000
AXPZ20 KNHC 130257
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC SAT DEC 13 2008

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W. 

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0230 UTC.

...ITCZ...
THE INTERTROPICAL CONVERGENCE ZONE...ALSO KNOWN AS THE ITCZ...IS 
ALONG THE LINE...06N77W TO 07N105W TO 13N120W TO 07N140W.
SCATTERED MODERATE WITH ISOLATED STRONG CONVECTION IS WITHIN 40 
NM OF THE POINT 07.5N86W. SCATTERED MODERATE WITH ISOLATED 
STRONG CONVECTION IS WITHIN 100 NM OF THE POINT 11.5N121.5W. 
SCATTERED MODERATE CONVECTION IS WITHIN 60 NM OF THE POINT 
11N128W.

...DISCUSSION...

GAP WINDS...
NORTHERLY WINDS OF GALE FORCE CONTINUE TO FUNNEL THROUGH THE 
GULF OF TEHUANTEPEC AND IS FORECAST TO CONTINUE THROUGH MIDDAY 
SATURDAY. WINDS WILL THEN RAPIDLY DIMINISH TO LESS THAN 20 KT 
SATURDAY NIGHT.

NE WINDS OF 20 TO 25 KT CONTINUE TO AFFECT THE GULF OF PAPAGAYO 
AND DOWNSTREAM THROUGH 42 HOURS THEN FALL TO LESS THAN 20 KT BY 
MIDDAY SUNDAY.

ELSEWHERE...
SHARP DEEP LAYER SHORTWAVE IS MOVING RAPIDLY THROUGH THE 
SOUTHWEST UNITED STATES AND MEXICO NORTH OF 30N. THE AXIS 
EXTENDS THROUGH 32N114W TO 30N118W. MULTI LEVEL OVERCAST CLOUDS 
PRECEDE THE TROUGH WITH MARKED DRYING OF THE MIDDLE AND UPPER 
LEVELS WEST OF THE TROUGH AXIS. THIS FEATURE IS NEAR THE  
NORTHERN END OF A LARGE SCALE DEEP LAYER TROUGH AXIS WHICH IS 
ALONG THE LINE THROUGH 30N118W TO 10N135W TO 10N140W. A 
WEAKENING CYCLONIC CIRCULATION IS CENTERED NEAR 27N132W. WITHIN 
480 NM OVER THE EAST QUADRANT OF THE CIRCULATION THE MIDDLE AND 
UPPER LEVELS ARE MOIST BUT MOSTLY CLOUD FREE. THE REMAINDER OF 
THE AREA WEST OF THE LARGE SCALE TROUGH AXIS IS DRY AND CLOUD 
FREE IN THE MIDDLE AND UPPER LEVELS WITH BROKEN TO OVERCAST 
STRATOCUMULUS IN THE LOWER LEVELS MOSTLY NORTH OF 14N. EAST OF 
THE TROUGH AXIS A LARGE AREA OF UPPER MOISTURE AND MULTI LEVEL 
OVERCAST CLOUDS ARE FLOWING NORTHEASTWARD OVER MEXICO N OF 20N 
EASTWARD TO THE RIDGE LINE OF THE SIERRA MADRE OCCIDENTAL. THE 
UPPER MOISTURE HOWEVER EXTENDS ACROSS ALL OF MEXICO NORTH OF A 
LINE FROM 23.5N98W TO 20N105W. SOUTH OF THIS LINE THE AREA IS 
DRY AND MOSTLY CLOUD FREE IN THE MIDDLE AND UPPER LEVELS WITH 
BROKEN TO OVERCAST COLD AIR STRATOCUMULUS OVER THE AREA EAST OF 
97W. SOME ENHANCED CONVECTION IS NOTED IN THE ITCZ REGION EAST 
OF THE LARGE SCALE TROUGH AXIS TO 113W.

REMAINDER OF THE AREA IS UNDER WEAK ANTICYCLONIC FLOW.

OVERCAST TO BROKEN STRATOCUMULUS ARE SOUTH OF THE ITCZ EAST OF 
132W.

MODERATE RIDGE IS NORTH OF 17N WEST OF 118W. ELSEWHERE BROAD 
TROUGH IS ANALYZED.

$$
LL