WW 607 SEVERE TSTM MN 202310Z - 210500Z
URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 607
NWS Storm Prediction Center Norman OK
610 PM CDT Thu Aug 20 2026
The NWS Storm Prediction Center has issued a
* Severe Thunderstorm Watch for portions of
Minnesota
* Effective this Thursday night from 610 PM until Midnight 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...Severe thunderstorms including some supercells should
continue to develop through early/mid-evening, with large hail and
damaging winds as the primary severe concerns, although a tornado
cannot be entirely ruled out.
The severe thunderstorm watch area is approximately along and 50
statute miles east and west of a line from 35 miles north of Hibbing
MN to 40 miles south southeast of Redwood Falls MN. For a complete
depiction of the watch see the associated watch outline update
(WOUS64 KWNS WOU7).
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 604...WW 605...WW 606...
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 550. Mean storm motion vector
29025.
...Guyer
WW 606 SEVERE TSTM AL AR LA MS 202210Z - 210300Z
URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 606
NWS Storm Prediction Center Norman OK
510 PM CDT Thu Aug 20 2026
The NWS Storm Prediction Center has issued a
* Severe Thunderstorm Watch for portions of
Western Alabama
Southeast Arkansas
Northeast Louisiana
Mississippi
* Effective this Thursday afternoon and evening from 510 PM until
1000 PM CDT.
* Primary threats include...
Scattered damaging wind gusts to 60 mph possible
SUMMARY...Widely scattered thunderstorms will continue to occur
across the region through at least sunset, but may sustain longer if
storms modestly organize into clusters and progress
south-southeastward across the region with wind damage as the
primary hazard.
The severe thunderstorm watch area is approximately along and 60
statute miles north and south of a line from 30 miles south of
Monticello AR to 45 miles southeast of Columbus MS. For a complete
depiction of the watch see the associated watch outline update
(WOUS64 KWNS WOU6).
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 604...WW 605...
AVIATION...A few severe thunderstorms with hail surface and aloft to
1 inch. Extreme turbulence and surface wind gusts to 50 knots. A few
cumulonimbi with maximum tops to 600. Mean storm motion vector
30020.
...Guyer
WW 605 TORNADO DC DE MD NJ PA VA CW 201855Z - 210200Z
URGENT - IMMEDIATE BROADCAST REQUESTED
Tornado Watch Number 605
NWS Storm Prediction Center Norman OK
255 PM EDT Thu Aug 20 2026
The NWS Storm Prediction Center has issued a
* Tornado Watch for portions of
District Of Columbia
Delaware
Central and Eastern Maryland
Central and Southern New Jersey
Southeast Pennsylvania
Northern Virginia
Coastal Waters
* Effective this Thursday afternoon and evening from 255 PM until
1000 PM EDT.
* Primary threats include...
A couple tornadoes possible
Scattered damaging winds likely with isolated significant gusts
to 75 mph possible
Isolated large hail events to 1.5 inches in diameter possible
SUMMARY...Scattered severe thunderstorms are forecast to continue to
develop and intensify through the afternoon and into the evening. A
few of the stronger storms will be supercells capable of a risk for
tornadoes, damaging gusts, and large hail. A consolidation of
storms will probably occur during the evening as one or two line
segments develops with an attendant risk for damaging winds and
possibly a tornado.
The tornado watch area is approximately along and 70 statute miles
north and south of a line from 15 miles southwest of Washington DC
to 45 miles east northeast of Dover DE. For a complete depiction of
the watch see the associated watch outline update (WOUS64 KWNS
WOU5).
PRECAUTIONARY/PREPAREDNESS ACTIONS...
REMEMBER...A Tornado Watch means conditions are favorable for
tornadoes and 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.
&&
OTHER WATCH INFORMATION...CONTINUE...WW 604...
AVIATION...Tornadoes and a few severe thunderstorms with hail
surface and aloft to 1.5 inches. Extreme turbulence and surface wind
gusts to 65 knots. A few cumulonimbi with maximum tops to 500. Mean
storm motion vector 26025.
...Smith
WW 604 SEVERE TSTM DC DE MD NC NJ PA VA CW 201830Z - 210200Z
URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 604
NWS Storm Prediction Center Norman OK
230 PM EDT Thu Aug 20 2026
The NWS Storm Prediction Center has issued a
* Severe Thunderstorm Watch for portions of
District Of Columbia
Delaware
Central and Eastern Maryland
Northeast North Carolina
Much of New Jersey
Eastern and Southeast Pennsylvania
Northern into Southern and Eastern Virginia
Coastal Waters
* Effective this Thursday afternoon and evening from 230 PM until
1000 PM EDT.
* Primary threats include...
Scattered damaging wind gusts to 70 mph likely
Isolated large hail events to 1.5 inches in diameter possible
A tornado or two possible
SUMMARY...Scattered severe thunderstorms are forecast to develop and
intensify this afternoon. The stronger thunderstorms will likely
organize into line segments and a few supercells. Scattered
damaging gusts will be the primary hazard but a tornado or two is
possible. Upscale growth into one or more line segments is expected
by the evening as this activity moves east towards the coast.
The severe thunderstorm watch area is approximately along and 90
statute miles east and west of a line from 20 miles north northwest
of Trenton NJ to 15 miles southeast of Roanoke Rapids NC. For a
complete depiction of the watch see the associated watch outline
update (WOUS64 KWNS WOU4).
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
1.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A
few cumulonimbi with maximum tops to 500. Mean storm motion vector
26025.
