[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 130557
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0515 UTC

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 8N13W 5N25W 5N40W 3N51W. SCATTERED
MODERATE CONVECTION IS WITHIN 180 NM N OF THE AXIS BETWEEN
34W-38W AND WITHIN 180 NM S OF THE AXIS BETWEEN 24W-29W.
SCATTERED MODERATE TO STRONG IS FROM 7N-13N BETWEEN 45W-58W AND
FROM 4N-6N E OF 12W.

DISCUSSION...
GULF OF MEXICO...
A COLD FRONT HAS WORKED ITS WAY INTO THE FAR NW CORNER OF THE
REGION EXTENDING FROM THE TEXAS/LOUISIANA BORDER TO NRN MEXICO
NEAR 25N97W. CONSIDERABLY COOLER AND DRIER AIR IS FILTERING IN
BEHIND THE FRONT. DOPPLER RADAR SHOWS A NARROW LINE OF SCATTERED
SHOWERS WITHIN 60 NM OF THE BOUNDARY. ELSEWHERE...SFC RIDGING
CONTINUES TO DOMINATE THE PATTERN EXTENDING WSW FROM A 1026 MB
HIGH S OF BERMUDA. 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 FAIRLY STATIONARY DIRECTLY
OVERHEAD ALLOWING THE FLOW ALOFT TO BE LIGHT AND ATMOSPHERE VERY
STABLE. A SHORTWAVE IS FURTHER NW 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 WILL BE MUCH
STRONGER ENTERING THE NW CORNER EARLY SAT.

CARIBBEAN SEA...
THE LAST ADVISORY WAS ISSUED ON T.D. OLGA EARLIER THIS EVENING.
THE REMNANTS ARE CURRENTLY CENTERED JUST N OF JAMAICA NEAR
19N78W MOVING W 10 KT OR SO. THE CIRCULATION IS STILL EASILY
IDENTIFIABLE ON NIGHT CHANNEL VIS IMAGES BUT CONVECTION IS
NEARLY ABSENT NEAR THE CENTER AND THERE ARE ONLY A FEW BANDS N
OF THE SYSTEM OVER ERN CUBA AND NEAR THE BAHAMAS. FAIRLY DENSE
LOW TO MID LEVEL CLOUDS AND SHALLOWER SHOWER/TSTM ACTIVITY IS
MOSTLY TO THE N AND E OF THE LOW-LEVEL CENTER N OF 17N BETWEEN
71W-78W. ONLY ISOLATED SHOWERS ARE AHEAD OF THE LOW N OF 17N
BETWEEN 78W-83W. SIMILAR ISOLATED ACTIVITY IS E OF 70W ENHANCED
BY AN INCREASE IN THE ELY TRADES.

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 70W-78W. LIGHTNING DATA DEPICTS THE
STRONGEST BANDS JUST N OF THE COAST OF CUBA AND NEAR THE N SHORE
OF THE HISPANIOLA TO THE S CENTRAL BAHAMAS. THE REMAINDER OF THE
DISCUSSION AREA IS DOMINATED BY MODERATE TO STRONG SFC RIDGING
SUPPORTED BY A 1026 MB HIGH LOCATED SE OF BERMUDA NEAR 31N63W
AND A 1024 MB NEAR 36N39W. THERE IS A SLIGHT WEAKNESS IN THE
RIDGE E OF ABOUT 40W DUE TO A DISSIPATING COLD FRONT THAT
EXTENDS TO 29N42W AND A LARGE INVERTED TROUGH NEAR THE AFRICAN
COAST N OF 18N. A 1014 MB LOW HAS DEVELOPED ALONG THE TROUGH
AXIS NEAR 25N17W AS NOTED IN A RECENT ASCAT PASS.

THE MID AND UPPER PATTERN CONSISTS OF A LONGWAVE RIDGE/TROUGH
IN THE SUBTROPICS WITH A SERIES OF EMBEDDED SHORTWAVES E OF
ABOUT 50W. THE ONLY AREA OF ORGANIZED CLOUDINESS IN THE
SUBTROPICS IS IN THE FAR E PORTION N OF 22N E OF 17W ASSOCIATED
WITH DIFFLUENCE ALOFT TO THE SE OF AN UPPER LOW NEAR 30N21W
AIDED BY SFC TROUGH NEAR THE AFRICAN COAST. IN THE TROPICS...THE
FLOW ALOFT IS FAIRLY ZONAL. STRONG WINDS S OF 13N AND A SLIGHTLY
DIFFLUENT PATTERN IS ENHANCING SCATTERED MODERATE TO STRONG
CONVECTION N OF THE ITCZ BETWEEN 45W-59W. DEBRIS MOISTURE HAS
SPREAD WELL E TO AFRICA MAINLY S OF 15N.

$$
CANGIALOSI


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