000
AXNT20 KNHC 211623
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SAT JUL 21 2007

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL 
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN 
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...METEOROLOGICAL ANALYSIS... 
WEATHER OBSERVATIONS...AND RADAR.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1600 UTC.

...TROPICAL WAVES...
TROPICAL WAVE OFF THE COAST OF AFRICA ALONG 19W S OF 17N MOVING 
W 15 KT. WELL DEFINED MID LEVEL CYCLONIC ROTATION IS ALONG THE 
WAVE AXIS NEAR 13N WITH LITTLE TO NO EVIDENCE OF A SURFACE LOW 
AT THIS TIME. CLUSTERS OF MODERATE CONVECTION ARE FROM 8N-12N 
BETWEEN THE 18W-22W. 

TROPICAL WAVE ALONG 53W S OF 22N MOVING W 15 KT. BROAD LOW LEVEL 
INVERTED-V SIGNATURE COVERS THE AREA FROM 45W-62W. NO 
ASSOCIATED SHOWERS/CONVECTION WITH THIS WAVE. 

TROPICAL WAVE IN THE CENTRAL CARIBBEAN ALONG 75W S OF 19N MOVING 
W 15 KT. A LARGE CLUSTER OF MODERATE TO STRONG CONVECTION IS 
FROM THE COAST OF S AMERICA TO 12N BETWEEN 74W-78W. 

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 9N21W 7N30W 13N50W 10N63W. CLUSTERS 
OF SCATTERED MODERATE CONVECTION ARE FROM 5N-10N BETWEEN 
19W-31W. 
 
...DISCUSSION...
GULF OF MEXICO...
A DEEP LAYERED TROUGH IS OVER THE GULF COAST N OF 25N ACROSS THE 
SE US WITH AN ASSOCIATED COLD FRONT EXTENDING FROM A SFC LOW 
OVER HALIFAX S ALONG THE U.S. EAST COAST AND INTO GEORGIA. A 
PRE-FRONTAL SFC TROUGH EXTENDS FROM THE W ATLC ACROSS CENTRAL
FLORIDA TO 27N83W. THE DEEP LAYERED TROUGH CONTINUES TO BRING 
SCATTERED SHOWERS/THUNDERSTORMS TO THE NORTH AND EAST 
GULF...MAINLY E OF 88W. A CUTOFF UPPER LEVEL LOW OVER THE 
WESTERN TIP OF CUBA IS GENERATING SCATTERED SHOWERS/ISOLATED 
THUNDERSTORMS ACROSS THE STRAIGHTS OF FLORIDA. DIFFLUENCE FROM 
AN UPPER LEVEL HIGH IS ENHANCING CONVECTIVE ACTIVITY OVER THE 
TEXAS/MEXICO BORDER. UPPER LEVEL OUTFLOW FROM THIS CONVECTION IS 
MOVING OVER THE NW GULF...OTHERWISE THE WESTERN GULF REMAINS 
FAIRLY TRANQUIL UNDER AN UPPER RIDGE.


CARIBBEAN SEA...
WEAKENING CUT-OFF UPPER LOW REMAINS CENTERED OVER THE WESTERN 
TIP OF CUBA NEAR 22N83W GENERATING SCATTERED SHOWERS/ISOLATED 
THUNDERSTORMS FROM EASTERN CUBA TO THE YUCATAN PENINSULA NORTH 
OF 18N. A CLUSTER OF MODERATE TO STRONG CONVECTION EMBEDDED WITH 
THUNDERSTORMS IS MOVING INTO THE SOUTH CENTRAL CARIBBEAN FROM A 
SFC LOW OVER COLOMBIA. BROAD UPPER HIGH ANCHORED JUST E OF THE 
LESSER ANTILLES EXTENDS A RIDGE AXIS W ACROSS THE REMAINDER OF 
THE CARIBBEAN. DRY AIR AND MODERATE SUBSIDENCE COVERS THE 
CARIBBEAN E OF 75W. MODERATE EASTERLY TRADE WINDS CONTINUE
ACROSS THE S/CENTRAL CARIBBEAN. 

ATLANTIC OCEAN...
DEEP LAYERED TROUGH IS INLAND OVER THE EASTERN US WITH A 
SHORTWAVE UPPER TROUGH EXTENDING THROUGH 25N73W AND A SURFACE 
TROUGH EXTENDING FROM 31N77W ACROSS CENTRAL FLORIDA INTO THE 
GULF OF MEXICO WHILE THE FRONTAL BOUNDARY REMAINS JUST N OF THE 
REGION. THIS IS GENERATING SCATTERED SHOWERS/THUNDERSTORMS 
WITHIN 100 NM OF A LINE FROM 27N80W TO BEYOND 32N73W. A CUT OFF 
UPPER LOW IS CENTERED NEAR 29N68W WITH AN ASSOCIATED SFC TROUGH 
EXTENDING FROM 25N66W SW TO 21N70W. SCATTERED SHOWERS AND 
ISOLATED THUNDERSTORMS ASSOCIATED WITH THIS SYSTEM ARE BETWEEN 
58W-70W NORTH OF 20N. THE REMAINDER OF THE ATLANTIC IS MARKED BY 
FAIR WEATHER CUMULUS CLOUDS BEING TRANSPORTED AROUND A SFC RIDGE 
ANCHORED BY A STRONG 1035 MB SFC HIGH WELL NORTH OF THE AREA. 
VISIBLE IMAGERY SHOWS AFRICAN DUST EXTENDING TO 33W BETWEEN 
12N-27N.


$$
WADDINGTON