000
AXPZ20 KNHC 220907
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC FRI MAY 22 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 07N78W TO 10N94W TO 11N108W TO 13N119W TO 
05N140W. CLUSTER OF SCATTERED MODERATE TO ISOLATED STRONG 
CONVECTION WITHIN 40 NM OF 05N93W. SIMILAR CONVECTION IS NOTED 
FROM 9N TO 14N BETWEEN 110W AND 120W. 

DISCUSSION...
NEARLY ZONAL FLOW DOMINATES THE FORECAST AREA N OF 20N. BROAD  
MID/UPPER LEVEL E-W RIDGE WITH AXIS BETWEEN 09N-12N STRETCHES E 
OF 128W MAINTAINING GOOD OUTFLOW OVER ITCZ AND ENHANCING 
CONVECTION CAUSED BY TWO 1008 MB SURFACE LOW PRES CENTERS 
LOCATED NEAR 13N110W AND 13N120W. A RECENT QSCAT PASS SHOWED NE 
WINDS OF 20 KT WITHIN AROUND 300 NM NW QUADRANT OF THIS SECOND 
LOW DUE THE PRES GRADIENT BETWEEN THE LOW ITSELF AND A SFC RIDGE 
WHICH DOMINATES THE NORTHERN FORECAST WATERS N OF 15N AND W OF 
115W. WINDS OF 20 KT ARE ALSO SEEN WITHIN 120 NM ON THE EASTERN 
SEMICIRCLE OF THE FIRST LOW. IN ADDITION...THE COMBINATION OF 
THE RIDGE WITH LOWER PRES OVER MEXICO IS PRODUCING NW WINDS OF 
UP TO 20 KT VERY CLOSE TO THE COAST OF BAJA CALIFORNIA. THE 
QSCAT PASS ALSO CONFIRMED THESE WIND SPEEDS.   

THE WESTERNMOST LOW PRES MENTIONED ABOVE IS FORECAST TO WEAKEN 
IN ABOUT 24 HOURS UNDER INCREASINGLY UNFAVORABLE UPPER-LEVEL 
WINDS. THE EASTERNMOST LOW PRES CENTER REMAINS CLOSE TO AN 
ANTICYCLONE ALOFT. HOWEVER...ENVIRONMENTAL CONDITIONS COULD ALSO 
TURN UNFAVORABLE FOR THIS SYSTEM DURING THE WEEKEND. THERE IS A 
LOW CHANCE...LESS THAN 30 PERCENT...OF THIS SYSTEM BECOMING A 
TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

N SWELLS ARE EXPECTED TO SPREAD ACROSS THE N WATERS N OF 28N IN 
ABOUT 24 HOURS.  

$$
GR