LIVE MAP (ABOVE) ... SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1257 AM CDT Thu Mar 30 2023
Valid 311200Z - 011200Z
...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS EASTERN
IOWA INTO NORTHWEST ILLINOIS...AND ACROSS NORTHEAST ARKANSAS...THE
MISSOURI BOOTHEEL...EXTREME WESTERN KENTUCKY...WESTERN
TENNESSEE...AND FAR NORTHWEST MISSISSIPPI...
...SUMMARY...
Intense and widespread severe thunderstorms are expected Friday
afternoon into the overnight hours across portions of the Middle
Mississippi Valley and Mid-South vicinity, eastward to the Lower
Ohio and Tennessee Valleys. Intense, damaging gusts and several
tornadoes (some strong and long-track) are expected.
...A bi-modal regional outbreak of severe storms is expected on
Friday from the Mid-Mississippi Valley into the Mid-South...
...Synopsis...
An amplified large-scale upper trough will be oriented from the
northern plains to the southern Rockies early Friday. The trough
will continue to deepen as it shifts east toward the MS Valley by
00z, and oriented from the upper Great Lakes to the TN Valley
vicinity by Saturday morning. With time, a closed low is expected to
develop over eastern SD/NE/IA and a 100+ kt 500 mb jet will
overspread the Mid-MS/OH Valley region. Intense southwesterly
low-level flow also will overspread the Mid-South through much of
the Midwest, with an 850 mb jet around 65-80 kt forecast by late
afternoon into the overnight hours.
At the surface, a deepening low centered over eastern NE/western IA
Friday morning will shift east across IA through the afternoon
before lifting toward southern Ontario overnight. A trailing cold
front will extend from the low into eastern KS/central
OK/west-central TX at 12z, and shift east across much of the Midwest
and Mid-South. Ahead of the eastward-advancing front, strong
southerly flow will transport 60s F dewpoints northward. Near-60 F
dewpoints are expected as far north as eastern IA into northern IL
during the afternoon. The warm sector will become more
narrow/pinched off with north and east extent toward the Ohio Valley
during the evening/overnight hours. However, near 60 F dewpoints are
still expected in a narrow corridor ahead of the surging cold front
into far southern IN and central KY. Richer boundary-layer moisture
will reside from the Mid-South into the Lower-MS/TN Valleys where
low to mid 60s F dewpoints are forecast.
...Mid-Mississippi Valley Vicinity...
The strongest forcing/DCVA will be located over northern portions of
the Mid-MS Valley close to the surface low/triple point. The
expectation is that rapid destabilization through the morning
(1000-2000 J/kg SBCAPE) and arrival of stronger forcing by early
afternoon will result in initial supercell development near the
surface low. All severe hazards will be possible with these fast
moving storms, including a couple of strong tornadoes, intense
damaging gusts and large hail. Cellular activity should spread
across eastern IA/northern MO and into northwest IL before tendency
toward upscale growth into linear convection ensues with eastward
extent as convection develops south and east ahead of the front from
east-central MO into northern/central IL. Damaging gusts will become
more prominent with linear convection, though QLCS tornadoes will
also be possible.
Additional storms will likely form near/just north of the warm front
and move into parts of far southeast MN and southern WI. This
activity should remain elevated, posing a risk for large hail and
strong gusts, though any cell rooting on the warm front will pose a
tornado risk as well, though the better warm sector is expected to
remain south of MN/WI.
...Mid-South Vicinity...
A concerning scenario appears to be developing across portions of
the MO Bootheel, northeast AR, western TN/KY and far northwest MS
vicinity during the afternoon/evening. At least mid-60s F dewpoints
are expected beneath modest midlevel lapse rates. This will support
1500-2000 J/kg MLCAPE amid intense vertical shear. Forecast
soundings indicate 0-1 km SRH increasing to around 400 m2/s2 by
early afternoon. Thunderstorms are expected to develop by early
afternoon ahead of the cold front within a pre-frontal
trough/low-level confluence zone. Storm motion near 50 kt with
supercell wind profiles will support cells capable of significant
and long-track tornadoes. With time, upscale growth into a QLCS is
expected, and intense wind gusts will be possible in addition to
mesovortex tornadoes.
...OH/TN Valley vicinity...
Low-level moisture/instability will begin to wane with north and
east extent into the nighttime hours. However forecast guidance has
consistently shown a few hundred J/kg MLCAPE with little/no
inhibition. Forecast guidance generally tends to under-forecast
north/east extent of severe potential in strongly forced, intense
shear system. As such, the ongoing outlook maintains a broad
gradient from Enhanced to Slight risk across this region. Damaging
gusts and a few QLCS tornadoes will be possible into the nighttime
hours.
..Leitman.. 03/30/2023
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