SPC 1200Z Day 1 Outlook

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
1155 PM CST Sun Jan 24 2021

Valid 251200Z - 261200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE ARKLATEX...MID MISSISSIPPI VALLEY...OHIO VALLEY AND TENNESSEE
VALLEY...

...SUMMARY...
A marginal severe threat is expected today from parts of the
Arklatex east-northeastward into the Ohio and Tennessee Valleys.

...Arklatex/Mid Mississippi Valley/Ohio and Tennessee Valleys...
A negatively-tilted shortwave trough will move quickly
east-northeastward across the southern High Plains this morning and
across the central Plains this afternoon. An associated surface low
will move from the southern Plains into the Ozarks. Thunderstorms
will likely be ongoing near and to the east of the surface low from
eastern Oklahoma across northern Arkansas and southern Missouri at
the start of the period. This convection will move
east-northeastward during the morning as a warm front advances
northward across the mid Mississippi Valley. A hail threat may exist
with the stronger elevated thunderstorms this morning. In the wake
of this activity, surface-based thunderstorm development will be
possible around midday along a front moving through the Ozarks.
Thunderstorm coverage could increase during the afternoon as the
front moves eastward into the mid Mississippi Valley.

By mid afternoon, the moist sector with surface dewpoints in the 60s
F is forecast to encompass eastern Arkansas, western Tennessee,
Mississippi and west-central Alabama. Surface heating should be
sufficient for the development of weak instability ahead of the
front with SBCAPE values peaking in the 500 to 800 J/kg range in the
afternoon. In addition, a belt of strong mid-level flow will be in
place across the mid Mississippi Valley. This will create strong
effective shear profiles favorable for a marginal severe threat. A
few strong wind gusts may occur as a band of thunderstorms tracks
east-northeastward across the northern edge of the moist sector from
Arkansas east-northeastward into western and middle Tennessee. Hail
will also be possible along this corridor extending northeastward
into parts of western and central Kentucky. Although there still
remains the possibility for organized storms in parts of the mid
Mississippi Valley this afternoon, model forecasts keep instability
weak ahead of the front. For that reason, will hold off on an
upgrade for this outlook.

..Broyles/Lyons.. 01/25/2021

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