Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1234 AM CDT Sat Aug 03 2024
Valid 031200Z - 041200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM
CENTRAL/EASTERN NORTH CAROLINA INTO SOUTHEAST PENNSYLVANIA AND
SOUTHERN NEW JERSEY...AND ACROSS EASTERN SOUTH
DAKOTA...CENTRAL/SOUTHERN MINNESOTA AND EXTREME NORTHWEST IOWA...
...SUMMARY...
Scattered severe storms are most likely this afternoon and evening
from eastern South Dakota into Minnesota with damaging winds and
hail possible. Scattered thunderstorms producing damaging gusts are
also expected across parts of the North Carolina Piedmont into the
Mid-Atlantic vicinity. A developing tropical cyclone may also impact
the Florida Keys and western Florida Peninsula. Meanwhile, isolated
strong storms are possible across the southern High Plains.
...Mid-Atlantic Vicinity into SC/GA...
An upper trough oriented from the lower Great Lakes/Ohio Valley to
northern AL/GA will shift east toward the northern Appalachians and
Mid-Atlantic vicinity through tonight. This will result in a belt of
25-35 kt southwesterly midlevel flow overspreading the NC/VA
Piedmont, northward toward southern New England. A surface front
will stall from eastern PA southwestward along the Blue Ridge
Mountains and into north GA. To the east of this surface boundary, a
very moist airmass will be in place, with dewpoints in the 70s F.
This will aid in moderate destabilization, with MLCAPE values
1500-2000 J/kg common. A few pockets with higher instability are
possible, but poor midlevel lapse rates will limit stronger
destabilization on a large scale. Nevertheless, 25-35 kt effective
shear magnitudes will support strong to severe thunderstorms.
Thunderstorm clusters will be possible, and scattered wind damage is
expected with this activity. A corridor of greater severe potential
is expected from central NC into southeast PA/southern NJ, where
greater storm coverage is expected along with increased potential
for forward-propagating clusters. A Slight (level 2 of 5) risk has
been included for this corridor.
...Eastern Dakotas/Upper Midwest...
Moderate northwesterly mid/upper flow will overspread the region on
the western periphery of a large Hudson Bay upper cyclone. A weak
surface low is forecast to develop over central SD, with a warm
front extending from southwest MN into central/eastern IA, and a
cold front developing southward across northern MN and the Dakotas.
A wedge of mid 60s to low 70s F dewpoints between these surface
features will foster moderate to strong destabilization during the
afternoon amid steep midlevel lapse rates. Vertically veering wind
profiles and elongated/straight hodographs, along with effective
shear magnitudes around 25-35 kt, should favor supercells. Damaging
gusts and large to very large hail will be possible with this
activity. Initial cellular activity may develop into a small MCS,
transitioning the risk to mainly damaging winds during the evening.
...Southwest FL Peninsula...
Per latest NHC guidance, Tropical Depression Four is forecast to
become a tropical storm by this evening as the system tracks over
the eastern Gulf of Mexico. Scattered thunderstorms will overspread
the southern Peninsula, where low/mid level east/southeasterly flow
will increase through the period. Sufficient low-level instability
and 0-1 km SRH increasing to greater than 200 m2/s2 will support
some risk for a couple of tornadoes.
...Southern High Plains...
A convectively enhanced vorticity max is forecast to develop south
across the central/southern High Plains vicinity this
afternoon/evening. Vertically veering wind profiles will support
rather robust effective shear magnitudes greater than 40 kt.
Boundary-layer moisture will remain modest, but steep midlevel lapse
rates will aid in at least weak destabilization (MLCAPE around
500-1000 J/kg) sufficient for high-based thunderstorm development. A
deeply mixed boundary layer with inverted-v sub-cloud thermodynamic
profiles will support strong outflow winds with any storms that
develop. If any longer-lived cells can be maintained, isolated large
hail is also possible.
..Leitman/Thornton.. 08/03/2024
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