000
AXNT20 KNHC 171126
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL  
805 AM EDT SAT OCT 17 2009

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL 
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS
OF SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST
FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED
ON SATELLITE IMAGERY...METEOROLOGICAL ANALYSIS...WEATHER 
OBSERVATIONS...AND RADAR.

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 1000 UTC.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 76W/77W S OF 17N MOVING W NEAR 15 KT. 
WAVE COINCIDES WITH A SURGE OF DEEP LAYER MOISTURE OBSERVED IN 
TOTAL PRECIPITABLE WATER IMAGERY. ISOLATED MODERATE CONVECTION 
FROM 11N-14N BETWEEN 75W-77W. SCATTERED STRONG CONVECTION IS 
FROM 9N-11N BETWEEN 77W-81W. THIS LATTER ACTIVITY MAY BE 
ASSOCIATED MORE WITH A PORTION OF THE E PACIFIC ITCZ EXTENDING 
ACROSS PANAMA.

...THE ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 10N14W 7N28W 8N44W 9N62W. THE 
ITCZ REMAINS ACTIVE THIS MORNING WITH SCATTERED MODERATE/STRONG 
CONVECTION WITHIN 200 NM OF THE AXIS BETWEEN 12W-30W. SCATTERED 
MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 100 NM OF THE AXIS 
BETWEEN 30W-38W. A LINE OF SCATTERED MODERATE/ISOLATED STRONG 
CONVECTION RUNS FROM 14N27W TO 11N43W. A SURFACE TROUGH IS 
EMBEDDED WITHIN THE ITCZ ALONG 47W/48W FROM 6N-11N. SCATTERED 
MODERATE/STRONG CONVECTION IS NEAR THE TROUGH AXIS FROM 6N-11N 
BETWEEN 45W-53W.

...DISCUSSION...

THE GULF OF MEXICO...
AS OF 0900 UTC...A COLD FRONT EXTENDS FROM THE WRN ATLC ACROSS 
FLORIDA ENTERING THE GULF OF MEXICO NEAR NAPLES AT 26N82W 
CONTINUING ALONG 24N90W BECOMING STATIONARY NEAR 23N96W TO N OF 
TAMPICO MEXICO NEAR 24N98W. SCATTERED SHOWERS/THUNDERSTORMS ARE 
WITHIN 100 NM BEHIND THE FRONT AND 25 NM AHEAD OF THE FRONT. AN 
UPPER LEVEL TROUGH OVER THE ERN CONUS EXTENDS OVER THE NRN GULF 
N OF 24N SUPPORTING THE FRONT. AN UPPER LEVEL RIDGE EXTENDING 
FROM MEXICO COVERS THE SW GULF. ISOLATED SHOWERS/THUNDERSTORMS 
ARE ALSO OVER THE FAR SW GULF S OF 22N W OF 92W. SURFACE WINDS 
OF 20 TO 25 KT ARE BEHIND THE FRONT. EXPECT THE FRONT TO 
CONTINUE MOVING SE ACROSS THE GULF REACHING THE STRAITS OF 
FLORIDA BY LATE TONIGHT AND INTO SUN. HIGH PRESSURE WILL BUILD 
IN THE WAKE OF THE FRONT.

THE CARIBBEAN SEA...
A TROPICAL WAVE ALONG 76W/77W IS SUPPORTING ISOLATED 
SHOWERS/THUNDERSTORMS ACROSS PORTIONS OF THE WRN CARIBBEAN. SEE 
ABOVE. A FEW ISOLATED SHOWERS/POSSIBLE THUNDERSTORMS ALSO REMAIN 
IN THE CENTRAL CARIBBEAN FROM 14N-16N BETWEEN 71W-74W. A SURFACE 
TROUGH IS ANALYZED IN THE ERN CARIBBEAN ALONG 65W FROM 9N-16N. 
ISOLATED SHOWERS ARE POSSIBLE NEAR THE TROUGH AXIS. IN THE UPPER 
LEVELS...AN UPPER LEVEL INVERTED TROUGH EXTENDS FROM NICARAGUA 
NEAR 14N86W TO THE WINDWARD PASSAGE NEAR 20N74W CONTINUING E TO 
20N67W. AN UPPER LEVEL RIDGE COVERS THE CENTRAL AND ERN 
CARIBBEAN CENTERED NEAR 13N71W. DIFFLUENT FLOW ALOFT BETWEEN THE 
UPPER TROUGH AND UPPER RIDGE IS SUPPORTING SCATTERED 
SHOWERS/THUNDERSTORMS IN THE SW CARIBBEAN S OF 11N 77W-81W NEAR 
THE TROPICAL WAVE AND E PACIFIC ITCZ. MODERATE TO FRESH TRADE 
WINDS ARE ACROSS MUCH OF THE BASIN. EXPECT THE TROPICAL WAVE IN 
THE WRN CARIBBEAN TO CONTINUE WWD.

THE ATLANTIC OCEAN...
AS OF 0900 UTC...A COLD FRONT ENTERS THE DISCUSSION AREA NEAR 
32N74W EXTENDING SW TO NEAR WEST PALM BEACH FLORIDA CONTINUING 
INTO THE GULF OF MEXICO. SCATTERED SHOWERS/THUNDERSTORMS ARE 
WITHIN 150 NM AHEAD OF THE FRONT. A PRE-FRONTAL TROUGH IS AHEAD 
OF THE FRONT ALONG 30N73W TO 25N82W ASSOCIATED WITH A LINE OF 
STRONG SHOWERS/THUNDERSTORMS. AN UPPER LEVEL TROUGH OVER THE ERN 
CONUS EXTENDING OVER THE WRN ATLC SUPPORTS THE FRONTAL SYSTEM. 
THE REMAINDER OF THE WRN ATLC IS DOMINATED BY A BROAD SURFACE 
RIDGE ANCHORED BY A 1020 MB HIGH NEAR 28N53W SUPPORTED BY AN 
UPPER LEVEL HIGH CENTERED NEAR 25N60W. FARTHER E...ANOTHER COLD 
FRONT ENTERS THE DISCUSSION AREA NEAR 32N35W ALONG 27N38W 
23N45W. ISOLATED SHOWERS ARE OUT AHEAD OF THE FRONT N OF 26N 
BETWEEN 31W-34W. A CLUSTER OF SHOWERS ARE ALSO AT THE TAIL END 
OF THE FRONT NEAR 23N45W. THE FRONT IS SUPPORTED BY AN UPPER 
LEVEL TROUGH ALONG 34W. A WEAK 1014 MB SURFACE LOW IS NEAR 
26N30W. A SURFACE TROUGH EXTENDS THROUGH THE LOW ALONG 29N28W 
23N31W 18N35W. ISOLATED SHOWERS ARE FROM 27N-30N BETWEEN 
23W-26W. THIS SYSTEM IS SUPPORTED BY ANOTHER UPPER LEVEL TROUGH 
EXTENDING FROM AN UPPER LOW NEAR 35N20W TO 13N33W. DIFFLUENCE 
ALOFT OVER THE TROPICAL ATLC IS SUPPORTING THE 
SHOWERS/THUNDERSTORMS ALONG THE ITCZ AXIS.

$$
WALTON