spc ac 150730
day 3 convective outlook
nws storm prediction center norman ok
0230 am cdt wed jul 15 2026
valid 171200z - 181200z
...no severe thunderstorm areas forecast...
...summary...
thunderstorms will be possible across much of the country on friday.
although a few strong storms may occur, areas of organized severe
weather are not currently forecast.
... synopsis ...
enhanced mid-level flow will persist across the pacific northwest
and the great lakes/northeast us along the periphery of a large
mid-level anticyclone centered across the central us. across the
northwest, strong southwesterly mid-level flow and embedded
vorticity/speed maxima will contribute to shower and thunderstorm
development during friday afternoon and evening. farther east,
northwesterly mid-level flow will be in place across the upper
midwest into the mid-atlantic and northeast regions. a strong trough
will be departing the northeast at the start of the forecast period,
and several smaller mid-level waves will be traversing the enhanced
mid-level flow during the day. a stronger mid-level wave is forecast
to approach the upper great lakes overnight friday into saturday.
at the surface, a residual synoptic boundary will stretch from the
upper peninsula of michigan southeast toward the vicinity of
washington d.c. early on friday. by late morning, this boundary will
begin lifting northeast across the great lakes region in response to
the approaching mid-level trough. farther southeast, this boundary
will still be slowly sagging southward during the morning before
stalling during the afternoon and quickly lifting northeast during
friday night into saturday morning.
a weak surface low will develop along this boundary across northern
minnesota by friday morning. this low will slowly move
east-southeast during the day, dragging a secondary cold front
southeast across the dakotas and into wisconsin/southern minnesota
by saturday morning.
... upper midwest southeast into the mid-atlantic ...
subtle/small vorticity maxima moving through the mid-level flow will
yield modest large-scale ascent along portions of the frontal
boundary. strong diurnal heating of the moist airmass along and
south of the boundary should support at least widely scattered
thunderstorms. the surface boundary will be on the southwest fringe
of the better mid-level flow, with effective-layer shear being
generally less than 30 knots. this should limit any
sustained/organized severe threat.
one complicating factor/unknown will be the extent smoke plumes from
northern minnesota are advected into/across the region and their
density. a thicker smoke plume may limit the degree of surface
heating and impact the overall number of thunderstorms.
there is a secondary potential for thunderstorms to develop along
the secondary cold front late friday into early saturday as stronger
large-scale ascent overspreads the upper great lakes. the
uncertainty as to whether this convection will be able to produce
severe weather is quite large owing to the impacts of both smoke
plumes and the cooler waters of lake superior.
at this time the uncertainty associated with afternoon convection
and the overnight convection is too great to introduce unconditional
severe weather probabilities with this outlook, however, this region
will be evaluated further with subsequent forecasts.
..marsh.. 07/15/2026
click to get wuus03 ptsdy3 product
note: the next day 3 outlook is scheduled by 1930z