WW 611 SEVERE TSTM LA TX 212025Z - 220200Z
URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 611
NWS Storm Prediction Center Norman OK
325 PM CDT Fri Aug 21 2026
The NWS Storm Prediction Center has issued a
* Severe Thunderstorm Watch for portions of
Southwestern into Northern Louisiana
East Texas
* Effective this Friday afternoon and evening from 325 PM until
900 PM CDT.
* Primary threats include...
Scattered damaging wind gusts to 70 mph possible
SUMMARY...Scattered strong to severe thunderstorms are forecast to
intensify this afternoon and persist through the early evening.
Damaging wind gusts associated with the stronger thunderstorm cores
are the primary severe hazard.
The severe thunderstorm watch area is approximately along and 70
statute miles north and south of a line from 45 miles north
northeast of Lafayette LA to 35 miles north of Lufkin TX. For a
complete depiction of the watch see the associated watch outline
update (WOUS64 KWNS WOU1).
PRECAUTIONARY/PREPAREDNESS ACTIONS...
REMEMBER...A Severe Thunderstorm Watch means conditions are
favorable for severe thunderstorms in and close to the watch area.
Persons in these areas should be on the lookout for threatening
weather conditions and listen for later statements and possible
warnings. Severe thunderstorms can and occasionally do produce
tornadoes.
&&
OTHER WATCH INFORMATION...CONTINUE...WW 608...WW 609...WW 610...
AVIATION...A few severe thunderstorms with hail surface and aloft to
1 inch. Extreme turbulence and surface wind gusts to 60 knots. A few
cumulonimbi with maximum tops to 500. Mean storm motion vector
01010.
...Smith
WW 610 SEVERE TSTM IA IL IN WI LM 211955Z - 220300Z
URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 610
NWS Storm Prediction Center Norman OK
255 PM CDT Fri Aug 21 2026
The NWS Storm Prediction Center has issued a
* Severe Thunderstorm Watch for portions of
Eastern Iowa
Northern and Central Illinois
Far Northwest Indiana
Southern Wisconsin
Lake Michigan
* Effective this Friday afternoon and evening from 255 PM until
1000 PM CDT.
* Primary threats include...
Scattered large hail and isolated very large hail events to 2
inches in diameter possible
Scattered damaging wind gusts to 70 mph possible
A tornado or two possible
SUMMARY...Scattered severe thunderstorms are forecast to develop
through the remainder of the afternoon and into the evening. A few
supercells and eventually some severe multicells organizing into a
linear cluster are expected. The threat for large hail and severe
gusts will accompany the stronger storms. A tornado is possible,
especially with a supercell favorably interacting with a stalled
outflow boundary across parts of the Watch area. This activity will
likely shift southward with time during the evening.
The severe thunderstorm watch area is approximately along and 90
statute miles east and west of a line from 20 miles east northeast
of Lonerock WI to 15 miles southeast of Bloomington IL. For a
complete depiction of the watch see the associated watch outline
update (WOUS64 KWNS WOU0).
PRECAUTIONARY/PREPAREDNESS ACTIONS...
REMEMBER...A Severe Thunderstorm Watch means conditions are
favorable for severe thunderstorms in and close to the watch area.
Persons in these areas should be on the lookout for threatening
weather conditions and listen for later statements and possible
warnings. Severe thunderstorms can and occasionally do produce
tornadoes.
&&
OTHER WATCH INFORMATION...CONTINUE...WW 608...WW 609...
AVIATION...A few severe thunderstorms with hail surface and aloft to
2 inches. Extreme turbulence and surface wind gusts to 60 knots. A
few cumulonimbi with maximum tops to 500. Mean storm motion vector
33020.
...Smith
WW 609 SEVERE TSTM AL FL LA MS CW 211900Z - 220100Z
URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 609
NWS Storm Prediction Center Norman OK
200 PM CDT Fri Aug 21 2026
The NWS Storm Prediction Center has issued a
* Severe Thunderstorm Watch for portions of
Southwest Alabama
Western Florida Panhandle
Southeast and Eastern Louisiana
Southern Mississippi
Coastal Waters
* Effective this Friday afternoon and evening from 200 PM until
800 PM CDT.
* Primary threats include...
