spc ac 130734
day 3 convective outlook
nws storm prediction center norman ok
0234 am cdt mon jul 13 2026
valid 151200z - 161200z
...no severe thunderstorm areas forecast...
...summary...
organized severe thunderstorms are not expected across the us on
wednesday.
... synopsis ...
a conus-wide mid-level ridge will remain entrenched across the
central us, with a closed mid-level low located on either side of it
-- one off the pacific northwest coast and the other across eastern
canada. a short-wave trough moving through the enhanced mid-level
flow will impinge upon the northwest periphery of the us ridge,
halting its westward expansion. on the eastern side, a strong
short-wave trough will continue digging southeast across new
england, helping to carve out a long wave trough across eastern
canada and the northeastern us. this in turn will suppress the us
ridge southward along the east coast, resulting in a
northwest-to-southeast ridge axis across the eastern us.
at the surface, a cold front will push south and westward across
southern new england toward the ohio valley and mid-atlantic. to the
north of this boundary, seasonably cool and dry conditions will
prevail, while along and south of this boundary, hot and humid
conditions continue.
... western and central montana ...
continued enhanced southwesterly mid-level flow will prevail across
the northern rockies on wednesday. embedded within this flow will be
subtle vorticity/speed maxima. large-scale ascent associated with
these features, combined with diurnal heating will support scattered
thunderstorms along the higher terrain of southwest montana. after
several days of repeated convection across montana and in the
mid-level lapse-rate source region upstream, uncertainty remains as
to the number and intensity of thunderstorms that do develop. should
vigorous convection develop, the overall strength of the mid-level
flow when coupled with steep lapse rates would support sporadic
strong thunderstorm winds.
..marsh.. 07/13/2026
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note: the next day 3 outlook is scheduled by 1930z