000
AXNT20 KNHC 091040
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT SUN AUG 09 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.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 20W/21W S OF 18N MOVING W 15-20 KT. 
LATEST VISIBLE SATELLITE IMAGERY INDICATES THE WELL DEFINED 
LOW/MID LEVEL CYCLONIC CIRCULATION CENTER MOVING JUST E OF THE 
WAVE AXIS. THE WAVE AXIS IS EMBEDDED WITHIN THE MOISTURE MAXIMUM 
OBSERVED IN TOTAL PRECIPITABLE WATER IMAGERY. CLUSTERS OF 
SCATTERED MODERATE TO ISOLATED STRONG CONVECTION ARE ASSOCIATED 
WITH THE LOW/MID LEVEL CIRCULATION COVERING THE AREA FROM 
9N-16N BETWEEN 19W-24W.

TROPICAL WAVE IS ALONG 36W S OF 19N MOVING W NEAR 15 KT. WAVE 
REMAINS EMBEDDED WITH A MOISTURE MAXIMUM OBSERVED IN TOTAL 
PRECIPITABLE WATER IMAGERY AND A BROAD AREA OF CYCLONIC 
CIRCULATION. THERE IS NO DEEP CONVECTION ASSOCIATED WITH THE 
WAVE. 

TROPICAL WAVE IS ALONG 46W/47W S OF 16N MOVING W NEAR 15 KT. 
WAVE IS ALONG THE TRAILING EDGE OF A MOISTURE MAXIMUM OBSERVED 
IN TOTAL PRECIPITABLE WATER IMAGERY WITH NO ASSOCIATED DEEP 
CONVECTION. 

TROPICAL WAVE IS ALONG 63W S OF 18N MOVING WNW NEAR 15 KT. WAVE 
REMAINS IN AN AREA BENEATH AN UPPER RIDGE PARTIALLY MASKING THE 
WAVE SIGNATURE AND ANY SHOWERS/CONVECTION IS MORE ASSOCIATED 
WITH THE UPPER LEVEL FEATURE THAN THE WAVE ITSELF. 

TROPICAL WAVE IS ALONG 84W/85W S OF 20N MOVING W NEAR 20 KT. 
WAVE REMAINS ALONG THE TRAILING EDGE OF A MOISTURE MAXIMUM 
OBSERVED IN TOTAL PRECIPITABLE WATER IMAGERY AND IS EMBEDDED IN 
RATHER DRY STABLE AIR WITH NO ASSOCIATED DEEP CONVECTION. 

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 15N15W 9N38W 12N55W 11N62W. A 
SURFACE TROUGH IS EMBEDDED WITHIN THE ITCZ EXTENDING FROM 17N52W 
TO 10N55W WITH CLUSTERS OF SCATTERED MODERATE TO ISOLATED STRONG 
CONVECTION W OF THE TROUGH AXIS WITHIN 60/75 NM OF LINE FROM 
16N523 ACROSS THE WINDWARD ISLANDS NEAR 12N62W. CLUSTERS OF 
SCATTERED MODERATE TO ISOLATED STRONG CONVECTION ARE WITHIN 90 
NM OF THE ITCZ BETWEEN 32W-50W. 

...DISCUSSION...

GULF OF MEXICO...
AN UPPER RIDGE ANCHORED OVER SOUTH CAROLINA CONTINUES TO DIG S 
OVER THE FAR W ATLC ACROSS THE FLORIDA PENINSULA INTO THE E GULF 
PUSHING ANY ISOLATED SHOWERS/THUNDERSTORMS OVER THE E GULF OF 
MEXICO WITHIN 75 NM OF LINE FROM THE MISSISSIPPI GULF COAST TO 
THE STRAITS OF FLORIDA NEAR 24N82W INCLUDING THE LOWER FLORIDA 
KEYS. ISOLATED SHOWERS WITH POSSIBLE STRAY THUNDERSTORMS ARE 
STREAMING NORTHWARD ACROSS THE REMAINDER OF THE N GULF N OF 26N 
W OF 84W. AN UPPER LEVEL TROUGH ANCHORED OVER CENTRAL MEXICO 
COVERS THE W GULF. A WEAKENING SURFACE TROUGH IS OVER THE E BAY 
OF CAMPECHE FROM 22N91W TO 18N93W AND COUPLED WITH THE UPPER 
RIDGE ARE GENERATING SCATTERED SHOWERS/THUNDERSTORMS SW OF A 
LINE FROM THE BAY OF CAMPECHE COAST NEAR 18N94W TO NE MEXICO 
NEAR 25N98W. THE REMAINDER OF THE GULF IS TRANQUIL AGAIN THIS 
MORNING. 

CARIBBEAN SEA...
AN UPPER RIDGE OVER THE W ATLC/E GULF OF MEXICO COVERS THE NW 
CARIBBEAN WITH AN UPPER TROUGH OVER THE CENTRAL CARIBBEAN AND A 
SECOND UPPER RIDGE OVER THE E CARIBBEAN. THE UPPER LEVEL 
DIFFLUENCE OVER THE W CARIBBEAN CONTINUES TO GENERATE SCATTERED 
SHOWERS/ISOLATED THUNDERSTORMS S OF 21N W OF 85W TO THE COAST OF 
CENTRAL AMERICA AND INLAND OVER THE YUCATAN PENINSULA. THE ITCZ 
EXTENDS ACROSS THE SW CARIBBEAN FROM COLOMBIA TO W PANAMA 
GENERATING SCATTERED SHOWERS/THUNDERSTORMS FROM 12N TO INLAND 
OVER PANAMA AND COSTA RICA BETWEEN 77W-84W. FRESH TO STRONG 
TRADE WINDS CONTINUE ACROSS MOST OF THE CARIBBEAN USHERING IN 
FAST MOVING ISOLATED SHOWERS MAINLY ACROSS THE E CARIBBEAN E OF 
70W WHILE THE REMAINDER OF THE AREA IS DOMINATED BY DRY STABLE 
AIR LIMITING SHOWER ACTIVITY. 

ATLANTIC OCEAN...
AN UPPER RIDGE ANCHORED OVER SOUTH CAROLINA COVERS THE W ATLC 
WITH A NARROW UPPER TROUGH TO THE E EXTENDING FROM 27N65W ACROSS 
THE WINDWARD PASSAGE/E CUBA AND OVER THE CENTRAL CARIBBEAN. THIS 
COMBINATION IS PROVIDING UPPER LEVEL DIFFLUENCE TO GENERATE 
CLUSTERS OF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN 150 
NM OF S OF A SURFACE TROUGH THAT EXTENDS FROM 30N70W 28N74W TO 
26N78W. THE LARGE UPPER LOW OVER THE CENTRAL ATLC IS BECOMING 
ELONGATED N/S AND CENTERED NEAR 32N47W WITH ANY SHOWER ACTIVITY 
N OF THE REGION AND A WEAKENING SURFACE TROUGH TO THE SW OF THE 
UPPER LOW EXTENDING FROM 30N53W TO 22N57W. THE REMAINDER OF THE 
ATLC REMAINS TRANQUIL AGAIN THIS MORNING WITH A BROAD AREA OF 
SAHARAN DUST COVERING MOST OF THE AREA E OF 75W. 

$$
WALLACE