481
ACUS02 KWNS 281723
SWODY2
SPC AC 281722

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1222 PM CDT Fri Jun 28 2024

Valid 291200Z - 301200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM OHIO INTO
PORTIONS WEST VIRGINIA...MARYLAND...PENNSYLVANIA AND NEW YORK...

...SUMMARY...
Scattered damaging winds and a couple tornadoes are possible on
Saturday from parts of Ohio into northern West Virginia/Maryland,
central and western Pennsylvania, and western New York.

...Ohio Valley to the Northeast...

Several vorticity maxima are forecast to migrate across the region
within an area of enhanced southwesterly flow aloft ahead of the
main upper shortwave trough progressing from the Upper Midwest to
the lower Great Lakes. At the surface, low pressure will spread
east/northeast from the upper Great Lakes into Ontario/Quebec. As
this occurs, strong theta-e advection on southwesterly low-level
flow will result in a very moist airmass spreading north/northeast
from the Midwest into much of the Northeast. Early cloudiness and
periods of showers may limit diurnal destabilization from eastern PA
into NY. Pockets of stronger instability will overlap 30-40 kt
westerly midlevel flow from parts of Ohio into western/central
PA/NY. While midlevel lapse rates will remain quite poor, sufficient
effective shear magnitudes amid rich boundary-layer moisture should
support organized clusters and line segments capable of
strong/damaging gusts. Vertically veering low-level winds will
support somewhat enlarged and curved hodographs, with sufficient
low-level instability and 0-1 km SRH. In addition to damaging gusts,
a couple of tornadoes also will be possible.

A more conditional risk may exist from late evening into the early
overnight hours across parts of northern NY into VT as the surface
front impinges on the area and the main upper shortwave trough
ejects eastward. Strong vertical shear will be in place amid a very
moist airmass. However, convection may remain elevated given poor
timing with the diurnal cycle and impacts from daytime convection.
If convection can become surface-based, damaging gusts will be
possible.

...OK/KS to the Mid-MS Valley...

Convection may be ongoing Saturday morning across parts of central
MO. This activity may weaken during the morning, or slowly
reintensify during the afternoon along outflow or the
southward-advancing surface cold front. Additional convection is
expected to develop along the sagging front across southern
KS/northern OK during the late afternoon/evening. A couple of
forward-propagating clusters are possible within this area of modest
vertical shear, but rich boundary-layer moisture (dewpoints in the
upper 60s/low 70s F) and moderate to strong instability. Isolated
severe/damaging gusts and a few instances of hail will be possible
with this activity. A corridor of higher probabilities may be needed
in subsequent outlooks if confidence increases in location of better
organized frontal convection.

...Central/Southern High Plains...

Isolated convection is expected during the evening in a post-frontal
upslope flow regime. Near 60 F surface dewpoints and steep midlevel
lapse rates will support a corridor of moderate instability. While
deep-layer flow will be light, vertically veering wind profiles will
support 30-40 kt effective shear magnitudes amid a deeply mixed
boundary-layer. Isolated strong to severe thunderstorms capable of
strong gusts and hail will be possible.

...Northern IL into eastern WI and MI...

Most forecast guidance is fairly sparse with convection across this
area on Saturday. However, a very moist and unstable airmass will be
in place ahead of the east/southeast-advancing cold front, along
with favorable vertical shear for organized storms. Large-scale
ascent will remain somewhat weak and ill-timed with the cold front
progression, and low-level frontal convergence also will be poor.
Severe probabilities have been adjusted some over the region based
on low storm coverage and latest trends. However, a conditional
severe threat will exist if storms develop.

..Leitman.. 06/28/2024

$$