RSS Mesoscale Discussions from Storm Prediction Center
SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0100 AM CDT Mon Apr 27 2026
Valid 271200Z - 281200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS PORTIONS OF THE
MID-MISSISSIPPI VALLEY INTO THE LOWER OHIO VALLEY AND PARTS OF THE
MID-SOUTH...
...SUMMARY...
Widespread strong to severe thunderstorm development appears
probable across the middle Mississippi into lower Ohio Valleys this
afternoon through this evening, accompanied by potential for a few
strong tornadoes, damaging wind gusts and large hail.
...Synopsis...
Water vapor imagery shows a prominent shortwave trough promoting
elevated strong to severe convection across central and eastern
Kansas. This activity is expected to move north and eastward through
Iowa/Missouri/Wisconsin/northern Illinois into daybreak and perhaps
part of the afternoon for some areas. The outflow from this
convection should act to limit the northern extent of greater
destabilization during the afternoon and thus the greatest severe
threat. A surface low will track northeastward along the parent
shortwave. Though this low has trended downward in intensity in
recent model runs, strong low-level wind fields are expected within
the warm sector throughout the day and into the evening. Areas of
pre-frontal convergence and a cold front will be the focus for
convective development along with more strongly forced convection
tied to the shortwave trough. The front will be draped south and
westward into the Ozarks and the southern Plains.
...Mid-Mississippi Valley/Lower Ohio Valley...
As mentioned, surface based buoyancy will be limited by early day
activity. The current expectation is for parts of central/eastern
Missouri into central/southern Illinois and western Kentucky to see
greater destabilization. There is activity ongoing within central
Missouri early this morning that may have some impact, however. This
is the source of greatest uncertainty for these regions. The
kinematic environment will certainly be favorable for supercells.
The moderate to strong 850 mb jet will also lead to potential for
several tornadoes, some of which could be strong. Lapse rates at
mid-levels will be rather steep. Large to very-large hail potential
is evident given the long hodographs. Some upscale growth into one
or more linear segments is expected to occur. This will increase
the threat for damaging winds. An increase in tornado probabilities
was considered. Given the questions regarding early day convection
and where favorable convergence zones/outflow boundaries might be
located reduces confidence. Convective trends into daybreak will
need to be closely monitored.
...Mid-South...
Models indicate potential for supercells along the cold front and
even potentially ahead of it. Forcing for ascent will be weaker, but
this may help to keep activity cellular longer. Some of this
activity could develop after 00Z. Mid-level lapse rates are expected
to be steep enough and mid-level flow strong enough to support large
to potentially very large hail and damaging winds. The tornado
threat will likely be lower given the time of day and tendency for
storms to be at least slightly elevated.
...Upper Midwest...
Observational and model trends suggest destabilization will be more
limited on account of convection at daybreak and beyond. Even so,
strong low-level and effective shear will still allow storms to be
organized and capable of large hail, damaging winds and a couple
tornadoes. There will be potential for both convection at daybreak
and also during the afternoon. The greatest potential for afternoon
supercells would be in parts of eastern Iowa along with the surface
low and colder air aloft.
...Western/central Texas...
As moisture returns westward during the evening, some model guidance
suggest convection might try to develop along the retreating
dryline. Buoyancy and shear would support a threat for large hail
and perhaps severe winds. However, mid-level ascent will be very
weak and models generally do not sustain these convective attempts.
Severe probabilities may be needed if confidence in development
increases.
..Wendt/Moore.. 04/27/2026
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SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1231 AM CDT Mon Apr 27 2026
Valid 281200Z - 291200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS TUESDAY AFTERNOON
AND EVENING IN A CORRIDOR ACROSS THE SOUTHEASTERN GREAT PLAINS
THROUGH LOWER MISSISSIPPI AND TENNESSEE VALLEYS...
...SUMMARY...
Scattered strong to severe thunderstorm development is probable
across parts of the southeastern Great Plains through the lower
Mississippi and Tennessee Valleys Tuesday afternoon and evening.
The evolution of a long-lived organized cluster accompanied by
potentially damaging wind gusts appears possible.
...Discussion...
Latest model output still indicates that the center of a fairly
broad surface cyclone may undergo further deepening while migrating
northeast of the upper Great Lakes region during this period,
particularly as it reaches the southeastern Hudson Bay vicinity,
near the southeastern periphery of an evolving mid-level low.
