000
AXPZ20 KNHC 251520
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC THU DEC 25 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...
THE INTERTROPICAL CONVERGENCE ZONE AXIS IS ALONG THE 
LINE...05N77W TO 06N105W TO 09N120W TO 07N130W TO 06N140W.
SCATTERED MODERATE WITH ISOLATED STRONG CONVECTION IS WITHIN 60 
NM EITHER SIDE OF THE ITCZ FROM 79W TO 83.5W. SCATTERED MODERATE 
CONVECTION IS WITHIN 60 NM EITHER SIDE OF THE ITCZ FROM 113W TO 
118W.

...DISCUSSION...
DEEP LAYER TROUGH IS OVER THE AREA NORTH OF 25N. A STRONG 
SHORTWAVE IS MOVING EAST 25 KNOTS OVER NORTHWEST MEXICO. 
CLOUDINESS ASSOCIATED WITH THIS FEATURE IS LIMITED AND MOSTLY 
MIDDLE AND HIGH CLOUDS OVER NORTHWESTERN MEXICO.  THE TROUGH IS 
FORECAST TO REMAIN STATIONARY DURING THE NEXT 48 HOURS BUT 
SLOWLY WEAKEN. AFTER 48 HOURS THE TROUGH IS FORECAST CONTINUE TO 
WEAKEN SLOWLY AND TO MOVE EAST OVER NORTHERN MEXICO WITH A WEAK 
RIDGE REPLACING THE TROUGH OVER THE PACIFIC OCEAN AREA.

THE LONG LIVED CUTOFF LOW CENTERED WEST OF THE AREA NEAR 16N151W 
CONTINUES TO WEAKEN SLIGHTLY AND TO MOVE WESTWARD. THE 
CIRCULATION IS FORECAST TO DRIFT A LITTLE WEST IN THE NEXT 24 
HOURS THEN WEAKEN THEREAFTER. BROAD SOUTHERLY FLOW TO THE EAST 
OF THE CIRCULATION CONTINUES TO ADVECT MOIST MIDDLE AND UPPER 
LEVEL AIR FROM THE ITCZ OVER THE AREA WEST OF 134W SOUTH OF 20N. 
AN AREA OF EMBEDDED CONVECTION IS NOTED WITHIN THIS FLOW WITH 
SCATTERED MODERATE WITH ISOLATED STRONG CONVECTION WITHIN 90 NM 
OF THE POINT 13.5N138W.

REMAINDER OF THE AREA IS UNDER BROAD ANTICYCLONIC FLOW...WITH A 
RIDGE EXTENDING FROM A HIGH CENTERED JUST EAST OF FLORIDA ACROSS 
SOUTHERN MEXICO/NORTHERN CENTRAL AMERICA AND TO NEAR 13N130W. 
THIS FEATURE IS FORECAST TO REMAIN WEAK BUT SLOWLY EXPAND OVER 
THE ENTIRE AREA BY SUNDAY AND MONDAY.

EXCEPT FOR MOISTURE EAST OF 84W...DUE TO ITCZ CONVECTION...THE 
AREA EAST OF 110W IS DRY AND CLOUD FREE IN THE MIDDLE AND UPPER 
LEVELS WITH ONLY AREAS OF SCATTERED LOW CLOUDS NORTH OF THE ITCZ 
AND BROKEN TO OVERCAST STRATOCUMULUS CLOUDS SOUTH OF THE ITCZ IN 
THE LOWER LEVELS.

WEAK SURFACE TROUGH IS OVER THE NORTHEAST PART OF THE PACIFIC 
OCEAN FROM 32N116W TO 27N119W. THIS FEATURE IS ASSOCIATED WITH 
THE SHORTWAVE MOVING OVER NORTHWEST MEXICO. A MODERATE SURFACE 
RIDGE IS BUILDING OVER THE NORTHWEST PART OF THE PACIFIC OCEAN. 
ELSEWHERE N OF ABOUT 15N WEST OF 120W AND NORTH OF 20N EAST OF 
120W A WEAK RIDGE IS ANALYZED AT THE SURFACE. ELSEWHERE A BROAD 
TROUGH IS ANALYZED AT THE SURFACE.

GAP WINDS WILL CONTINUE THROUGH AT LEAST 48 HOURS IN THE GULF OF 
PAPAGAYO REGION OF ABOUT 20 TO 25 KT. THE FLOW WILL BE STRONGER 
AT NIGHT WITH WINDS OF 20 KNOTS DURING THE DAY. THIS LIMITED 
FETCH WILL KEEP THE SEAS TO 8 FEET OR LESS.

GULF OF CALIFORNIA...LOW LEVEL WINDS WILL BECOME SOUTHERLY OVER 
THE NORTHERN GULF OF CALIFORNIA AHEAD OF THE TROUGH FRI AND 
SHIFT TO THE NNW AT 15 TO 20 KT ON SAT...FURTHER INCREASING TO 
20 TO 25 KT THROUGHOUT THE ENTIRE GULF OF CALIFORNIA BY LATE 
SUN. GLOBAL MODELS SUGGEST SURFACE PRES OVER THE W UNITED STATES 
COULD POSSIBLE TRIGGER LOCALIZED NEAR GALE WINDS OVER THE  
NORTHERN GULF OF CALIFORNIA SUNDAY.

$$
LL