[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 292346
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST SAT DEC 29 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 07N12W TO
06N14W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM
06N14W TO 03N30W TO 02N41W TO THE EQUATOR NEAR 47W. SCATTERED
MODERATE CONVECTION IS FROM 02N-05N BETWEEN 17W-27W. WIDELY
SCATTERED MODERATE CONVECTION IS FROM 01N-07N BETWEEN 27W-43W.

...DISCUSSION...

GULF OF MEXICO...
A PAIR OF MIDDLE TO UPPER LEVEL SHORTWAVE TROUGHS ARE
PROGRESSING EASTWARD OVER THE GREAT LAKES AND NORTHEAST CONUS
THIS EVENING WHICH SUPPORT A COLD FRONT ANALYZED INTO THE GULF
REGION NEAR 27N82W SW TO 24N85W TO 22N90W WHERE THE FRONT
BECOMES STATIONARY TO THE SOUTHERN MEXICO COAST NEAR 19N93W. THE
PORTION OF THE FRONT ACROSS THE GULF BASIN THIS EVENING REMAINS
FAIRLY PRECIPITATION-FREE AS THE BOUNDARY IS FAR REMOVED FROM
THE STRONGER DYNAMICS N OF 30N. WHILE LOW-LEVEL MOISTURE AND
POSSIBLE ISOLATED SHOWERS ARE WITHIN 90 NM EITHER SIDE OF THE
FRONT...AN UPPER LEVEL ANTICYCLONIC CIRCULATION CENTERED NEAR
20N84W CONTINUES TO PROVIDE STABLE CONDITIONS ALOFT OVER MUCH OF
THE GULF S OF 27N. THIS UPPER LEVEL FEATURE...ALONG WITH UPPER
LEVEL RIDGING OVER CENTRAL PORTIONS OF THE CONUS SUPPORT A 1032
MB HIGH CENTERED OVER NORTH TEXAS NEAR 33N99W. THE SURFACE RIDGE
AXIS EXTENDS SOUTHWARD ALONG 99W AND THE EASTERN MEXICO
COASTLINE TO 19N. STRONG NORTHERLY WINDS ARE FORECAST TO
DOMINATE THROUGH THE OVERNIGHT HOURS AS THE RIDGE SHIFTS
EASTWARD ACROSS THE SE CONUS ON SUNDAY.

CARIBBEAN SEA...
MUCH OF THE CARIBBEAN SEA W OF 74W IS UNDER THE INFLUENCE OF AN
ANTICYCLONIC CIRCULATION CENTERED NEAR 20N84W. WATER VAPOR
IMAGERY INDICATES THAT MOSTLY DRY AIR AND SUBSIDENCE DOMINATES
THIS AREA AND SKIES REMAIN CLEAR THIS EVENING. FARTHER EAST...
THE REMAINDER OF THE BASIN IS ALSO UNDER VERY DRY AND SUBSIDENT
CONDITIONS AS NORTHERLY FLOW ALOFT E OF 74W IS PROVIDING FOR
OVERALL CONVECTIVE-FREE SKIES. TRADE WINDS REMAIN IN THE
RANGE OF 10 TO 25 KT WITH THE HIGHER RANGE SPEEDS LOCATED
BETWEEN 70W-80W. OTHERWISE...A FEW ISOLATED LOW-TOPPED SHOWERS
ARE NOTED ON SATELLITE IMAGERY ACROSS THE EASTERN CARIBBEAN FROM
12N-18N BETWEEN 62W-72W.

ATLANTIC OCEAN...
MIDDLE TO UPPER LEVEL TROUGHING IS NOTED ON WATER VAPOR IMAGERY
ACROSS THE GREAT LAKES REGION AND NORTHEAST CONUS THAT SUPPORTS
A COLD FRONT ANALYZED INTO THE DISCUSSION AREA NEAR 32N77W
EXTENDING SW TO THE FLORIDA PENINSULA NEAR CAPE CANAVERAL.
LOW-LEVEL MOISTURE CONVERGENCE IN THE VICINITY OF THE FRONT AND
MAXIMIZED MIDDLE TO UPPER LEVEL DIFFLUENCE IS GENERATING
SCATTERED SHOWERS AND TSTMS N OF 29N BETWEEN 66W AND THE FRONT.
OTHERWISE THE REMAINDER OF THE SW NORTH ATLC IS UNDER THE
INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1022 MB HIGH CENTERED
NEAR 29N54W. THE RIDGE AXIS EXTENDS FROM THE HIGH TO THE SE
BAHAMAS NEAR 23N75W. FINALLY...AN UPPER LEVEL LOW IS CENTERED
OVER THE EASTERN ATLC NEAR 25N36W THAT SUPPORTS A 1018 MB LOW
CENTERED NEAR 23N43W. A SURFACE TROUGH AXIS EXTENDS NORTHWARD
FROM THE LOW TO 30N41W AND SOUTHWARD FROM THE LOW TO 18N43W.
EARLIER SCATTEROMETER PASSES FROM THIS MORNING INDICATED THE
BROAD TROUGHING THAT EXISTS BETWEEN 40W-45W. ISOLATED SHOWERS
ARE OCCURRING FROM 20N-24N BETWEEN 36W-43W.

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

$$
HUFFMAN




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