[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 051136
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 AM EST WED DEC 05 2012

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1045 UTC.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS W AFRICA INTO THE FAR E
TROPICAL ATLC NEAR 8N13W TO 8N15W WHERE THE ITCZ BEGINS AND
CONTINUES ALONG 6N21W 6N35W 9N52W TO SOUTH AMERICA NEAR 9N61W.
NUMEROUS TO SCATTERED STRONG CONVECTION IS FROM 3N-7N BETWEEN
25W-31W. SCATTERED MODERATE/STRONG CONVECTION IS WITHIN 120 NM N
OF THE ITCZ BETWEEN 21W-25W AND WITHIN 120 NM S OF THE ITCZ
BETWEEN 31W-33W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION
IS WITHIN 90 NM N OF THE ITCZ BETWEEN 16W-21W. CLUSTERS OF
SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE WITHIN 75 NM
OF LINE FROM THE COAST OF LIBERIA NEAR 6N10W TO 3N16W. CLUSTERS
OF SCATTERED MODERATE CONVECTION ARE FROM 5N-9N BETWEEN
40W-43W.

...DISCUSSION...

GULF OF MEXICO...
A NARROW UPPER TROUGH EXTENDS INTO THE GULF FROM OVER LOUISIANA
TO NEAR 22N95W SUPPORTING A COLD FRONT THAT AT 05/0900 UTC
EXTENDS ACROSS PORT ARTHUR TEXAS ALONG 29N94W WHERE IT BECOMES
STATIONARY TO A NEWLY DEVELOPED 1019 MB LOW ALONG THE COAST NEAR
BROWNSVILLE THEN CONTINUES AS A COLD FRONT SW INTO NE MEXICO.
SCATTERED SHOWERS/THUNDERSTORMS ARE WITHIN 45/60 NM OF LINE FROM
26N94W TO NE MEXICO NEAR MATAMOROS AND WITHIN 45 NM ALONG THE
COAST OF MEXICO N OF TAMPICO. A WEAK 1018 MB LOW IS OVER LAKE
PONTCHARTRAIN WITH A SURFACE TROUGH EXTENDING INTO THE GULF TO
25N93W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 180
NM E OF THE TROUGH WITH SCATTERED SHOWERS AND POSSIBLE ISOLATED
THUNDERSTORMS W OF THE TROUGH TO THE ABOVE FRONT. AN UPPER RIDGE
EXTENDS ALONG 80W FROM CUBA TO BEYOND 32N COVERING THE FAR E
GULF. THE SURFACE RIDGE IS SHIFTING E AHEAD OF THE FRONT
ANCHORED BY A PAIR OF 1025 MB HIGHS...ONE IS LOCATED NEAR 33N72W
AND THE SECOND ALONG THE COAST OF GEORGIA/SOUTH CAROLINA BORDER.
ISOLATED SHOWERS ARE OVER THE SE GULF FROM 23N-26N E OF 87W
ACROSS S FLORIDA AND THROUGH THE STRAITS OF FLORIDA. FRONT WILL
STALL OVER THE W/CENTRAL GULF WED AND DISSIPATE THROUGH THU.
HIGH PRESSURE WILL BUILD ACROSS THE REGION FRI THROUGH THE
WEEKEND.

CARIBBEAN SEA...
A BROAD UPPER RIDGE IN THE TROPICAL ATLC EXTENDS A RIDGE AXIS
ALONG THE N COAST OF SOUTH AMERICA TO OVER COSTA RICA NEAR
10N84W GIVING THE CARIBBEAN MAINLY SW TO W FLOW ALOFT. MODERATE
TO STRONG SUBSIDENCE WITH DRY STABLE AIR ALOFT DOMINATES MOST OF
THE CARIBBEAN THIS MORNING. LIGHT TO MODERATE NE TO E TRADE
WINDS ACROSS THE CARIBBEAN CONTINUE TO BANK SCATTERED SHOWERS
AND POSSIBLE ISOLATED THUNDERSTORMS WITHIN 60 NM ALONG THE COAST
OF E HONDURAS TO W PANAMA BETWEEN 80W-84W. A SHEAR LINE IS
ANALYZED FROM THE CENTRAL ATLC NEAR 17N60W BETWEEN THE LEEWARD
AND WINDWARD ISLANDS TO 15N73W GENERATING SCATTERED SHOWERS
WITHIN 120 NM N OF THE SHEAR LINE. THE REMAINDER OF THE
CARIBBEAN IS UNDER MOSTLY CLEAR SKIES THIS MORNING. BROAD
SURFACE RIDGE OVER THE W ATLC WILL MAINTAIN THE TRADE WINDS
ACROSS MOST OF THE REGION WITH GRADUALLY DIMINISHING FRESH TO
STRONG WINDS IN THE NW CARIBBEAN AND ATLC PASSAGES THROUGH WED.
THE PRESSURE GRADIENT WILL WEAKEN THU AND FRI AND INCREASE IN
THE CENTRAL CARIBBEAN OVER THE WEEKEND AS HIGH PRESSURE REBUILDS
TO THE N.

ATLANTIC OCEAN...
AN UPPER RIDGE COVERS THE FAR E GULF INTO THE FAR W ATLC W OF
70W. A WEAKENING SURFACE RIDGE DOMINATES THE W ATLC ANCHORED BY
A PAIR OF 1025 MB HIGH...ONE IS LOCATED NEAR 33N72W AND THE
SECOND ALONG THE COAST OF GEORGIA/SOUTH CAROLINA BORDER. THE
EASTERLY SURFACE FLOW OVER THE FAR W ATLC IS GENERATING
SCATTERED SHOWERS FROM 26N-29N W OF 78W TO OVER FLORIDA. A
SURFACE TROUGH IS JUST E OF THE BAHAMA ISLANDS EXTENDING FROM
28N74W TO 22N73W. AN UPPER TROUGH EXTENDS INTO THE CENTRAL ATLC
THROUGH 32N51W TO 23N51W SUPPORTING A SURFACE TROUGH THAT
EXTENDS FROM 31N36W ALONG 25N45W THROUGH A 1010 MB LOW NEAR
24N51W TO 17N60W WHERE A SHEAR LINE CONTINUES INTO THE CARIBBEAN
NEAR THROUGH THE LEEWARD/WINDWARD ISLANDS. AN UPPER RIDGE IS TO
THE E EXTENDING FROM 20N40W TO BEYOND 32N32W PROVIDING
DIFFLUENCE ALOFT TO GENERATE DENSE CLOUD COVER WITH SCATTERED
SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS FROM 20N TO BEYOND
32N BETWEEN 35W-47W. AN UPPER TROUGH IS WELL N OF THE DISCUSSION
AREA SUPPORTING A COLD FRONT THAT EXTENDS TO 31N36W. A SURFACE
RIDGE DOMINATES THE REMAINDER OF THE E ATLC N OF 14N E OF 30W
ANCHORED BY A 1028 MB HIGH NE OF MADEIRA ISLANDS. FRESH NE WINDS
S OF 27N WILL LINGER EVEN AFTER THE HIGH PRESSURE N OF THE AREA
WEAKENS AND SHIFTS EAST TODAY. A TROUGH JUST E OF THE BAHAMAS
WILL AMPLIFY AS IT DRIFTS W INTO FLORIDA THROUGH FRI. A WEAK
COLD FRONT WILL BRUSH PAST THE N WATERS WED THROUGH THU. STRONG
HIGH PRESSURE WILL BUILD NE OF THE AREA THU NIGHT THROUGH SUN.

FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$
PAW






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