[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 101710
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST FRI 10 DEC 2004

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHEASTERN
SECTIONS OF SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN
COAST FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION IS
BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...
AND METEOROLOGICAL ANALYSIS.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1645 UTC.

...ITCZ...

AXIS OF ITCZ IS CENTERED ALONG 9N10W 4N26W 6N38W 7N50W. THE AXIS
IS NOT WELL-DEFINED BETWEEN 50W-70W BUT THEN BECOMES
RE-ESTABLISHED ALONG 10N73W 6.5N80W. WIDELY SCATTERED MODERATE
CONVECTION WITHIN 175/200 NM OF THE AXIS BETWEEN 11W-25W. WIDELY
SCATTERED MODERATE FROM 4N-11N BETWEEN 27W-35W. SCATTERED
MODERATE FROM NEAR CARTAGENA COLUMBIA SW THROUGH SE PANAMA.

...DISCUSSION...

GULF OF MEXICO...
A LARGE AND COMPLEX LOW PRESSURE SYSTEM IS MOVING ACROSS THE
EASTERN UNITED STATES WITH A COLD FRONT EXTENDING FROM NEAR
JACKSONVILLE FLORIDA SWWD ACROSS THE GULF ALONG 30N81W 25N90W
22N97W TO NEAR TAMPICO MEXICO. A BROAD LONGWAVE TROF IS LOCATED
OVER THE MISSISSIPPI VALLEY AND EXTENDS INTO THE W GULF BUT THE
SWLY FLOW AHEAD OF THE MAIN AXIS IS NOT REALLY THAT DIFFLUENT S
OF 30N...WHICH IS PROHIBITING WIDESPREAD CONVECTION ALONG THE
FRONT. VISIBLE AND INFRARED IMAGERY DO INDICATE THAT WIDELY
SCATTERED SHOWERS/TSTMS HAVE BEGUN TO DEVELOP UP TO 200 NM AHEAD
OF THE BOUNDARY N OF 24N. SOME OF THESE SHOWERS HAVE ALREADY
BEGUN TO SPREAD ACROSS PARTS OF S/CNTRL FLORIDA. THE FRONT WILL
MOVE THROUGH THE ENTIRE GULF AND FLORIDA PENINSULA BY SAT
AFTERNOON WITH MUCH DRIER AND COOLER AIR SWEEPING IN FROM THE
NORTH. ELSEWHERE...A WEAK SFC TROF HAS DEVELOPED JUST N OF THE
ISTHMUS OF TEHUANTEPEC OVER THE BAY OF CAMPECHE WITH ISOLATED
SHOWERS/TSTMS FROM 18N-21N BETWEEN 93W-95W.

CARIBBEAN...
THE ATLC SFC RIDGE IS LOCATED N OF THE GREATER ANTILLES WHICH IS
KEEPING PERSISTENT EASTERLY TRADES OVER THE REGION. THE UPPER
FLOW OVER THE AREA IS SOMEWHAT AMPLIFIED BUT MOISTURE IS ALMOST
NON-EXISTENT AND SO THERE IS VERY LITTLE SHOWER/TSTM ACTIVITY.
AN UPPER TROF IS ALIGNED JUST OFF THE MOSQUITO COAST OF
NICARAGUA DOWN TO COSTA RICA WITH A DOWNSTREAM RIDGE AXIS
EXTENDING FROM LAKE MARACAIBO TO JAMAICA AND E CUBA. THE DRIEST
AIR IS LOCATED E OF THE RIDGE AXIS WHERE CONFLUENT FLOW IS
PRODUCING STRONG SUBSIDENCE. WIDELY SCATTERED SHOWERS/TSTMS ARE
LOCATED OVER SE PANAMA ALONG THE ITCZ AS WELL AS MOVING W ACROSS
TRINIDAD AND THE NE COAST OF VENEZUELA.

WEST ATLANTIC...
STRONG SFC HIGH PRESSURE IS IN CONTROL W OF 50W AN SO THERE IS
VERY LITTLE ACTIVE WEATHER IN THE AREA. THE HIGH HAS A PRESSURE
OF 1026 MB AND IS CENTERED NEAR 31N58W WITH A RIDGE EXTENDING SW
ACROSS THE CNTRL BAHAMAS TO E CUBA. IN THE UPPER LEVELS...A
RIDGE EXTENDS NE OF THE BAHAMAS BUT STRONG SWLY FLOW AHEAD OF
THE U.S. TROF HAS IMPINGED ON THE AXIS AND GIVEN IT A MORE E/W
ORIENTATION ALONG 22N72W 26N65W 25N50W. THIS HAS INCREASED THE
CONVERGENCE ALONG THE AXIS AND SUBSIDENCE HAS RESPONDED BY
BECOMING STRONGER OVER THE W ATLC. A TROF AXIS IS LOCATED JUST S
OF THE RIDGE ALONG 21N AND HAS INITIATED A FEW SHOWERS/TSTMS
ALONG A LINE ABOUT 200/300 NM NE OF THE NORTHERN LEEWARD ISLANDS.

EAST/CENTRAL ATLANTIC...
EXTENSIVE MID/UPPER LEVEL CLOUDINESS SPANS ACROSS A GOOD CHUNK
OF THE E ATLC WATERS AND A RETREATING UPPER LEVEL JET OVER W
AFRICA IS DRAWING THIS MOISTURE EWD TOWARDS THE CONTINENT. A
MID/UPPER LOW IS CENTERED NEAR 21N50W AND UPPER LEVEL DIFFLUENCE
EAST OF THIS FEATURE AND THE TRAILING TROF IS PRODUCING WIDELY
SCATTERED MODERATE CONVECTION FROM 9N-21N BETWEEN 37W-50W...WITH
THE CONVECTIVE CIRRUS EXPANDING DOWNSTREAM. ELSEWHERE...A
WEAKENING COLD FRONT IS SINKING SWD EXTENDING FROM MADEIRA
ISLAND TO A 1018 MB LOW NEAR 28N21...OR 200 NM W OF THE CANARY
ISLANDS...THEN CONTINUING SW TO 25N24W 24N37W. A NARROW BAND OF
CLOUDS LIES ALONG THE FRONT WITH SOME SHOWERS POSSIBLE PRIMARILY
N OF 30N...AND THIS FEATURE IS EXPECTED TO DISSIPATE NEAR THE
CANARY ISLANDS OVER THE NEXT 2 DAYS. FARTHER S...A WELL-DEFINED
UPPER HIGH IS CENTERED NEAR 8N20W WITH A NARROW RIDGE EXTENDING
NW TO 11N34W. A LINE OF DIVERGENCE W OF THE HIGH ALONG 6N IS
ENHANCING CONVECTION ALONG THE ITCZ E OF 32W.

$$
BERG






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