000
AXNT20 KNHC 291744
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL  
205 PM EDT THU OCT 29 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1715 UTC.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 30W/31W S OF 19N WITH A 1014 MB LOW ALONG 
THE WAVE NEAR 15N MOVING W NEAR 10 KT. SATELLITE IMAGERY CLEARLY 
SHOWS THE LOW LEVEL CIRCULATION ALONG THE WAVE AXIS WITH THE 
WAVE AXIS AT THE PEAK OF A MOISTURE MAXIMUM AS INDICATED BY THE 
TOTAL PRECIPITABLE WATER IMAGERY. CLUSTERS OF SCATTERED 
MODERATE/ISOLATED STRONG CONVECTION ARE FROM 14N-20N BETWEEN 
30W-33W.

TROPICAL WAVE IS ALONG 57W S OF 16N MOVING W 10-15 KT. ANY LOW 
LEVEL SIGNATURE IS OBSCURED BY CIRRUS CLOUDS AS WAVE IS LOCATED 
BENEATH AN UPPER RIDGE. ANY CONVECTION IS S OF THE ITCZ AXIS. 

TROPICAL WAVE IS ALONG 69W/70W S OF 17N MOVING W 10-15 KT. 
CARIBBEAN IS DOMINATED BY DEEP LAYERED MOISTURE OF WHICH THE 
WAVE IS EMBEDDED WITH POSITION BASED ON PERSISTENCE. EVEN WITH 
DEEP MOISTURE THERE IS NO ASSOCIATED SHOWERS/CONVECTION. 

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 10N12W 6N21W 10N46W 10N62W. 
CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE 
WITHIN 120 NM OF THE ITCZ FROM 17W-27W AND FROM 32W-43W AND S OF 
THE ITCZ AXIS W OF 50W TO INLAND OVER SOUTH AMERICA. 

...DISCUSSION...

GULF OF MEXICO...
THE QUASI-STATIONARY FRONT REMAINS ACROSS THE N GULF FROM THE W 
ATLC OVER THE FLORIDA PANHANDLE FROM JACKSONVILLE TO PANAMA CITY 
CONTINUING W OVER SE LOUISIANA NEAR NEW ORLEANS AS A WARM FRONT. 
MOST OF THE UPPER LEVEL SUPPORT FOR THIS FRONT HAS MOVED E INTO 
THE W/CENTRAL ATLC AND THE LINGERING FRONT IS GENERATING A FEW 
ISOLATED SHOWERS OVER THE NW GULF N OF 24N W OF 93W. BROAD UPPER 
RIDGE DOMINATES THE GULF ANCHORED NEAR 25N86W. STRONG SE TO E 
SURFACE WINDS ARE ACROSS THE CENTRAL AND W GULF WHICH WILL SHIFT 
AROUND TO THE N BEHIND A FRONT THAT IS EXPECTED TO ENTER THE 
GULF LATE TONIGHT/EARLY FRI. A SURFACE RIDGE COVERS THE FAR E 
GULF INTO THE W ATLC AND WILL SHIFT E WITH THE APPROACHING FRONT 
EXPECTED ON FRI. STRONG SUBSIDENCE AND DRY STABLE AIR COVER THE 
E GULF...THUS CLEAR SKIES OVER MOST OF THE GULF THIS AFTERNOON. 

CARIBBEAN SEA...
BROAD UPPER LOW COVERS THE W CARIBBEAN CENTERED NEAR 14N80W AND 
COUPLED WITH THE ITCZ AXIS THAT EXTENDS FROM OVER COLOMBIA TO 
COSTA RICA INTO THE E PACIFIC REGION ARE GENERATING SCATTERED 
SHOWERS/ISOLATED THUNDERSTORMS S OF 16N BETWEEN 74W-84W. AN 
UPPER RIDGE EXTENDS FROM THE TROPICAL ATLC W ALONG THE N COAST 
OF SOUTH AMERICA PRODUCING SCATTERED CIRRUS CLOUDS ACROSS THE E 
CARIBBEAN. THE HIGH PRESSURE OVER THE ATLC AND LOWER PRESSURE 
OVER SOUTH AMERICA IS GENERATING MODERATE EASTERLY TRADE WINDS 
ACROSS THE CARIBBEAN USHERING IN SOME ISOLATED FAST MOVING 
SHOWERS. 

ATLANTIC OCEAN...
A DEEP LAYERED TROUGH IS DIGGING S OVER THE W/CENTRAL ATLC N OF 
28N W OF 50W SUPPORTING A COLD FRONT THAT ENTERS THE REGION NEAR 
BERMUDA ALONG 31N70W TO 30N77W BECOMING QUASI-STATIONARY ACROSS 
NE FLORIDA INTO THE GULF OF MEXICO NEAR JACKSONVILLE FLORIDA. 
THIS UPPER TROUGH IS BRINGING IN DRIER AIR AND STRONG SUBSIDENCE 
N OF 30N FROM 59W-73W THUS NO SHOWERS ARE ASSOCIATED WITH THE 
FRONT. A SURFACE RIDGE COVERS THE W ATLC ACROSS FLORIDA INTO THE 
GULF OF MEXICO ANCHORED BY A 1020 MB HIGH NEAR 27N72W AND IS 
BRIDGING THE FRONTAL BOUNDARY ABOVE. A VERY LARGE UPPER LOW IS 
WELL N OF THE REGION OVER THE FAR NE ATLC SUPPORTING A 
STATIONARY BOUNDARY ENTERING THE E ATLC NEAR 23N28W EXTENDING SW 
TO 27N42W. THE MOISTURE AND THUS ANY SHOWER ACTIVITY IS N OF THE 
REGION. IN THE TROPICS...AN UPPER RIDGE EXTENDS NEAR 4N35W NW 
ALONG 10N54W THEN ALONG THE N COAST OF SOUTH AMERICA GIVING MOST 
OF THE TROPICS BROKEN TO OVERCAST CIRRUS CLOUDS. 

$$
WALLACE