000
AXPZ20 KNHC 310917
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC SAT OCT 31 2009

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

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0900 UTC.

...ITCZ...
AXIS ALONG 11N86W 12N95W 10N120W 6N140W. SCATTERED MODERATE 
ISOLATED STRONG CONVECTION WITHIN 150 NM OF S OF AXIS FROM
103W-110W. SCATTERED TO NUMEROUS MODERATE TO STRONG CONVECTION 
FROM 6N-11N BETWEEN 131W-135W.

...DISCUSSION...
AN UPPER LEVEL CYCLONIC CIRCULATION IS CENTERED NEAR 23N134W 
WITH A TROUGH EXTENDING FROM THE CYCLONIC CIRCULATION SW TO 
17N140W. AN UPPER LEVEL RIDGE IS BUILDING NW OF THE TROUGH OVER 
THE FAR NW PORTION OF THE AREA. A WEAK JETSTREAM IS SE OF THE 
TROUGH AXIS FROM 14N140W TO 20N124W. BROKEN CIRRUS CLOUDS ARE 
WITHIN 180 NM S OF THE JET AXIS. MODERATE TO STRONG SUBSIDENCE 
WITH DRY STABLE AIR AT THE MIDDLE AND UPPER LEVELS OF THE 
ATMOSPHERE IS NW OF THE JET EXCEPT FOR SOME LIMITED UPPER LEVEL 
MOISTURE MOVING SWD IN THE NLY FLOW BETWEEN THE UPPER RIDGE AND 
THE CYCLONIC CIRCULATION.

A LARGE ANTICYCLONIC CIRCULATION IS CENTERED OVER THE NORTHERN
BAJA PENINSULA NEAR 30N116W. DEEP LAYER TROUGH IS OVER NORTHERN 
MEXICO EXTEND FROM THE BIG BEND OF TEXAS ACROSS SOUTHERN BAJA 
CALIFORNIA TO 25N1115W. THE TROUGH IS FORECAST TO WEAKEN SOME 
AND MOVE E REACHING THE WESTERN GULF OF MEXICO LATER TODAY.

A BROAD UPPER LEVEL ANTICYCLONIC CIRCULATION IN THE DEEP TROPICS 
IS CENTERED NEAR 10N117W. ANTICYCLONIC FLOW COVERS THE AREA S OF 
20N BETWEEN 105W AND 130W. UPPER LEVEL DIVERGENCE IS ENHANCING
CONVECTIVE ACTIVITY ALONG THE ITCZ FROM 126W-131W. AN UPPER 
LEVEL CYCLONIC CIRCULATION IS LOCATED GUATEMALA. 

SURFACE RIDGE COVERS THE AREA N OF 15N W OF 115W. THE RIDGE IS 
SUPPORTING 20 KT ELY WINDS W OF AROUND 130W. BROKEN TO OVERCAST 
STRATOCUMULUS CLOUDS BLANKET THE AREA N OF 15N W OF 125W. 
SEVERAL TROUGHS ARE ANALYZED ALONG THE ITCZ. THE FIRST EXTENDS 
FROM A 1008 MB LOW PRES NEAR 10N96W TO 17N104W. THERE ARE A FEW
SHOWERS ALONG THE TROUGH N OF 14N. ANOTHER TROUGH WITH AXIS FROM 
11N115W TO 6N116W. NO SIGNIFICANT WEATHER IS ASSOCIATED WITH 
TROUGH. YET ANOTHER TROUGH EXTENDS FROM 13N121W TO 8N122W. NO
SIGNIFICANT WEATHER ASSOCIATED WITH THE TROUGH. ANOTHER TROUGH
EXTENDS FROM 11N127W TO 6N131W. SCATTERED TO NUMEROUS MODERATE
TO STRONG CONVECTION IS WITHIN 90 NM EITHER SIDE OF TROUGH.
AN FINALLY WEAK TROUGH FROM 9N137N TO 4N138W. A FEW SHOWERS ARE 
ALONG THE TROUGH.

HIGH PRES BUILDING SE ACROSS SOUTHERN MEXICO IN THE WAKE OF A 
COLD FRONT OVER THE WESTERN GULF OF MEXICO WILL INCREASE N-NE 
WINDS OF 20-30 KT THROUGH THE GULF OF TEHUANTEPEC BEGINNING LATE 
THIS AFTERNOON OR EARLY EVENING THEN INCREASING TO GALE FORCE 
EARLY SUN MORNING WITH SEAS BUILDING UP TO 15 FT.

$$
DGS