000
AXPZ20 KNHC 280933
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC THU AUG 28 2008

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 
0915 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE ALONG 98W N OF 10N IS MOVING W AT 10 KT. A LOW- 
TO MID-LEVEL CYCLONIC TURNING IS EVIDENT IN NIGHTTIME VISIBLE 
SATELLITE IMAGERY ALONG THE NORTHERN END OF THE WAVE IN THE 
VICINITY OF THE GULF OF TEHUANTEPEC. GLOBAL MODELS DRAG THIS 
FEATURE INLAND OVER SW MEXICO AND DISSIPATE IT...WHICH SHOULD 
PRECLUDE ANY DEVELOPMENT. BESIDES...SIMILAR TO THE LAST FEW 
DAYS...AN ANOMALOUS AND PERSISTENT LOW-LEVEL SW TO W FLOW 
DOMINATES THE TROPICAL EAST PACIFIC W OF 110W WITH NO EASTERLY 
TRADES. THIS PATTERN DOES NOT FAVOR TROPICAL CYCLOGENESIS.
ISOLATED TO SCATTERED CONVECTION ASSOCIATED WITH THE WAVE DOTS 
THE AREA N OF 14N BETWEEN 94W AND 98W AND IS ALSO ENHANCING 
CONVECTION OVER THE ITCZ TO THE S.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 09N85W TO 12N98W TO 16N116W TO 
10N127W TO 10N140W. SCATTERED MODERATE ISOLATED STRONG 
CONVECTION WITHIN 240 NM S OF AXIS BETWEEN 83W AND 101W. 
SCATTERED MODERATE CONVECTION IS WITHIN 120 NM N AND 60 NM S 
OF AXIS BETWEEN 122W AND 140W. 

NUMEROUS STRONG WITHIN 90 NM EITHER SIDE OF AXIS FROM 13N105W TO 
16N108.5W. 

NUMEROUS STRONG N OF 21N E OF 107W.

...DISCUSSION...

A SHORTWAVE TROUGH...WHICH PASSED THROUGH THE NW CONUS A FEW 
DAYS AGO...HAS LEFT BEHIND AN ANOMALOUSLY STRONG SURFACE RIDGING 
OVER THE NE PACIFIC...N OF THE AREA.  THE SUDDEN INCREASE IN 
PRESSURE HAS RESULTED IN AN ENHANCED NW TO N FLOW DIRECTLY 
OFFSHORE THE CALIFORNIA COAST FOR THE PAST 24 TO 36 HOURS...WITH 
A LARGE AREA OF GALE OR NEAR-GALE CONDITIONS STILL BEING 
REPORTED. THE ENHANCED NW TO NW FLOW VEERS MORE NE OVER THE NW 
WATERS...WHERE RECENT QUIKSCAT IMAGERY REVEALED SPOTTY NE 20 KT 
WINDS. THE STRONG WINDS ARE CREATING LONG PERIOD NW TO N 
SWELL...WHICH CONTINUES TO ARRIVE OFF OF THE WATERS W OF THE 
BAJA CALIFORNIA PENINSULA.  THE SWELL BECOMES NE OVER THE FAR NW 
WATERS...WITH WAVE HEIGHTS OF UP TO 8 OR 9 FT.

LATE THIS WEEKEND...A DYNAMIC AND DEEP SHORTWAVE TROUGH IS 
FORECAST TO BEGIN DIGGING INTO THE WESTERN CONUS...WHICH SHOULD 
DRIVE A STRONG COLD FRONT UNUSUALLY FAR S OVER THE NORTHERN 
WATERS OF THE E PACIFIC. AFTER THE FRONT PASSES...N TO NE FLOW 
OF 20 AND PERHAPS UP TO 25 KT SHOULD OVERSPREAD THE AREA N OF 
27N...WITH THE HIGHEST WINDS LIKELY CLOSER TO 30N. NORTHERLY 
SWELL FROM OFFSHORE THE W COAST OF THE U.S. SHOULD TRAVEL 
SOUTHWARD AND ENTER THIS SAME AREA...WITH A LARGE AREA OF 8 TO 
12 FT SEAS LIKELY. THE SWELL TRAIN WILL BE SO SIGNIFICANT THAT 
IT WILL ALSO LIKELY REACH AS FAR S AS THE WESTERN END OF THE 
ITCZ OVER THE E PACIFIC BY LATE SUN.

ELSEWHERE...QUIKSCAT AND ASCAT DATA INDICATE SOUTHERLY WINDS OF 
UP TO 20 KT S OF THE ITCZ BETWEEN 90W AND 110W. THESE WINDS ARE 
EXPECTED TO PERSIST FOR ANOTHER DAY OR TWO AT THE SAME TIME LONG 
PERIOD SW SWELL FROM THE SOUTHERN HEMISPHERE CONTINUES TO ARRIVE 
OVER THE FAR SOUTHERN WATERS. THE SWELL SHOULD REMAIN FAIRLY 
STEADY BUT THEN INCREASE LATER THIS WEEKEND...AS ANOTHER 
SIGNIFICANT SWELL TRAIN CROSSES THE EQUATOR. WAVE HEIGHTS SHOULD 
BUILD UP TO 8 TO 10 FT FROM THE SW COAST OF MEXICO SW TO 01N140W.

$$
KIMBERLAIN