RSS Mesoscale Discussions from Storm Prediction Center
SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1205 AM CDT Wed May 20 2026
Valid 201200Z - 211200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
WEST TEXAS...
...SUMMARY...
Scattered severe storms with large hail and isolated severe gusts
are expected today across parts of west Texas. A few storms with
isolated severe gusts and hail will also be possible from the
central Appalachians into the Mid-Atlantic and far southern New
England.
...Southern High Plains...
Southwesterly mid-level flow will remain in place today over the
south-central U.S. At the surface, a quasi-stationary front will be
positioned from west Texas eastward into the Texas Hill Country.
South of the front, surface dewpoints in the 70s F will result in an
axis of moderate instability. The strongest instability is forecast
to develop from the lower Rio Grande River Valley
north-northwestward into far west Texas and eastern new Mexico. As
instability increases during the day and low-level convergence
becomes focused along the front, scattered thunderstorms are
expected to develop across far west Texas. These storms will move
eastward into west-central Texas by early to mid evening. Additional
storms may develop further north-northwest into eastern New Mexico.
RAP forecast soundings along the instability axis in the late
afternoon from Fort Stockton northward to Midland have MLCAPE near
2000 J/kg. 0-6 km is forecast to be around 50 knots with 700-500 mb
lapse rate from 7 to 8 C/km. This environment will be favorable for
supercells with large hail. The more dominant storms will have
potential for hailstones greater than 2 inches in diameter. Isolated
severe wind gusts will also be possible. A more isolated severe
threat may also develop further north-northwest across the southern
High Plains along the instability axis.
...Central Appalachians/Mid-Atlantic/Far Southern New England...
West-southwesterly mid-level flow will be in place today across much
of the eastern U.S. At the surface, a cold front will advance
southward across the central Appalachians and Mid-Atlantic. To the
south of the front, surface dewpoints in the upper 60s F will enable
an axis of moderate instability to develop by afternoon. MLCAPE is
forecast to peak in the 1000 to 2000 J/kg range in most areas ahead
of the front. Increasing low-level convergence near the front will
lead to scattered thunderstorm development during the afternoon.
These storms will move eastward across the central Appalachians,
Mid-Atlantic and far southern New England. RAP forecast soundings at
21Z along and near the instability axis have 0-6 km shear up to 25
knots with steep low-level lapse rates. This should support a severe
threat with multicell storms. Isolated severe wind gusts and hail
will be possible. The severe threat may persist into the early
evening.
..Broyles/Squitieri.. 05/20/2026
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SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1252 AM CDT Wed May 20 2026
Valid 211200Z - 221200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF SOUTHEASTERN COLORADO...NORTHEASTERN NEW MEXICO...AND THE FAR
WESTERN OKLAHOMA AND TEXAS PANHANDLES...
...SUMMARY...
Isolated severe storms are possible across parts of the central and
southern High Plains Thursday afternoon and evening.
...Synopsis...
A mid-level shortwave will translate eastward across the central
Rockies on D2/Thursday. At the surface, a cold front will move
through the northern High Plains while a secondary stationary front
remains in place from the Carolinas through the Tennessee Valley
into Ozark Plateau. A few strong to severe storms capable of large
hail and damaging wind will be possible near the front range in
Colorado.
...Central and Southern High Plains...
Upslope flow into eastern Colorado will combine with modest
upper-level forcing for ascent to allow for isolated to widely
scattered thunderstorms near the high terrain. Steep lapse rates,
MLCAPE 500-1000 J/kg, and deep layer shear around 30-35 kts from
south of I-70 will allow for a few better organized cells capable of
large hail and damaging wind. This threat will decrease with eastern
extent into KS/OK where strengthening MLCIN will temper the severe
threat downstream.
Additional areas of scattered thunderstorm activity will be possible
across southern Oklahoma into northern/central Texas and across far
western Texas in the afternoon. Generally weak deep layer shear
should limit the severe risk. A few instances of gusty winds and
small hail will be possible.
...Elsewhere...
Widely scattered thunderstorms are expected across the northern
Rockies into the northern Plains near the upper-low. Weak moisture
and limited instability will likely keep storms sub-severe. Widely
scattered thunderstorms will also be likely south of the stationary
front from the Carolinas into the Tennessee and Mississippi Valleys.
While marginal instability will be in place, weak deep layer shear
profiles will lead to more disorganized storms and limit the overall
severe threat.
..Thornton.. 05/20/2026
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SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0222 AM CDT Wed May 20 2026
Valid 221200Z - 231200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
FAR SOUTHWESTERN KANSAS INTO THE OKLAHOMA AND TEXAS PANHANDLES AND
WESTERN OKLAHOMA...
...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 mid-level wave will move across the central Plains on D3/Friday. A
weak lee low will develop across northeastern New
Mexico/southeastern Colorado, with a dryline extending from the
OK/TX Panhandles into southwestern Texas. Scattered thunderstorms
are expected along and east of the dryline by Friday afternoon, with
potential for large hail and damaging wind.
...Texas/Oklahoma Panhandles into portions of southwestern Kansas,
western Oklahoma, and northwestern Texas...
While there remains some uncertainty in the exact eastward placement
of the dryline Friday afternoon, guidance continues to suggest
eroding MLCIN and potential for convective development by the
afternoon as weak ascent spreads across KS into northern OK. Ahead
of the dryline, the environment will be characterized by steep low
to mid-level lapse rates and moderate to strong instability. Deep
layer shear around 30-35 kts would support potential for initial
supercells capable of large hail and damaging wind. Clustering and
more multi-cell mixed mode thunderstorms may evolve into a damaging
wind threat through time.
...Lower Mississippi Valley into Southeast...
Widely scattered thunderstorm activity is expected south of a
stationary boundary extending from the lower Mississippi Valley into
Tennessee and south into northern Georgia. Though weak to moderate
instability will be in place, weak flow aloft and weak deep layer
shear will likely keep storms sub-severe.
..Thornton.. 05/20/2026
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