RSS Mesoscale Discussions from Storm Prediction Center
No watches are valid as of Sat Apr 18 19:21:02 UTC 2026.
No Mesoscale Discussions are in effect as of Sat Apr 18 19:21:02 UTC 2026.
SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1103 AM CDT Sat Apr 18 2026
Valid 181630Z - 191200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
ACROSS PARTS OF THE UPPER OHIO VALLEY AND LOWER GREAT LAKES
REGION....
...SUMMARY...
Widely scattered strong to severe thunderstorms capable mainly of
damaging winds will be possible today across the Upper Ohio Valley
and Lower Great Lakes.
...Upper OH Valley...
Latest surface analysis shows a cold front pushing eastward across
western OH, associated with a band of widespread clouds and light
precipitation. Mostly clear skies are present ahead of the front,
where temperatures are warming through the 70s. This will lead to a
corridor of marginal afternoon instability and the potential for
scattered thunderstorm intensification along the front. Forecast
soundings show strong mid-level winds and steep low-level lapse
rates, supportive of strong downdrafts in any vigorous convection.
However, CAM guidance is consistent in showing very few
organized/strong storms through the day. Will maintain the SLGT
risk for the conditional risk of a few damaging wind events, but
with limited confidence.
...TX...
Isolated intense thunderstorms have been ongoing this morning in the
post-frontal regime across central TX. These storms have produced
hail and gusty winds for several hours. It appears likely that this
scenario will shift eastward and weaken early this afternoon as the
primary upper jet moves into AR and away from the region, but will
maintain the MRGL risk area for a few more hours and extend it into
parts of AR/LA.
..Hart/Chalmers.. 04/18/2026
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SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1223 PM CDT Sat Apr 18 2026
Valid 191200Z - 201200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Severe thunderstorms are not expected on Sunday.
...Discussion...
An amplified midlevel trough will move eastward from the Great Lakes
into the Northeast on Sunday, while a related cold front moves off
the Eastern Seaboard and the FL Peninsula. Preceding the trough,
large-scale ascent will support isolated/elevated thunderstorms
across coastal New England into the afternoon. Similarly, a couple
thunderstorms are possible ahead of the front over coastal NC and
farther south over the central/southern FL Peninsula (aided by an
Atlantic sea breeze), though much of this activity may develop
offshore. Farther west over the lower Great Lakes, lapse rates will
quickly steepen beneath the core of the midlevel trough, and
sufficient (albeit weak) buoyancy will support a couple
thunderstorms -- given increasing ascent in the left-exit region of
a midlevel jet.
Finally, isolated/elevated thunderstorms will be possible within a
post-frontal air mass across southwest TX, where weak warm-air
advection will develop amid modestly steep midlevel lapse rates.
..Weinman.. 04/18/2026
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SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0215 PM CDT Sat Apr 18 2026
Valid 201200Z - 211200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Severe storms are not expected on Monday.
...Discussion...
A midlevel trough will move from the Northeast off the New England
coast on Monday, while the tail end of a related cold front
continues southward into the Caribbean Sea. North of the front in
southern FL, diurnal heating amid a moist post-frontal air mass
should support isolated to widely scattered thunderstorms, though
weak buoyancy and limited large-scale forcing for ascent should
limit the severe risk.
Farther west, weak low-level warm advection and modest moisture
return ahead of a low-amplitude midlevel impulse moving into south
TX will support a couple rounds of isolated/elevated thunderstorms
across southwest TX. Isolated thunderstorm potential could spread
further north into central TX late in the period, though confidence
in this scenario is currently low. Additional diurnal thunderstorms
are possible across the Southwest as the midlevel moisture impinges
on the region, with most of this activity expected over the higher
terrain.
..Weinman.. 04/18/2026
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SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
1142 AM CDT Sat Apr 18 2026
Valid 181700Z - 191200Z
...CRITICAL FIRE WEATHER AREA FOR ORTIONS OF WESTERN AND CENTRAL
NEBRASKA INTO NORTHWESTERN KS...
...Central/southern Plains...
Only minor changes were made for this forecast update. A dry, post
frontal air mass filtering into the Central Plains within a
favorable downslope regime has contributed to surface dewpoints
falling into the 15-20 F range across the high plains of CO
southwestern NE and western KS. Deep layer northwesterly flow and
boundary layer mixing should allow for northwest winds of 15-25 mph
to develop across portions of NE into northwestern KS. Critical fire
weather highlights were expanded southward where forecast model
guidance and surface observation trends indicate a corridor of lower
relative humidity around 15% by this afternoon.
...Southeast and Mid Atlantic...
Southwest winds will increase across the Southeast and Mid Atlantic
region ahead of an approaching upper-level trough and associated
surface cold front. A lingering dry air mass resulting in minimum RH
ranging from 25-30% by mid afternoon combined with southwest winds
of around 10 mph (locally 15 mph) and exceptionally dry fuels will
support a broad region of Elevated fire weather conditions.
Thunderstorms are likely along the eastward advancing cold front
later today and through tonight across the Appalachians. Although a
limited dry thunderstorm environment will be present, with
precipitable water values above 1.0" and a relatively moist boundary
layer, some lightning ignitions are possible given the receptive
fuelscape.
..Williams.. 04/18/2026
.PREV DISCUSSION... /ISSUED 0118 AM CDT Sat Apr 18 2026/
...Synopsis...
