Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0757 PM CDT Mon Apr 20 2026

Valid 210100Z - 211200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe storms are not expected through tonight.

...Discussion...
Scattered thunderstorms persist across central and southern TX this
evening, where southerly 850 mb winds are aiding lift/warm advection
atop the relatively cool boundary layer. In addition, a weak wave
aloft is moving across the southern Plains. As such, storms may
increase in coverage through tonight, expanding into northern and
eastern TX. Effective shear will remain weak especially over
northern areas, and severe storms are not expected.

Elsewhere, showers will generally decrease over far southern FL with
the loss of heating. Farther west, an isolated lightning flash
cannot be ruled out over parts of the WA/OR Cascades as an offshore
upper trough slowly pushes east.

..Jewell.. 04/21/2026

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
1237 AM CDT Tue Apr 21 2026

Valid 211200Z - 221200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Thunderstorms are expected today over much of Texas, from Illinois
into Ohio, and over portions of central California. Severe weather
is not currently forecast.

...Synopsis...
An upper ridge will move into the Plains as an upper trough moves
inland over the West, with a strong cyclonic speed max moving across
CA and into the Great Basin. Meanwhile, northwest flow aloft will
extend from the Great Lakes into the Mid Atlantic. Farther south, a
weakening disturbance will move out of TX and toward the lower MS
Valley.

At the surface, high pressure will remain over much of the eastern
states and across the Gulf Coast. Southerly winds across the Plains
and around this high may support mid to upper 50s F dewpoints as far
north as IA and IL by 00Z, while higher dewpoints remain relegated
to southern TX. Here, scattered showers and thunderstorms will
likely be ongoing early on Tuesday where weak elevated instability
will remain.

...IL/IN/OH...
A surface trough is forecast to develop from Lower MI into southern
WI and northern IL by late afternoon, beneath the northwest flow
regime and with cool midlevel temperatures. Southwest surface winds
and daytime heating should lead to 40s and 50s F dewpoints, with a
relatively dry boundary layer overall. Models suggest at least
isolated late day and evening thunderstorms will develop ahead of
this trough, though instability levels are uncertain. Despite
marginal dewpoints/moisture, the cool temperatures aloft may support
a few cells capable of small hail from IL into IN by late afternoon.
Wind gust potential is more uncertain and dependent on storm
coverage/outflow production, with the dry boundary layer
conditionally helping strong gust potential into the evening and
perhaps overnight.

...Central CA...
Cold temperatures aloft north of the midlevel jet will support weak
instability over parts of the central Valleys. Given early
precipitation and clouds, as well as marginal low-level shear,
severe storms appear unlikely. However, a few strong storms may
occur late in the afternoon if sufficient heating occurs behind the
early day rain. Small hail appears most probable with the strongest
cells.

..Jewell.. 04/21/2026

Day 1 Fire Weather Outlook  
NWS Storm Prediction Center Norman OK
1220 AM CDT Tue Apr 21 2026

Valid 211200Z - 221200Z

...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF CENTRAL FLORIDA AND
THE WEST FLORIDA COAST...

...Synopsis...
Broad northwest flow aloft will encompass much of Northeast and Mid
Atlantic in the wake of a departing upper-trough. A dry airmass will
remain in place across the eastern U.S., Southeast and Deep South as
surface high pressure shifts into the Atlantic. Farther west, a
negatively-tilted upper trough will surge into the Western U.S.,
with dry and breezy conditions focused over the Great Basin ahead of
an advancing cold front.

...Florida into Southern Georgia...
East to northeast winds of 10-15 mph on the southern fringe of the
surface high are expected today across portions of southern GA into
FL. Stronger sustained east winds of 15 mph (with higher gusts) will
be located farther south across the FL Peninsula, while drier
conditions including relative humidity as low as 15% amid higher
temperatures in the lower 80s will be displaced to the north over
the FL Panhandle and southern GA. Critical fire weather conditions
are expected across portions of central FL and the West FL Coast
where sustained winds are likely to reach 15 mph and RH falls into
the 25-35% range. Elevated fire weather concerns were extended into
much of the FL Panhandle where offshore trajectories will maintain a
dry boundary layer through much of the afternoon. Fuels remain very
receptive amid worsening drought conditions with ongoing fire
activity.

...Lower Mississippi Valley...
A relative minimum in recent rainfall and existing dry fuels 
coupled with dry return flow on the western periphery of the broad
surface high pressure moving off the Mid Atlantic, will bring a fire
weather threat to portions of western TN/MS and eastern AR. South to
southwest winds of 10-15 mph amid relative humidity of 20-25%
supports a continuation of Elevated fire weather highlights across
portions of the lower MS River Valley.

...East-Central Wyoming...
A limited fire weather threat will emerge across east-central WY
with a weak downslope warming and drying regime in place across the
central High Plains. A shallow near-surface temperature inversion
will quickly mix out under mostly sunny skies through the late
morning hours, following possible poor RH recoveries overnight in
eastern WY/CO. RH of 10% or below is likely by the afternoon across
the central High Plains. However, weak boundary layer flow and lack
of substantial surface lee troughing across the region should limit
spatial extent and duration of sustained west winds of up to 15 mph
across east-central WY, precluding introduction of Elevated
Highlights.

..Williams.. 04/21/2026

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