000
AXNT20 KNHC 231058
TWDAT 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT SAT SEP 23 2006

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

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1015 UTC.

...SPECIAL FEATURES...
TROPICAL STORM HELENE IS CENTERED NEAR 37.2N 48.2W OR ABOUT 1008 
NM WEST OF THE AZORES AT 23/0900 UTC MOVING EAST-NORTHEAST AT 22 
KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 982 MB. MAXIMUM 
SUSTAINED WIND SPEED IS 60 KT WITH GUSTS TO 75 KT. SEE THE 
LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT3/ 
WTNT23 KNHC FOR MORE DETAILS. THE LOW LEVEL CENTER IS BECOMING 
EXPOSED WITH SCATTERED MODERATE CONVECTION WITHIN A 30/45 NM 
RADIUS OF 37.5N49W. DENSE OVERCAST CLOUDS WITH SHOWERS/ 
THUNDERSTORMS COVERS A LARGER AREA FROM 35N-45N BETWEEN 42W-55W. 

...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 41W/42W S OF 21N WITH A 1010 MB LOW ALONG 
THE WAVE NEAR 14N MOVING W 10 KT. BROAD LOW/MID LEVEL CYCLONIC 
ROTATION COVERING A LARGE AREA WITH CLUSTERS OF SCATTERED 
MODERATE/STRONG CONVECTION FROM 11N-23N BETWEEN 35W-45W. THIS 
WAVE HAS SOME POTENTIAL FOR FURTHER DEVELOPMENT SLOWLY OVER THE 
NEXT FEW DAYS.

TROPICAL WAVE IS ALONG 56W S OF 20N WITH A 1011 MB LOW ALONG THE 
WAVE NEAR 13N MOVING W 10 KT. BROAD CYCLONIC ROTATION COVERS THE 
AREA WITH ISOLATED SHOWERS FROM 12N-20N BETWEEN 52W-60W.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 10N14W 7N27W 13N39W 10N49W 12N58W 
9N62W ACROSS N PORTION OF SOUTH AMERICA THEN S OF PANAMA INTO 
THE E PACIFIC REGION. APART FROM THE CONVECTION ASSOCIATED WITH 
THE TROPICAL WAVES...SCATTERED MODERATE/ISOLATED STRONG 
CONVECTION IS FROM 5N-10N BETWEEN 25W-30W WITH CLUSTERS OF 
SIMILAR CONVECTION FROM 7N-13N BETWEEN 19W AND THE COAST OF 
AFRICA. 

...DISCUSSION...
GULF OF MEXICO...
VERY LARGE UPPER LOW IS SITUATED OVER THE N/CENTRAL PLAIN STATES 
WITH AN UPPER TROUGH EXTENDING S ACROSS TEXAS AND THE FAR NW 
GULF COAST. THIS CONTINUES TO BRING DRY AIR TO THE AREA 
INCLUDING THE SE US S OF THE MAJOR THUNDERSTORMS MOVING ACROSS 
THE STATES FROM THE CENTRAL MISSISSIPPI VALLEY TO THE NE 
APPALACHIAN MOUNTAINS. AN UPPER LOW IN THE SE GULF IS JUST N OF 
THE YUCATAN PENINSULA/CHANNEL NEAR 23N87W COVERS THE E GULF S OF 
29N E OF 92W GENERATING SCATTERED SHOWERS E OF 87W. STRONG 
RETURN SURFACE FLOW COVERS MUCH OF THE GULF THIS MORNING.  

CARIBBEAN SEA...
THE UPPER LOW CENTERED IN THE SE GULF COVERS THE AREA N OF 19N W 
OF 81W TO OVER THE YUCATAN PENINSULA/CHANNEL AND W CUBA COMBINED 
WITH THE BROAD UPPER RIDGE OVER THE W ATLC IS GENERATING 
SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS N OF 17N 
FROM 71W-85W AND GIVING THE REMAINDER OF THE CARIBBEAN NE UPPER 
FLOW WITH MOSTLY DRY AIR. SCATTERED SHOWERS/ISOLATED 
THUNDERSTORMS ARE S OF 10N FROM COLOMBIA TO COSTA RICA. 
SCATTERED SHOWERS ARE MOVING OVER THE WINDWARD ISLANDS AHEAD OF 
THE TROPICAL WAVE ALONG 56W. 

ATLANTIC OCEAN...
BROAD UPPER RIDGE COVERS THE W ATLC ANCHORED BY AN UPPER HIGH 
OFF THE NE FLORIDA COAST NEAR 29N77W AND COVERING THE AREA W OF 
66W INCLUDING AND GIVING THE CARIBBEAN NE UPPER FLOW. A WEAK 
UPPER LOW MOVING SW IS CENTERED N OF THE LEEWARD ISLANDS NEAR 
21N62W AND COULD BRING ISOLATED SHOWERS TO THOSE ISLANDS. NARROW 
UPPER TROUGH EXTENDS FROM AN UPPER LOW N OF THE REGION NEAR 
32N40W SSW INTO THE W TROPICAL ATLC NEAR 17N55W. BROAD UPPER 
HIGH ANCHORED NW OF THE CAPE VERDE ISLANDS NEAR 17N27W COVERS 
THE REMAINDER OF THE E ATLC. AT THE SURFACE...A WEAK SURFACE 
TROUGH IS IN THE CENTRAL ATLC FROM BEYOND 32N51W SW TO 26N60W 
IN THE WAKE OF TROPICAL STORM HELENE SPLITTING THE SUBTROPICAL 
RIDGE THAT DOMINATES THE MUCH OF THE ATLC. W ATLC SURFACE RIDGE 
EXTENDS FROM A 1023 MB HIGH WELL N OF THE REGION THROUGH 32N72W 
ACROSS CENTRAL CUBA TO NEAR 20N80W AND COVERS THE FAR E GULF OF 
MEXICO. THE E ATLC RIDGE COVERS THE REGION N OF 24N FROM 20W-45W 
ANCHORED BY A 1021 MB HIGH NEAR 32N35W. THIS IS GIVING MOST OF 
THE ATLC FAIR WEATHER THIS MORNING. 

$$
WALLACE