spc ac 270730
day 3 convective outlook
nws storm prediction center norman ok
0230 am cdt mon apr 27 2026
valid 291200z - 301200z
...there is a marginal risk of severe thunderstorms wednesday
afternoon and evening across parts of the allegheny plateau into mid
atlantic and across the northwestern through north central gulf
coast...
...summary...
strong storms could impact parts of the allegheny plateau into mid
atlantic, as well as portions of the northwestern through north
central gulf coast, wednesday afternoon and evening, accompanied by
at least some risk for severe weather.
...discussion...
models indicate that mid-level ridging will continue to build inland
across the canadian rockies/pacific northwest through this period,
but it appears that attempts at a developing embedded high near the
pacific northwest coast will become suppressed by a short wave
impulse within the westerlies approaching the british columbia
coast. farther south, a mid-level low merging into a belt of
westerlies emanating from the subtropical eastern pacific may
accelerate toward southern california/northern baja coastal areas,
but models vary concerning whether this will accelerate inland prior
to 12z thursday.
a downstream subtropical high, initially centered over southern
mexico, may undergo at least some further southwestward suppression,
but it still may maintain considerable influence as far north as the
northwestern gulf coast wednesday through wednesday night. at the
same time, in higher latitudes, large-scale troughing encompassing
much of north central and northeastern north america is forecast to
continue slowly digging toward the northern/mid atlantic seaboard.
a broad embedded cyclonic mid-level circulation may begin to form
near/north of the great lakes region.
the confluent mid-level regime across and east of the rockies will
likely support southeastward development of cool surface ridging
across much of the great plains and mississippi valley, in the wake
of a southeastward advancing cold front. models generally suggest
that a modest surface low evolving along this front will migrate
from the lower ohio valley northeastward through the lower great
lakes region, with a modest secondary surface low forming along a
developing warm front to the east of the blue ridge by late
wednesday afternoon into evening.
...gulf coast vicinity...
it remains uncertain the extent to which pre-frontal convective
outflow may impact subsequent destabilization across the north
central gulf coast region, and perhaps beneath the stronger
mid-level ridging into the texas coastal plain and rio grande
valley. however, guidance suggests that a seasonably moist
boundary-layer may contribute to moderately large cape with
sufficient insolation, beneath at least modest west-northwesterly
mid-level flow. this environment might become conducive to at least
widely scattered storms with potential to produce severe hail and
wind. it is still possible that categorical and severe probabilties
could be increased further in later outlooks for this period.
...allegheny plateau into mid atlantic...
the influence of potentially widespread remnant early period
convective precipitation on subsequent destabilization through the
day wednesday remain unclear. however, as a fairly significant
short wave perturbation overspreads the region late wednesday
afternoon and evening, the cold front approaching the allegheny
mountains, surface troughing and the developing low/warm front to
the east of the blue ridge could become the focus for strong to
severe thunderstorm with sufficient destabilization in the presence
of strong deep-layer shear. it is still possible that categorical
and severe probabilities could be increased further in later
outlooks for this period.
..kerr.. 04/27/2026
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note: the next day 3 outlook is scheduled by 1930z