Surrounding this low, it appears that larger-scale mid-level
troughing, encompassing much of interior North America to the east
of the northern Rockies, may make slow further progress toward the
northern/mid Atlantic Seaboard, while perhaps undergoing some
amplification along an axis southward through the upper and middle
Mississippi Valley by late Tuesday night. This may support modest
surface wave development along a stalling cold front across the
southeastern Great Plains through lower Ohio Valley, and contribute
to suppression of mid-level ridging across northern portions of the
eastern Gulf Coast states.
Otherwise, mid-level ridging to the north of a prominent subtropical
high, still centered over southern Mexico, is likely to build across
the southern Rockies and adjacent Great Plains, downstream of a low
over the southern mid- to subtropical latitudes of the eastern
Pacific. Only a slow eastward progression of this low is forecast,
to the south of mid/upper ridging building northeastward into
British Columbia and the Pacific Northwest.
...Southeastern Great Plains into Tennessee Valley...
There is continuing spread within the latest model output, but a
consensus of guidance suggests that pre-cold frontal outflow,
generated by convection today through tonight, will remain a notable
feature into and through this period. It appears that the leading
edge of this air mass may curve from parts of the southern
Appalachians/Tennessee Valley toward the Ark-La-Tex at 12Z Tuesday.
The extent to which this advances southward through the eastern Gulf
Coast states on its eastern flank, while retreating northeastward
through the lower Mississippi Valley on its western flank, remains
unclear. However, it seems probable that it will become a focus for
intensifying thunderstorm development by late Tuesday afternoon in
response to boundary-layer destabilization along and to its south,
and forcing for ascent aided by low-level warm advection.
At the same time, a corridor of stronger pre-frontal surface heating
across parts of northeastern Texas through north central Arkansas
may become the focus for stronger convective development, in the
presence of larger CAPE supported by steeper mid-level lapse rates.
More strongly capping elevated mixed-layer air may continue to
inhibit more than isolated thunderstorm initiation farther to
southwest, along the dryline across central Texas into areas
near/south of Del Rio TX.
Strengthening shear with the approach of digging mid-level troughing
on the southern fringe of the westerlies is likely provide support
for a few supercells across the southeastern Great Plains, and
upscale growing and organizing clusters propagating into the lower
Mississippi Valley. There appears a consensus within the model
output that the intersection of this activity with the preceding
outflow boundary may ultimately provide the focus for the most
prominent evolving cluster, which may pose a risk for widespread
strong to severe gusts across parts of Arkansas through the lower
Mississippi Valley by late Tuesday evening.
Too many uncertainties exist to upgrade the categorical severe
threat at this time, but this remains possible in later outlooks for
this period.
..Kerr.. 04/27/2026
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SPC 0730Z Day 3 Outlook
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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Day 4-8 Outlook
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0343 AM CDT Mon Apr 27 2026
Valid 301200Z - 051200Z
...DISCUSSION...
Medium-range guidance continues to indicate that the prevailing
split flow will evolve in a manner that maintains a broadly
confluent regime across and east of the Rockies through this period.
Within the northern branch, it appears that a fairly significant low
will form within broad troughing overspreading the Northeast by
early next weekend, perhaps trailed by another developing low across
parts of the Upper Midwest/Great Lakes by early next week. At the
same time, an initially prominent subtropical high centered over
southern Mexico is forecast to become suppressed, as a mid/upper low
emanating from the subtropical eastern Pacific is forced eastward
into and through the confluent regime across the southern tier of
the United States.
It still appears that the shearing subtropical impulse, and perhaps
a trailing perturbation, will be preceded by broad cool surface
ridging overspreading much of the central and eastern U.S., as far
south as the Gulf Coast region by Thursday. The frontal zone on the
leading edge of this air mass is generally forecast to progress into
the Gulf Basin and Florida Peninsula, where it is likely to linger
through early next week. While forcing for ascent and
destabilization might support increasing thunderstorm development
across parts of central and southern Texas late this work week
(mostly above/to the cool side of the stalling frontal zone) into
Florida and adjacent portions of the Southeast by late next weekend,
the risk for severe weather still appears relatively minor at this
time.
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