Scattered damaging wind gusts to 70 mph possible
Isolated large hail events to 1 inch in diameter possible
SUMMARY...Scattered thunderstorms are forecast to intensify this
afternoon and wet microbursts will be associated with the stronger
storms. Damaging wind gusts with the more intense downdrafts will
probably range 55 to 70 mph. An isolated threat for marginally
severe hail may also accompany the more intense storms.
The severe thunderstorm watch area is approximately along and 60
statute miles north and south of a line from 15 miles southeast of
Evergreen AL to 40 miles southwest of Natchez MS. For a complete
depiction of the watch see the associated watch outline update
(WOUS64 KWNS WOU9).
PRECAUTIONARY/PREPAREDNESS ACTIONS...
REMEMBER...A Severe Thunderstorm Watch means conditions are
favorable for severe thunderstorms in and close to the watch area.
Persons in these areas should be on the lookout for threatening
weather conditions and listen for later statements and possible
warnings. Severe thunderstorms can and occasionally do produce
tornadoes.
&&
OTHER WATCH INFORMATION...CONTINUE...WW 608...
AVIATION...A few severe thunderstorms with hail surface and aloft to
1 inch. Extreme turbulence and surface wind gusts to 60 knots. A few
cumulonimbi with maximum tops to 500. Mean storm motion vector
34010.
...Smith
WW 608 SEVERE TSTM GA NC SC CW 211740Z - 220100Z
URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 608
NWS Storm Prediction Center Norman OK
140 PM EDT Fri Aug 21 2026
The NWS Storm Prediction Center has issued a
* Severe Thunderstorm Watch for portions of
Eastern Georgia
Southern and Eastern North Carolina
Central and Northeast South Carolina
Coastal Waters
* Effective this Friday afternoon and evening from 140 PM until
900 PM EDT.
* Primary threats include...
Scattered damaging wind gusts to 65 mph possible
Isolated large hail events to 1 inch in diameter possible
SUMMARY...Scattered thunderstorms are forecast to continue to
develop and intensify through the afternoon across the Piedmont into
the coastal plain. The stronger thunderstorms will be capable of
wind damage in the vicinity of the more intense water-loaded
downdrafts. Peak gusts will likely range 55 to 65 mph and isolated
large hail around 1 inch in diameter is also possible.
The severe thunderstorm watch area is approximately along and 70
statute miles north and south of a line from 50 miles south of
Greenville SC to 10 miles south of New Bern NC. For a complete
depiction of the watch see the associated watch outline update
(WOUS64 KWNS WOU8).
PRECAUTIONARY/PREPAREDNESS ACTIONS...
REMEMBER...A Severe Thunderstorm Watch means conditions are
favorable for severe thunderstorms in and close to the watch area.
Persons in these areas should be on the lookout for threatening
weather conditions and listen for later statements and possible
warnings. Severe thunderstorms can and occasionally do produce
tornadoes.
&&
AVIATION...A few severe thunderstorms with hail surface and aloft to
1 inch. Extreme turbulence and surface wind gusts to 55 knots. A few
cumulonimbi with maximum tops to 500. Mean storm motion vector
24015.
...Smith
WW 0611 Status Updates
STATUS FOR WATCH 0611 HAS NOT BEEN ISSUED YET
WW 0610 Status Updates
STATUS REPORT ON WW 610
THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA.
..MEAD..08/21/26
ATTN...WFO...ARX...DVN...LOT...ILX...MKX...
