SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1229 PM CDT Wed Aug 09 2023
Valid 101200Z - 111200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CAROLINAS AND SOUTHEASTERN VIRGINIA...AND OVER PORTIONS OF THE
NORTHERN PLAINS/MID MISSOURI VALLEY AREA...
...SUMMARY...
Strong to severe thunderstorms are possible across parts of the
northern Plains, and from the Alabama vicinity to the coastal
Carolinas/southeast Virginia on Thursday.
...Synopsis...
Within the belt of moderate west-southwesterly mid-level flow across
the U.S. Thursday, two short-wave troughs will be associated with
two distinct areas of convective/severe potential. The first of
these troughs is expected to cross the central and southern
Appalachians region during the day, and then should move off the
Mid-Atlantic/Carolina Coasts during the evening. Meanwhile, the
second trough -- expected over the northern and central High Plains
area early in the day --will move east-southeastward across the
Plains through the afternoon, and to the Mid and Upper Mississippi
Valley region by the end of the period.
At the surface, a compact low/frontal system is forecast to cross
the central and southern Appalachians region early, and then across
Virginia and the Carolinas through the day. The front should clear
the East coast from New Jersey southward through late
afternoon/early evening, with the low then continuing across
southern New England into the overnight hours. Meanwhile, a weaker
low/trough is forecast to cross the Plains through the
afternoon/evening hours.
...Parts of the Southeast and Mid-Atlantic regions...
Thunderstorms -- possibly in the form of an at least loosely
organized band -- will likely be ongoing at the start of the period
across the western Carolinas vicinity. These storms may be
accompanied by ongoing risk for locally damaging wind gusts, and
possibly a tornado.
Some decrease in intensity may occur with this convection into the
afternoon, though indications are that subsequent storm
redevelopment may occur across the southeastern Virginia/eastern
Carolinas area during the afternoon, ahead of the advancing cold
front. These storms would also likely pose a risk for damaging
winds locally, along with potential for hail and a tornado or two
before storms move offshore during the evening.
...Northern Plains and Mid-Missouri Valley area...
Diurnal heating ahead of an advancing/weak cool front will result in
moderate afternoon warm-sector destabilization across the central
and northern Plains region. As the boundary advances in tandem with
weak upper short-wave troughing, isolated to widely scattered storm
development is expected by latter stages of the afternoon period.
CAM output from various models differs, with respect to storm
coverage, though several suggest upscale/linear growth with time,
and possibly even an eventual southeastward-moving, bowing MCS
across the Mid-Missouri Valley area during the evening and possibly
into the overnight hours.
In any case, with 35 to 45 kt mid-level west-northwesterlies across
the area, atop low-level southerly warm-sector winds, shear will
support potential for organized storms, and attendant risks for
locally damaging wind gusts, and severe-caliber hail. A tornado
cannot be ruled out, mainly across the eastern South Dakota vicinity
where slightly backed low-level flow is anticipated ahead of the
weak surface low.
While storm coverage remains uncertain, current indications are that
upgrade to SLGT risk is warranted for the afternoon and evening
hours.
...Southern New England...
As a deepening surface low crosses southern New England during the
second half of Thursday, meager CAPE may support a few
thunderstorms. Within the northeast quadrant of the low -- across
southeastern New England -- a very favorable flow field is
anticipated, with low-level winds veering/increasing rapidly with
height. While the thermodynamic deficiency that is anticipated
should substantially limit overall potential, conditional risk for a
couple of stronger wind gusts and/or a tornado or two is evident,
mainly from late afternoon through late evening, until the low and
associated front sweep northeastward/offshore.
..Goss.. 08/09/2023
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