000
AXPZ20 KNHC 191520
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC SUN OCT 19 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 ITCZ AXIS IS ALONG THE LINE FROM 06N77W TO 07N105W TO 
08N140W. SCATTERED MODERATE WITH ISOLATED STRONG CONVECTION IS 
WITHIN 120 NM OF THE POINT 06N80W. OTHERWISE THERE IS NOT MUCH 
CONVECTION ALONG THE ITCZ.

...DISCUSSION...

THE STRONG SURFACE PRESSURE GRADIENT OVER SOUTHERN MEXICO 
BETWEEN HIGH PRESSURE OVER THE WESTERN GULF OF MEXICO AND 
NORTHERN MEXICO AND BROAD LOW PRESSURE WHICH EXTENDS FROM THE 
GULF OF HONDURAS SOUTHWESTWARD TOWARD A LOW PRESSURE CENTER NEAR 
11N94W IS INDUCING A GALE FORCE WIND EVENT IN THE GULF OF 
TEHUANTEPEC WHICH SHOULD PERSIST THROUGH 48 HOURS. FORECAST 
GUIDANCE AGREES ON MOVING THE PACIFIC LOW PRESSURE SYSTEM 
WESTWARD THROUGH THE REGION OF MODERATE TO STRONG DEEP LAYERED 
NORTHEAST FLOW.  THIS SHOULD LIMIT THE DEVELOPMENT OF DEEP 
CONVECTION ASSOCIATED WITH THE LOW.

UPPER LEVEL DIFFLUENCE BETWEEN AN ANTICYCLONE OVER THE CARIBBEAN 
AND RELATIVELY STRONG EASTERLY FLOW S OF 10N E OF 90W SHOULD 
PERSIST TODAY...ALLOWING FOR ENHANCED CONVECTION OVER THE 
REGION.  CURRENTLY...SCATTERED MODERATE WITH ISOLATED STRONG 
CONVECTION CAN BE FOUND WITHIN 120 NM OF THE POINT 06N80W.

OVER NW WATERS...DEEP LAYER TROUGH STRETCHED OVER NW WATERS 
NORTH OF A LINE THROUGH 32N115W TO 18N140W. THE TROUGH WILL PASS 
EASTWARD INTO THE BAJA LATER TODAY AS IT IS INCORPORATED IN THE 
MIDDLE LATITUDE WESTERLIES. THE TROUGH WILL LEAVE BEHIND SOME 
MID LEVEL VORTICITY NORTH OF 25N THROUGH THE NEXT SEVERAL DAYS.
THIS FLOW PATTERN WILL CARRY THE MOISTURE ASSOCIATED WITH 
WEAKENING CONVECTION IN THE WESTERN PORTIONS OF THE ITCZ. THE 
AREA OF THE TROUGH IS CLOUD FREE IN THE MIDDLE AND UPPER LEVELS 
WITH BROKEN TO OVERCAST STRATOCUMULUS IN THE LOWER LEVELS. 

BROKEN TO OVERCAST STRATOCUMULUS IN THE LOWER LEVELS IS ALSO 
FOUND SOUTH OF THE ITCZ WITH CLEAR SKIES IN THE MIDDLE AND UPPER 
LEVELS.

MODERATE SURFACE RIDGE IS NORTH OF ABOUT 12N WEST OF 110W. THIS 
RIDGE IS FORECAST TO CHANGE LITTLE THROUGH 48 HOURS. ELSEWHERE 
...EXCEPT FOR THE LOW NEAR 11N94W A BROAD TROUGH IS ANALYZED.

$$
LL