000
AXPZ20 KNHC 300918
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC SAT MAY 30 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 
0900 UTC.

...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 100W FROM 03N TO 14N MOVING W 10-15 KT. 
THE WAVE STRUCTURE HAS IMPROVED SLIGHTLY OVER THE PAST DAY AS 
MID-LEVEL CYCLONIC TURNING HAS BECOME MORE PRONOUNCED ON 
SHORTWAVE IR IMAGERY. CONVECTION HAS ALSO INCREASED AND IS LESS 
LINEAR IN NATURE...MAINLY WITHIN 360 NM E OF THE ANALYZED AXIS. 
THE WAVE REMAINS VERY BROAD WITH CLOUD MOTIONS SUGGESTING TWO 
VORTICITY MAXIMUMS E AND W OF THE AXIS...NEAR 08N92W AND 
08N103W. MANY OF THE GLOBAL MODELS SHOW SOME DEVELOPMENT OF THIS 
SYSTEM OVER THE NEXT FEW DAYS AS IT MOVES W-NW.

...ITCZ...
THE ITCZ AXIS IS ALONG 08N79W TO 10N97W TO 06N103W TO 09N128W TO 
05N140W. SCATTERED MODERATE TO STRONG CONVECTION IS FROM 06N TO 
12N BETWEEN 95W AND 102W.

...DISCUSSION...
A GALE FORCE LOW N OF THE AREA NEAR 39N140W IS DRIVING A COLD 
FRONT ACROSS THE NW CORNER FROM 30N135W TO 26N140W. QUIKSCAT 
DATA FROM 04 Z INDICATED THAT WINDS HAVE FALLEN BELOW 20 KT NEAR 
THE BOUNDARY. HOWEVER...THE STRONG WINDS NEAR THE LOW IS 
SPREADING NW SWELL INTO THE AREA W OF THE FRONT ENHANCING SEAS 
TO 8-11 FT. THE FRONT IS EXPECTED TO GRADUALLY DISSIPATE INTO 
EARLY NEXT WEEK AS THE ASSOCIATED LOW WEAKENS AND MOVES SE. THIS 
WILL ALLOW SEAS TO SUBSIDE BELOW 8 FT BY SUN NIGHT. A 1019 MB 
HIGH NEAR 26N130W IS ALLOWING WINDS TO BE LIGHT ACROSS MUCH OF 
THE SUBTROPICAL EPAC. THE EXCEPTION IS NEAR THE COAST OF BAJA S 
OF 28N...AS QUIKSCAT REVEALED 20 KT NW-N FLOW. THESE WINDS ARE 
BEING GENERATED BY THE TIGHTENED PRESSURE GRADIENT BETWEEN THE 
HIGH AND BROAD TROUGHING OVER MEXICO WITH A SECONDARY 
TOPOGRAPHIC ENHANCEMENT. LITTLE CHANGE IN THIS FLOW IS EXPECTED 
OVER THE NEXT 24 HOURS AS THE SFC PATTERN REMAINS SIMILAR. TRADE 
WINDS ARE FAIRLY RELAXED ACROSS THE TROPICS...WITH ONLY A SMALL 
AREA OF MARGINAL 20 KT WINDS W OF A DAMPENING SFC TROUGH FROM 
12N127W TO 07N130W.

AN UPPER RIDGE OVER THE TROPICAL EPAC...CENTERED S OF THE GULF 
OF TEHUANTEPEC...IS PROVIDING A FAVORABLE ENVIRONMENT FOR 
CONVECTIVE ACTIVITY NEAR THE TROPICAL WAVE DISCUSSED ABOVE. THIS 
HIGH AND LOW-LEVEL CONVERGENCE ENHANCED BY NOCTURNAL DRAINAGE 
FLOW OVER S MEXICO IS RESULTING IN MODERATE TO STRONG CONVECTION 
OVER THE GULF OF TEHUANTEPEC AND OFF THE COASTS OF COSTA RICA 
AND NICARAGUA. 

$$
CANGIALOSI