RSS Mesoscale Discussions from Storm Prediction Center
SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0256 PM CDT Wed May 20 2026
Valid 202000Z - 211200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM EASTERN
KENTUCKY INTO PARTS OF THE MID-ATLANTIC AND SOUTHERN NEW
ENGLAND...AND PARTS OF SOUTHWEST TEXAS...
...SUMMARY...
Scattered severe/damaging winds and isolated hail will be possible
with thunderstorms from the central Appalachians into the
Mid-Atlantic and southern New England this afternoon and evening.
Severe thunderstorms with large hail and isolated severe gusts may
also occur today across parts of west/south-central Texas.
...20Z Update...
The forecast remains largely on track. Only minor adjustment to the
wind probabilities were made based on current observations and
recent guidance.
..Wendt.. 05/20/2026
.PREV DISCUSSION... /ISSUED 1101 AM CDT Wed May 20 2026/
...WV to Southern New England...
A broad upper ridge is present today over the southeastern U.S.,
with the southern fringe of stronger westerlies extending from the
OH Valley into the Mid-Atlantic region. Visible satellite imagery
shows a zone of relatively clear skies from KY/WV into southeast
PA/NJ and southern New England. Strong heating in this corridor
will lead to moderate CAPE by mid-afternoon. Scattered thunderstorm
development is expected, with steep low-level lapse rates and
sufficient westerly flow above the boundary-layer supporting a risk
of damaging wind gusts and some hail in the strongest
cores/clusters.
...Southwest TX...
Water vapor imagery shows a southern stream shortwave trough moving
into northwest Mexico, with large scale ascent approaching west TX.
Considerable cloud cover will persist in this region today, limiting
heating/destabilization. Easterly low-level upslope flow will aid
in the development of afternoon thunderstorms over the Davis
mountains, with storms spreading slowly eastward through the
evening. A few severe storms are possible, capable of large hail
and gusty/damaging winds.
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SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1224 PM CDT Wed May 20 2026
Valid 211200Z - 221200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS EASTERN
COLORADO...
...SUMMARY...
Widely scattered severe storms are expected to develop across
eastern Colorado Thursday afternoon and evening. Large hail will be
the predominant hazard, with locally severe wind gusts and perhaps a
brief tornado or two also possible.
...Synopsis...
A short-wave trough and associated jet streak initially over the
northern Rockies Thursday morning will progress southeast into the
central Rockies by Thursday night. Farther to the south, a
short-wave trough will translate from the southern Plains into lower
MS Valley.
At the surface, a weak surface low is expected to develop from
southeast WY into western SD by Thursday evening, along a front
advancing through the northern High Plains. A lee trough will deepen
from the vicinity of low south through eastern parts of CO and NM.
Elsewhere, a cold front will push south from VA into the Carolinas
with the western extension of that boundary lifting north through
the lower MS Valley Thursday night in response to weak cyclogenesis
in that area.
...Central High Plains...
While low-level moisture will remain somewhat limited, the presence
of steep low/mid-level lapse rates will contribute to MLCAPE of
750-1000+ J/kg during the peak of the diurnal heating cycle.
Low-level upslope flow will be augmented by increased forcing for
ascent downstream from the approaching short-wave trough to foster
widely scattered thunderstorm development along favored terrain by
mid to late afternoon.
Strengthening mid-level flow coupled with the southeasterly
low-level wind component will yield effective bulk shear of 40-50
kt, supportive of supercell storm modes with the predominant hazard
being large hail. A brief tornado or two is possible, owing to
strengthening low-level shear by early evening. however, the
marginal moisture content is expected to limit a more robust threat.
...Western Dakotas...
At least a marginally unstable air mass is expected to develop ahead
of the front, supporting widely scattered thunderstorm development
by afternoon. Stronger vertical shear is expected to reside to the
south of the area, limiting the potential for organized storm modes.
Nonetheless, locally strong wind gusts and sub-severe hail appear
possible with the strongest storms.
...West Texas...
There is some model signal that a broken band of thunderstorms may
evolve near the NM/TX state line by late afternoon or evening,
amidst a steep lapse rate environment. Some potential will exist for
locally strong wind gusts and/or hail with that activity.
