000
AXNT20 KNHC 282341
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SAT JUL 28 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...SPECIAL FEATURE...

A SURFACE TROUGH IS LOCATED FROM 29N73W INTO THE CENTRAL 
BAHAMAS. ENVIRONMENTAL CONDITIONS ARE FORECAST TO BECOME MORE 
FAVORABLE FOR TROPICAL CYCLONE DEVELOPMENT AS THE SYSTEM MOVES 
NORTH-NORTHEASTWARD OVER THE NEXT DAY OR TWO. RIDGING ALOFT 
COVERS THE AREA SURROUNDING THE TROUGH AND SCATTERED SHOWERS AND 
THUNDERSTORMS ARE LOCATED ABOUT THREE DEGREES EITHER SIDE OF THE 
TROUGH AXIS.

...TROPICAL WAVES...

A TROPICAL WAVE IS LOCATED OVER THE EAST ATLANTIC ALONG 21W FROM 
5N TO 18N AND IS MOVING WEST ABOUT 10 KNOTS. CONVECTION IS 
CONFINED TO THE AREA ALONG THE ITCZ.    

A TROPICAL WAVE IS LOCATED OVER THE CENTRAL ATLANTIC ALONG 40W 
FROM 4N TO 17N AND IS MOVING WEST ABOUT 10 KNOTS. LOW LEVEL 
WINDS ARE MOSTLY NORTHEASTERLY EITHER SIDE OF THE WAVE AXIS.

A TROPICAL WAVE IS LOCATED ALONG 56W SOUTH OF 19N AND IS MOVING 
WEST 10 TO 15 KNOTS. VISIBLE IMAGERY LATE IN THE DAY INDICATES 
AN INVERTED-V PATTERN. HOWEVER...CONVECTION IS MINIMAL.

A TROPICAL WAVE IS LOCATED OVER THE FAR WESTERN CARIBBEAN ALONG 
88W S OF 18N AND IS MOVING WEST 15 KNOTS. CONVECTION IS LIMITED 
OVER THE CARIBBEAN BUT STRONG THUNDERSTORMS COVER MOST OF 
HONDURAS.  

...THE ITCZ...

ITCZ AXIS IS CENTERED ALONG 10N14W 8N30W 11N46W 9N61W. SCATTERED 
MODERATE ISOLATED STRONG CONVECTION IS LOCATED WITHIN 60 NM 
EITHER SIDE OF A 9N21W 7N27W LINE...WITHIN A 60 NM RADIUS OF 
9N28W...AND WITHIN A 90 NM RADIUS OF 8N43W.

...DISCUSSION...

WEST OF 68W...
NORTHEASTERLY FLOW ALOFT COVERS NEARLY ALL OF THE GULF OF MEXICO 
AND THE NORTHWEST CARIBBEAN WITH THE STRONGEST WINDS...TO 40 
KNOTS...OVER THE SOUTH CENTRAL GULF. SCATTERED STRONG 
THUNDERSTORMS COVER MOST OF CUBA...THE GULF SOUTH OF 25N TO THE 
YUCATAN CHANNEL BETWEEN 85W AND 90W...AND ALL BUT THE SOUTHERN 
PART OF THE FLORIDA PENINSULA. MOVING TO THE EAST...A TROUGH 
AXIS IS LOCATED OVER THE FAR WESTERN ATLANTIC FROM 32N76W TO 
24N79W WITH CYCLONIC FLOW LOCATED WITHIN THREE OR FOUR DEGREES 
EITHER SIDE OF THE AXIS. A BROAD AREA OF ANTICYCLONIC FLOW AT 
THE MIDDLE TO UPPER LEVELS IS LOCATED OVER THE CENTRAL AND 
SOUTHWEST CARIBBEAN.  

EAST OF 68W...
A WELL-DEFINED ELONGATED MIDDLE/UPPER LEVEL CYCLONIC CIRCULATION 
IS CENTERED NEAR 32N63W AND IS DRIFTING NORTHEAST. A TROUGH AXIS 
EXTENDS SOUTHWARD FROM THE CIRCULATION TO NEAR 22N60W WITH 
CYCLONIC FLOW NOTED FOUR TO FIVE DEGREES EITHER SIDE OF THE 
TROUGH AXIS. BROAD RIDGING ALOFT COVERS THE ATLANTIC ROUGHLY 
BETWEEN 45W AND 55W. CONTINUING DOWNSTREAM...THE SOUTHERN PART 
OF A LARGE MIDDLE/UPPER LEVEL TROUGH OVER THE NORTH ATLANTIC IS 
LOCATED NORTH OF 27N BETWEEN 30W AND 45W. A MIDDLE/UPPER LEVEL 
RIDGE IS LOCATED OVER THE FAR EAST ATLANTIC NORTH OF ABOUT 18N 
EAST OF 30W. WATER VAPOR IMAGERY INDICATES A LARGE AREA OF 
SUBSIDENCE OVER THE EAST HALF OF THE CARIBBEAN CONTINUING EAST 
OF THE LEEWARD AND WINDWARD ISLANDS AND ALSO THE ATLANTIC NORTH 
OF 15N EAST OF 55W. AT THE SURFACE...A 1022 MB HIGH IS CENTERED 
NEAR 31N50W WITH A RIDGE AXIS SOUTHWEST TO NEAR PUERTO RICO. IN 
THE DEEP TROPICS SOUTH OF ABOUT 15N FLOW ALOFT IS MOSTLY 
EASTERLY.

$$
CAB