[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 191737
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST MON DEC 19 2011

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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1700 UTC.

...THE ITCZ/THE MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS INLAND OVER W AFRICA TO THE COAST OF
GUINEA NEAR 9N13W CONTINUING SW TO 7N16W. THE ITCZ CONTINUES
FROM 7N16W ALONG 4N26W 5N43W. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION IS FROM 2N-5N BETWEEN 17W-28W.

...DISCUSSION...

GULF OF MEXICO...
SURFACE RIDGING DOMINATES THE GULF OF MEXICO TODAY AROUND A 1030
MB HIGH JUST OFF THE COAST OF NORTH CAROLINA NEAR 35N76W. THIS
PATTERN IS PROVIDING MAINLY E-SE FLOW OF 15 KTS ACROSS MUCH OF
THE BASIN WITH STRONGER WINDS UP TO 20 KTS IN THE NW CORNER
ALONG THE TEXAS COAST. ALOFT...AN UPPER LEVEL RIDGE IS ACROSS
THE BASIN EXTENDING FROM THE NW CARIBBEAN AND NWD ACROSS THE ERN
CONUS SUPPORTING THE SURFACE RIDGE. DRY AIR ACCOMPANYING THE
UPPER RIDGE IS KEEPING THE MAJORITY OF THE BASIN UNDER MOSTLY
CLEAR SKIES AND FAIR WEATHER. A FEW AREAS OF STRATOCUMULUS
CLOUDS DOT THE NE AND WRN PORTIONS WITH RADAR IMAGERY INDICATING
ISOLATED SHOWERS ARE ALSO ALONG THE TEXAS COASTLINE. THE SURFACE
RIDGE IS EXPECTED TO SHIFT EWD AS A COLD FRONT MOVES OFF THE
TEXAS COAST IN ABOUT 24 HOURS.

CARIBBEAN SEA...
NE-E TRADEWIND FLOW OF 15-20 KTS IS ACROSS MUCH OF THE CARIBBEAN
TODAY WITH A FEW OBSERVATIONS S OF HISPANIOLA INDICATING 25 KTS.
PATCHES OF ISOLATED SHOWERS ARE EMBEDDED WITHIN THE TRADEWIND
FLOW WITH MORE CONCENTRATED ACTIVITY OVER THE NW CARIBBEAN AND
ALONG THE COAST OF CENTRAL AMERICA DUE TO DIFFLUENCE ALOFT
BETWEEN AN UPPER LEVEL TROUGH OVER THE E PACIFIC AND AN UPPER
LEVEL RIDGE COVERING THE CARIBBEAN EXTENDING FROM VENEZUELA TO
WRN CUBA AND NWD ACROSS THE ERN CONUS. SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS ARE ALSO IN THE SW CARIBBEAN S OF
11N BETWEEN 76W-84W DUE TO SURFACE CONVERGENCE NEAR THE MONSOON
TROUGH EXTENDING ACROSS PANAMA TO NRN COLOMBIA. EXPECT A FRONTAL
BOUNDARY N OF THE BASIN IN THE W ATLC TO BEGIN BRINGING SHOWERS
TO HISPANIOLA AND THE NRN LEEWARD ISLANDS WITHIN THE NEXT 12-24
HOURS. A SURFACE TROUGH AND ASSOCIATED CONVECTION IS ALSO E OF
THE WINDWARD ISLANDS AND IS EXPECTED TO ADVECT WWD WHICH WILL
IMPACT THE SRN WINDWARD ISLANDS.

ATLANTIC OCEAN...
A SHORTWAVE UPPER TROUGH OVER THE NW ATLC IS SUPPORTING A COLD
FRONT ENTERING THE DISCUSSION AREA ALONG 32N54W 26N58W 22N67W
22N76W AND DISSIPATING TO CENTRAL CUBA. GALE FORCE WINDS ARE
NOTED N OF 29N BEHIND THE FRONT. DUE TO DRY AIR ALOFT...ISOLATED
SHOWERS ARE ONLY WITHIN 60 NM AHEAD OF THE AXIS WITH WIDESPREAD
STRATOCUMULUS CLOUDS BEHIND IT. A PRE-FRONTAL TROUGH IE E OF THE
FRONT ALONG 50W N OF 25N. POSSIBLE ISOLATED SHOWERS ARE ALONG
THE TROUGH AXIS. A SURFACE RIDGE IS BUILDING IN
BEHIND THE FRONT CURRENTLY ANCHORED AROUND A 1030 MB HIGH JUST
OFFSHORE OF NORTH CAROLINA. FARTHER S IN THE TROPICAL ATLC...A
SURFACE TROUGH IS ALONG 14N52W TO 9N56W. SCATTERED SHOWERS ARE
WITHIN 200 NM NW OF THE AXIS. THE REMAINDER OF THE ERN ATLC IS
UNDER THE INFLUENCE OF SURFACE RIDGING AROUND A 1034 MB HIGH
OVER THE AZORES ISLANDS. ALOFT...AN UPPER LEVEL RIDGE IS
CENTERED NEAR 34N25W SUPPORTING THE SURFACE RIDGE. A WEAK
SHORTWAVE UPPER TROUGH IS ALONG 33N42W TO 21N32W CAUSING LITTLE
SIGNIFICANT WEATHER. EXPECT THE FRONTAL SYSTEM IN THE CENTRAL
ATLC TO MOVE NE OVER THE NEXT SEVERAL DAYS.

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

$$
WALTON





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