No watches are valid as of Sun Sep 27 23:30:02 UTC 2026.MD 2329 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PARTS OF THE NE SAND HILLS REGION
Mesoscale Discussion 2329
NWS Storm Prediction Center Norman OK
0627 PM CDT Sun Sep 27 2026
Areas affected...Parts of the NE Sand Hills region
Concerning...Severe potential...Watch unlikely
Valid 272327Z - 280100Z
Probability of Watch Issuance...20 percent
SUMMARY...An isolated supercell may continue through sunset, with
additional development possible.
DISCUSSION...A nearly stationary supercell is ongoing across
west-central Cherry County Nebraska this evening. While deep-layer
flow/shear is generally rather modest, locally enhanced effective
SRH near a surface boundary is likely helping to sustain this
supercell, within a moderately unstable environment. MRMS data
suggest that this cell is likely producing severe hail, and it will
continue to pose a hail threat and potential for locally strong
gusts for as long as it persists. 0-1 km SRH of 100-150 m2/s2 may
also be sufficient for a brief tornado threat.
This storm has generally remained nearly stationary, but some slow
southward propagation will be possible for as long as it persists.
Other recent development has been noted across western Cherry
County. While uncertain, this additional development within a
favorable environment could eventually evolve into a supercell as
well, or help to maintain the dominant supercell through cell
mergers. The ongoing surface-based storms should generally begin to
weaken near/after dusk, as MLCINH begins to increase with nocturnal
cooling.
..Dean/Hart.. 09/27/2026
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...LBF...
LAT...LON 42690186 42640139 42540107 42190097 41810101 41790148
41780260 42230244 42450228 42690186
MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 90 MPH
MOST PROBABLE PEAK WIND GUST...UP TO 60 MPH
MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN
SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0257 PM CDT Sun Sep 27 2026
Valid 272000Z - 281200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Organized severe storms are not expected through early Monday.
...20z Update...
No changes were made to the existing outlook with this update cycle.
Isolated convective development is ongoing across portions of
central/north Texas as of 1945 UTC. While an isolated
strong/damaging wind gust cannot be ruled out with this activity
owing to steep low-level lapse rates and moderate buoyancy, weak
lower tropospheric flow (as depicted by regional VWPs), limited
effective shear, and poor mid-level lapse rates should largely
temper overall convective intensity. Thus, the severe threat
continues to appear too low (less than 5%) to warrant the inclusion
of severe probabilities. See the discussion below for additional
details.
..Chalmers/Guyer.. 09/27/2026
.PREV DISCUSSION... /ISSUED 1137 AM CDT Sun Sep 27 2026/
...Synopsis...
An occluded cyclone will slowly weaken near the northern
Mid-Atlantic coast, with lingering potential for elevated convection
and isolated lightning flashes to its northeast across southeast New
England. Farther west, weak ridging aloft will extend from the
southern High Plains toward MN. A few thunderstorms will be
possible late this afternoon/evening along a diffuse surface
boundary from north TX into southern OK. The strongest storms may
produce gusty outflow winds given steep low-level lapse rates with
afternoon mixing, but the severe threat appears too low to justify
adding severe-wind probabilities.
Slightly elevated convection is ongoing across central SD in a zone
of weak low-level frontogenesis, coincident with midlevel lapse
rates near 8 C/km and MUCAPE close to 1000 J/kg. Deep-layer
vertical shear is on the lower margins for storm organization, but
it appears this convection has already peaked. Additional elevated
thunderstorms are expected overnight from western SD into ND as
low-level warm advection increases in association with embedded
speed maxima downstream from a midlevel trough moving across CA/NV.
While an isolated hail report could occur overnight as far northeast
as southwest ND, the overall threat is low and when combined with
the questionable threat for diurnal convection across the central
High Plains, the MRGL area has been removed.
SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0228 PM CDT Sun Sep 27 2026
Valid 291200Z - 301200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Severe potential appears low on Tuesday.
...Synopsis...
The primary upper-level features of interest will be the main low in
the Southwest that will phase with the post-tropical remnants of
Polo. Moisture advecting northward will interact with a weak surface
boundary extending over much of the Plains. The upper low will
eventually move into the southern High Plains during the
evening/overnight period. Deep-layer flow, with a large southerly
component, will intensify as this occurs. Scattered to numerous
storms will develop within the Southwest and spread eastward into
the southern High Plains. Cloud cover will generally be expansive
ahead of the upper-level system, limiting afternoon heating. Storm
coverage will be greatest during the evening and overnight. Wind
fields would support some stronger gusts with convection despite
limited destabilization. Coupled with poor mid-level lapse rates
from the tropical airmass and largely meridional shear vector,
overall potential for organized/severe activity appears low.
..Wendt.. 09/27/2026
SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0227 PM CDT Sun Sep 27 2026
Valid 281200Z - 291200Z
...Southern California...
Surface high pressure building into the Intermountain West as a
closed upper low pivots into central/southern CA will support a
period of dry, offshore flow for portions of southern CA beginning
Monday. Elevated fire weather conditions are expected particularly
in wind-prone area and terrain gaps in the San Gabriel, San Rafael,
Santa Ynez, and Sierra Madre ranges. Northerly winds could reach
15-20 mph in some areas with gusts to 30-35 mph, lasting through
Monday night into Tuesday. RH reductions will reach 15-20% at times
during the late afternoon and early evening. Fuels continue to dry
across the area where wetting rains (0.10" or greater) has not
fallen in more than 150 days. These dry and breezy offshore winds
along with drying fuels will support elevated fire weather
conditions where highlights have been introduced.
..Williams.. 09/27/2026
.PREV DISCUSSION... /ISSUED 0143 AM CDT Sun Sep 27 2026/
...Synopsis...
A closed midlevel low will track eastward across the southern Great
Basin into the Southwest on Monday, while a midlevel ridge and
accompanying surface high pressure build over the Intermountain
West. This pattern will support dry/breezy offshore flow across
portions of southern CA, with locally elevated fire-weather
conditions possible (especially across the mountains and other
wind-prone areas). However, the overlap of dry/breezy conditions
with sufficiently receptive fuels currently appears too limited for
highlights.
...Please see www.spc.noaa.gov/fire for graphic product...
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