[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 121141
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 AM EST WED DEC 12 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
1115 UTC.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 10N14W TO
06N19W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM
06N19W TO 03N30W TO 03N44W TO 02N50W. SCATTERED MODERATE
CONVECTION IS FROM 03N-10N BETWEEN 38W-49W.

...DISCUSSION...

GULF OF MEXICO...
MIDDLE TO UPPER LEVEL SOUTHWESTERLY FLOW DOMINATES OVER THE GULF
THIS MORNING BETWEEN UPPER LEVEL TROUGHING LOCATED OVER THE
CENTRAL CONUS AND AN UPPER LEVEL RIDGE CENTERED NEAR 25N69W OVER
THE SW NORTH ATLC. WITH A MID-LEVEL SHORTWAVE TROUGH AXIS OVER
SE OKLAHOMA AND EASTERN TEXAS...THE TROUGHING SUPPORTS A COLD
FRONT ANALYZED FROM NORTHERN FLORIDA NEAR 29N82W TO 28N85W WHICH
THEN BECOMES STATIONARY TO 25N90W TO 20N94W. PLENTY OF MIDDLE TO
UPPER LEVEL MOISTURE CONTINUES TO STREAM E-NE FROM THE PACIFIC
REGION OVER CENTRAL MEXICO TO THE SE CONUS WITH SCATTERED
SHOWERS AND OCCURRING WITHIN 150 NM EITHER SIDE OF A LINE FROM
30N85W TO 21N97W. OTHERWISE...THE REMAINDER OF THE GULF IS UNDER
THE INFLUENCE OF PRE-FRONTAL SURFACE TROUGHING WITH A SURFACE
TROUGH AXIS ANALYZED FROM THE TAMPA BAY REGION NEAR 28N83W SW TO
THE YUCATAN PENINSULA NEAR 21N89W. SCATTERED SHOWERS AND TSTMS
ARE OCCURRING EAST OF A LINE FROM 28N83W TO 22N88W. THE FRONTAL
BOUNDARY IS EXPECTED TO INCREASE IN EASTWARD MOVEMENT AS ENERGY
ASSOCIATED WITH THE MID-LEVEL SHORTWAVE TROUGH PROGRESSES EAST
OVER THE NEXT 24 TO 36 HOURS WITH THE FRONT CLEARING THE GULF
REGION BY THURSDAY. HIGH PRESSURE WILL THEN BUILD IN ACROSS THE
GULF WITH PERSISTENT N-NE WINDS.

CARIBBEAN SEA...
MUCH OF THE BASIN IS UNDER FAIRLY TRANQUIL CONDITIONS AS WATER
VAPOR IMAGERY INDICATES AN UPPER LEVEL RIDGE WITH AXIS EXTENDING
FROM THE SW CARIBBEAN NEAR 13N80W TO BEYOND 24N70W. THE RIDGING
IS PROVIDING A RELATIVELY DRY AND STABLE ATMOSPHERE E OF
85W...HOWEVER A FEW ISOLATED SHOWERS AND TSTMS ARE OCCURRING
OVER PORTIONS OF THE SW CARIBBEAN S OF 12N DUE TO CLOSE
PROXIMITY OF THE MONSOON TROUGH AXIS WHICH EXTENDS FROM THE
EASTERN PACIFIC REGION ALONG 08N TO NORTHERN COLOMBIA NEAR
08N77W. OTHERWISE...A FEW PASSING LOW-TOPPED ISOLATED SHOWERS
ARE NOTED ON SATELLITE IMAGERY ACROSS THE NORTH-CENTRAL
CARIBBEAN N OF 16N BETWEEN 67W-76W AND THE SE CARIBBEAN S OF 16N
E OF 68W. WHILE CONDITIONS ARE CONVECTIVELY QUIET...THE EXISTING
PRESSURE GRADIENT BETWEEN A STRONG CENTRAL ATLC RIDGE AND LOWER
PRESSURE ACROSS NORTHERN SOUTH AMERICA IS PROVIDING FOR ENHANCED
EASTERLY TRADE WIND FLOW IN THE RANGE OF 20 TO 30 KT. THESE
TRADES ARE EXPECTED TO PERSIST THROUGH LATE THURSDAY.

ATLANTIC OCEAN...
A MIDDLE TO UPPER LEVEL RIDGE IS OVER THE SW NORTH ATLC WITH
AXIS EXTENDING FROM THE SW CARIBBEAN SEA NORTHEASTWARD TO BEYOND
32N64W. WATER VAPOR IMAGERY INDICATES FAIRLY DRY AIR REMAINS
EAST OF A LINE FROM 32N68W TO 22N80W...HOWEVER WITH THE PRESENCE
OF A COLD FRONT FROM 32N78W TO 30N81W AND THE APPROACH OF A
FRONTAL TROUGH CURRENTLY OVER THE FLORIDA PENINSULA AND EASTERN
GULF OF MEXICO...SCATTERED SHOWERS AND TSTMS ARE OCCURRING
ACROSS THE FLORIDA PENINSULA AND SW NORTH ATLC WATERS NW OF A
LINE FROM 32N72W TO 23N80W. OTHERWISE...THE REMAINDER OF THE SW
NORTH ATLC AND CENTRAL ATLC ARE UNDER THE INFLUENCE OF A BROAD
RIDGE ANCHORED BY A 1028 MB HIGH AND 1029 MB HIGH CENTERED NEAR
31N54W AND 33N40W RESPECTIVELY. ON THE SOUTHERN PERIPHERY OF THE
RIDGE...AN UPPER LEVEL LOW AND TROUGH AXIS IS NOTED ON WATER
VAPOR IMAGERY IN THE VICINITY OF 22N48W THAT SUPPORTS A SURFACE
TROUGH AXIS ANALYZED FROM 18N47W TO 09N52W. ASIDE FROM LOW-LEVEL
MOISTURE CONVERGENCE EAST OF THE SURFACE TROUGH...STRONG MIDDLE
TO UPPER LEVEL DIFFLUENCE IS GENERATING SCATTERED SHOWERS AND
TSTMS FROM 10N-21N BETWEEN 37W-52W.

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

$$
HUFFMAN



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