633
ACUS02 KWNS 151735
SWODY2
SPC AC 151733

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1233 PM CDT Mon Jul 15 2024

Valid 161200Z - 171200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE UPPER OHIO VALLEY INTO THE NORTHEAST AND MID-ATLANTIC
VICINITY...AS WELL AS OVER THE CENTRAL PLAINS...

...SUMMARY...
Strong to severe thunderstorms are possible from the central Plains
across the Mid Mississippi and Ohio Valleys into the Northeast on
Tuesday. Greater severe-thunderstorm potential is anticipated across
the central Plains vicinity, and from the Upper Ohio Valley into the
Northeast.

...Synopsis...

A somewhat complicated forecast is evident for the Day 2/Tue period.
In general, broad cyclonically curved mid/upper flow associated with
an upper trough developing east/southeast over the Great Lakes
region will extend from the northern Plains to the Northeast. At the
surface, a myriad of boundaries will be in place from the Plains to
the Midwest, including outflow boundaries associated with Day 1/Mon
overnight convection and a couple of cold fronts. Boundary locations
and any ongoing convection/cloud debris will impact severe potential
during the afternoon evening.

...Upper OH Valley into the Northeast and Mid-Atlantic...

Forecast guidance has trended further east/south with thunderstorm
development, likely due to outflow and a convectively enhanced
vorticity maxima tracking across the region by midday. A very moist
airmass will be in place amid strong heating into the mid 80s
(north) to upper 90s (south). Moderate to strong instability will
support robust convective development. Vertical shear will be
strongest over NY and vicinity (around 30-40 kt effective shear),
and decrease with southward extent across PA into WV/VA. Organized
cells and line segments producing severe/damaging gusts will be the
main risk into early evening.

...Central/Southern Plains Vicinity...

A couple of surface cold fronts will sag southward across the Plains
on Tuesday. The first will be oriented from northern MO into
northwest OK and the northern TX Panhandle during the morning. This
front will sag southward and stall across the TX panhandle and
northern OK during the afternoon. Meanwhile, another cold front will
develop southward across the northern Plains into NE by late
afternoon, and continue southward across NE/KS overnight. A
post-frontal upslope flow regime between these two features is
expected across western KS into eastern CO. Boundary-layer moisture
will be somewhat modest across parts of CO/KS/NE (upper 50s to low
60s F dewpoints), with richer boundary-layer moisture along the
southern Plains surface boundary (mid/upper 60s F dewpoints).
Nevertheless, steep midlevel lapse rates will aid in modest
destabilization across eastern CO into NE, with strong instability
aligned along the TX/OK boundary. Both surface boundaries, as well
as upslope flow along a surface trough across eastern CO will focus
thunderstorm development during the afternoon and evening.

More isolated supercell storms are expected to develop across NE,
posing mainly large hail and strong gust potential. More widespread
coverage is expected across eastern CO/western KS. Clustering and
consolidating outflow associated with this activity may allow for
MCS development by evening. A bowing MCS producing damaging gusts
may shift southeast along the instability gradient/surface boundary
into the OK/TX Panhandles and northwest OK.

...Mid-MS/Lower OH Valleys...

Uncertainty is greatest from MO into the Lower OH Valley. Convection
may be ongoing across the Mid-MS Valley Tuesday morning. This
activity, along with any downstream cloud debris may impact the
airmass for later convective development. However, a very moist
airmass will be in place with dewpoints in the upper 60s to low 70s
F, and even modest heating will allow for strong destabilization.
Vertical shear is forecast to be weak across this area, but if an
MCV is present (associated with overnight Day 1/early Day 2
activity) this could locally enhance vertical shear. Forecast
solutions remain varied concerning where any afternoon thunderstorm
clusters/MCSs may develop. Any storms that form will have damaging
wind potential given potentially large instability and high PW
supporting water-loaded downdrafts. Outlook upgrades may be needed
in subsequent outlooks if confidence increases in a corridor of
greater damaging wind potential.

...Southeast AZ...

Modest instability amid 20-25 kt midlevel easterly flow and
inverted-v thermodynamic profiles is expected across the area
Tuesday afternoon/evening. This may support thunderstorm clusters
propagating east/southeast off higher terrain with an accompany risk
for isolated strong/severe gusts.

..Leitman.. 07/15/2024

$$