STATUS REPORT FOR WS 610
SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS
ILC007-011-015-031-037-043-053-057-063-073-075-085-089-091-093-
095-097-099-103-105-111-113-123-131-141-143-155-161-175-177-179-
195-197-201-203-212140-
IL
. ILLINOIS COUNTIES INCLUDED ARE
BOONE BUREAU CARROLL
COOK DE KALB DUPAGE
FORD FULTON GRUNDY
HENRY IROQUOIS JO DAVIESS
KANE KANKAKEE KENDALL
KNOX LAKE LA SALLE
LEE LIVINGSTON MCHENRY
MCLEAN MARSHALL MERCER
OGLE PEORIA PUTNAM
ROCK ISLAND STARK STEPHENSON
TAZEWELL WHITESIDE WILL
WINNEBAGO WOODFORD
INC089-111-212140-
IN
. INDIANA COUNTIES INCLUDED ARE
WW 0609 Status Updates
STATUS REPORT ON WW 609
THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA.
FOR ADDITIONAL INFORMATION SEE MESOSCALE DISCUSSION 2071
..CHALMERS..08/21/26
ATTN...WFO...MOB...JAN...LIX...
STATUS REPORT FOR WS 609
SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS
ALC003-023-025-035-053-097-099-129-212140-
AL
. ALABAMA COUNTIES INCLUDED ARE
BALDWIN CHOCTAW CLARKE
CONECUH ESCAMBIA MOBILE
MONROE WASHINGTON
FLC033-113-212140-
FL
. FLORIDA COUNTIES INCLUDED ARE
ESCAMBIA SANTA ROSA
LAC025-029-033-037-063-077-091-103-105-117-121-125-212140-
LA
. LOUISIANA PARISHES INCLUDED ARE
CATAHOULA CONCORDIA EAST BATON ROUGE
WW 0608 Status Updates
STATUS REPORT ON WW 608
SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 35 WSW AGS
TO 25 N AGS TO 35 NW CAE TO 20 SSW CLT TO 35 NNE CLT.
FOR ADDITIONAL INFORMATION SEE MESOSCALE DISCUSSION 2069
..CHALMERS..08/21/26
ATTN...WFO...CAE...RAH...ILM...GSP...MHX...
STATUS REPORT FOR WS 608
SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS
GAC033-073-189-245-212140-
GA
. GEORGIA COUNTIES INCLUDED ARE
BURKE COLUMBIA MCDUFFIE
RICHMOND
NCC007-017-019-025-047-049-051-061-085-093-101-103-105-107-119-
123-125-129-133-137-141-153-155-163-165-167-179-191-212140-
NC
. NORTH CAROLINA COUNTIES INCLUDED ARE
ANSON BLADEN BRUNSWICK
CABARRUS COLUMBUS CRAVEN
CUMBERLAND DUPLIN HARNETT
HOKE JOHNSTON JONES
LEE LENOIR MECKLENBURG
MONTGOMERY MOORE NEW HANOVER
ONSLOW PAMLICO PENDER
RICHMOND ROBESON SAMPSON
MD 2072 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR NORTH-CENTRAL AND NORTHEAST NEVADA...NORTHWEST UTAH...FAR SOUTHEAST OREGON...AND SOUTHERN IDAHO.
Mesoscale Discussion 2072
NWS Storm Prediction Center Norman OK
0335 PM CDT Fri Aug 21 2026
Areas affected...north-central and northeast Nevada...northwest
Utah...far southeast Oregon...and southern Idaho.
Concerning...Severe potential...Watch unlikely
Valid 212035Z - 212300Z
Probability of Watch Issuance...5 percent
SUMMARY...The threat for a few severe wind gusts up to 70-80 mph is
expected to increase by mid to late afternoon. A watch is not
expected due to the isolated nature of the threat.
DISCUSSION...Subtle mid-level disturbances embedded in a moist,
southerly flow regime are contributing to a gradual increase in
thunderstorms this afternoon across portions of central and southern
NV. Modification of the 18Z LKN sounding for hotter surface
conditions currently observed over northeast NV into northwest UT
yields MUCAPE of 500-750 J/kg atop a 3-4 km deep, well-mixed
boundary layer. As such, thunderstorms are expected to move/develop
north through the region this afternoon into evening with an
associated risk for locally severe wind gusts up to 70-80 mph,
driven by strong evaporational cooling potential in the sub-cloud
layer. Explicit wind gust fields from the latest CAM data continue
to highlight portions of north-central and northeast NV into
southwest ID as a most likely corridor for the strongest gusts to
occur.
