[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 042346
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT THU OCT 04 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 FEATURES...
NONE.

...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 45W/46W S OF 17N MOVING W NEAR 10 KT WITH
A WEAK 1010 MB LOW ALONG THE WAVE AXIS NEAR 10N. WAVE IS BENEATH
A BROAD E/W UPPER RIDGE MASKING THE SATELLITE SIGNATURE.
CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE
FROM 9N-12N BETWEEN 41W-48W.

TROPICAL WAVE IS ALONG 56W/57W S OF 16N MOVING W NEAR 10 KT.
WEAK LOW LEVEL INVERTED-V CURVATURE WITH NO ASSOCIATED DEEP
CONVECTION. THE ENERGY ASSOCIATED WITH THIS WAVE HAS BEEN
ABSORBED INTO THE TROPICAL SYSTEM PREVIOUSLY NAMED
MELISSA...THEREFORE THIS SYSTEM WILL BE DROPPED ON THE NEXT
ANALYSIS.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 10N12W 5N19W 4N33W 8N42W 9N62W. IN
ADDITION TO CONVECTION ASSOCIATED WITH TROPICAL WAVE...CLUSTERS
OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE FROM 6N-9N
BETWEEN 28W-35W.

DISCUSSION...

GULF OF MEXICO...
A PAIR OF UPPER LOWS DOMINATE THE W GULF WITH THE SMALLEST ONE
LOCATED OFF THE MISSISSIPPI DELTA OF LOUISIANA NEAR 28N88W
GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN 60 NM
OF LINE FROM 28N87W TO OVER SE LOUISIANA NEAR NEAR 30N90W. THE
SECOND LARGER UPPER LOW IS JUST INLAND ALONG THE COAST OF MEXICO
N OF VERACRUZ NEAR 20N97W WITH ANY SHOWER ACTIVITY INLAND OVER
MEXICO. A LARGE UPPER HIGH IS ANCHORED IN THE FLORIDA STRAITS
BETWEEN S FLORIDA AND CUBA NEAR 24N80W COVERING THE REMAINDER OF
THE GULF. THIS IS DRAWING SCATTERED SHOWERS AND WIDELY ISOLATED
THUNDERSTORMS FROM OVER CUBA INTO THE GULF AND SEABREEZE
THUNDERSTORMS OVER THE FLORIDA PENINSULA ARE BEING FORCED E INTO
THE W ATLC. THE ONLY SURFACE FEATURE IN THE GULF IS A 1006 MB
LOW CENTERED NEAR 27N91W AND CHARACTERIZED BY LOW LEVEL SWIRL.

CARIBBEAN SEA...
THE BROAD UPPER HIGH IN THE FLORIDA STRAITS EXTENDS AN UPPER
RIDGE AXIS E ACROSS THE SW ATLC AND DOMINATING THE ENTIRE
CARIBBEAN. UPPER DIFFLUENCE AND TROPICAL MOISTURE ARE ACROSS THE
CENTRAL CARIBBEAN GENERATING CLUSTERS OF SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS BETWEEN 74W-83W WITH CLUSTERS OF
SCATTERED MODERATE/ISOLATED STRONG CONVECTION COVERING THE
GREATER ANTILLES TO OVER THE LEEWARD ISLANDS PUSHING S INTO THE
CARIBBEAN WATERS. AT THE SURFACE...A WEAK SURFACE TROUGH IS IN
THE W/CENTRAL CARIBBEAN EXTENDING FROM 20N82W TO 13N80W.

ATLANTIC OCEAN...
AN UPPER HIGH IS IN THE FLORIDA STRAITS NEAR 24N80W COVERING THE
W ATLC W OF 71W AND EXTENDING AN UPPER RIDGE AXIS E TO 22N60W.
AN UPPER TROUGH EXTENDING INTO THE REGION NEAR 32N55W W ALONG
28N61W TO 26N70W. A SURFACE TROUGH EXTENDS ALONG THE BOUNDARY
BETWEEN THE UPPER LEVEL FEATURES WITH A RAPIDLY WEAKENING 1011
MB LOW ALONG THE SURFACE TROUGH NE OF THE BAHAMAS NEAR 26N73W.
UPPER DIFFLUENCE AND ABUNDANCE OF TROPICAL MOISTURE ARE S OF THE
SURFACE TROUGH GENERATING CLUSTERS OF SCATTERED MODERATE/
ISOLATED STRONG CONVECTION S OF 26 TO ACROSS THE TURKS AND
CAICOS ISLANDS AND OVER THE GREATER ANTILLES. SCATTERED SHOWERS
AND WIDELY ISOLATED THUNDERSTORMS COVER THE AREA FROM 17N-26N
BETWEEN 58W-68W INCLUDING THE VIRGIN AND LEEWARD ISLANDS. A
SMALL UPPER LOW IS IN THE CENTRAL ATLC NEAR 23N54W WITH A WEAK
1014 MB SURFACE LOW...REMNANTS OF MELISSA...CENTERED NEAR 23N51W
WITH AN WEAK UPPER RIDGE TO THE E EXTENDING FROM 22N43W TO
29N46W AND IS GENERATING CLUSTERS OF SCATTERED MODERATE/ISOLATED
STRONG CONVECTION FROM 20N-26N BETWEEN 41W-53W. A DEEP LAYERED
TROUGH EXTENDS INTO THE E/CENTRAL ATLC N OF 25N FROM 23W-40W
WITH A COLD FRONT ENTERING THE REGION ALONG 32N24W TO 25N42W
BECOMING STATIONARY TO 30N61W WITH A SCATTERED SHOWERS AND
WIDELY ISOLATED THUNDERSTORMS WITHIN 120 NM S AND E OF THE COLD
FRONT. BROAD E/W UPPER RIDGE EXETNDS FROM OFF AFRICA TO NEAR 45W
WITH THE AXIS ALONG 12W/13N. UPPER LEVEL DIFFLUENCE AND TROPICAL
MOISTURE ARE THE ACTIVITY ASSOCIATED WITH THE TROPICAL WAVE
ALONG 45W/46W. OTHERWISE THE E ATLC REMAINS RATHER CLEAR TONIGHT
ALTHOUGH A COPIOUS AMOUNT OF AFRICAN DUST HAS SPREAD ACROSS THE
TROPICAL ATLC S OF 20N TO AT LEAST 35W.

$$
WALLACE




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