SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0108 AM CDT Tue Jul 30 2024
Valid 301200Z - 311200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE CENTRAL
PLAINS INTO PARTS OF THE MS/OH/TN VALLEYS...AND ALSO ACROSS THE
NORTHERN PLAINS...
...SUMMARY...
Severe storms are possible today into tonight across a broad area
from eastern Nebraska and Iowa into parts of the Mississippi, Ohio,
and Tennessee Valleys. There is some potential for a swath of
severe/damaging winds within this corridor. A few severe storms are
also possible across parts of the northern Plains.
...Synopsis...
An upper-level ridge will remain in place across the southern Great
Plains today. North of the ridge, multiple shortwave troughs and
embedded MCVs will move eastward from the northern Rockies/Plains
into the upper Midwest, Ohio Valley, and Northeast. The surface
pattern will be complicated by the potential influence of
overnight/morning convection, but in general, a broad surface low
will remain in place across the central Plains, with a surface
trough extending northward across the western Dakotas. Very rich
low-level moisture will remain in place from the central Plains
eastward into parts of the MS/OH Valleys. Farther east, a surface
low is expected to move across the lower Great Lakes vicinity, as a
trailing surface trough moves through parts of the Northeast and Mid
Atlantic.
...Central Plains into parts of the upper Midwest...mid/upper MS
Valley and OH/TN Valleys...
Considerable uncertainty remains regarding storm evolution later
today, but there is some potential for a swath of severe/damaging
gusts from parts of NE/IA into parts of the MS/OH Valleys.
At least one remnant or ongoing MCS may be ongoing across parts of
the upper Midwest later this morning. Strong destabilization will be
possible within a very moist environment from NE/IA into the mid MS
Valley, though the effects of morning outflow on the instability
reservoir remain somewhat uncertain. With modestly favorable
deep-layer shear in place, a broad area will have conditional
potential for organized severe storms.
If the cold pool from an ongoing or developing MCS can be maintained
or intensify later this morning into the afternoon (as suggested by
some HREF members and recent HRRR runs), there is potential for a
rather long-lived MCS to produce a swath of damaging wind gusts
(potentially in excess of 75 mph) as it moves southeastward. A
significant wind (hatched) area has been added to highlight this
potential, and greater unconditional wind probabilities will be
needed if confidence in this scenario increases.
Even if a dominant MCS does not develop, more localized severe storm
development will be possible by late afternoon, especially near any
remnant outflow boundaries. Any discrete convection could evolve
into a supercells with a conditional risk of all severe hazards,
though a tendency toward storm clustering is expected with time,
with some guidance suggesting multiple potentially severe storm
clusters emanating out of the central Plains.
Father southeast, some intensification of remnant overnight
convection across the Ohio Valley could occur across parts of TN
into the Southeast, within a modest northwesterly flow regime.
Isolated to scattered damaging wind should be the primary threat.
Any intense MCS that develops upstream could eventually approach
this region from the northwest, potentially posing another round of
damaging-wind potential.
...Northern Plains...
Weak height falls amid moderate to strong instability may lead to
widely scattered thunderstorm development along a surface
trough/dryline across the Dakotas this afternoon. Moderate
westerlies should support moderate deep-layer vertical shear around
30 to 35 kt from 0-6 km, sufficient a few organized storms capable
of both large hail and damaging gusts.
...Northern NY into northern New England...
Moderate buoyancy may develop this afternoon from northern NY into
northern New England. While storm coverage remains somewhat
uncertain, deep-layer shear and relatively cool temperatures aloft
could support a couple modestly organized storms capable of locally
damaging wind, and possibly some hail.
...Mid Atlantic vicinity...
A mid/upper-level trough and possibly an MCV will move across the
Mid Atlantic vicinity later today. Scattered thunderstorm
development is expected by afternoon from northern VA into parts of
PA. While there is some uncertainty regarding the extent of heating
and destabilization, a couple stronger cells/clusters may become
capable of producing isolated damaging wind.
..Dean/Weinman.. 07/30/2024
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