000
AXPZ20 KNHC 081521
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC SUN NOV 08 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 IS ALONG THE LINE...07N77W TO 
07N100W TO 10N110W TO 10N120W TO 09N140W. SCATTERED MODERATE 
WITH ISOLATED STRONG CONVECTION IS WITHIN 90 NM OF THE POINT 
10N107W. SCATTERED MODERATE WITH ISOLATED STRONG CONVECTION IS 
WITHIN 60 NM OF THE POINT 14N116.5W. SCATTERED MODERATE WITH 
ISOLATED STRONG CONVECTION IS WITHIN 60 NM EITHER SIDE OF THE 
ITCZ AXIS FROM 119W TO 135W.

...DISCUSSION...

DEEP LAYER SHORTWAVE IS OVER NORTH MEXICO. THE SYSTEM IS MOVING 
EAST AND WEAKENING AND WILL CROSS INTO TEXAS LATER TODAY. MULTI 
LEVEL BROKEN TO OVERCAST CLOUDS ARE OVER MEXICO NEAR THE RIO 
GRANDE. SOME LIGHT RAIN MAY BE EMBEDDED WITHIN THE CLOUD AREA. 

A MOSTLY UPPER TROUGH EXTENDS ACROSS THE AREA WITH AN AXIS FROM 
SOUTHERN BAJA CALIFORNIA TO 21N130W THEN SOUTH TO 11N140W. THE 
WESTERN PART OF THIS FEATURE IS PART OF A LARGE UPPER LEVEL 
CYCLONIC CIRCULATION MOSTLY WEST OF THE AREA. NORTH AND WEST OF 
THIS TROUGH AXIS TO A LINE FROM 30N110W TO 25N140W THE 
ATMOSPHERE IS DRY AND CLOUD FREE IN THE MIDDLE AND UPPER LEVELS. 
NORTH OF THIS DRY AREA SOME UPPER MOISTURE IS PRESENT WITH SOME 
THIN BROKEN MOSTLY UPPER CLOUDS. THROUGHOUT MOST OF THIS AREA 
NORTH OF THE TROUGH AXIS THE LOWER LEVELS ARE COVERED BY BROKEN 
TO OVERCAST STRATOCUMULUS CLOUDS. W OF 116W SOUTH OF THE TROUGH 
AXIS A PLUME OF UPPER MOISTURE IS BEING ADVECTED NORTHEASTWARD  
WITH THIN BROKEN MOSTLY UPPER CLOUDS.

A SHARP MOSTLY UPPER TROUGH CONTINUES FROM THE WESTERN GULF OF 
MEXICO ACROSS THE EASTERN PART OF THE ISTHMUS OF TEHUANTEPEC 
CONTINUING TO THE ITCZ NEAR 90W. OUTSIDE THE ITCZ THE AREA OVER 
THE OCEAN AND MEXICO WEST OF THE TROUGH AXIS IS DRY AND CLOUD 
FREE IN THE MIDDLE AND UPPER LEVELS. OVER EASTERN MEXICO AND 
GUATEMALA AND BELIZE AND WESTERN HONDURAS MULTI LEVEL CLOUDS ARE 
PRESENT WITH SOME EMBEDDED CONVECTION. THIS CONVECTION 
IS ASSOCIATED WITH A WEAK LOW THAT HAS BEEN OFF THE COAST OF 
GUATEMALA FOR THE LAST SEVERAL DAYS AND IS NOW MOVING INLAND.  
THE LOW IS FORECAST TO DRIFT NORTH AND THE STRONG SOUTHERLY DRY 
FLOW OVER THE LOW SHOULD PRECLUDE ANY DEVELOPMENT OF THE LOW.

LOW NEAR 11N119W WITH A CENTRAL PRESSURE OF 1007 MB IS MOVING 
SLOWLY WEST. CONVECTION HAS BEEN OCCASIONALLY DEVELOPING NEAR 
THE CENTER AND IS ORGANIZED BY THE LOW LEVEL CIRCULATION. THE 
LOW IS NEAR THE ITCZ AND THIS IS NOT A FAVORABLE CONDITION FOR 
DEVELOPMENT. THE COMPUTER MODELS WEAKEN THE SYSTEM AS IT SLOWLY 
MOVES WEST.
 
ANOTHER LOW NEAR THE ITCZ IS LOCATED NEAR 11N110W WITH A CENTRAL 
PRESSURE OF 1010 MB. THIS FEATURE HAS ALSO OCCASIONALLY HAD 
CONVECTION DEVELOP NEAR THE CENTER BUT HAS NOT BEEN ORGANIZED BY 
THE LOW LEVEL CIRCULATION. THE LOW IS FORECAST TO TRANSITION TO 
A TROUGH TODAY AND DRIFT WEST.
 
REMAINDER OF THE MIDDLE AND UPPER LEVELS IS BROAD ANTICYCLONIC 
FLOW.

MODERATE SURFACE RIDGE IS NORTH OF 15N WEST OF 113W. ELSEWHERE 
BESIDES THE LOWS MENTIONED ABOVE A BROAD TROUGH IS ANALYZED AT 
THE SURFACE.

WINDS HAVE DIMINISHED IN THE GULF OF TEHUANTEPEC REGION TO LESS 
THAN GALE FORCE AND ARE FORECAST TO DIMINISH TO LESS THAN 20 KT 
THIS AFTERNOON. AS HIGH PRESSURE BUILDS OVER THE WESTERN GULF 
WEST OF IDA GAP WINDS WILL BEGIN AGAIN MONDAY NIGHT.

$$
LL