[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 061143
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 AM EST THU DEC 06 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 7N12W 5N28W 7N39W 5N46W 3N51W.
SCATTERED MODERATE CONVECTION IS WITHIN 90 NM OF THE AXIS
BETWEEN 28W-33W. SIMILAR CONVECTION IS WITHIN 180 NM N AND 60 NM
S OF THE AXIS BETWEEN 34W-42W.

DISCUSSION...

THE GULF OF MEXICO...
A WEAK COLD FRONT HAS PUSHED OFF THE N GULF COAST EXTENDING FROM
THE BIG BEND AREA OF FLORIDA TO S TEXAS...AS OF 09Z. THIS FRONT
IS VERY DRY WITH LITTLE CLOUDS SEEN ON SAT IMAGES NEAR THE
BOUNDARY. THERE IS SOME CLOUDINESS...HOWEVER...IN THE SE GULF
NEAR THE TAIL END OF A PREFRONTAL TROUGH. MIAMI AND KEY WEST
DOPPLER RADARS REVEAL A LINE OF SCATTERED TSTMS IN THE FL
STRAITS PUSHING TOWARD THE NW BAHAMAS. ISOLATED ACTIVITY IS OVER
PORTIONS OF S FLORIDA. OTHERWISE...A VERY WEAK SFC PRES PATTERN
AHEAD OF THE FRONT IS RESULTING IN LIGHT AND VARIABLE WINDS
ACROSS THE CENTRAL AND W PORTIONS. IN THE MID AND UPPER
LEVELS...A WELL DEFINED CUT OFF LOW CONTINUES TO SIT AND SPIN
OVER CENTRAL MEXICO. EXTENSIVE SWLY FLOW ALOFT TO THE E OF THE
LOW IS ADVECTING A PLUME OF HIGH LEVEL CLOUDINESS ACROSS MUCH OF
THE W GULF.

THE CARIBBEAN SEA...
QUIET CONDITIONS DOMINATE MUCH OF THE CARIB BASIN THIS MORNING
WITH NIGHT CHANNEL VIS IMAGERY ONLY REVEALING TYPICAL NARROW
SCATTERED STREAMS OF LOW-LEVEL CLOUDINESS. SAN JUAN DOPPLER
RADAR DEPICTS SOME EMBEDDED SHOWER ACTIVITY MOSTLY S OF THE
ISLAND...BUT MUCH LESS SO THAN THE PAST FEW DAYS. LIKE THE GULF
OF MEXICO...WEAK SFC PRES PATTERN INDUCED BY THE SERIES OF WEAK
FRONTAL TROUGHS N OF THE AREA IS ALLOWING ELY TRADES TO BE LIGHT
ACROSS THE ENTIRE AREA...EVEN VARIABLE IN THE NW CARIB WHERE A
WEAK SFC HIGH IS ANALYZED. ALOFT...SW TO WLY FLOW IS THE THEME
ON THE NW SIDE OF A VERY BROAD RIDGE CENTERED ABOVE THE TROPICAL
ATLC. A SWATH OF MID-HIGH LEVEL CLOUDINESS IS SEEN ON WV IMAGES
IN THE SW CARIB S OF 15N W OF 75W AND IN THE SE CARIB S OF 14N W
OF 67W...BUT NOT MUCH SENSIBLE WEATHER. THE RELAXED TRADE WIND
FLOW IS NOT EXPECTED TO LAST MUCH LONGER AS STRONG RIDGING
BUILDS NE OF THE AREA. WINDS ARE EXPECTED TO INCREASE FROM E-W
LATER TODAY.

THE ATLANTIC OCEAN...
A RATHER QUICK MOVING COLD FRONT HAS PUSHED OFF THE E COAST OF
THE U.S. EXTENDING FROM 32N76W THRU N CENTRAL FLORIDA. THIS
FRONT IS FAIRLY WEAK AND DRY IN NATURE. A PREFRONTAL
TROUGH...POSSIBLY ASSOCIATED WITH A PORTION OF AN OLD
FRONT...EXTENDS FROM 32N72W ACROSS THE NW BAHAMAS AND INTO THE
FLA STRAITS. LOW-LEVEL CONVERGENCE ALONG THIS BOUNDARY IS
PRODUCING PATCHY CLOUDINESS AND A FEW LINES OF SCATTERED TSTM
ACTIVITY IN THE FL STRAITS...EVIDENT IN KEY WEST RADAR. SIMILAR
ACTIVITY IS LIKELY OCCURRING IN THE NW BAHAMAS. A CLUSTER OF
TSTM ACTIVITY...WHICH APPEARS TO BE ASSOCIATED WITH MID-LEVEL
VORTICITY...HAS BEEN TRAVELING NE WITH THE MID AND UPPER FLOW
CURRENTLY FROM 28N-32N BETWEEN 64W-66W. A SMALL WEAK SFC TROUGH
IS ALONG 55W FROM 21N-26N ONLY CAUSING SCATTERED CLOUDS AND
SLIGHT CYCLONIC VEERING IN THE SFC WINDS. THE REMAINDER OF THE
AREA W OF 50W IS FAIRLY QUIET UNDER MODERATELY STABLE AIR AND
FAIRLY UNIFORM ZONAL UPPER FLOW.

THE CENTRAL AND E ATLC IS DOMINATED BY STRONG SFC RIDGING
ANCHORED BY A 1036 MB HIGH MIDWAY BETWEEN THE AZORES AND THE
IBERIAN PENINSULA NEAR 38N17W. SAT IMAGES SUGGEST THAT A SFC
TROUGH HAS DEVELOPED ON THE SW PERIPHERY OF THE RIDGE ALONG
41W/42W FROM 13N-26N. ASSOCIATED SCATTERED SHOWERS EXIST FROM
16N-23N BETWEEN 38W-43W. TIGHT PRES GRADIENT BETWEEN THE TROUGH
AND THE MENTIONED HIGH IS CREATING A LARGE AREA OF STRONG ELY
TRADES ACROSS MOST OF THE DISCUSSION AREA E OF THE TROUGH AXIS.
THE MID AND UPPER PATTERN IS QUITE AMPLIFIED CONSISTING OF A
LARGE ANTICYCLONE OVER THE AZORES AND A BROAD ELONGATED TROUGH
TRAPPED S OF THE HIGH. THE BROAD TROUGH HAS AN EMBEDDED UPPER
LOW JUST SW OF THE CAPE VERDE ISLANDS NEAR 26N21W. STRONG UPPER
WINDS ON THE S SIDE OF THE TROUGH IS GENERATING AND TRANSPORTING
SCATTERED SHOWERS AND TSTMS N OF THE ITCZ ROUGHLY FROM 5N-13N
BETWEEN 33W-44W.

$$
CANGIALOSI


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