[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 121123
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 AM EST SAT JAN 12 2008

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...
THE ITCZ AXIS IS CENTERED ALONG 8N13W 4N25W 2N35W 2S46W.
SCATTERED MODERATE CONVECTION IS FROM THE EQUATOR TO 4N BETWEEN
14W AND 25W AND ALSO FROM 5N TO 7N BETWEEN 27W AND 30W.

...DISCUSSION...

THE GULF OF MEXICO...
A STATIONARY FRONT EXTENDS FROM THE FLORIDA PANHANDLE IN THE
VICINITY OF APALACHEE BAY THROUGH 25N90W TO THE BAY OF CAMPECHE
NEAR 18N95W. SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ARE
WITHIN 60 NM EAST OF THE FRONT NEAR CEDAR KEY FLORIDA WITH MORE
EXTENSIVE ACTIVITY OVER NORTH FLORIDA. ADDITIONAL SHOWER AND
ISOLATED THUNDERSTORM ACTIVITY IS JUST TO THE WEST OF THE DRY
TORTUGAS. LIGHT SWLY WINDS OF 5-10 KT ARE NOTED IN ADVANCE OF
THE FRONT WITH LIGHT N TO NE WINDS OF 10 KT OR LESS W OF THE
FRONT. IN THE UPPER LEVELS...WSWLY FLOW COVERS THE ENTIRE GULF
OF MEXICO AND IS MOSTLY PARALLEL TO THE STATIONARY FRONT IN
ADDITION TO PROVIDING VERY LITTLE SUPPORT TO THE FRONT ITSELF. A
PATCH OF UPPER LEVEL MOISTURE IS OVER THE GULF S OF 28N AND
WAS CAPPED BY AN UPPER LEVEL WIND MAX WITH SATELLITE DERIVED
WINDS OF 60-70 KT NOTED. THIS AREA OF MOISTURE WAS LIFTING
NORTHWARD AS THE UPPER LEVEL FLOW WAS BACKING IN ADVANCE OF
A DIGGING TROUGH OVER TEXAS. STRONG SUBSIDENCE WAS EXITING THE
FAR NE CORNER OF THE GULF. THE STATIONARY FRONT WILL BEGIN
MOVING SLOWLY EASTWARD WITHIN THE NEXT 24 HOURS WITH SHOWER
ACTIVITY IN THE INCREASE AS STRONG UPPER LEVEL SUPPORT ARRIVES
FROM TEXAS ALLOWING LOW PRESSURE TO DEVELOP OFF THE GEORGIA
SOUTH CAROLINA COAST ON SUNDAY.

THE CARIBBEAN SEA...
LIGHT TO MODERATE TRADEWINDS ARE OVER THE ENTIRE CARIBBEAN SEA
WITH PATCHES OF BROKEN LOW CLOUDS AND SCATTERED SHOWERS OVER
PANAMA AND COSTA RICA. ANOTHER PATCH OF LOW CLOUDS/SHOWERS WAS
NOTED OVER THE W-CENTRAL CARIBBEAN EXTENDING NORTHWARD OVER
JAMAICA AND CUBA. A MORE CONCENTRATED AREA OF SHOWERS ARE NOTED
OVER THE CARIBBEAN E OF 65W AND EXTENDING EASTWARD OVER THE
WINDWARD ISLANDS. IN THE UPPER LEVELS...CONFLUENT WSWLY FLOW IS
OVER CENTRAL AMERICA AND THE CARIBBEAN AND WAS RESULTING IN A
LARGE AREA OF STRONG SUBSIDENCE WHICH WAS MOST PRONOUNCED EAST
OF 75W. THE SURFACE TROUGH JUST TO THE EAST OF THE WINDWARD
ISLANDS HAS BECOME DIFFUSE AND EXPECTED TO DISSIPATE OVER THE
NEXT SEVERAL HOURS...HOWEVER SHOWER ACTIVITY IS EXPECTED TO
PERSIST OVER THE WINDWARD ISLANDS FOR THE NEXT 24 HOURS OR SO.

THE ATLANTIC OCEAN...
A 1013 MB LOW IS OVER THE CENTRAL ATLANTIC NEAR 27N59.5W. THE
LOW WAS ALONG A SURFACE TROUGH WHICH EXTENDED FROM 31N60W S TO
22N59W. SURFACE RIDGE COVERED THE ATLANTIC N AND W OF THE
SURFACE LOW. FURTHER EAST A QUASI-STATIONARY 1029 MB HIGH IS
OVER THE E ATLANTIC NEAR 34N34W AND DOMINATES THE LOW LEVEL FLOW
OVER THE ATLANTIC N OF THE ITCZ AND E OF 46W. IN THE UPPER
LEVELS...A NARROW RIDGE IS OVER THE NW ATLANTIC N OF 20N W OF
62W WITH AXIS ALONG 67W. A WELL DEFINED UPPER LEVEL LOW WHICH IS
NEARLY VERTICALLY STACKED WITH THE SURFACE LOW NOTED ABOVE NEAR
27N59W IS BEGINNING TO DRIFT TO THE SE. ASSOCIATED TROUGH DIGS
SWD TO 20N OVER THE CENTRAL ATLANTIC BETWEEN 50W AND 62W. UPPER
LEVEL DIFFLUENCE IS E OF THE TROUGH AND UPPER LOW PRODUCING A
LARGE AREA OF MULTI-LAYERED CLOUDS WITH SCATTERED SHOWERS AND
ISOLATED THUNDERSTORMS FROM 20N-31N BETWEEN 45W-54W...AND WITHIN
120-150 NM IN THE SE SEMICIRCLE OF THE STACKED UPPER/SURFACE
LOW. AN UPPER RIDGE IS N OF 17N BETWEEN 30W-50W. MOSTLY ZONAL
FLOW IS E OF 30W WITH A TROPICAL WIND MAX NOTED ALONG 15N WHICH
WAS CAPPING AN EXTENSIVE AREA OF MAINLY MID AND UPPER LEVEL
CLOUDS.

$$
COBB







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