000
AXPZ20 KNHC 300244
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC FRI OCT 30 2009

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 IS CENTERED ALONG THE LINE... 
05N77W TO 11N100W TO 11N120W TO 09N140W. SCATTERED MODERATE WITH 
ISOLATED STRONG CONVECTION IS WITHIN THE AREA FROM 06N TO 09N 
FROM 85W TO 91W. SCATTERED MODERATE TO STRONG CONVECTION IS 
WITHIN 60 NM OF THE POINT 11N100.5W.

...DISCUSSION...

STRONG DEEP LAYER TROUGH IS OVER MEXICO NORTH OF A LINE FROM THE 
RIO GRANDE NEAR 100W TO THE MEXICAN PACIFIC OCEAN COAST NEAR 
22N. THE TROUGH ALSO EXTENDS OVER THE NORTHEAST PART OF THE 
PACIFIC OCEAN AREA NORTH AND EAST OF A LINE THROUGH 32N122W TO 
22N115W TO 22N105W. THE TROUGH IS FORECAST TO PERSIST THROUGH 
MIDDAY FRIDAY THEN WEAKEN SOME AND MOVE EAST SATURDAY. A WEAKER 
MOSTLY UPPER TROUGH EXTENDS FROM THE MAIN TROUGH WEST SOUTHWEST 
OVER THE PACIFIC FROM NEAR THE COAST OF MEXICO AT 22N TO NEAR 
12N140W. MOST OF THE AREA NORTHWEST OF THE TROUGH IS DOMINATED 
BY A LARGE ANTICYCLONE CENTERED NEAR 30N140W. DRY MIDDLE AND 
UPPER LEVELS INDICATES SUBSIDENCE IN THIS LARGE AREA. IN THE 
LOWER LEVELS OVERCAST STRATOCUMULUS IS NORTH OF 17N WEST OF 132W 
AND BROKEN TO OVERCAST STRATOCUMULUS SOUTH OF 25N AND NORTH OF 
THE TROUGH TO THE EAST OF 130W. WITHIN 300 NM SOUTHEAST AND 
SOUTH OF THE WEAKER TROUGH THE ATMOSPHERE IS MOIST IN THE DEEP 
LAYER WITH MULTI LEVEL CLOUDS FROM MOISTURE EMANATING FROM ITCZ 
CONVECTION.

MOST OF THE REGION NORTH OF THE ITCZ EAST OF 105W AND SOUTHEAST 
OF THE ABOVE TROUGH IS DIFFLUENT ALOFT WITH DEEP LAYER MOISTURE 
WITH MULTI LEVEL CLOUDS AND EMBEDDED AREAS OF CONVECTION. WIDELY 
SCATTERED MODERATE WITH ISOLATED STRONG CONVECTION IS NORTH OF 
THE ITCZ FROM 95W TO 102W. THE CONVECTION EXTENDS NORTH TO THE 
COAST OF MEXICO. WITH SOUTHERLY DEEP LAYER FLOW OVER THIS REGION 
HEAVY RAINFALL IS POSSIBLE IN THE COASTAL AND NEARBY MOUNTAINOUS 
REGION OF MEXICO FROM 96W TO 104W.

A LARGE CYCLONIC CIRCULATION IS OVER THE WESTERN CARIBBEAN AND 
IS ASSOCIATED WITH DRY MIDDLE AND UPPER LEVELS AND CLEAR SKIES 
IN THE MIDDLE AND UPPER LEVELS. THIS FEATURE EXTENDS WESTWARD 
OVER NORTHERN CENTRAL AMERICA AND THE EASTERN PART OF MEXICO 
EAST OF 95W WITH SUPPRESSED CONVECTION OVER THIS AREA FROM 
NICARAGUA NORTH TO EAST MEXICO. THE CENTER OF THE CYCLONIC 
CIRCULATION IS APPROACHING NICARAGUA AND SOME MOISTURE FROM 
EARLIER CONVECTION IS OVER HONDURAS AND NICARAGUA. FURTHER EAST 
OVER THE PACIFIC OCEAN WITHIN THE ITCZ DIFFLUENT FLOW ALOFT IS 
ASSOCIATED WITH MULTI LEVEL CLOUDS AND EMBEDDED AREAS OF 
CONVECTION. 

MODERATE SURFACE RIDGE IS NORTH OF 15N WEST OF 115W. NORTH TO  
NORTHEAST WINDS ARE ASSOCIATED WITH THE RIDGE WITH 20 KNOTS 
WINDS. THESE WINDS ARE FORECAST TO CONTINUE TO DIMINISH TO LESS 
THAN 20 KT FRIDAY AS THE SURFACE HIGH WEAKENS AND CONTRACTS IN 
SIZE WHILE A COLD FRONT APPROACHES FROM THE NORTHWEST. WEAK 
SURFACE LOW IS NEAR 17N103W WITH A CENTRAL PRESSURE OF 1005 MB. 
THE LOW IS FORECAST TO BE STATIONARY. ELSEWHERE AT THE SURFACE A 
BROAD TROUGH IS ANALYZED.

$$
LL