Valid 311200Z – 011200Z
…THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE MID-ATLANTIC TO NEAR NEW YORK CITY…
Thunderstorms associated with damaging wind gusts will be possible
from parts of the Mid-Atlantic to near New York City this afternoon.
A few severe storms will also be possible in the northern High
Plains and lower to mid Missouri Valley.
…Mid-Atlantic into the Northeast…
An upper-level trough will move across the eastern U.S. today. At
the surface, a cold front will move southeastward toward the
Mid-Atlantic as a pre-frontal trough strengthens during the day.
Ahead of the front, surface dewpoints in the upper 60s to near 70 F
will contribute to a pocket of moderate instability by midday.
Thunderstorms are expected to develop in the foothills of the
Appalachians, moving eastward toward the coastal areas during the
afternoon. The moderate instability combined with steep low-level
lapse rates should result in a wind-damage threat with the stronger
multicell line segments. A slight risk is added to the outlook from
the Mid-Atlantic northeastward to near New York City, where the
potential appears the greatest for damaging wind gusts.
…Northern High Plains…
An upper-level ridge will move slowly eastward across the northern
High Plains today. At the surface, a cold front is forecast to move
into eastern Montana and northwestern North Dakota. Ahead of this
feature, a corridor of maximized low-level moisture will exist with
surface dewpoints in the mid 60s F. In response, moderate
instability should develop by midday. In spite of limited
large-scale ascent, isolated thunderstorms should initiate along the
front during the mid to late afternoon. Directional shear in the low
to mid-levels and steep lapse rates should be enough for a marginal
severe threat. Hail and strong gusty winds will be the primary
…Lower to Mid Missouri Valley…
Northwest mid-level flow will be in place across the central U.S.
today. At the surface, a low will likely deepen across the central
Plains as winds remain southeasterly across the lower to mid
Missouri Valley. This will help a corridor of maximized low-level
moisture to develop across eastern Kansas into southeast Nebraska,
where moderate instability appears likely by afternoon. Model
forecasts develop convection near a minor shortwave trough along the
eastern edge of instability during the late afternoon and early
evening. Convection will be mostly likely from near Omaha southward
to near the Kansas City Metro early this evening. Moderate to strong
deep-layer shear and steep mid-level lapse rates should result in a
marginal hail threat. A few damaging wind gusts will be possible as