000
AXPZ20 KNHC 092132
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC TUE DEC 09 2008

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

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2100 UTC.

...ITCZ...
THE INTERTROPICAL CONVERGENCE ZONE IS ALONG THE LINE...06N77W TO 
06N110W TO 08N120W TO 08N140W. SCATTERED MODERATE CONVECTION IS  
WITHIN 75 NM OF THE POINT 06N79W. SCATTERED MODERATE TO STRONG 
CONVECTION IS WITHIN A LARGE AREA OF ABOUT 180 NM OF THE POINT 
08.5N115.5W. SCATTERED MODERATE CONVECTION IS WITHIN 75 NM OF 
THE POINT 09N121W.

...DISCUSSION...
DEEP LAYER TROUGH IS OVER MEXICO NORTH OF ABOUT 23N. LARGE SCALE 
SUBSIDENCE IS WITHIN THIS AREA WITH DRY AND CLOUD FREE 
CONDITIONS OBSERVED IN THE MIDDLE AND UPPER LEVELS. EXCEPT FOR 
SOME SCATTERED TO BROKEN CLOUDS TO THE WEST OF THE RIDGE OF THE 
SIERRA MADRE OCCIDENTAL THE LOWER LEVELS ARE ALSO CLOUD FREE. 
THE TROUGH IS FORECAST TO REMAIN IN PLACE AND EVEN EXTEND 
SOUTHWARD TO COVER ALL OF MEXICO IN 48 HOURS.

A DEEP LAYER CYCLONIC CIRCULATION IS CENTERED NEAR 21N136W. AN 
ASSOCIATED TROUGH EXTENDS FROM NEAR 20N125W TO THE ITCZ NEAR 
137W. A LARGE AREA OF DIFLUENT UPPER FLOW EXTENDS 800 NM EAST OF 
THE TROUGH WITH MULTI LEVEL OVERCAST CLOUDS THAT ORIGINATED FROM 
ITCZ CONVECTION. ANOTHER BROAD AREA OF UPPER MOISTURE AND BROKEN 
MULTI LEVEL CLOUDS EXTENDS WITHIN 800 NM OF THE CYCLONIC 
CIRCULATION IN THE NORTHEAST SEMICIRCLE. THIS FEATURE IS 
FORECAST TO WEAKEN BUT REMAIN IN PLACE THROUGH 48 HOURS.

SURFACE LOW PRESSURE NEAR 13N129W 1009 MB IS ASSOCIATED WITH THE 
UPPER CIRCULATION. MODERATE SURFACE RIDGE IS NORTH OF 18N WEST 
OF BAJA CALIFORNIA AND WEST OF 105W FROM 23N TO 18N. NORTHEAST 
TO EAST WINDS OF 20 TO 25 KNOTS BETWEEN THIS RIDGE AND THE LOW 
PRESSURE COVER THE AREA FROM 11N TO 25N WEST OF 118W.

OTHERWISE BROAD SURFACE TROUGH IS ANALYZED OVER THE AREA.

GAP WINDS ACROSS ISTHMUS OF TEHUANTEPEC WILL BEGIN LATE 
WEDNESDAY AND RAPIDLY INCREASE TO GALE FORCE WEDNESDAY NIGHT.
 
$$
LL