[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 131142
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 AM EST THU DEC 13 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1115 UTC

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 8N13W 6N21W 4N30W 3N40W EQUATOR49W.
SCATTERED MODERATE CONVECTION IS FROM 4N-6N E OF 14W...FROM
1N-4N BETWEEN 24W-29W...FROM 5N-8N BETWEEN 33W-38W AND AIDED BY
A WLY UPPER JET FROM 8N-11N BETWEEN 41W-60W.

DISCUSSION...
GULF OF MEXICO...
A SLOW MOVING COLD FRONT HAS WORKED ITS WAY INTO THE FAR NW
CORNER OF THE REGION EXTENDING FROM SW LOUISIANA TO NRN MEXICO
NEAR 24N98W AND THEN STATIONARY ALONG THE E SLOPES OF THE SIERRA
MADRE. CONSIDERABLY COOLER AND DRIER AIR IS FILTERING IN BEHIND
THE FRONT. DOPPLER RADAR SHOWS A NARROW LINE OF SCATTERED
SHOWERS WITHIN 30 NM AHEAD OF THE BOUNDARY. ELSEWHERE
...MODERATE SFC RIDGING CONTINUES TO DOMINATE EXTENDING W FROM
THE WRN ATLC. LOW-LEVEL ELY FLOW IS ADVECTING ISOLATED TO
SCATTERED SHOWERS FROM THE ATLC INTO THE FLA STRAITS. IN THE MID
AND UPPER LEVELS...A RIDGE HAS BEEN SLOW TO MOVE OVERHEAD
ALLOWING THE FLOW ALOFT TO BE LIGHT AND ATMOSPHERE VERY STABLE.
A SHORTWAVE IS OVER THE CENTRAL U.S. PROVIDING SUPPORT FOR THE
COLD FRONT MENTIONED. THIS TROUGH...HOWEVER...IS EXPECTED TO
FLATTEN OUT LATER TODAY LIMITING THE PROGRESS OF THE COLD FRONT.
THE NEXT TROUGH/FRONT IS ANTICIPATED TO BE MUCH STRONGER
ENTERING THE NW WATERS EARLY SAT.

CARIBBEAN SEA...
THE LAST ADVISORY WAS ISSUED ON T.D. OLGA YESTERDAY EVENING.
THE REMNANT LOW IS CURRENTLY CENTERED IN THE NW CARIB NEAR
19N79W MOVING W 10-15 KT. THE LOW-LEVEL CIRCULATION IS STILL
EASILY IDENTIFIABLE ON NIGHT CHANNEL VIS IMAGES BUT CONVECTION
IS CONFINED TO A FEW SMALL BANDS N OF THE CENTER AND SLIGHTLY
LARGER OUTER BANDS FARTHER N OVER AND JUST N OF CUBA AND
PORTIONS OF THE BAHAMAS...AS NOTED IN CUBAN DOPPLER RADAR IMAGES
AND LIGHTNING DATA. FAIRLY DENSE LOW TO MID LEVEL CLOUDS AND
SHALLOWER SHOWER/TSTM ACTIVITY IS ELSEWHERE N AND E OF THE
CENTER N OF 17N BETWEEN 73W-80W. ONLY ISOLATED SHOWERS ARE ON
THE W SIDE OF THE LOW N OF 16N BETWEEN 79W-83W. SIMILAR ISOLATED
ACTIVITY IS E OF 73W ENHANCED BY AN INCREASE IN THE ELY TRADE
WIND FLOW.

ATLANTIC OCEAN...
BANDS OF SHOWERS/TSTMS...ASSOCIATED WITH THE REMNANTS OF T.D.
OLGA...IS AFFECTING PORTIONS OF THE SW ATLC INCLUDING THE
BAHAMAS S OF 25N BETWEEN 72W-79W. LIGHTNING DATA DEPICTS THE
STRONGEST BANDS OVER AND JUST N OF THE COAST OF CUBA. SEE CARIB
SECTION FOR MORE DETAILS. THE REMAINDER OF THE DISCUSSION AREA
IS DOMINATED BY MODERATE TO STRONG SFC RIDGING SUPPORTED BY A
1023 MB HIGH OFF THE GEORGIA COAST NEAR 31N79W...1026 MB HIGH
LOCATED SE OF BERMUDA NEAR 28N60W AND A 1024 MB NEAR 34N38W AND
STRONGER HIGH PRES OVER N AFRICA AND SW EUROPE. THERE IS A
SLIGHT WEAKNESS IN THE RIDGE E OF ABOUT 40W DUE TO A DISSIPATING
COLD FRONT THAT EXTENDS TO 27N38W AND A LARGE INVERTED TROUGH
NEAR THE AFRICAN COAST N OF 22N. A 1014 MB LOW HAS DEVELOPED
ALONG THE TROUGH AXIS S OF THE CANARY ISLANDS NEAR 26N17W AS
NOTED IN EARLIER ASCAT PASS.

THE MID AND UPPER PATTERN CONSISTS OF A LONGWAVE RIDGE/TROUGH N
OF 16N WITH A SERIES OF EMBEDDED SHORTWAVES E OF ABOUT 50W. THE
ONLY AREA OF ORGANIZED CLOUDINESS IN THE SUBTROPICS...BESIDES
FOR THE REMNANTS OF OLGA...IS IN THE FAR E PORTION N OF 23N E OF
16W ASSOCIATED WITH DIFFLUENCE ALOFT TO THE SE OF AN UPPER LOW
NEAR 30N21W AIDED BY AN ASSOCIATED SFC TROUGH NEAR THE AFRICAN
COAST. IN THE DEEP TROPICS...THE FLOW ALOFT IS FAIRLY ZONAL AND
QUITE STRONG. THIS STRONG FLOW AND A SLIGHTLY DIFFLUENT PATTERN
IS ENHANCING SCATTERED MODERATE TO STRONG CONVECTION FROM 5N-11N
BETWEEN 33W-60W. DEBRIS MOISTURE HAS SPREAD WELL E TO AFRICA
MAINLY S OF 18N.

$$
CANGIALOSI




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