[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 071757
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST WED DEC 07 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
1715 UTC.

...ITCZ/MONSOON TROUGH...

THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 06N10W TO
04N35W TO 04N51W. SCATTERED MODERATE CONVECTION IS FROM 02N-08N
BETWEEN 33W-49W...AND FROM 08N-13N BETWEEN 45W-50W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER LEVEL SHORTWAVE TROUGH IS PROGRESSING EASTWARD OVER THE
MISSISSIPPI RIVER VALLEY AND SUPPORTS A COLD FRONT EXTENDING
INTO THE GULF NEAR 30N84W TO 25N89W WHERE IT BECOMES STATIONARY
INTO THE SW GULF TO 18N93W. ISOLATED SHOWERS ARE OCCURRING
WITHIN 30 NM EITHER SIDE OF THE FRONT WITH MOSTLY OVERCAST SKIES
OBSERVED WITHIN 180 NM WEST OF THE FRONT N OF 25N AND OVER THE
REMAINDER OF THE SW GULF WEST OF THE FRONT S OF 25N. AS HIGH
PRESSURE BUILDS IN ACROSS THE NW GULF...STRONG NORTHERLY WINDS
ARE NOTED WEST OF THE FRONT WITH CLOUD COVER CONSISTING OF
SCATTERED TO BROKEN STRATOCUMULUS CLOUDS N OF 25N W OF 90W. EAST
OF THE FRONT...A PRE-FRONTAL SURFACE TROUGH IS ANALYZED FROM
27N85W TO 22N86W WITH ISOLATED SHOWERS WITHIN 45 NM EAST OF THE
BOUNDARY. THE FRONT IS FORECAST TO SWEEP EAST OF THE GULF WATERS
BY THURSDAY MORNING AS THE HIGH PRESSURE AREA BUILDS IN ACROSS
THE GULF COASTAL PLAINS AND SE CONUS OVER THE WEEKEND.

CARIBBEAN SEA...
AN UPPER LEVEL LOW IS CENTERED IN THE SW NORTH ATLC NEAR 23N62W
AND EXTENDS A TROUGH AXIS SOUTHWESTWARD INTO THE CENTRAL
CARIBBEAN TO NEAR 14N79W. NORTH AND WEST OF THIS UPPER LEVEL
TROUGH AN ANTICYCLONIC CIRCULATION IS CENTERED NEAR 22N82W WHICH
IS ACCOMPANIED BY VERY DRY AND STABLE AIR ALOFT AS NOTED ON
WATER VAPOR IMAGERY. WHILE CONDITIONS REMAIN STABLE ALOFT...NE
WINDS PREVAIL AT THE SURFACE W OF 70W AND ONLY A FEW ISOLATED
LOW-TOPPED SHOWERS ARE NOTED ON VISIBLE SATELLITE IMAGERY
OCCURRING MOSTLY IN THE VICINITY OF THE CENTRAL AMERICAN
COASTLINE AND GULF OF HONDURAS DUE TO WEAK LOW-LEVEL MOISTURE
CONVERGENCE. FARTHER EAST...THE UPPER LEVEL TROUGHING IS
PROVIDING AMPLE MIDDLE TO UPPER LEVEL DIFFLUENCE GENERATING AN
AREA OF WIDELY SCATTERED SHOWERS SE OF A LINE FROM ANTIGUA TO
BONAIRE. OVER THE NEXT FEW DAYS...THE UPPER LEVEL LOW IS
FORECAST TO SLOWLY LIFT NORTHWARD INTO THE SW NORTH ATLC WATERS
AS A WEAK UPPER LEVEL RIDGE ESTABLISHES ITSELF OVER THE CENTRAL
CARIBBEAN ALONG 70W.

ATLANTIC OCEAN...
AN UPPER LEVEL LOW IS CENTERED NEAR 23N62W WITH A TROUGH AXIS
EXTENDING NE TO BEYOND 32N50W...AND SW INTO THE NE CARIBBEAN SEA
TO 18N70W. THIS TROUGHING SUPPORTS A 1010 MB LOW CENTERED NEAR
21N54W WITH A LENGTHY SURFACE TROUGH EXTENDING NE TO 32N43W AND
SW TO THE WINDWARD ISLANDS NEAR 14N61W. SCATTERED MODERATE
CONVECTION APPEARS TO BE SHEARED TO THE NE OF THE LOW CENTER
OCCURRING FROM 20N-25N BETWEEN 47W-53W. ELSEWHERE...ISOLATED
SHOWERS ARE OCCURRING WITHIN 150 NM EITHER SIDE OF THE ENTIRE
SURFACE TROUGH...AND ELSEWHERE FROM 20N-30N BETWEEN 40W AND THE
SURFACE TROUGH BOUNDARY. MOST OF THE STRONGER CONVECTIVE
ACTIVITY IS ENHANCED DUE TO MIDDLE TO UPPER LEVEL DIFFLUENCE
FOCUSED EAST OF THE UPPER LEVEL TROUGH AXIS. OVER THE REMAINDER
OF THE SW NORTH ATLC...SURFACE HIGH PRESSURE INFLUENCE CONTINUES
W OF 60W ON THE SOUTHERN PERIPHERY OF A 1024 MB HIGH CENTERED NE
OF BERMUDA NEAR 35N61W. AN APPROACHING COLD FRONT...CURRENTLY
ANALYZED ACROSS CENTRAL GEORGIA AND THE FLORIDA PANHANDLE INTO
THE NE GULF OF MEXICO...WILL ENTER THE FAR SW NORTH ATLC WATERS
BY LATE THIS EVENING INTO THURSDAY MORNING USHERING IN STRONG
NORTHWESTERLY WINDS. FARTHER EAST...AN UPPER LEVEL LOW IS
CENTERED NEAR 31N27W BUT HAS MINIMAL IMPACT AT THE SURFACE AS A
RIDGE...ANCHORED BY A 1034 MB HIGH CENTERED E-NE OF THE AZORES
NEAR 41N17W...CONTINUES TO INFLUENCE MUCH OF THE EASTERN ATLC E
OF 40W.

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

$$
HUFFMAN




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