Day 1 Severe Weather Outlook

Valid 211630Z – 221200Z


Severe thunderstorms are expected this afternoon and evening across
parts of the Northeast/Mid-Atlantic States, with other severe storms
possible across the central Great Plains.

…Northeast/Mid-Atlantic States…
A shortwave trough will continue to progress east-northeastward from
eastern New York toward northern New England, while a warm front
slowly spreads northward across southern New England. With broken
cloud cover lingering in most areas, modest overall destabilization
is expected along/south of the warm front where low-level/deep-layer
shear will be maximized. The environment will support the
possibility of supercells/bowing segments particularly across
southeast New York and southern New England, with severe hail/wind
possible along with some tornado risk. Multicells with damaging
winds are possible farther south within the warm sector. For
additional short-term details, see Mesoscale Discussion 1825.

…Kansas/Missouri/far southeast Nebraska to Missouri/Illinois…
The remnants of overnight convection continue to decay across the
region with cloud cover/outflow influencing an effective boundary
across southern portions of Kansas/Missouri. Surface-based
thunderstorms should develop/intensify later this afternoon
particularly across southern/eastern Kansas into western Missouri
within a moist/unstable environment. Relatively weak tropospheric
winds may limit overall storm organization, but the strongest storms
will pose a damaging wind/severe hail risk.

…Wyoming/Colorado Front Range to central High Plains…
Isolated to widely scattered thunderstorms should develop this
afternoon over the eastern mountains and foothills from northern
Wyoming across central/southern Colorado, offering the potential for
isolated severe hail and gusts. Activity is expected predominantly
in the post-frontal/upslope region where lift is maximized by a
combination of upslope flow and diabatic surface heating of the
higher terrain (minimizing MLCINH). Mid-level flow is forecast to be
modest; however, vertical shear will be stronger than over lower
elevations ahead of the front because of the backed boundary-layer
winds and relatively extended low-level hodographs. As such, a
mixture of supercellular and multicellular structures are possible.

..Guyer/Coniglio.. 08/21/2019


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