SPC 0700Z Day 2 Outlook

Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
1210 AM CST Sun Nov 29 2020

Valid 301200Z - 011200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS FAR
SOUTHEAST VA AND COASTAL NC...

...SUMMARY...
Isolated strong to severe thunderstorms capable of producing
damaging winds and perhaps a couple of tornadoes appear possible on
Monday from parts of Florida and coastal Georgia into the Carolinas
and Mid-Atlantic.

...Synopsis...
A deep upper trough is forecast to extend from eastern Ontario into
the Lower MS Valley early Monday morning. An embedded shortwave
trough will likely be centered over the southern Appalachians, with
another shortwave trough in its wake centered over the Ozark
Plateau. Quick northeastward progression is anticipated by the lead
wave with the Ozarks shortwave digging southward and then eastward
across the Southeast. This pattern evolution will be accompanied by
strengthening low to mid-level flow and cyclogenesis. By the end of
the period, a mature mid-latitude cyclone will likely be centered
over the central Appalachians, with strong, deep-layer flow
extending throughout its eastern periphery along the East Coast. 

Surface low associated with this cyclone is forecast to begin to the
period over the central Appalachians with a cold front extending
southward/south-southwestward to the FL Big Bend. This surface low
is then expected to move north-northeastward and become increasingly
occluded throughout the day. At the same time, the attendant cold
front will sweep eastward off the East Coast.

...Much of the East Coast...
Dewpoints in the low 60s will likely extend as far north as the VA
Tidewater region early Monday morning. Mid to upper 60s dewpoints
are expected to be in place farther south across southeast GA and
most of FL, with mid 50s dewpoints extending up into the Delmarva.
The overall environment ahead of the cold front will be
characterized by abundant cloud cover, moist profiles and poor
mid-level lapse rates. Even so, the modest low-level moisture is
expected to result in limited instability and the potential for a
few deeper updrafts capable of either damaging wind gusts and/or
brief tornadoes. This potential severe threat will exist along the
length of the front, from the Mid-Atlantic into FL, but the threat
appears to be maximized over coastal NC Monday morning. In that
area, southerly/south-southeasterly surface winds beneath strong
(i.e. 50-55 kt) 850-mb winds will result in low-level kinematic
profiles very supportive of rotation. Previously mentioned limited
instability will result in predominantly transient updrafts,
particularly ahead of the front in warm sector, with limited depth
and persistence. However, any deeper, more persistent updrafts may
be able to produce damaging wind gusts and/or a tornado or two.

Farther north (from the Delmarva into coastal southern New England),
the primary severe threat will be later into the afternoon as the
triple point moves across the region. Low probability potential
exists for the development of a narrow and shallow line of
convective along the cold front extending southward from the triple
point. Even less instability is anticipated here than farther south
and any convection will likely become elevated above a low-level
stable layer, but the very strong wind fields suggest than even a
shallow, elevated storm may be able to produce a strong gust at the
surface.

..Mosier.. 11/29/2020

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