An amplified upper trough will move towards the upper Great Lakes
and Ohio Valley as temporary upper ridging builds over the West. In
the wake of the upper trough, a post-frontal dry airmass and
northwesterly flow will promote widespread fire weather conditions
across portions of the central and southern Plains. Enhanced
southwest winds ahead of an eastward progressing cold front will
pose an Elevated fire weather threat across parts of the Southeast
and Mid-Atlantic.
...Central/southern Plains...
Within a post-frontal environment, northwesterly winds of 15-20 mph
and RH of 15-25 percent over dry fuels will pose an Elevated fire
weather threat for portions of the central and southern Plains this
afternoon. A confined region of northwesterly winds of up to 25 mph
and gusts over 30 mph are expected in central/western Nebraska.
Despite model guidance indicating daytime RH to remain above 15
percent within this region, strong winds atop recently receptive
fuels and expected 90th-95th percentile ERCs will promote Critical
fire weather concerns.
...Southeast/Mid-Atlantic...
Increasing southwest flow ahead of an advancing cold front coupled
with the lack of appreciable moisture return from the Gulf and
resultant low RH will promote an Elevated fire weather threat across
much of the Southeast into the Mid-Atlantic. At peak heating,
widespread RH of 20-30 percent will combine with southwesterly winds
of 10-15 mph atop receptive fuels. Thunderstorms are expected to
form along/ahead of the approaching cold front in the
southern/central Appalachians late afternoon into the overnight
hours. With relatively minimal precipitation (less than 0.25")
expected on eastern slopes of the Appalachians towards the Piedmont
Plateau, the potential exists for lightning ignitions. Given a
continuous environment of above normal temperatures and
exceptionally dry fuels, there is a concern for increased spread
potential of any existing and new ignitions.
...Please see www.spc.noaa.gov/fire for graphic product...
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SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0218 PM CDT Sat Apr 18 2026
Valid 191200Z - 201200Z
...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF THE SOUTHERN PLAINS...
...Central and Southern Plains...
A subtle mid-level short wave embedded in broader, but modest
northwest flow aloft will move into the Central/Southern Rockies,
with a subsequent lee surface trough emerging across eastern CO on
Sunday. Resultant south/southwest winds of 15-25 mph will evolve
across the Southern Plains within a very dry air mass, promoting
elevated to critical fire weather conditions. Single digit RH values
are likely across eastern CO but stronger winds around 25 mph will
be displaced to the southeast across southwest KS and the TX/OK
Panhandles where RH could fall to as low as 10% during peak
afternoon heating after poor overnight recoveries. Critical fire
weather highlights were expanded into northeastern NM based on
latest forecast guidance suggesting a higher likelihood of sustained
south winds of around 20 mph. Elevated highlights were also
introduced in leeward locations of the Sangre de Cristo Mountains
where enhanced downslope westerly winds approaching 20 mph, relative
humidity around 15% and dry fuels align.
...Southeast and Mid-Atlantic...
Dry and breezy post-frontal flow is still expected to bring elevated
fire weather concerns for portions of the Southeast and Mid Atlantic
Sunday. Rainfall associated with a cold front will be limited across
the Piedmont region tonight into Sunday, allowing very receptive
fuels to persist. Northwest winds of 10-15 mph and RH of 20-30% are
expected during the day despite cloud cover, with RH in some
downslope favored areas adjacent to the Appalachians falling to
around 15% by Sunday afternoon. An elevated fire weather threat will
likely linger into the evening hours closer to the northern Gulf
Coast. Elevated highlights have been extended southward into the
Florida Panhandle where exceptional drought and very dry fuels
persist.
..Williams.. 04/18/2026
.PREV DISCUSSION... /ISSUED 0120 AM CDT Sat Apr 18 2026/
...Synopsis...
Upper ridging across the West will slide eastward over the
Continental Divide as an amplified large-scale trough will traverse
the eastern U.S. on Sunday. Broad northwest flow will prevail over
the High Plains as surface high pressure shifts east and lee surface
troughing enhances fire weather concerns over the southern Plains.
Beneath the aforementioned trough, an associated cold front will
advance off the Eastern Seaboard as a dry and breezy post-frontal
airmass will pose an elevated fire weather threat across much of the
Piedmont and Southeast.
...Central/southern Plains...
Dry return flow and lee surface troughing will result in continued
Elevated and Critical fire weather conditions on Sunday. A
combination of south-southwesterly sustained winds of up to 25 mph
(gusts up to 35 mph) and very low RH of 10-15 percent (single digits
locally) will pose a Critical fire weather threat over portions of
southwestern Kansas, southeastern Colorado, northeastern New Mexico,
and the OK/TX Panhandles. Poor overnight humidity recoveries and
mainly clear skies during the afternoon will further exacerbate the
fire environment amid 90th-97th percentile ERCs. High/mid-level
clouds will increase during the afternoon across West TX and eastern
NM, however, sustained surface winds from 10-20 mph with 10-15
percent RH atop dry fuels maintain an Elevated fire weather threat.
...Southeast/Mid-Atlantic...
In a post-frontal environment, dry and breezy northerly flow will
develop east of the Appalachians into the Southeast on Sunday.
North-northwest sustained winds of 10-15 mph and widespread low RH
of 15-30 percent atop exceptionally dry fuels will promote Elevated
fire weather conditions from the Mid-Atlantic to the Florida
Panhandle. Elevated highlights may be adjusted in future outlooks
depending on the anticipated rainfall on Day 1/Saturday into Day
2/Sunday morning.
...Please see www.spc.noaa.gov/fire for graphic product...
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