000
AXNT20 KNHC 191051
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT WED AUG 19 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 
1015 UTC.

...SPECIAL FEATURES...
HURRICANE BILL IS CENTERED NEAR 18.0N 54.9W OR ABOUT 400 NM EAST 
OF THE LEEWARD ISLANDS MOVING WNW AT 14 KT. ESTIMATED MINIMUM 
CENTRAL PRESSURE IS 948 MB. MAXIMUM SUSTAINED WIND SPEED IS 115 
KT WITH GUSTS TO 140 KT. SEE THE LATEST FORECAST/ADVISORY UNDER 
AWIPS/WMO HEADERS TCMAT3/WTNT23 KNHC FOR MORE DETAILS. HURRICANE 
BILL DISPLAYED A WELL DEFINED EYE WITH SCATTERED/NUMEROUS STRONG 
CONVECTION IS WITHIN 60 NM OF THE CENTER IN ALL QUADRANTS AND 
SCATTERED MODERATE/ISOLATED STRONG CONVECTION COVERING THE 
REMAINDER OF THE AREA FROM 15N-22N BETWEEN 51W-57W.

...TROPICAL WAVES...
TROPICAL WAVE IS INTRODUCED ALONG 19W S OF 16N MOVING W 10-15 
KT. WAVE LOCATION IS AT THE LEADING EDGE OF AN AREA DEEP LAYER 
MOISTURE MAXIMUM OBSERVED IN TOTAL PRECIPITABLE WATER IMAGERY 
AND IS CLEARLY DEFINED MAINLY IN THE MID/UPPER LEVELS. CLUSTERS 
OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE WITHIN 120 
NM OF THE WAVE FROM 8N-11N. 

TROPICAL WAVE REMAINS TILED DUE TO HURRICANE BILL EXTENDING FROM 
16N41W TO 8N36W MOVING W 15-20 KT. WAVE CONTINUES TO BE AT THE 
LEADING EDGE OF AN AREA DEEP LAYER MOISTURE MAXIMUM OBSERVED IN 
TOTAL PRECIPITABLE WATER IMAGERY. ISOLATED SHOWERS ARE WITHIN 
60 NM OF THE AXIS FROM 13N-16N. 

TROPICAL WAVE IS ALONG 82W S OF 22N MOVING W NEAR 25 KT. THIS 
WAVE RESULTED FROM THE REMNANTS OF ANA AND IS NOT DISPLAYING THE 
TYPICAL CHARACTERISTICS OF A TROPICAL WAVE...SUCH AS BEING 
EMBEDDED WITHIN DEEP LAYERED MOISTURE. IT IS IN AN AREA OF DRY 
STABLE AIR AND NOT PRODUCING ANY SHOWERS/CONVECTION. 

...THE ITCZ...
THE ITCZ AXIS IS CENTERED ALONG 13N16W 9N28W 8N46W 11N62W. 
CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE 
INLAND AND WITHIN 90/120 NM ALONG THE COAST OF W AFRICA BETWEEN 
8N-16N AND WITHIN 75 NM OF LINE FROM 11N29W TO 13N37W. CLUSTERS 
OF SCATTERED MODERATE CONVECTION ARE WITHIN 60/75 NM OF 8N  
BETWEEN 22W-30W. 

...DISCUSSION...

GULF OF MEXICO...
BROAD UPPER RIDGE COVERS THE W GULF WHILE A UPPER LOW IN THE 
CARIBBEAN EXTENDS AN UPPER TROUGH OVER THE E GULF CONTINUING TO 
PROVIDE ABUNDANCE OF UPPER LEVEL MOISTURE ACROSS THE ENTIRE 
AREA. THE SURFACE RIDGE FROM THE W ATLC IS BEGINNING TO BUILD 
ACROSS THE GULF FROM THE NE TO SW. SCATTERED SHOWERS/ 
THUNDERSTORMS ARE IN THE BAY OF CAMPECHE S OF 21N W OF 92W TO 
INLAND OVER MEXICO. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE 
OVER THE SE GULF WITHIN 75 NM OF LINE FROM 27N85W TO THE NE TIP 
OF THE YUCATAN PENINSULA. ISOLATED SHOWERS DOT THE REMAINDER OF 
THE GULF. 

CARIBBEAN SEA...
THE MOST SIGNIFICANT FEATURE FOR THE CARIBBEAN THIS MORNING 
REMAINS THE UPPER LOW CENTERED NEAR 20N84W COVERING THE NW 
CARIBBEAN AND EXTENDING AN UPPER TROUGH N OVER THE E GULF OF 
MEXICO AND SE TO NEAR 12N80W. THIS FEATURE IS GENERATING 
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS W OF 83W FROM CENTRAL 
AMERICA TO OVER CUBA AND N OF 20N TO OVER CUBA BETWEEN 80W-83W. 
UPPER LEVEL DIFFLUENCE COMBINED WITH LOW LEVEL CONVERGENCE ARE 
GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS OVER THE SW 
CARIBBEAN S OF 15N W OF 77W TO INLAND OVER CENTRAL AMERICA. 
FRESH TO STRONG EASTERLY TRADE WINDS CONTINUE ACROSS THE AREA. 
DRY STABLE AIR IS ACROSS THE REMAINDER OF THE AREA E OF 80W 
LIMITING ANY SHOWERS RESULTING IN FAIR CONDITIONS THIS MORNING 
WITH THE EXCEPTION OF THE FAR NE CARIBBEAN. SCATTERED SHOWERS 
AND POSSIBLE ISOLATED THUNDERSTORMS ARE MOVING ACROSS THE 
LEEWARD ISLANDS TO PUERTO RICO BEING PUSHED AHEAD OF HURRICANE 
BILL AS IT MOVES TO NW OF THE ISLANDS. 

ATLANTIC OCEAN...
THE MAIN FOCUS THIS MORNING FOR THE ATLC IS HURRICANE BILL. THE 
A SURFACE TROUGH IS OFF THE SE COAST OF FLORIDA JUST W OF THE 
BAHAMAS FROM 23N79W TO 28N78W GENERATING SCATTERED SHOWERS/ 
THUNDERSTORMS FROM 23N-27N BETWEEN 76W AND THE SURFACE TROUGH 
AND SCATTERED SHOWERS/ISOLATED THUNDERSTORMS FROM 24N-26N 
BETWEEN W OF THE SURFACE TROUGH ACROSS THE S FLORIDA PENINSULA 
AND THE FLORIDA KEYS. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS 
AN UPPER RIDGE IS OVER THE FAR W ATLC EXTENDING FROM E CUBA TO 
JUST W OF BERMUDA BETWEEN A NARROW UPPER TROUGH EXTENDING 
THROUGH 32N75W TO 28N78W AND AN UPPER LOW TO THE E OF BERMUDA 
NEAR 32N60W. DIFFLUENCE ALOFT IS GENERATING SCATTERED SHOWERS/ 
ISOLATED THUNDERSTORMS FROM 28N-30N BETWEEN 69W-71W. OTHERWISE 
THE ATLC BASIN IS DOMINATED BY A SURFACE RIDGE OVER THE W ATLC 
ANCHORED BY A 1021 MB HIGH BETWEEN BERMUDA AND NORTH CAROLINA 
COAST AND BY A 1022 MB HIGH NEAR 30N31W IN THE E WITH A 
WEAKNESS OVER THE CENTRAL ATLC COMPLIMENTS OF HURRICANE BILL. 

$$
WALLACE