...Eastern Oklahoma into Northeast Texas...
The 12z convection-allowing models indicate a broader-scale complex
of storms evolving across the area Thursday. Weak vertical shear and
poor lapses are expected to limit the potential for storm
organization. However, the presence of a moist and moderately
unstable air mass will support briefly vigorous up/downdrafts
capable of locally strong wind gusts.
...Deep South Texas...
Remnants of overnight storms may be ongoing Thursday morning with
another round of thunderstorms potentially moving through the area
late Thursday night into Friday morning. Some potential will exist
for a few strong storms capable of gusty winds and hail.
...Lower MS Valley...
The models suggest that low-level shear will strengthen late
Thursday night into Friday morning in response to weak cyclogenesis
over the area. Lapse rates will be poor, limiting instability.
However, given the presence of a moist/low-lcl boundary layer, some
potential for low-level updraft rotation will exist with any deeper
convective elements, with a non-zero risk for a brief tornado.
...Southern VA into the Carolinas....
A hot, well-mixed boundary layer is forecast ahead of the front
Thursday afternoon. However, forecast soundings indicate warm
mid-level temperatures (500 mb and above), which are expected to
limit overall parcel buoyancy. Nonetheless, a few locally strong
wind gusts appear possible with storms developing along and ahead of
the boundary.
..Mead.. 05/20/2026
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SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0224 PM CDT Wed May 20 2026
Valid 221200Z - 231200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE SOUTHERN PLAINS...
...SUMMARY...
Scattered strong to severe storms will be possible across portions
of the southern Plains with potential for large hail and damaging
wind.
...Synopsis...
A short-wave trough initially over the northern and central High
Plains Friday morning is expected to become negatively tilted as it
translates into the upper MS Valley Friday night. A belt of enhanced
mid/upper-level flow will accompany that feature across the central
Plains. A separate, weaker disturbance is expected to be loosely
phased with the north-central U.S. system, tracking from the Ozark
Plateau and lower MS Valley into the OH and TN Valleys.
At the surface, A cold front associated with the former disturbance
mentioned above is forecast to move through the northern and central
Plains with the trailing extension of that boundary pushing into the
southern High Plains, where it will link with a surface low. Farther
east, a secondary surface low (tied to the lower-latitude impulse)
is expected to develop from the lower MS into OH Valley with an
associated warm front lifting north through the TN into OH Valley.
...Southern Plains...
Despite rising mid-level heights through the day, convergence along
the front and/or upslope flow in its immediate wake are expected to
support widely scattered thunderstorm development over parts of
northeast/east-central NM into the TX Panhandle by mid to late
afternoon. The combination of steep low/mid-level lapse rates and
boundary-layer dewpoints in the 50s to low 60s will support a
moderately unstable air mass amidst a kinematic environment
featuring a vertically veering wind profile with effective bulk
shear of 30-35 kt. That parameter space will support organized
multicell or supercell storm modes initially with the predominant
hazard being large hail. The 12z models suggest upscale growth of
the initial storms into an MCS with an isolated hail and wind threat
continuing east across parts of OK and northwest TX Friday evening
into Friday night.
...Central Plains...
An axis of 50s to low 60s dewpoints are expected to spread north
from KS into eastern NE ahead of the cold front. However, widespread
clouds and areas of precipitation are expected to limit
boundary-layer heating and air mass destabilization. So, despite
increased forcing for ascent and strengthening low-level and
deep-layer shear, the unfavorable thermodynamic environment is
expected to preclude severe-storm potential.
...TN and OH Valleys...
Numerous showers and thunderstorms are expected through the forecast
period along and south of the warm front, aiding by forcing for
ascent associated with the short-wave trough moving through the
region. Generally weak lapse rates are expected to limit air mass
destabilization, despite the presence of boundary-layer dewpoints in
the 60s to low 70s. However, a modest enhancement of mid-level winds
attending the short-wave trough, and more so, intensifying 850-mb
flow Friday afternoon into night, will result in strengthening
vertical shear, especially across the OH Valley Friday night. As
such, potential will exist for transient supercell structures to be
embedded in the broader-scale convective shield with a non-zero risk
for a brief tornado.
..Mead.. 05/20/2026
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