000
AXPZ20 KNHC 281555
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC THU AUG 28 2008

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 
1545 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE N OF 04N BETWEEN 96W AND 98W IS ESTIMATED TO BE 
MOVING W AT 10 KT. THIS WAVE SPUN OFF A LOW PRES SYSTEM OVER THE 
BAY OF CAMPECHE ANALYZED AT 1007 MB WITH CONVECTION BURSTING 
THIS MORNING. JUST TO THE SW OVER INTERIOR MEXICO ANOTHER AREA 
OF CYCLONIC TURNING IS NOTED. ALTHOUGH SCATTERED MODERATE 
ISOLATED STRONG CONVECTION IS OBSERVED OVER THE PACIFIC N OF 08N 
BETWEEN 90W AND 100W...LITTLE TURNING IS NOTED.
     
...ITCZ...

ITCZ AXIS IS CENTERED ALONG 09N80W TO 13N91W TO 11N107W TO 
14N117W TO 10N140W. SCATTERED MODERATE ISOLATED STRONG 
CONVECTION IS NOTED WITHIN 180 NM EITHER SIDE OF LINE FROM 
06N81W TO 15N109W TO 11N140W. SCATTERED MODERATE CONVECTION IS 
ALSO OBSERVED WITHIN 90 NM EITHER SIDE OF LINE FROM 07N103W TO 
07N112W. 

...DISCUSSION...

THE NW PORTION OF THE DISCUSSION AREA IS DOMINATED BY FOUR 
FEATURES ALOFT. AN UPPER SHORTWAVE TROUGH EXTENDS ALONG 32N125W 
TO 27N137W. NW OF THIS TROUGH AN UPPER ANTICYCLONE IS NEAR 
36N134W WITH RIDGE SW TO NEAR 32N143W. ANOTHER MORE PRONOUNCED 
UPPER ANTICYCLONE IS AT 25N121W WITH A RIDGE EXTENDING W-SW TO 
NEAR 22N134W AND A RIDGE EXTENDING E TO NEAR 24N112W. A DEEP 
LAYERED TROUGH EXTENDS S ALONG 30N109W TO A BASE AT 24N108W. 
CONVECTION IS ENHANCED OVER OLD MEXICO E OF THIS TROUGH...AND 
ALSO OVER THE PACIFIC NEAR THE BASE OF THE TROUGH AT 
22N107W...WHERE THE UPPER RIDGE FROM THE W ALSO CRESTS. SOME THE 
RESULTANT DEBRIS MOISTURE IS SPREADING SW AROUND THE RIDGE OVER 
THE AREA FROM 10N TO 20N BETWEEN 105W AND 112W. OTHERWISE...THE 
UPPER LEVELS APPEAR DRY N OF 15N W OF 125W AND ALSO N OF 22N 
BETWEEN 125W AND 108W.
 
NE FLOW DOMINATES THE UPPER LEVELS OF THE DEEP TROPICAL PACIFIC 
ADVECTING DEBRIS MOISTURE FROM ITCZ CONVECTION SW. 

AT THE LOW LEVELS...A RIDGE EXTENDS FROM 30N140W TO 20N115W. A 
SERIES OF DRY COLD FRONTS WILL ROTATE AROUND THE NE PART OF THE 
RIDGE INTO THE DISCUSSION WITH NE SURFACE WINDS TO 20 KT...AND 
DRIVING N SWELLS TO 10 FT INTO THE NW PORTION INTO THIS WEEKEND. 
FURTHER S AND W OF 90W...SOUTHERLY SWELLS TO 9 FT AREA CROSSING 
THE EQUATOR REACHING TO ALONG 11N THEN SUBSIDING TO ABOUT 7 FT 
AS THEY APPROACH THE PACIFIC COAST CENTRAL AMERICA.  

$$
NELSON