..Mead/Smith.. 08/21/2026
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...SLC...PIH...BOI...LKN...
LAT...LON 43221740 41011740 40001622 39931493 40041384 40401316
41211270 42481266 43081310 43351414 43621572 43221740
MOST PROBABLE PEAK WIND GUST...65-80 MPH
MD 2071 CONCERNING SEVERE THUNDERSTORM WATCH 609... FOR LOWER MISSISSIPPI RIVER VALLEY
Mesoscale Discussion 2071
NWS Storm Prediction Center Norman OK
0333 PM CDT Fri Aug 21 2026
Areas affected...Lower Mississippi River Valley
Concerning...Severe Thunderstorm Watch 609...
Valid 212033Z - 212230Z
The severe weather threat for Severe Thunderstorm Watch 609
continues.
SUMMARY...The potential for damaging winds will continue through
late afternoon across the lower Mississippi River Valley.
DISCUSSION...Regional radar imagery out of southern MS and eastern
LA depicts poorly organized, and largely outflow-dominant,
convection. These cells/clusters have been producing occasionally
strong downbursts with velocity data depicting 40-50 knot outflow
within the lowest 1-2 kft ARL. Additionally, surface stations that
have been impacted by outflow have reported temperature reductions
on the order of 20 F. Given these conditions within the convective
cold pools and weak low-level shear sampled by regional VWPs,
outflow boundaries should become more prominent within the next hour
or so. Boundary collisions downstream across east/southeast LA will
likely promote additional updraft development within a hot and
unstable air mass (characterized by low-level lapse rates
approaching 9 C/km and MLCAPE estimated to be around 2500-3000
J/kg). Intense downbursts will be possible with the more vigorous
updraft pulses as additional convection develops and spreads south
into this air mass over the next few hours. Given the thermodynamic
conditions, embedded swaths of 45-60 mph appear possible within the
strongest downbursts.
..Moore.. 08/21/2026
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...JAN...LIX...LCH...SHV...
LAT...LON 30859220 31719195 32069162 32249124 32259096 32169064
31869029 31359017 30909009 30529019 30369031 30189054
30109085 30119122 30159150 30269183 30499206 30859220
MOST PROBABLE PEAK WIND GUST...UP TO 60 MPH
SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0300 PM CDT Fri Aug 21 2026
Valid 212000Z - 221200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CENTRAL PLAINS...MIDWEST...LOWER MS VALLEY...AND CAROLINAS...
...SUMMARY...
Scattered severe thunderstorms capable of producing large hail (some
2+ inches) and severe winds may occur over parts of the central
Plains into the Midwest this afternoon and evening. Damaging winds
also remain possible with scattered to numerous thunderstorms across
portions of the Carolinas and northern Gulf Coast states.
...20z Update...
...Lower MS Valley and Carolinas...
The forecast generally remains on track with only a minor eastward
expansion of the 15% wind probabilities in southern Alabama and the
far western Florida Panhandle. Modestly stronger low-to-mid level
flow (evident in the MOB VWP) and favorable thermodynamic profiles
(steep low-level lapse rates and high PW) should support stronger
downbursts and scattered damaging wind gusts, similar to areas
farther east. See Mesoscale Discussion #2069 for additional
short-term details.
...Midwest...
The Level 1/Marginal risk and Level 2/Slight risk areas were
expanded slightly northwestward based on observed convective
development ongoing across as of 1945 UTC across southwestern
Wisconsin. Some consideration was given to adding a targeted 5%
tornado probability area along the remnant outflow boundary
extending from southeast of Rockford, IL, into southwestern
Wisconsin; however, uncertainty regarding the longevity of a
supercellular storm mode (owing to the potential for cell
mergers/interactions) and the presence of only modest low-level
hodograph curvature/SRH precludes a 5% area at this time. See
Mesoscale Discussion #2070 for additional short-term details.
