RSS Mesoscale Discussions from Storm Prediction Center
No watches are valid as of Mon Apr 20 17:27:01 UTC 2026.
No Mesoscale Discussions are in effect as of Mon Apr 20 17:27:01 UTC 2026.
SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1052 AM CDT Mon Apr 20 2026
Valid 201630Z - 211200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Severe storms are not expected today.
...Synopsis...
An upper impulse will continue to pose a risk of scattered
thunderstorms over parts of NM and south/west TX through the
afternoon, with activity spreading into north-central TX late
tonight.
Other thunderstorms are possible this afternoon and evening over
south FL in a moist and marginally unstable air mass, along the
coast of southern New England, and over portions of OR/WA. In all
areas, weak instability will preclude the risk of organized severe
storms.
..Hart/Flournoy.. 04/20/2026
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SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1224 PM CDT Mon Apr 20 2026
Valid 211200Z - 221200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Thunderstorms will be possible across the West, portions of the
southern Plains, and the southern Great Lakes on Tuesday. Potential
for severe weather appears low.
...Synopsis...
Upper-level ridging is expected to build into the Plains on Tuesday.
Moderate northwesterly flow aloft will remain across the Upper
Midwest/Great Lakes. In the West, an upper trough will move into
California and the western Great Basin. At the surface, a high
pressure system will persist in the Southeast. Initial moisture
return around the western flank of this anticyclone will occur
through the day. This moisture will interact with a weak boundary
within the Midwest/Lower Great Lakes.
...Midwest/Lower Great Lakes...
Ahead of the weak surface boundary, some increase in low-level
moisture can be expected. Moisture should generally be greater along
the Iowa/Missouri border with diminishing dewpoints towards the
Lower Great Lakes/Ohio Valley. Within moderate northwesterly flow
aloft, a subtle shortwave trough is expected to move towards
southern Lake Michigan during the afternoon. Temperatures at 500 mb
of around -18C should promote some convection along the boundary by
late afternoon. Farther west, forcing for ascent will be weaker and
capping will be stronger. The main question in this scenario
continues to be the quantity of moisture return ahead of the
boundary. Guidance does suggest low 50s F are possible, but given
how dry the current airmass across the region is and how late this
initial moisture return will be, confidence in that forecast is low.
The current expectation is that isolated to widely scattered storms
are possible by late afternoon/early evening, particularly near
southern Lake Michigan. These storms may briefly strengthen and be
capable of gusty winds/small hail. Thereafter, nocturnal cooling
should lead to a weakening trend. Development near the Iowa/Missouri
is far more conditional.
...Trans-Pecos/Big Bend into Central Texas...
Convection will be ongoing Tuesday morning in central Texas.
Isolated small hail and gusty winds are possible, but deep-layer
shear will be weakening as the ridge builds into the Plains through
the day. Farther west, a weak dryline is possible into the Big Bend
region. An isolated storm or two could develop. Weak vertical shear
and marginal buoyancy should limit severe potential.
...California Central Valley...
After an initial period of precipitation in the morning, pockets of
surface heating in the afternoon may lead to MLCAPE of 250-500 J/kg.
While a stronger storm or two is possible, the severe threat will be
limited by weak deep-layer shear.
..Wendt.. 04/20/2026
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SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
1053 AM CDT Mon Apr 20 2026
Valid 201700Z - 211200Z
...Morning Update...
No changes were made to the previous forecast. Current surface
observations depict widespread RH values of 10-30 percent across
portions of the central/southern Plains owing to poor overnight
humidity recoveries. Parts of the Southeast also experienced poor
humidity recoveries, with current RH values in the upper 20s. Any
new ignitions and ongoing wildfires in this region will experience
elevated to locally critical fire weather conditions this afternoon
as northeasterly winds increase and RH decreases atop exceptionally
dry fuels. See the previous discussion for more information.
..Elizalde-Garcia.. 04/20/2026
.PREV DISCUSSION... /ISSUED 0128 AM CDT Mon Apr 20 2026/
...Synopsis...
Upper-level ridging will gradually shift eastward from the Rockies
into the Plains through today as an upper-level trough departs the
East Coast and a second, closed upper trough approaches the West
Coast. Surface high pressure will shift east over the
Southeast/Mid-Atlantic while a lee trough deepens along the
central/northern High Plains.
...Portions of the central High Plains...
A deepening lee trough along the central High Plains will support
strengthening westerly downslope winds to the west of the trough
axis across portions of southeastern Wyoming into southwest South
Dakota and much of western/central Nebraska. Farther south/east,
high pressure over the Lower Mississippi Valley in conjunction with
the lee trough will yield a tightened surface pressure gradient and
strengthening southerly winds from the TX/OK Panhandle vicinity
northeastward into central Kansas and south-central Nebraska.
Sustained winds of 15-20 mph are expected within both of these
regimes. RH minimums of 10-15% (locally lower) are expected across
southeast Wyoming, southwest South Dakota, and western Nebraska
where downslope wind will depress moisture content within an
antecedent dry air mass. Farther south/east, the northern fringe of
returning moisture may limit RH reductions to some degree, but RH
minimums are still forecast to fall to 15-25% southeastern Colorado
northeastward into south-central Nebraska. With dry, receptive fuels
across much of the region, this will support widespread elevated
fire weather conditions for a few hours this afternoon. Locally
critical conditions will also be possible in the lee of the Laramie
Mountains in southeastern Wyoming where winds may occasionally gust
to 30-35 mph.
...Portions of the Southeast...
A dry air mass will continue to reside across much of the Southeast
where fuels remain exceptionally dry (ERCs above the 95th
percentile) amid continuing drought. Sustained northeasterly winds
of 10-15 mph along the southern periphery of surface high pressure
are forecast to overlap minimum RH values of 15-25% across much of
the Florida Panhandle and adjacent areas of southern
Alabama/Georgia. Farther north, modest westerly/northwesterly
downslope winds of 10-15 mph are forecast behind a dry, secondary
cold frontal passage, with minimum RH of 20-30% (locally lower)
expected. This combination of winds/RH is expected to support
elevated fire weather concerns across much of the Southeast this
afternoon.
...Portions of New Mexico into eastern Arizona...
Low to mid-level moisture return is forecast across southern Texas
into portions of the Southwest through this afternoon. Although
forcing for ascent will remain modest under an upper-level ridge, a
combination of localized orographic ascent, deeply mixed boundary
layers with minimal inhibition, and a weak, subtle mid-level
shortwave trough will support isolated thunderstorm development this
afternoon. Slow storm motions (around 10 kts) will likely support
pockets of wetting precipitation, but PWAT values of 0.4-0.7" atop a
dry sub-cloud layer will likely support dry lightning strikes while
largely limiting precipitation. With regional ERCs near the 75th to
80th percentile, lightning ignitions appear possible. While
prevailing flow is forecast to remain weak, gusty outflow winds may
create erratic fire behavior with any new ignitions.
...Portions of the Upper Midwest...
A tightened surface pressure gradient will promote sustained
southwesterly winds of 20-25 mph, with the potential for gusts to
30-35 mph, across portions of the Upper Midwest, especially across
the eastern Dakotas and much of Minnesota. RH values are forecast to
fall to 25-30% this afternoon, with lower values possible should
forecast cloud cover clear more quickly this morning/afternoon. This
combination of wind/RH may promote locally elevated fire weather
concerns this afternoon, especially in pockets of drier fine fuels.
Recent precipitation across portions of this area along with
marginal fuel receptiveness and uncertainty regarding cloud cover
preclude the addition of Elevated highlights at this time.
...Please see www.spc.noaa.gov/fire for graphic product...
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