spc ac 150558
day 2 convective outlook
nws storm prediction center norman ok
1258 am cdt wed jul 15 2026
valid 161200z - 171200z
...there is a marginal risk of severe thunderstorms across parts of
western montana...
...summary...
strong-to-severe thunderstorms will be possible across portions of
western montana thursday afternoon and evening.
... synopsis ...
an expansive mid-level ridge will remain in place across much of the
conus on thursday. on the western side of the ridge, a closed
mid-level low will lift northward, helping to raise mid-level
heights northward into canada. on the eastern side of the ridge, a
strong mid-level trough will move across new england, within the
basal region of a long-wave trough centered across northern quebec
and extending southward along the east coast of north america.
at the surface, a frontal boundary across the northern mid-atlantic
region will delineate a moist airmass to the south from a slightly
less moist airmass to the north. a secondary front will push south
across new england associated with the passing mid-level wave. this
secondary front will bring a reinforcing shot of seasonably cool,
dry air.
... western montana ...
this area will be on the eastern periphery of a zone of large-scale
ascent associated with the lifting eastern pacific mid-level low.
this large-scale ascent will combine with surface dewpoints in the
mid 50fs and surface temperatures in the upper-80fs to low-90fs to
support scattered thunderstorm development in the afternoon.
relatively long hodographs and mucape between 1000-2000 j/kg will
support a marginal threat for large hail and gusty thunderstorm
outflows. should the number of thunderstorms be greater than
currently anticipated, higher severe probabilities may become
necessary.
... mid-atlantic region ...
this evening's (20260715 00utc) href shows afternoon temperatures
riding to near 100f in the presence of surface dewpoints in the
mid-to-upper 60fs. this combination results in ensemble mean mlcape
between 1500-2000 j/kg. as the aforementioned surface boundary moves
south during the afternoon and evening, isolated thunderstorms may
develop along the front. steep low-level lapse rates would support
some wind damage potential should these storms develop.
however, the 20260715 00utc hrrr vertically integrated smoke
forecasts show a dense ribbon of smoke stretching from the upper
midwest southeast into the mid atlantic. should this ribbon of dense
smoke materialize, afternoon high temperatures would likely be lower
than expected, and low- and mid-level lapse rates weaker than
forecast. this in turn would lower atmospheric buoyancy and may
limit thunderstorm coverage and/or intensity.
given the already marginal nature of the severe potential absent the
presence of smoke, the uncertainty introduced by the presence of
smoke results in too much uncertainty to introduce unconditional
severe probabilities at this time. this area will continued to be
re-evaluated with subsequent forecasts.
..marsh.. 07/15/2026
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note: the next day 2 outlook is scheduled by 1730z