...Central Plains...
Latest high-res guidance has poorly captured the evolution of
morning and ongoing convection across portions of central and
eastern Nebraska through early this afternoon, which lends
uncertainty to the evolution of the severe threat through the rest
of the period. Given the continued potential for ongoing convection
to intensify and/or for additional redevelopment through the
evening, however, severe probabilities have been maintained with
only minor expansions made to the CIG1 wind and hail areas.
...Northern Great Basin into the Snake Valley...
Convective development is ongoing across portions of central/eastern
Nevada, with thunderstorms forecast to evolve northward through the
afternoon. The 5% wind probabilities and CIG1 area were expanded
westward and northward based on the placement of ongoing
thunderstorm activity and the latest HRRR/RRFS runs.
..Chalmers/Moore.. 08/21/2026
.PREV DISCUSSION... /ISSUED 1124 AM CDT Fri Aug 21 2026/
...Central Plains into the Midwest...
A northwest flow regime will result in a weakly forced and in a
limited confidence severe setup across the central Plains. Ongoing
widely scattered storm activity may persist and reinvigorate during
the afternoon, or new development occurs along residual outflow as
the airmass becomes moderately to strongly unstable. Forecast
sounding profiles show moist low levels beneath steep 700-500 mb
lapse rates amid veering and strengthening flow with height. Large
hail (some 2+ inches) would be a threat with any sustained
supercells along with severe gusts (60-75 mph). If a small cluster
can eventually develop, the severe-wind hazard would likely focus
with these potential storms.
A small west to east oriented band of storms is moving south across
southern WI to the east of a weak surface low and immediately
downstream of an associated mid-level perturbation. While effective
bulk shear is forecast to remain fairly modest (around 20-30 kt), a
mix of multicells and marginal supercells is expected to develop
later this afternoon across parts of southern WI into
northern/central IL along and ahead of a weak front. Severe hail
may occur with any persistent cells, while the threat for damaging
winds should increase as small clusters form and spread
east-southeastward through the early evening. While low-level
flow is not forecast to become overly strong, sufficient veering
with height through low/mid levels should exist to support modest
low-level hodograph curvature and some risk for a brief tornado.
...Carolinas...
Weakened shower/thunderstorm activity associated with an MCV over
the western Carolinas will likely dissipate during the early
afternoon. However, renewed storm development is forecast in
proximity to this upper disturbance, as well as near residual
outflow from the earlier convection and a surface cool front draped
from the GA/SC Piedmont northeastward into the coastal plain of
eastern NC. Strong heating of a seasonably moist boundary layer
will result in strong instability by mid afternoon. Sufficient
deep-layer shear for some organized multicell potential will be
greatest near the upper-level feature. Farther southeast near the
SC Low Country, weaker flow will result in a pulse thunderstorm
mode. Scattered damaging gusts are possible with the stronger
thunderstorms through the early evening before nocturnal stability
weakens storms and ends the severe threat.
...North TX east into northern Gulf Coast states...
Antecedent outflow from overnight storm clusters over the lower MS
Valley and AL will serve as a focus for storm development this
afternoon. Farther west, a more pronounced decaying MCS and
associated southward-moving MCV over east-central OK will also focus
storm activity across east TX into western LA. The 12 UTC Little
Rock raob showed a belt of enhanced flow around the 4-5 km layer
(35-40 kt). Other than a localized corridor where moderate
northerly flow will overspread a strongly destabilizing boundary
layer, slightly weaker northerly to northeasterly flow will
encompass this larger region from north TX to Mobile Bay.
Nonetheless, the development of very steep 0-3 km lapse rates (9 deg
C/km) by early to mid afternoon and high PW (1.75-2.0 inches) will
support scattered wind damage with the more intense downdrafts (most
likely and concentrated from east TX through southern MS).
...Northern Great Basin into the Snake Valley...
