Wednesday Evening Tropical Weather Discussion

AXNT20 KNHC 182341
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT WED JUN 18 2008

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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 45W S OF 17N MOVING W 15-20 KT. A MID
LEVEL LOW IS AHEAD OF THE WAVE AXIS NEAR 13N49W WITH THE CLASSIC
INVERTED-V SIGNATURE VISIBLE ON SATELLITE IMAGERY. SCATTERED
MODERATE/STRING CONVECTION IS ASSOCIATED WITH THE MID LEVEL LOW
FROM 13N-14N BETWEEN 47W-49W. CLUSTERS OF SCATTERED MODERATE/
ISOLATED STRONG CONVECTION ARE FROM 10-13N BETWEEN 39W-47W.

THE TROPICAL WAVE THAT WAS ALONG 59W/60W IS NOW INLAND OVER
SOUTH AMERICA AND IS NO LONGER DISCERNIBLE AND HAS BEEN DROPPED
FROM THE SURFACE ANALYSIS. THIS WAVE MAY EMERGED INTO THE E
PACIFIC REGION IN A COUPLE OF DAYS.

TROPICAL WAVE IS ALONG 92W S OF 21N MOVING W NEAR 10 KT. THIS
WAVE IS NOT WELL DEFINED ON SATELLITE IMAGERY AND WITH THE
AFTERNOON THUNDERSTORMS DEVELOPING INLAND OVER MEXICO AND THE
YUCATAN PENINSULA THE AXIS IS EVEN HARDER TO FIND. THE WAVE
POSITION IS BASED ON CONTINUITY.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 9N12W 4N26W 7N42W 4N53W. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS MOVING OFF AFRICA FROM
8N-13N E OF 18W BUT IS RAPIDLY WEAKENING. CLUSTERS OF SCATTERED
MODERATE/STRONG CONVECTION ARE INLAND OVER SOUTH AMERICA AND
WITHIN 60 NM ALONG THE COAST FROM 47W-50W. SMALL CLUSTERS OF
SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE WITHIN 200 NM
OF THE ITCZ FROM 16W-37W.

...DISCUSSION...

GULF OF MEXICO...
BROAD UPPER RIDGE REMAINS OVER N MEXICO COVERING THE NW GULF N
OF 23N W OF 92W. THE REMAINDER OF THE GULF IS DOMINATED BY AN
UPPER LEVEL TROUGH THAT EXTENDS FROM A BROADER UPPER TROUGH N OF
THE AREA ACROSS THE FLORIDA PENINSULA TO THE BAY OF CAMPECHE.
THE ASSOCIATED COLD FRONT IS CURRENTLY HAVING LITTLE IMPACT AND
EXTENDS FROM THE W ATLC ACROSS FLORIDA NEAR DAYTONA BEACH TO N
OF TAMPA INTO THE GULF TO 28N89W THEN DISSIPATES TO 28N94W.
DIFFLUENCE ALOFT ON THE SE SIDE OF THE UPPER TROUGH IS HAVING A
GREATER IMPACT ON THE WEATHER OVER THE SE GULF GENERATING
NUMEROUS SHOWERS/THUNDERSTORMS THAT COVERS THE AREA E OF A LINE
FROM NE YUCATAN TO NEAR NAPLES FLORIDA THEN N OVER THE FLORIDA
PENINSULA. THESE SHOWERS/THUNDERSTORMS ARE FORMING OVER THE
CENTRAL FLORIDA PENINSULA N OF LAKE OKEECHOBEE MOVING E INTO THE
W ATLC WHILE S OF THE LAKE THE ACTIVITY CONTINUES TO STREAM FROM
CUBA NE ACROSS S FLORIDA AND THE FLORIDA STRAITS. SOME ISOLATED
SHOWERS ARE POSSIBLE WITHIN 60 NM OF THE FRONT BUT OTHERWISE THE
REMAINDER OF THE GULF IS ENJOYING FAIR WEATHER THIS EVENING.

CARIBBEAN...
A RATHER BROAD UPPER-LEVEL COVERS THE AREA ANCHORED NEAR 16N76W
DOMINATING THE WEATHER PATTERN WITH MODERATE/STRONG SUBSIDENCE S
OF THE GRATER ANTILLES KEEPING THE CENTRAL AND E CARIBBEAN
MOSTLY CLEAR. DIFFLUENCE ALOFT BETWEEN THIS RIDGE AND THE UPPER
TROUGH OVER THE GULF OF MEXICO IS GENERATING NUMEROUS SHOWERS/
THUNDERSTORMS MAINLY INLAND FROM OVER THE YUCATAN PENINSULA
THROUGH THE YUCATAN CHANNEL TO OVER W CUBA WITH SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS N OF 19N W OF 81W. ALTHOUGH THE
ATLC SURFACE RIDGE HAS WEAKENED OVER THE PAST FEW DAYS
MODERATE/STRONG EASTERLY SURFACE WINDS REMAIN ACROSS THE AREA.

ATLANTIC...
BROAD UPPER TROUGH COVERS THE E US AND NW ATLC WITH A NARROW
TROUGH EXTENDING INTO THE GULF OF MEXICO. THE ASSOCIATED COLD
FRONT ENTERS THE W ATLC THROUGH A 1009 MB LOW NEAR 32N78W ACROSS
FLORIDA NEAR DAYTONA BEACH. THE UPPER RIDGE IN THE CARIBBEAN
EXTENDS A RIDGE AXIS N ACROSS CENTRAL CUBA NE TO BEYOND 32N60W
PROVIDING ENOUGH DIFFLUENCE ALOFT TO GENERATE NUMEROUS SHOWERS/
THUNDERSTORMS S OF 32N TO OVER CUBA W OF 76W TO INLAND OVER
FLORIDA AND THROUGH THE FLORIDA STRAITS. A WEAK SURFACE TROUGH
EXTENDS FROM 30N67W TO 27N74W WITH CLUSTERS OF SCATTERED
SHOWERS/THUNDERSTORMS WITHIN 120 NM OF THE TROUGH AXIS. BROAD
ELONGATED UPPER LOW IS IN THE E ATLC EXTENDING FROM MADEIRA
ISLANDS W OF THE CANARY ISLANDS TO NEAR 20N30W. A SURFACE RIDGE
DOMINATES THE ATLC E OF 70W ANCHORED BY A 1023 MB HIGH NEAR
28N38W AS WELL AS MODERATE/STRONG SUBSIDENCE AND DRY STABLE AIR.
THIS LEAVES THE ATLC E OF 60W ENJOYING FAIR WEATHER THIS
EVENING.

$$
WALLACE


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