Doppler Dale's Weather Daily: December 6, 2011

Cold air continues to filter into the East and Southeast as a strong cold front continues its eastward progression. Still seeing two pieces of energy in the upper levels of the atmosphere with the one in the northern branch of the jet stream producing some light snow through the Mid-Mississippi Valley, including St. Louis. The second wave was beginning to round the bend in southern New Mexico and is poised to head east-northeast through the next few days.

Memphis Snow
As it moves into the Lower Mississippi Valley, Wednesday morning, a new area of light precipitation will begin to break out across the Mid-South. This precipitation will likely begin as drizzle and light rain and then mix with sleet and snow and transition to all snow as cold air continues to filter into the region. The precipitation will begin in the Memphis metro area 10 pm to Midnight and begin mixing with frozen precipitation between 1am and 3am and to all snow by 6 am and ending by 10 am. Minor accumulation of upto 1/2" in grass is possible but just wet pavement is forecast due to pavement temperatures remaining warm.

Nashville, Huntsville Snow
This area of precipitation will continue to track eastward along the I-40 corridor through Tennessee and through northern Mississippi and Alabama towards the metros of Nashville and Huntsville. The upper level energy pieces will actually be merging into one stronger system over Mississippi and Alabama, Wednesday. Add in a bit more deeper moisture and the precipitation should intensify some. Again, the precipitation will likely begin as drizzle and light rain for these areas (around midnight) and transition to a wintry mix towards the morning rush hour and then eventually to all snow by mid morning. Minor, mainly grassy accumulation of up to 1/2" is possible in heavier bursts of snow/sleet, mainly closer to I-40 and along the Cumberland Plateau, but again roads stay warm enough to keep them wet.

Appalachia and I-95 Corridor Snow
The winners with this snow even will be locations along the Appalachians from northeast Georgia to into southern New York. The merged and stronger piece of upper level energy will spin up a strong surface low that will lift up along the Eastern Seaboard. This allows for abundant moisture to be thrown into arriving cold air. 6" to 12" of snow will be possible along the spine of the Appalachians, especially from West Virginia into Northeast Pennsylvania The southern Appalachians from northeast Georgia into West Virginia will be hit tonight and Wednesday with the northern Appalachians being hit Wednesday night into Thursday. I do anticipate the rain to turn over to snow in Washington DC, Baltimore, Philadelphia, New York City and Boston. How much, you ask? Here you go:

Washington DC: 2"-4" (Changes Over 9pm-11pm Wednesday)
Baltimore: 2"-4" (Changes Over 9pm-11pm Wednesday)
Philadelphia: 2"-4" (Changes Over 11pm-1am Wednesday Night)
New York: 1"-3" (Changes Over 1am-3am Thursday)
Boston: 3"-6" (Changes Over 2am-4am Thursday)

Late Work Week Snow
We will watch yet another piece of energy dive southeastward in  the northern branch of the jet through the northern Plains and towards the Mid-Mississippi Valley. This piece of energy could also bring a band of light snow with it for Thursday into Friday, especially across South Dakota into Nebraska. I will hit on this more tomorrow.

I will also be watching for the potential of a northern branch piece of energy and southern branch piece of energy merging again into a bigger system late next week.