A mid-level vorticity max rotating northward around the western
periphery of the Four Corners upper high, will move into northern
NV/UT by late afternoon. Deep inverted-V profiles will develop by
mid afternoon with a dry sub-cloud layer featuring large surface
temperature-dewpoint spreads. A linear cluster of storms is
expected to evolve and move north across the NV/UT/ID vicinity
during the late afternoon and early evening. Evaporatively cooled
downdrafts will be potentially capable of severe gusts 60-75 mph.
SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1226 PM CDT Fri Aug 21 2026
Valid 221200Z - 231200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SATURDAY INTO
SATURDAY EVENING ACROSS PARTS OF THE NORTHERN INTERMOUNTAIN REGION
INTO NORTHERN ROCKIES...THE FRONT RANGE INTO CENTRAL GREAT
PLAINS...THE SOUTHEASTERN GREAT PLAINS...MIDDLE/UPPER OHIO VALLEY
AND ADJACENT LOWER GREAT LAKES REGION...
...SUMMARY...
Scattered strong storms may impact a corridor from near the northern
Rockies into the southeastern Great Plains, as well as the middle
and upper Ohio Valley vicinity, Saturday. These may pose at least
some potential to produce severe wind and hail.
...Discussion...
Models indicate that the increasingly deformed remnants of a
mid-level low will be forced inland across the northern U.S. Pacific
coast during this period, with a still vigorous remnant perturbation
approaching the Canadian/northern U.S. Rockies by late Saturday
night. Downstream, the center of a prominent mid-level ridge is
forecast to slowly shift across and east of the southern Rockies,
with amplified ridging within the westerlies to the north
overspreading much the Canadian Prairies and northern U.S. Great
Plains.
To the east of this ridging, it appears that large-scale troughing
will undergo further amplification across areas east of the
Mississippi Valley through the Atlantic Seaboard. Within this
regime, guidance indicates that one vigorous short wave impulse will
dig southeast of the Upper Midwest/adjacent Great Lakes through the
upper Ohio Valley by late Saturday night, trailed by a similar
strength impulse across northwestern Ontario toward the northern
Great Lakes vicinity. These are likely to be preceded by at least a
couple of increasingly sheared perturbations, including one
generally forecast to accelerate northeastward offshore of the
southern Mid Atlantic coast early in the period.
Near the southwestern flank of the larger-scale troughing, a
convectively generated or augmented perturbation might maintain
strength within modest north-northwesterly flow, around the eastern
periphery of the stronger mid-level ridging, across the southeastern
Great Plains toward northwestern Gulf coast.
In lower-levels, it appears that the leading edge of a series of
surges of cooler air, probably reinforced by convective outflow
across at least portions of the Great Plains, may reach central
Texas and northern portions of the remainder of the Gulf Coast into
southern Mid Atlantic Seaboard by 12Z Sunday. This is expected in
the wake of a modestly deepening surface low to the north of the
lower Great Lakes, and a weaker secondary low developing
near/offshore of the Mid Atlantic.
...Ohio Valley into lower Great Lakes region...
In advance of the vigorous lead digging short wave trough, and an
associated influx of surface cooling, a corridor of low-level
moistening may contribute to potential for moderate boundary-layer
destabilization by late afternoon. It appears that this will have
to occur in the wake of early period warm advection driven
convective cloud cover and precipitation likely to overspread the
region. However, breaks in the cloud cover and the onset of cooling
aloft may become sufficient to support scattered vigorous
thunderstorm development. Despite generally modest to weak vertical
shear, modest steepening of lower into mid-level lapse rates of
temperature and potential wet-bulb temperature may be sufficient to
contribute to profiles conducive to localized downbursts, in
addition to marginally severe hail.
...Front Range into southeastern Great Plains...
Latest convection-allowing guidance and other model output remains
rather varied concerning the potential evolution of storms and the
associated risk for severe weather through this period. However,
there do appear at least a couple of corridors with a somewhat
higher likelihood for thunderstorm initiation and organization
Saturday through Saturday night.
