SPC 0600Z Day 2 Outlook

Day 2 Outlook Image

Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
1248 AM CDT Sat Jul 31 2021

Valid 011200Z - 021200Z


Several severe storms will be possible Sunday over eastern North
Carolina and southeast Virginia. Isolated severe storms will be
possible over parts of Pennsylvania and New York.

Cyclonic flow aloft will persist over the Great Lakes and Northeast,
with an upper speed max moving across the OH Valley and into the
Northeast. This feature will provide large-scale lift as well as
increasing deep-layer shear. Meanwhile, a leading speed max will
move off the East Coast with the right-entrance region of the upper
jet sweeping across the Mid Atlantic.

At the surface, a steadily deepening low will move across Lake Erie
and Ontario during the day, with a lee trough over eastern VA and
NC. A cold front will extend southwestward from the Mid Atlantic
across the Deep South and into northern TX, with ample moisture and
MUCAPE to 3000 J/kg ahead of the front.

Weaker instability is expected near the northern low and cold front
in the 500-1000 J/kg MUCAPE range as dewpoints only average 55-60 F.
This front is forecast to move into western and central NY and PA
prior to 00Z.

Elsewhere, an upper high will be centered over the Four Corners
states with ridge extending north into Alberta, with scattered
daytime storms over the West.

...Mid Atlantic...
Rain and thunderstorms may be ongoing across parts of eastern VA
into the Delmarva Sunday morning, in a region of low-level
warm/moist advection. Behind this activity, dewpoints are expected
to rise into the lower 70s F into VA, with mid to upper 70s F over
the eastern Carolinas. A plume of steep lapse rates will develop
across the Carolinas, with MUCAPE over 3000 J/kg expected. While
low-level winds will be relatively weak, they will veer with height,
becoming westerly at around 40 kt in the midlevels. This should
create hodographs favorable for a supercell or two, although storm
interference appears likely given CAM trends. Effective SRH over 100
m2/s2 is expected. Diurnal storms are expected to form between
18-21Z over central NC, with upscale growth possible as they
progress east. Damaging winds appear likely, along with marginal
hail and perhaps a tornado. Less storm coverage is anticipated
farther south into SC, but robust instability may favor a few
damaging gusts there.

...NY and PA...
Storms will initially develop over southwest Ontario, and are likely
to cross into the USA after 18Z, from northeast OH into western NY.
Heating ahead of this frontal activity should allow for a steady
ramp up of low-topped convection, with damaging gusts the primary
concern as cells merge along the front. Marginal hail may occur
before storm mode becomes linear. Weak instability and low-level
winds suggest any gusts over 50 kt will be isolated.

..Jewell.. 07/31/2021

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