Sunday blizzard for Northeast?

Storm #1 is currently underway across the central portion of the United States. A couple of lines of thundershowers have moved across south-central KY Wednesday with several inches of snow occurring north of I-80 in the Midwest. For the latest on the severe threat I will defer to the experts at the SPC. Storm #2 is currently over California and will move across Texas and into the Mid-South Friday-Saturday. The models are suggesting this storm will take a dramatically different track from previous runs and signs are pointing to a major Northeast Blizzard for Sunday-Monday.

The classic Kocin-Uccellini book details the ingredients necessary for a major Northeast blizzard and all of the important pieces are coming together this weekend.

Ingredient #1: There must be an upper level low near 50N/50W to provide downstream blocking. Our current storm #1 will provide the 50-50 low which you can see sitting near Newfoundland by late Friday.

Ingredient #2: A cold arctic high must be centered over southeastern Canada upstream of the 50-50 low. By early Saturday an arctic high with 850 mb temps around -6C with an average thickness of 534 dm can be seen across SE Canada and New England. This ridge will become highly amplified as the warm advection ahead of storm #2 raises heights while the stalled out storm #1 blocks the flow aloft.

Ingredient #3: Trough must be negatively tilted to allow for rapid deepening of the surface low.
Watch how the trough goes from a positive tilt Saturday afternoon to a neutral tilt Sunday morning to a negative tilt by Sunday afternoon. Also note that the surface pressure falls from 1004 to <980 mb in 24 hours. Classic explosive cyclogenesis. The reason the Ohio Valley trough becomes tilted is because of the upstream blocking from the 50-50 low and the amplifying ridge over SE Canada.

Ingredient #4: Dual jet streak leads to transverse vertical circulation. This is the only ingredient that is marginal in this situation. For maximum upward motion in the precipitation producing regions of the East Coast storm, you’d like to have an offset dual jet streak that maximizes the combined uplift from the right-rear quadrant of the polar jet streak and the left-front quadrant of the sub-tropical jet streak. This uplift combined with moisture and temperature advection of the low-level jet produce the heaviest snowfall associated with a Nor’Easter. As you can see here, the dual jet streak set-up is not there, which will minimize somewhat the maximum snowfall potential from this storm.

It is too early to make an exact call on the track of this storm, so it is unknown how close to the coast heavy snow will be found. The severe weather potential across the Southeast will be limited to the Gulf Coast states. Heavy snow will occur from the higher elevations of the southern Appalachians to New England Saturday night through Monday although the heaviest snow amounts will occur over interior portions of New England.

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