Day 1 Convective Outlook CORR 1
NWS Storm Prediction Center Norman OK
1137 AM CDT Sun Sep 27 2026

Valid 271630Z - 281200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

CORRECTED TO REMOVE DUPLICATE TSTM AREA IN NEW ENGLAND

...SUMMARY...
Organized severe storms are not expected through early Monday.

...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.

..Thompson/Chalmers.. 09/27/2026

Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
1228 PM CDT Sun Sep 27 2026

Valid 281200Z - 291200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorm probability remains low on Monday.

...Synopsis...
The broad western trough will evolve into an upper low over the
Lower Colorado Valley with a low-amplitude trough over the northern
Rockies on Monday. Low-level moisture will be maintained into the
northern Plains by persistent low-level southerly flow. A cold front
will eventually move southeast through parts of the Dakotas by
Tuesday morning.

...Northwest South Dakota Vicinity...
Precipitation associated with low-level jet warm advection will
likely be ongoing in the morning. Ahead of a low-amplitude trough in
the northern Rockies, a weak surface trough/broad cyclone is
expected to develop near the Wyoming/South Dakota border and move
east-northeast through the afternoon/early evening. Despite
increasing mid/high-level clouds, some filtered surface
heating/destabilization is possible. Some CAM guidance suggests a
narrow zone in time and space for storm development is possible
along the surface trough by late afternoon. While the environment
could conditionally support a strong to marginally severe storm or
two, development/coverage remains uncertain given the modest warming
aloft that will occur during much of the period as well as weak
low/mid-level forcing for ascent. It is more probable that
convection develops along the advancing cold front well after 00Z as
the low-level jet intensifies. By that time, the thermodynamic
environment will be less favorable for severe storms.

..Wendt.. 09/27/2026

Day 1 Fire Weather Outlook  
NWS Storm Prediction Center Norman OK
1142 AM CDT Sun Sep 27 2026

Valid 271700Z - 281200Z

...Central and Northeastern Nevada... 
Existing Elevated highlights across portions of NV were shifted
slightly to the northwest and northeast. Increasing mid-level
south-southwesterly flow will overspread the Great Basin this
afternoon as an amplifying upper trough enters the northern CA
coast. Observed wind gusts already near 30 mph from the
south-southwest have occurred in higher elevations across central
and eastern Nevada this morning. Daytime boundary layer
heating/mixing should manifest in accelerating south-southwest winds
across central/northeastern NV to between 15-20 mph by this
afternoon. Current relative humidity in central NV valleys already
in the 20-25% range will fall close to 10% in some locations by peak
heating. These dry and breezy conditions will lead to an Elevated
fire weather threat across central and northeastern NV this
afternoon where receptive fuels exist.

..Williams.. 09/27/2026

.PREV DISCUSSION... /ISSUED 0142 AM CDT Sun Sep 27 2026/

...Synopsis...
An amplifying western CONUS trough will support strengthening
deep-layer south-southwesterly flow across portions of the Great
Basin today. Afternoon boundary-layer mixing will yield sustained
south-southwesterly surface winds of 15-20 mph (with higher gusts)
amid 10-15 percent RH. These dry/breezy conditions, combined with
sufficiently receptive fuels, will lead to elevated fire-weather
conditions across portions of central/eastern NV.

...Please see www.spc.noaa.gov/fire for graphic product...