RSS Mesoscale Discussions from Storm Prediction Center
SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1128 AM CDT Thu Jun 04 2026
Valid 041630Z - 051200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND
EVENING OVER PORTIONS OF THE NORTHERN PLAINS...
...SUMMARY...
Severe thunderstorms capable of large to very large hail and
damaging winds are possible today from parts of the northern High
Plains across northern Nebraska and much of South Dakota. More
isolated occurrences of large hail and damaging winds appear
possible farther south across portions of the central Plains.
...Southeast MT through the Dakotas into southern MN...
Morning surface analysis places a weakening cold front from
northwest MN through south-central SD to a weak low near the
WY/SD/NE border intersection. Western portion of this boundary (from
central SD westward) is forecast to stall, with perhaps some retreat
northward during the late afternoon, while the eastern portion over
MN progresses slowly eastward. Dewpoints will likely stay in the 60s
along this boundary, with moderate to strong buoyancy developing by
late afternoon. Moisture convergence, augmented by modest
large-scale ascent attendant to a shortwave moving across MT, will
likely result in scattered convective initiation by the late
afternoon. Additional storms are expected farther west across
eastern MT ahead of the aforementioned shortwave. Moderate
deep-layer shear will support occasional supercells, with large to
isolated very large hail as the primary risk. Storms will spread
into the central Dakotas through the evening with a continued severe
threat.
Farther east, late afternoon thunderstorm development is expected
along the cold front. Deep-layer shear will be weaker than areas
farther west, and a more outflow-dominant storm mode appears likely.
Isolated hail is still possible early in the convective cycle,
particularly into central SD where steeper mid-level lapse are
expected.
...Central/Eastern KS into southeast NE/northwest MO/western IA...
Morning satellite imagery shows a well-defined MCV over western KS,
with widespread cloud cover throughout its eastern periphery from
central KS across south-central and eastern NE. Surface observations
show dewpoints in the mid 60s beneath this cloud cover, with
temperatures ranging from the upper 60s across central KS to the mid
70s across southwest IA. Southerly flow is anticipated throughout
the day today, maintaining low-level moisture advection within this
corridor. This increasing moisture coupled with sheltered/cloudy
conditions will likely result in dewpoints climbing into the upper
60s (perhaps even some low 70s) across this region by the late
afternoon. Modest heating is anticipated as well, with temperatures
likely in the mid 70s to low 80s. Mid-level lapse rates are poor
(generally less than 6 deg C per km from 700 to 500 mb), but the
ample low-level moisture will still support afternoon/late afternoon
MLCAPE around 1500 to 2000 J/kg and little, if any, convective
inhibition.
Ascent attendant to the MCV and low-level convergence throughout its
eastern periphery will support widespread thunderstorm development
within this unstable and uncapped environment. Deep-layer shear will
be weak (less than 25 kt from 0-6 km) across much of the region,
with a largely multicellular mode anticipated. That being said, an
increase in low-level southerly flow is expected throughout the
eastern periphery of the MCV, contributing to some moderate
lengthening of the low-level hodograph. This stronger low-level
southerly flow combined with the ample moisture in place (i.e. PW
values approaching 1.8" by the late afternoon, which is above the
90th percentile at TOP) results in a unique environment supportive
of brief tornadoes. Even so, the lack of stronger deep-layer shear
still suggests a predominantly disorganized storm mode, which should
keep any tornado threat isolated enough to keep probabilities at 2%.
A few water-loaded downbursts are possible as well.
..Mosier/Chalmers.. 06/04/2026
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SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1230 PM CDT Thu Jun 04 2026
Valid 051200Z - 061200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS CENTRAL AND
EASTERN NEBRASKA...NORTH KANSAS...MUCH OF IOWA...SOUTHEAST
MINNESOTA...AND FAR WESTERN WISCONSIN...
...SUMMARY...
