Severe Storm Outlook Narrative (AC)
Issued by NWS
ACUS03 KWNS 290724
SPC AC 290723
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0223 AM CDT Sat Apr 29 2017
Valid 011200Z - 021200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PARTS OF
THE GULF COAST REGION TO THE LOWER GREAT LAKES...
A few severe storms will be possible from parts of the lower Great
Lakes to the southeast states on Monday, with the highest likelihood
from West Virginia to parts of Pennsylvania.
An expansive closed low will continue lifting northeast towards the
Upper Great Lakes on Monday, with broad cyclonic flow enveloping a
majority of the contiguous US. Within this flow, embedded impulses
will likely translate northeast across parts of the Midwest,
Mid-Atlantic, and Northeast.
...Gulf Coast to the Lower Great Lakes...
Along/ahead of a cold front pushing east, an expansive corridor of
showers and thunderstorms will likely be ongoing from the Gulf Coast
northward to the Ohio Valley Monday. Near the southern end of this
corridor, a few strong to marginally severe storms may be ongoing in
the morning, aided by rich low-level moisture and weak/moderate
buoyancy. However, these storms will likely weaken through the first
half of the day, as stronger ascent becomes increasingly displaced
Across the central Appalachians and northward, storms will likely
form/re-intensify along the surface front and/or a pre-frontal
trough during the afternoon hours. Strong mid-level flow and modest
veering with height will offer favorable low-level/deep-layer shear
for updraft organization. In terms of forecast buoyancy, cloud cover
may limit the amount of heating/destabilization over the region, and
most forecast soundings depict relatively narrow mixed-layer CAPE
profiles. Nonetheless, sufficient buoyancy for at least a few severe
storms, capable of strong winds, severe hail, and perhaps a tornado
or two, appears probable. Additionally, portions of the Marginal
(most likely West Virginia, northwest Virginia, and points
northward) may require an upgrade to Slight if confidence in
sufficient surface-based buoyancy continues to increase.