000
AXPZ20 KNHC 111627
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC THU DEC 11 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 
1500 UTC.

...ITCZ...
ITCZ IS ALONG 06N77W TO 05N94W TO 09N103W TO 10N120W TO 07N140W. 
NUMEROUS STRONG CONVECTION N OF 05N AND E OF 83W. SCATTERED 
MODERATE ISOLATED STRONG CONVECTION WITHIN 90 NM S AND BETWEEN 
120 AND 240 NM N OF AXIS BETWEEN 114W AND 123W.

...DISCUSSION...
PERSISTENT MID/UPPER LEVEL CYCLONIC CIRCULATION HAS BECOME 
ELONGATED WITH MAIN CENTER NEAR 27N128W WITH TROUGH FROM THE 
CIRCULATION TO 23N140W...WITH A WEAK INVERTED TROUGH REFLECTED 
DOWN TO THE SURFACE. SCATTERED MODERATE CONVECTION PERSISTING 
WITHIN 360 NM NE OF THE CYCLONIC CIRCULATION IS EXPECTED TO 
DIMINISH AS THE LOW CONTINUES TO FILL. DOWNSTREAM BLOCKING UPPER 
LEVEL RIDGE WITH AXIS FROM ANTICYCLONIC CENTER NEAR 14N106W NW 
TO JUST OFFSHORE OF THE COAST OF BAJA CALIFORNIA AND THEN TO 
COASTAL SOUTHERN CALIFORNIA. TROUGH-RIDGE-TROUGH PATTERN 
EXTENDING FROM THE EASTERN PACIFIC ACROSS THE CENTRAL U.S. HAS 
DRIFTED SLIGHTLY EASTWARD IN THE PAST 12 HOURS. BROKEN/OVERCAST 
MID AND HIGH CLOUDS BEING SHEARED N AND NE FROM TROPICAL 
CONVECTION ALONG AND N OF THE ITCZ COVER THE AREA BETWEEN THE 
RIDGE AND UPPER TROUGH. UPPER-LEVEL TROUGH EXTENDS FROM DEEP 
LAYERED LOW ALONG NORTH COASTAL GULF OF MEXICO TO HONDURAS TO A 
CYCLONIC CIRCULATION NEAR 03N98W...AND SUPPORTS A STRONG COLD 
FRONTAL SYSTEM. COLD MODIFIED ARCTIC AIR SPILLING INTO THE WEST 
HALF OF THE GULF OF MEXICO BEHIND THE FRONTAL BOUNDARY IS 
ENHANCING THE STRONG N FLOW FUNNELING ACROSS SE MEXICO AND INTO 
THE GULF OF TEHUANTEPEC...WITH A MORNING QUIKSCAT PASS 
INDICATING WINDS 40 TO 55 KT DIRECTLY DOWNWIND. LITTLE CHANGE IN 
THIS STRONG TEHUANTEPEC EVENT IS EXPECTED DURING THE NEXT 12 
HOURS...WITH THE EVENT GRADUALLY WINDING DOWN THEREAFTER. THE 
FRONT SHOULD EVEN SURGE THROUGH PARTS OF CENTRAL AMERICA LATER 
TODAY AND EARLY FRI...CAUSING NE FLOW TO INTENSIFY NEAR AND 
DOWNWIND OF THE GULF OF PAPAGAYO.

SURFACE TROUGH IS ANALYZED ALONG THE ITCZ FROM 07-14N ALONG 
120W. SCATTERED SHOWERS AND ISOLATED TSTMS ARE WITHIN 80 NM OF 
THE TROUGH. OTHERWISE SURFACE HIGH PRES RIDGE DOMINATES THE AREA 
N OF 17NW OF 115W. AN ENHANCED LOW-LEVEL SUBTROPICAL RIDGE OVER 
THE WESTERN HALF OF THE AREA...GENERALLY FROM 11N TO 24N W OF 
125W FAVORS SCATTERED NE TO E WINDS OF 20 KT AND SEAS OF 8 TO 
POSSIBLY 11 FT IN E SWELL.
 
$$
STRIPLING/KIMBERLAIN