000
AXPZ20 KNHC 081535
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC FRI MAY 08 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 
1515 UTC.

...ITCZ...
AXIS ALONG 07N77W TO 08N86W TO 06N92W TO 08N108W TO 04N140W. 
SCATTERED MODERATE TO STRONG WITHIN 120 NM N OF AXIS BETWEEN 
110W AND 118W. SCATTERED MODERATE ISOLATED STRONG WITHIN 75 NM S 
OF AXIS BETWEEN 84W AND 88W.

...DISCUSSION...
BLOCKING PATTERN CONTINUES OVER THE EPAC BETWEEN 100W AND 130W 
WITH A WELL DEFINED ANTICYCLONE CENTERED OVER BAJA CALIFORNIA
NEAR 28N113W WITH RIDGE AXIS EXTENDING EWD OVER NRN MEXICO ALONG 
29N AND SW TO NEAR 18N126W. MID TO UPPER LEVEL UPPER LOW WAS 
TRAPPED S OF THE ANTICYCLONE NEAR 19N116W...BUT WAS MOVING WWD 
AT 10 KT. UPSTREAM CYCLONIC SHEAR AXIS EXTENDED FROM A WEAK 
CIRCULATION NEAR 27N132W SWD TO NEAR 16N133W. FEATURE WAS 
WEAKENING IN THE FACE OF THE BLOCKING ANTICYCLONE NOTED ABOVE 
WITH A DIMINISHING AREA OF MID TO UPPER LEVEL MOISTURE 
ASSOCIATED WITH THE FEATURE AS IT ENCOUNTERS STABLE AIR 
ASSOCIATED WITH AN ELONGATED DEFORMATION ZONE SITUATED ALONG 
127W/128W FROM 12N TO 25N.
 
THE SRN STREAM UPPER WLYS REMAIN ACTIVE AND WILL CONTINUE 
THROUGH AN UPCOMING PATTERN CHANGE NEXT WEEK. THESE WLYS 
WILL CONTINUE TO FAVORABLY INTERACT WITH THE ITCZ MOISTURE AND 
ENHANCE CONVECTION E OF 140W. UPPER LEVEL DIFFLUENT FLOW WITHIN 
THE WESTERLIES S OF THE UPPER LOW NOTED ABOVE WAS RESULTING 
IN AN AREA OF SCATTERED MODERATE TO STRONG CONVECTION WITHIN 120 
NM N OF THE ITCZ BETWEEN 110W AND 118W WITH THE STRONGEST 
CONVECTION CLOSER TO 118W WHERE CLOUD TOPS TO -77C AND COLDER 
NOTED. 

AT THE SURFACE...A 1028 MB HIGH WAS CENTERED WELL N OF THE AREA 
NEAR 39N133W WITH AN ASSOCIATED RIDGE AXIS EXTENDING SE THROUGH 
30N130W TO 20N118W. THE GRADIENT BETWEEN THIS HIGH PRESSURE AND 
LOW PRESSURE OVER SOUTHERN CALIFORNIA HAS RESULTED IN FRESH NW 
WINDS OF 20-25 KT ALONG THE COAST OF CALIFORNIA AND EXTENDING 
SWD INTO THE FAR NE PORTION OF THE DISCUSSION AREA. WINDS WILL 
GENERATE PULSES OF NW SWELL WHICH ARE MOVING INTO THE REGION TO 
MAINTAIN SEA HEIGHTS TO 12-13 FT ACROSS THE FAR N PORTIONS OF 
THE AREA. ADDITIONALLY...VERY LONG PERIOD SRN HEMISPHERE SWELL
HAS REACHED THE PACIFIC COASTS OF CENTRAL AMERICA...AND WILL 
PRODUCE MODERATE TO OCCASIONALLY LARGE SURF ALONG THE COAST OF 
MEXICO/CENTRAL AMERICA DURING THE NEXT 48 HOURS.

$$
COBB