[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 141714
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST FRI DEC 14 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1415 UTC.

...ITCZ/MONSOON TROUGH...
THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM THE AFRICAN
COAST NEAR 08N13W TO 02N28W TO 08N45W. SCATTERED MODERATE AND
ISOLATED STRONG CONVECTION IS S OF THE AXIS TO 03N BETWEEN 10W
AND 14W. SCATTERED MODERATE CONVECTION IS FROM 03N TO 05N
BETWEEN 22W AND 26W AS WELL AS WITHIN 210 NM S OF THE AXIS AND
45 NM N OF THE AXIS BETWEEN 34W AND 40W.

...DISCUSSION...

GULF OF MEXICO...
MOSTLY WEST-NORTHWESTERLY UPPER LEVEL FLOW IS OVER THE GULF
BASIN TODAY WITH WATER VAPOR IMAGERY INDICATING RELATIVELY DRY
AND STABLE CONDITIONS E OF 87W. THE SOUTHWESTERN EXTENT OF AN
UPPER LEVEL TROUGH HAS PROGRESSED EASTWARD THROUGH THE FLORIDA
PENINSULA AND INTO THE SW NORTH ATLC REGION...CARRYING ITS
DISSIPATING SURFACE FRONT SE OF THE GULF OF MEXICO.
OTHERWISE...THE REMAINDER OF THE BASIN IS UNDER THE INFLUENCE OF
A SURFACE RIDGE ANCHORED BY 1030 MB HIGH CENTERED OVER THE
APPALACHIAN MOUNTAINS IN WEST VIRGINIA. MOSTLY NE TO E WINDS
PREVAIL E OF 90W...WITH SE WINDS W OF 90W. WEAK LOW-LEVEL
MOISTURE CONVERGENCE AND ISOLATED SHOWERS ARE OCCURRING IN THE
NW GULF W OF 95W. THE RETURN FLOW IS FORECAST TO CONTINUE
SPREADING EASTWARD THROUGH THE WEEKEND AS THE HIGH OVER THE
CONUS SLIDES EAST INTO THE NORTH ATLC. UPPER FLOW BETWEEN
RIDGING OVER THE GULF AND A MEAN TROUGH TO THE W OF THE AREA IS
DIRECTING MIDDLE TO UPPER LEVEL PACIFIC MOISTURE OVER THE
WESTERN GULF OF MEXICO. THE TROUGH IS EXPECTED TO WEAKEN AS IT
PROGRESSES EASTWARD THROUGH THE CONUS...WITH ITS ASSOCIATED
SURFACE FRONT EXPECTED TO REACH THE TEXAS COAST BY THE END OF
THE WEEKEND.

CARIBBEAN SEA...
UPPER LEVEL WESTERLY TO NORTHWESTERLY FLOW DOMINATES THE
CARIBBEAN BASIN TODAY BETWEEN AN UPPER LEVEL ANTICYCLONIC
CIRCULATION CENTERED IN THE EAST PACIFIC NEAR 13N92W AND AN
UPPER LEVEL LOW CENTERED OVER THE CENTRAL ATLC NEAR 21N50W.
WATER VAPOR IMAGERY INDICATES THAT VERY DRY AIR AND SUBSIDENCE
PREVAILS IN THE MIDDLE AND UPPER LEVELS OF THE ATMOSPHERE OVER
THE VAST MAJORITY OF THE CARIBBEAN. AT THE SURFACE...THE
PRESSURE GRADIENT IS RELATIVELY RELAXED WITH E-NE TRADES
GENERALLY FROM 10 TO 20 KT. WHILE NO SIGNIFICANT DEEP CONVECTION
IS OCCURRING...A FEW ISOLATED SHOWERS AND TSTMS ARE NOTED ON
SATELLITE IMAGERY S OF 11N IN THE SW CARIBBEAN NEAR THE MONSOON
TROUGH AXIS ANALYZED ACROSS EASTERN PANAMA AND INTO COLOMBIA
ALONG 10N. SCATTERED SHOWERS PERSIST OVER THE NE CARIBBEAN NEAR
A DISSIPATING LOW LEVEL BOUNDARY THAT EXTENDS FROM EASTERN CUBA
NEAR 22N83W TO 19N88W. ELSEWHERE...THE GREATEST CONCENTRATION OF
LOW-LEVEL MOISTURE IS FOUND OVER MONA PASSAGE WITH WIDELY
SCATTERED LOW-TOPPED SHOWERS OCCURRING N OF 15N BETWEEN 67W AND
72W...INCLUDING OVER PORTIONS OF THE DOMINICAN REPUBLIC. THIS
OVERALL SYNOPTIC PATTERN OF FAIRLY TRANQUIL WEATHER IS EXPECTED
TO CONTINUE THROUGH THE WEEKEND.

ATLANTIC OCEAN...
A WEAKENING MIDDLE TO UPPER LEVEL SHORTWAVE TROUGH IS OVER THE
SW NORTH ATLC WITH ITS AXIS EXTENDING FROM 32N67W TO A BASE OVER
NORTHERN CUBA. THIS TROUGHING SUPPORTS A COLD FRONT ANALYZED
INTO THE DISCUSSION AREA NEAR 32N64W AND EXTENDS SW TO THE
CENTRAL BAHAMAS NEAR 25N77W AND INTO THE FLORIDA STRAITS AS A
DISSIPATING STATIONARY FRONT TO 22N82W. LOW LEVEL MOISTURE
CONVERGENCE NEAR THE COLD FRONT IS GENERATING SCATTERED SHOWERS
PRIMARILY WITHIN 90 NM AHEAD OF THE FRONT E OF THE BAHAMAS WITH
MORE ISOLATED SHOWERS FOUND OVER THE BAHAMAS AND WESTWARD INTO
THE STRAITS OF FLORIDA. THIS FRONT IS FORECAST TO WEAKEN AS IT
PULLS NORTHEASTWARD THROUGH THE WEEKEND. FARTHER EAST...A MIDDLE
TO UPPER LEVEL LOW IS CENTERED NEAR 21N50W THAT SUPPORTS AN
ILL-DEFINED 1008 MB LOW AT THE SURFACE NEAR 19N52W WITH A
SURFACE TROUGH AXIS THAT EXTENDS NE FROM THE LOW TO 23N47W AND
SOUTH-SOUTHWEST FROM THE LOW THROUGH 17N52W TO 14N56W.
CONVECTION ASSOCIATED WITH THIS SYSTEM IS DISPLACED WELL E OF
THE CENTER AND IS FOUND MAINLY WITHIN 120 NM EITHER SIDE OF A
LINE FROM 26N40W TO 18N45W. WATER VAPOR IMAGERY INDICATES THAT
DRIER AIR IS WRAPPING INTO THE LOW CENTER ALOFT FROM THE WEST
AND NORTHWEST. THE FORECAST CALLS FOR THIS UPPER LOW TO WEAKEN
AS IT LIFTS NORTHEASTWARD OVER THE WEEKEND INTO THE LEADING EDGE
OF THE TROUGH SUPPORTING THE COLD FRONT THAT CURRENTLY EXTENDS
TO THE BAHAMAS...LEAVING BEHIND SOME MID LEVEL ENERGY IN THE
VICINITY OF THE SURFACE LOW THAT WILL ALSO WEAKEN OVER THE NEXT
FEW DAYS. THE REMAINDER OF THE EASTERN ATLC IS UNDER THE
INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1025 MB HIGH CENTERED
NEAR 28N35W.

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

$$
SCHAUER/HUFFMAN



This weather bulletin was brought to you by:
www.nashvilleweather.net