SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0258 PM CDT Thu Aug 01 2024
Valid 012000Z - 021200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM MOST OF
KENTUCKY INTO OHIO...AND OVER PARTS OF INDIANA AND WEST VIRGINIA...
...SUMMARY...
Severe thunderstorms remain possible today across parts of the
Midwest and Ohio Valley, with the primary threat being damaging
winds.
...20Z Update...
Minor changes were made to the existing outlook primarily behind the
ongoing severe MCS now over southern IN and into far northern KY. A
moist and unstable air mass remains downstream of this system, and
the potential remains for north and/or southward growth as the cold
pool increases. In addition, storms may develop into OH ahead of the
main system, with localized downbursts possible. For more
information see mesoscale discussion 1788.
To the north, an unstable air mass has developed over WI, with
scattered cells noted. Shear will remain weak, but continued heating
beneath the cool upper trough may support isolated severe storms
with wind and/or hail. Some of this activity may persist into the
evening into northern IL and IN. With time, severity is expected to
decrease. For more information see mesoscale discussion 1787.
Elsewhere, a band of strong instability continues to develop in an
east-west oriented zone near a weak front extending from the TX
Panhandle toward the Ozarks. Isolated storms are expected later
today, but the severe threat should remain localized. Although lift
is very weak, any cells that develop will have severe gust or brief
hail potential.
..Jewell.. 08/01/2024
.PREV DISCUSSION... /ISSUED 1130 AM CDT Thu Aug 01 2024/
...Upper Midwest/Ohio Valley...
Primary upper trough located over the Upper Midwest late this
morning is forecast to develop generally east-southeastward across
the Great Lakes and OH Valley through the period. Multiple
convectively enhanced MCVs are present over the Midwest, along with
outflow boundaries from prior convection. These features will likely
serve as forcing mechanisms for additional robust thunderstorm
development across the OH Valley this afternoon and evening. One
such MCV located over far eastern MO into western IL should track
eastward through the day, while aiding a cluster of thunderstorms
that have already started strengthening across southern IL. The
outflow boundary extending across southern IN and vicinity will
likely serve as a focus for the subsequent MCS track, as the airmass
along/south of this boundary is rapidly destabilizing.
Given the mainly linear mode expected and sufficient deep-layer
shear present, scattered severe/damaging winds should be the main
threat. But, a line-embedded tornado or two may also occur,
especially near the outflow boundary. See recently issued Mesoscale
Discussion 1784 for more details. The northward extent of MCS
development into northern/central IN/OH remains uncertain given
lingering cloudiness and the outflow boundary remaining farther
south. Still, there may be additional strong to severe thunderstorm
development across these areas in association with another MCV over
northeast IL/northwest IN. Have therefore made no changes to the
northern edge of the Slight Risk in the OH Valley with this update.
Farther northwest, a separate area of strong to locally severe
thunderstorm development may occur closer to the mid/upper-level
cyclone across parts of WI into northern IL. Deep-layer shear is
forecast to remain modest, but moderate instability could support
isolated hail and damaging wind with the strongest cores.
...Mid-Atlantic into the Carolinas and Southeast...
Strong heating of a moist environment will result in the development
of moderate to locally strong instability from GA and the Carolinas
into southern parts of the Mid-Atlantic. Large-scale ascent across
this region should remain rather weak/nebulous. Accordingly,
thunderstorm coverage remains uncertain, and could be isolated to
widely scattered. However, robust thunderstorms may still form by
late afternoon into early evening, as lingering convective
inhibition erodes. Modest mid-level northwesterly flow in the wake
of the departing upper-level trough along the East Coast may provide
sufficient effective bulk shear for modest updraft organization,
with a threat of isolated damaging winds and perhaps marginally
severe hail.
...Southern/Central High Plains to the Mid-South...
The outflow-reinforced front has nearly stalled over the
south-central High Plains into northeast NM. Initial development may
occur near the Raton Mesa NM vicinity in a modest low-level upslope
flow regime, with more isolated development possible farther east
along the front into the OK/TX Panhandles, and potentially farther
east along the boundary into northern OK/AR and southern MO.
Low/midlevel flow will remain rather weak. Still, sufficient veering
of winds with height should support effective shear generally around
20-30 kt. This should be sufficient for some convective organization
with of moderate to strong instability present along/near the
boundary. Initially discrete thunderstorms could produce large hail,
but outflow and convective consolidation/clustering with the
well-mixed boundary layer should lead to an increasing threat for
isolated severe gusts later in the convective evolution.
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