One may develop on the eastern periphery of the mid-level high
across the southeastern Great Plains, where stronger
lower/mid-tropospheric warm advection may focus near the nose of an
increasingly suppressed plume of elevated mixed-layer air. Wind
fields/vertical shear may be modest to weak, but a corridor of
higher low-level moisture content may support storm inflow with
large CAPE ahead of a remnant convective perturbation, supporting
potential for the evolution of an intensifying and organizing
south/southwestward propagating storm cluster with risk for severe
hail and wind.
Another may focus in moistening upslope flow along/east of the
Laramie mountains through Colorado Front Range by late Saturday
afternoon. Perhaps aided by a weak short wave impulse slowly
pivoting across this region, around the periphery of the mid-level
high, convection may consolidate into an intensifying and organizing
cluster propagating into the adjacent Great Plains by Saturday
evening, aided by updraft inflow of air characterized by moderately
large CAPE.
...Eastern Idaho into western Montana...
Multiple waves of scattered thunderstorm development appear possible
across the region Saturday into Saturday night, ahead of the inland
advancing short wave trough. In the wake of an initial round of
overnight/early period convection, models suggest that boundary
layer moistening will be sufficient to support increasing, though
still rather modest to weak, CAPE with heating and deep mixing by
late Saturday afternoon. Still, thermodynamic profiles may become
conducive to a few localized downbursts into Saturday evening.
..Kerr.. 08/21/2026
SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0228 PM CDT Fri Aug 21 2026
Valid 231200Z - 241200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SUNDAY INTO
SUNDAY NIGHT ACROSS PARTS OF THE NORTHERN ROCKIES INTO NORTHERN
GREAT PLAINS AND ACROSS PARTS OF THE NORTHEAST...
...SUMMARY...
Strong thunderstorm activity posing at least some risk for severe
hail and wind appears possible across parts of the northern Rockies
and Great Plains, and across parts of the Northeast, Sunday through
Sunday night.
...Discussion...
Models indicate that prominent mid/upper ridging centered across the
southern Rockies through southern Great Plains will be maintained
through this period. However, initially amplified ridging extending
through the westerlies to the north of this feature is likely to
become suppressed by a notable mid-level short wave trough, slowly
progressing east-northeast of the Canadian/northern U.S. Rockies
through the southern Canadian Prairies and adjacent international
border vicinity.
Downstream, large-scale mid-level troughing is forecast to only make
very slow eastward progress east of the Mississippi Valley through
Atlantic Seaboard/western Atlantic vicinity, while an evolving
embedded low slowly shifts eastward near/north of the lower Great
Lakes region, in response to at least a couple of shorter wavelength
perturbations pivoting around it.
In lower-levels, the primary surface cyclone is forecast to migrate
northward toward James Bay, with a weaker secondary low perhaps
migrating inland across parts of the northern Mid Atlantic/southern
New England, before weakening further. It appears that the
composite leading edge of cooler low-level air trailing this
feature, will stall and weaken across parts of the southern Great
Plains and Gulf Coast into southern Mid Atlantic.
...Central and eastern Montana...
There remains a signal in latest model output that forcing for
ascent within the base of the progressive short wave trough will
support increasing thunderstorm development across the higher
terrain of central Montana by late afternoon. Coincident with
strengthening westerly mid-level flow to 30-40+ kt, and the
evolution of a strongly heated and fairy deeply mixed downstream
boundary-layer (with at least modest CAPE in excess of 1000 J/kg),
there appears potential for the evolution of an upscale growing and
organizing cluster into early evening. If this occurs, the
environment appears conducive to an accompanying swath of strong to
severe gusts across parts of central into eastern Montana by late
Sunday evening.
...Dakotas...
Forcing aided by lower/mid-tropospheric warm advection downstream of
the progressive short wave trough may become increasingly conducive
to upscale growing thunderstorm development from the west/central
Dakotas state border through central/eastern South Dakota Sunday
evening into Sunday night. Aided by inflow of seasonably moist
boundary-layer air supportive of CAPE on the order of 2000 J/kg,
there appears potential for activity to become organized with
potential to produce a swath or two of strong to severe gusts. The
21/12Z NAM, in particular, generates a fairly notable convective
perturbation in association with this development. If this signal
becomes supported by more model output in later runs, severe
probabilities may need to be upgraded further.
