SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1228 PM CDT Sat Apr 15 2023
Valid 161200Z - 171200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE GREAT
LAKES TO THE CAROLINAS...AND ACROSS PORTIONS OF FLORIDA...
...SUMMARY...
Marginally severe thunderstorms, associated with isolated damaging
winds and hail will be possible in parts of the Southeast and
Carolinas, northward into the Appalachians and southern Great Lakes
...Synopsis...
An upper low progged to lie over the eastern Iowa/northeastern
Missouri/western Illinois vicinity at the start of the period, will
shift east-northeastward toward Lake Michigan, while deepening
through the period. Broad cyclonic flow surrounding the low will
spread across much of the eastern third of the country, as broad
mid-level height falls encompass nearly all of the eastern U.S. west
and south of New England. In conjunction with the upper low's
advance, a cold front will shift eastward across the eastern half of
the country, reaching/cresting the Appalachians by early evening and
then clearing the middle and southern Atlantic coastal region
overnight.
Elsewhere, an upper low over the northeastern Pacific will advance
southeastward toward western Canada and the Pacific Northwest, with
ridging sandwiched between the two upper lows to shift slowly
eastward across the Intermountain West through the period.
...Portions of the Great Lakes region southeastward to the
Carolinas...
In the wake of diminishing/dissipating Day 1 convection across the
mid Ohio and Tennessee Valleys, early-day convective redevelopment
is expected along the advancing cold front. Initial redevelopment
should occur nearer the upper low -- i.e. across lower Michigan and
parts of the Midwest -- where somewhat steeper lapse rates aloft
will reside. Eventually, with the aid of daytime
heating/destabilization, storms should expand southward along the
front into the southern Appalachians.
While CAPE should remain limited overall -- in part due to prior-day
convection and lingering cloud cover, strong flow aloft surrounding
the upper low suggests some potential for organized storms/storm
clusters, along with attendant/local potential for a few strong to
severe wind gusts. Greatest potential may evolve across the Ohio
vicinity during the afternoon, but questions regarding
degree/coverage of wind potential preclude upgrade to slight risk at
this time. Convection should spread into the central Appalachians
during the evening, where some risk for a couple of strong gusts may
linger.
Meanwhile, there is some potential that ongoing convection early in
the period may be crossing the Carolinas, which also could be
accompanied by the risk for a strong gust or two, before moving
offshore.
...Parts of central and southern Florida...
Continued passage of weak disturbances aloft embedded in the
southern-stream westerlies will result in weak height falls across
Florida. This is reflected at the surface as development of weak
troughing across central Florida per 12Z NAM guidance.
Despite weak lapse rates aloft, daytime heating/destabilization
should support scattered to isolated, afternoon storm development,
which is depicted in several CAM runs across central and parts of
southern Florida. With the southern fringe of the stronger
mid-level westerlies aloft extending southward across central
Florida, a strong to severe wind gust or two will be possible
through early evening when convection should be weakening and moving
offshore.
..Goss.. 04/15/2023
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