583
ACUS01 KWNS 181247
SWODY1
SPC AC 181245

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0745 AM CDT Tue Jun 18 2024

Valid 181300Z - 191200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE UPPER
MISSISSIPPI VALLEY TO THE CENTRAL PLAINS...

...SUMMARY...
Scattered strong to severe storms are expected this afternoon into
evening over parts of the Upper Mississippi Valley southwestward
into the central High Plains.

...Upper Midwest/Middle Missouri Valley/Central Plains...
In the short term, a moderately organized quasi-linear segment over
far northeast Minnesota/Arrowhead could pose a localized severe risk
this morning, although overall severe potential has waned in the
predawn hours and this downward intensity trend should generally
continue as it encounters a more stable air mass downstream.

Otherwise, a prominent mid/upper-level trough over the northern High
Plains early today will continue an east-northeastward progression
over the Dakotas/northern Minnesota through tonight. While weak
mid-level height falls will extend along this corridor early, much
of the CONUS will actually experience neutral-weak height rises as
the eastern CONUS anticyclone dominates and builds west into the
Ohio Valley. This evolution will result in a notable surface low
tracking from eastern South Dakota, across northern Minnesota into
Ontario by mid-afternoon. Building surface pressures over the Plains
will force a cold front southeastward, and this boundary will serve
as the focus for potentially strong/severe convection by late
afternoon.

The strongest mid-level flow and deep-layer shear will be noted
across the upper Mississippi Valley, but adequate shear will extend
the length of the front into the central High Plains where a few
supercells are expected to develop, including west-central/southwest
Kansas, and potentially toward the Colorado/Oklahoma/Kansas border
region. The primary risk for organized and more intense updrafts
will be during the late afternoon through early evening hours when
instability will be maximized. Large hail and damaging winds are the
primary risks.

...Upper Ohio Valley to upstate New York/northern New England...
Water-vapor/regional radar imagery reflect multiple widely dispersed
thunderstorm clusters and MCVs regionally early today, occurring on
the western/northern periphery of a prominent upper ridge centered
over the Mid-Atlantic States and Carolinas. Surface heating will
contribute to ample destabilization across a broad portion of the
upper Ohio River Valley into upstate New York and northern New
England. Isolated to widely scattered thunderstorms will once again
develop and increase into the afternoon, influenced in some areas by
the aforementioned MCVs, with localized downbursts/strong wind gusts
regionally possible through the diurnal heating cycle.

...Lower/Middle Texas Coast...
Low-level easterly winds should strengthen tonight toward the coast
in relation to Potential Tropical Cyclone One. Current thinking is
that mini-supercell-conducive ingredients will remain focused
offshore through tonight, but this scenario will be reevaluated in
subsequent outlooks.

..Guyer/Leitman.. 06/18/2024

$$