000
AXPZ20 KNHC 210914
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC THU MAY 21 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.

...ITCZ...
THE ITCZ AXIS IS ALONG 08N78W TO 08N90W TO 10N106W TO 12N118W TO 
11N122W TO 05N140W. SCATTERED MODERATE TO STRONG WITHIN 120 NM 
OF LOW. SCATTERED MODERATE TO ISOLATED STRONG FROM 09N-12N 
BETWEEN 112W AND 121W...AND NEAR 13N119W. SIMILAR CONVECTION IS 
ALSO FOUND NEAR 7N126W.

.DISCUSSION...
A WELL DEFINED 1007 MB LOW IS LOCATED ALONG THE ITCZ AT 11N109W. 
A QSCAT PASS FROM AROUND 0130 UTC CLEARLY SHOWED THE CYCLONIC 
CIRCULATION ASSOCIATED WITH THIS SYSTEM. THE ASSOCIATED 
THUNDERSTORM ACTIVITY IS NOT WELL ORGANIZED AND DEVELOPMENT OF 
THIS SYSTEM...IF ANY...IS EXPECTED TO BE SLOW TO OCCUR AS IT 
MOVES SLOWLY WEST-NORTHWESTWARD. THERE IS A LOW CHANCE...LESS 
THAN 30 PERCENT...OF THIS SYSTEM BECOMING A TROPICAL CYCLONE 
DURING THE NEXT 48 HOURS. THIS BROAD CIRCULATION IS FORECAST BY 
THE COMPUTER MODELS TO LIFT NE AND E LATE SUN INTO EARLY NEXT 
WEEK WITH SOME POTENTIAL FOR TROPICAL DEVELOPMENT. SE WINDS OF 
20 KT AND SEAS TO 8 FT ARE NOTED TO THE SE QUADRANT OF LOW 
CENTER. A SURFACE TROUGH IS ALONG 119W FROM 10N TO 16N. A WEAK 
SFC LOW IS EMBEDDED WITHIN THE TROUGH AXIS NEAR 13N. THIS LOW IS 
FORECAST TO WEAKEN IN ABOUT 24 TO 48 HOURS DUE TO INCREASING 
UPPER LEVEL WINDS ALOFT. A 1030 MB HIGH PRES LOCATED WELL N OF 
AREA EXTENDS A RIDGE OVER THE NORTHERN FORECAST WATERS N OF 15N 
AND W OF 115W. SCATTERED SHOWERS AND ISOLATED TSTMS ARE NEAR 
ACAPULCO.
  
IN THE UPPER LEVELS...
WLY FLOW DOMINATES MOST OF THE AREA N OF 20N. A DIFFLUENT 
PATTERN ALOFT ASSOCIATED WITH AN UPPER-LEVEL RIDGE IS NOTED 
ACROSS A LARGE AREA S OF 20N. THIS RIDGE IS HELPING TO INDUCE 
CONVECTION ALONG THE ITCZ AS WELL AS NEAR THE SFC LOWS MENTIONED 
ABOVE.    

GAP WINDS...
N TO NE WINDS OF 20 KT AND SEAS TO 8 FT ARE STILL NOTED ACROSS 
THE GULF OF TEHUANTEPEC. 

$$
GR