000
AXPZ20 KNHC 121517
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC THU NOV 12 2009

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 LIES ALONG A LINE FROM... 
06N77W TO 06N120W TO 09N140W. SCATTERED MODERATE WITH ISOLATED 
STRONG CONVECTION IS WITHIN THE AREA NORTH OF 05N FROM 78W TO 
84W. SCATTERED MODERATE WITH ISOLATED STRONG CONVECTION IS 
WITHIN THE AREA FROM 06N TO 08N FROM 100W TO 105W. SCATTERED 
MODERATE CONVECTION IS WITHIN 75 NM EITHER SIDE OF THE ITCZ AXIS 
FROM 115W TO 130W. SCATTERED MODERATE TO STRONG CONVECTION IS 
WITHIN THE AREA FROM 12N TO 14N FROM 126W TO 130W.

...DISCUSSION...

A MOSTLY UPPER TROUGH EXTENDS ACROSS THE AREA WITH AN AXIS FROM 
NORTHEAST MEXICO GULF OF MEXICO COAST NEAR 25N TO 10N120W. NORTH 
AND WEST OF THIS TROUGH AXIS TO A LINE FROM NEAR 30N100W TO 
25N105W TO 25N123W TO 12N125W TO THE TROUGH AXIS AT 12N THE 
ATMOSPHERE IS DRY AND CLOUD FREE IN THE MIDDLE AND UPPER LEVELS. 
NORTH OF THIS DRY AREA UPPER MOISTURE IS PRESENT WITH THIN 
SCATTERED TO BROKEN UPPER CLOUDS. THROUGHOUT MOST OF THIS 
AREA NORTH OF THE TROUGH AXIS THE LOWER LEVELS ARE COVERED BY 
BROKEN TO OVERCAST STRATOCUMULUS CLOUDS WEST OF 117W. A 
DIMINISHING PLUME OF UPPER MOISTURE IS BEING ADVECTED 
NORTHEASTWARD FROM ITCZ CONVECTION WITHIN 100 NM EITHER SIDE OF 
LINE FROM 21N97W TO 15N105W TO 11N120W. WITHIN THIS PLUME ARE 
SOME THIN MOSTLY SCATTERED HIGH CLOUDS WITH SOME EMBEDDED 
CONVECTION. THE CONVECTION IS CONFINED TO SOUTH OF 14N.

A STRONG DEEP LAYER TROUGH EXTENDS FROM CENTRAL CALIFORNIA 
SOUTHWESTWARD ACROSS THE NORTHWEST PART OF THE PACIFIC OCEAN 
AREA. A NARROW DRY AREA MARKS THE TROUGH AND IS 200 NM NW OF A 
LINE THROUGH 32N129W TO 29N135W TO 28N140W. ASSOCIATED SURFACE 
TROUGH IS ALONG A LINE FROM NEAR THE CALIFORNIA MEXICO BORDER TO 
NEAR 25N140W. INCREASING NORTHEASTERLY WINDS ARE BEHIND THIS 
TROUGH. THE UPPER TROUGH IS FORECAST TO MOVE ACROSS THE NORTHERN 
PART OF THE PACIFIC AREA THROUGH THE NEXT SEVERAL DAYS.

A WEAKENING MOSTLY UPPER TROUGH EXTENDS FROM THE NORTHWEST 
CARIBBEAN ACROSS WESTERN HONDURAS TO A CYCLONIC CIRCULATION 
CENTER NEAR 12N100W. THE AREA OVER THE OCEAN AND CENTRAL AMERICA 
WEST OF THE TROUGH AXIS TO THE ABOVE MENTIONED MOISTURE PLUME IS 
DRY AND CLOUD FREE IN THE MIDDLE AND UPPER LEVELS. OVER NORTHERN 
CENTRAL AMERICA SOME LOW TO MIDDLE CLOUDS WITH SOME EMBEDDED LOW 
TOPPED CONVECTION IS NOTED. MORE EXTENSIVE CLOUDINESS EMANATING 
FROM ITCZ CONVECTION IS OVER PANAMA AND COSTA RICA.
 
REMAINDER OF THE MIDDLE AND UPPER LEVELS IS BROAD ANTICYCLONIC 
FLOW. 

WEAK SURFACE RIDGE IS NORTH OF 17N WEST OF 110W AND IS BUILDING 
OVER THE NORTHWEST PART OF THE AREA. REMAINDER OF THE AREA A 
BROAD TROUGH IS ANALYZED AT THE SURFACE.

GALE FORCE WINDS IN THE GULF OF TEHUANTEPEC REGION ARE FORECAST 
TO PERSIST THROUGH TODAY AND TONIGHT AND DIMINISH FURTHER 
FRIDAY.

$$
LL