THE NW CORNER OF THE AREA IN ABOUT 24 HOURS THEN SLOWLY 
WEAKEN AS THE LOW PULLS FURTHER W.  

AT THE SURFACE...RAPIDLY WEAKENING HIGH PRES CENTER N OF THE 
AREA MOVED FURTHER NE ALLOWING FAST MOVING UPSTREAM TROUGH TO 
MOVE E AND DIMINISHING THE TRADE WINDS W OF 130W FROM 15N-23N.  
AS NOTED ABOVE SE WINDS WILL INCREASE NEXT 24 HOURS OVER THE NW 
CORNER OF THE AREA. LONG PERIOD SW SWELLS ON THE ORDER OF 16-18 
SECONDS ARE MOVING NORTHWARD OVER THE AREAS S OF 10N AND SHOULD 
ARRIVE ALONG THE MEXICAN AND CENTRAL AMERICAN COAST LATER TODAY 
AND CONTINUE INTO FRI. 

GAP WINDS ACROSS GULF OF PAPAGAYO REMAIN AROUND 20 KT BUT ARE 
FORECAST TO WEAKEN FURTHER BY LATE FRI. PULSES OF GAP WIND FLOW 
OVER THE GULF OF PANAMAS WILL CONTINUE OVER THE NEXT 48 
HOURS...INTO LATE FRI. 

$$
COBB