...Northern Mid Atlantic into southern New England...
Forcing for ascent aided by an initial short wave impulse pivoting
around the southeastern through eastern periphery of the Great Lakes
mid-level low probably will provide support for increasing
thunderstorm development across parts of eastern New York and
Pennsylvania into southern New England during the day Sunday.
Inland destabilization and vertical shear across this region remains
a bit uncertain, but it possible the environment could become
supportive of strong storms with potential to produce severe hail
and wind.
..Kerr.. 08/21/2026
SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0259 PM CDT Fri Aug 21 2026
Valid 221200Z - 231200Z
...CRITICAL FIRE WEATHER AREA FOR MUCH OF NORTHERN WASHINGTON AND
THE FAR NORTHERN IDAHO PANHANDLE...
...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF
SOUTH-CENTRAL/SOUTHEAST WASHINGTON AND FAR NORTH-CENTRAL OREGON...
...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF NORTHEAST
CALIFORNIA...NORTHWEST NEVADA...AND SOUTH-CENTRAL/SOUTHEAST
OREGON...
An area of Scattered Dry Thunderstorms was added to much of northern
WA state and the far northern ID Panhandle. This area will
experience greater coverage of dry thunderstorms amid high-based,
fast moving, and drier air aloft behind the frontal passage later in
the day as the trough continues a slow eastward progression. While
more northwestern extents of the Scattered Dry Thunderstorm area are
expected to accumulate higher rainfall amounts, it will be amid some
of the driest and heaviest fuel loading.
An area of Critical Wind/RH was also introduced over central
portions of the Columbia River Basin. Ahead of the cold front
passage, sustained southwesterly winds of 15-25 mph amid afternoon
RHs of 15-25% within this area. Winds will turn west-northwesterly
as the front passes through central WA and OR in the late
afternoon/early evening time frame. The existing Critical Wind/RH
area along with the larger Elevated and Isolated Dry Thunderstorm
area remain on track.
..Stearns.. 08/21/2026
.PREV DISCUSSION... /ISSUED 0201 AM CDT Fri Aug 21 2026/
...Synopsis...
A robust midlevel trough and accompanying south-southwesterly jet
max will overspread the Northwest through the period -- along the
northwestern periphery of an upper ridge centered on the Rockies. In
the low-levels, a cold front will move eastward across parts of WA
and OR during the day.
...Northern/Central Intermountain West...
Beneath the midlevel jet streak, enhanced deep-layer
south-southwesterly flow will overspread a dry antecedent air mass
across parts of the northern and central Intermountain West. This
will result in a broad area of 15-20 mph sustained
west-southwesterly surface winds and 15-20 percent RH during the
afternoon. Given receptive fuels across the region, elevated
fire-weather conditions are expected. Over parts of northeast CA,
northwest NV, and south-central/southeast OR, the overlap of 20-25
mph sustained southwesterly surface winds and around 15 percent RH
will favor critical fire-weather conditions. Locally critical
conditions will also be possible within the Cascade gaps, though
these conditions appear too localized for an additional Critical
area at this time.
...Dry Thunderstorms...
Robust midlevel height falls/forcing for ascent accompanying the
midlevel trough will overspread the northern Intermountain West into
the northern Rockies during the day. Here, deep boundary-layer
mixing beneath a midlevel moisture plume will yield sufficient
buoyancy for isolated to widely scattered high-based thunderstorms
regionally. While 0.7-1 inch PW will support a mix of wet and dry
storms, quick storm motions and the deep/dry boundary layer should
tend to limit overall rainfall. Therefore, isolated
lightning-induced ignitions will be possible atop increasingly
dry/receptive fuels. Additionally, the stronger storms will be
capable of producing strong to severe outflow winds (especially
toward the northern Rockies). For details on the severe risk, see
the SPC Day 2 Convective Outlook.
...Please see www.spc.noaa.gov/fire for graphic product...
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