Scattered severe storms capable of large to very large hail,
damaging winds with potentially significant gusts, and perhaps a
couple of tornadoes are expected Friday afternoon into night across
portions of the central Plains into upper Great Lakes.
...Synopsis...
A weak mid-level shortwave trough in the western Great Lakes Friday
morning is forecast to weaken as it moves eastward through the day.
A mid-level ridge will build across the central/northern Plains
through the day with a strong trough approaching the Northwest. At
the surface, high pressure will move off the Southeast coast with
weak lee troughing across the central High Plains vicinity within an
otherwise nebulous surface pattern.
...Central Plains into the Upper Midwest...
Thunderstorms will be ongoing at the beginning of the period, likely
from northern Missouri into Iowa and southeast Wisconsin. Strong
instability is expected to develop south/west of this activity where
steep lapse rates advect over a moist airmass featuring low 70s
dewpoints. Height rises across this region (southeast Nebraska into
southwest Iowa) cast some doubt on diurnal storm development.
Several members of the 12Z HREF show storms developing within this
zone, but most others (most notably the HRRR, do not). Therefore,
while the environment would support strong supercells with a threat
for very large hail, damaging winds, and perhaps a tornado, the
uncertainty related to storm coverage precludes higher probabilities
at this time.
Regardless of if afternoon storms develop, additional convection is
expected during the evening as the low-level jet strengthens. These
storms may initially begin as supercells, but will likely grow into
a linear segment relatively quickly. Given the strengthening
low-level jet and forecast soundings that do not show clearly
elevated thermodynamic profiles, expanded the 2% tornado
probabilities east to account for some tornado threat during the
evening hours.
Additional storms are possible farther northeast from northeast Iowa
into Wisconsin along a diffuse cold front. While mid-level flow (and
thus deep-layer shear) will be stronger across this region,
instability is forecast to be more limited due to that
morning/previous night convection that moved across the region and a
lack of a strong low-level moisture advection into the region.
Therefore, some strong to isolated severe storms are possible, but
may be too isolated/marginal for higher probabilities at this time.
..Bentley.. 06/04/2026
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SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0148 PM CDT Thu Jun 04 2026
Valid 061200Z - 071200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS NORTHEAST
MONTANA AND NORTHWEST NORTH DAKOTA AND FROM NORTHERN OHIO INTO
WESTERN PENNSYLVANIA...
...SUMMARY...
Scattered severe storms capable of large hail and damaging winds are
possible from portions of the Great Lakes and Ohio Valley into the
Northeast, and over the northern High Plains.
...Synopsis...
On Saturday, a ridge will build across the Plains into the Upper
Midwest with an amplifying trough across the Northeast/eastern Great
Lakes and another trough centered over the Northwest. At the
surface, a weak surface low will be present across the Northeast
with a stronger surface low in the lee of the northern Rockies.
...Eastern Montana and western North Dakota...
As lee troughing intensifies on Saturday, low-level moisture will
advect northwestward into western North Dakota and eastern Montana.
This will result in strong to very strong instability by mid to late
afternoon. As the broader trough shifts east and height falls
overspread the Plains, expect storms to develop along the lee
trough/dryline in eastern Montana and move northeastward. As
mid-level flow strengthens through the day, shear will strengthen
and should support supercell storm mode. Large hail should be the
primary threat, but given relatively steep lapse rates across the
region, some severe wind threat will also exist.
...Great Lakes into the Ohio Valley...
A cold front will extend from the surface low in southern Quebec/New
England into the eastern Great Lakes Saturday morning. Moisture will
increase ahead of this front from west to east with increasing
instability, especially across Indiana and into western
Pennslylvania. Within this same zone, moderate mid-level flow will
overspread the region with moderate deep-layer shear forecast.
Storms are expected to develop along the front by mid afternoon and
move south-southeastward into the evening. Farther northeast,
dewpoints will remain in the low to mid 60s which should limit
instability somewhat which should support lesser storm
coverage/intensity along the font.
..Bentley.. 06/04/2026
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