...Smith
WW 0607 Status Updates
STATUS REPORT ON WW 607
SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 30 NW BRD TO
15 WNW HIB TO 20 SE ELO.
FOR ADDITIONAL INFORMATION SEE MESOSCALE DISCUSSION 2062
..SQUITIERI..08/21/26
ATTN...WFO...DLH...MPX...
STATUS REPORT FOR WS 607
SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS
MNC001-009-013-015-017-019-035-059-065-067-079-085-093-095-097-
103-115-127-129-137-139-141-143-145-153-165-171-210140-
MN
. MINNESOTA COUNTIES INCLUDED ARE
AITKIN BENTON BLUE EARTH
BROWN CARLTON CARVER
CROW WING ISANTI KANABEC
KANDIYOHI LE SUEUR MCLEOD
MEEKER MILLE LACS MORRISON
NICOLLET PINE REDWOOD
RENVILLE ST. LOUIS SCOTT
SHERBURNE SIBLEY STEARNS
TODD WATONWAN WRIGHT
THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE
REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL
INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES
CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES.
WW 0606 Status Updates
STATUS REPORT ON WW 606
SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 35 WSW UOX
TO 40 ENE GWO TO 5 WSW CBM TO 40 S MSL.
..WEINMAN..08/21/26
ATTN...WFO...BMX...JAN...MEG...
STATUS REPORT FOR WS 606
SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS
ALC063-075-107-119-210140-
AL
. ALABAMA COUNTIES INCLUDED ARE
GREENE LAMAR PICKENS
SUMTER
ARC003-017-210140-
AR
. ARKANSAS COUNTIES INCLUDED ARE
ASHLEY CHICOT
LAC035-065-067-083-123-210140-
LA
. LOUISIANA PARISHES INCLUDED ARE
EAST CARROLL MADISON MOREHOUSE
RICHLAND WEST CARROLL
WW 0605 Status Updates
STATUS REPORT ON WW 605
SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 20 ENE RIC
TO 10 ESE NHK TO 25 SSE ACY.
..WEINMAN..08/21/26
ATTN...WFO...LWX...PHI...AKQ...
STATUS REPORT FOR WT 605
SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS
DEC005-210140-
DE
. DELAWARE COUNTIES INCLUDED ARE
SUSSEX
MDC037-039-045-047-210140-
MD
. MARYLAND COUNTIES INCLUDED ARE
ST. MARYS SOMERSET WICOMICO
WORCESTER
ANZ454-455-534-537-543-650-210140-
CW
. ADJACENT COASTAL WATERS INCLUDED ARE
COASTAL WATERS FROM CAPE MAY NJ TO CAPE HENLOPEN DE OUT 20 NM
WW 0604 Status Updates
STATUS REPORT ON WW 604
SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 5 SE DAN TO
25 NE AVC TO 15 NNE RIC TO 45 E ACY.
..WEINMAN..08/21/26
ATTN...WFO...LWX...PHI...AKQ...CTP...
STATUS REPORT FOR WS 604
SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS
NCC015-029-041-053-073-091-131-139-143-210140-
NC
. NORTH CAROLINA COUNTIES INCLUDED ARE
BERTIE CAMDEN CHOWAN
CURRITUCK GATES HERTFORD
NORTHAMPTON PASQUOTANK PERQUIMANS
VAC001-025-036-053-073-081-093-095-097-101-103-115-117-119-127-
131-133-149-175-181-183-199-550-570-595-620-650-670-700-710-730-
735-740-800-810-830-210140-
VA
. VIRGINIA COUNTIES INCLUDED ARE
ACCOMACK BRUNSWICK CHARLES CITY
DINWIDDIE GLOUCESTER GREENSVILLE
ISLE OF WIGHT JAMES CITY KING AND QUEEN
KING WILLIAM LANCASTER MATHEWS
MECKLENBURG MIDDLESEX NEW KENT
NORTHAMPTON NORTHUMBERLAND PRINCE GEORGE
SOUTHAMPTON SURRY SUSSEX
YORK
MD 2062 CONCERNING SEVERE THUNDERSTORM WATCH 607... FOR MUCH OF CENTRAL MINNESOTA
Mesoscale Discussion 2062
NWS Storm Prediction Center Norman OK
0746 PM CDT Thu Aug 20 2026
Areas affected...much of central Minnesota
Concerning...Severe Thunderstorm Watch 607...
Valid 210046Z - 210215Z
The severe weather threat for Severe Thunderstorm Watch 607
continues.
SUMMARY...Severe hail remains a concern with the stronger sustained
supercells this evening.
DISCUSSION...Multiple sustained supercells have progressed across
central MN over the past few hours, with marginally severe hail
reported (particularly with the storms over northern MN). 2000-3000
J/kg MLCAPE remains in place, along with 35-40 kts of effective bulk
shear per 00Z mesoanalysis. The 00Z MPX observed sounding also shows
a hodograph with appreciable low-level curvature and modest
elongation, suggesting that supercells will remain the dominant mode
of the convection through the evening hours. Large hail should
remain the primary threat, though a damaging gust or tornado cannot
be ruled out.
..Squitieri.. 08/21/2026
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...DLH...MPX...FSD...
LAT...LON 44089567 46809443 47319349 47429279 46979247 45499294
44519376 44119442 44089567
MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 90 MPH
MOST PROBABLE PEAK WIND GUST...UP TO 60 MPH
MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN
MD 2061 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PORTIONS OF CENTRAL NEBRASKA INTO FAR NORTHWESTERN KANSAS
Mesoscale Discussion 2061
NWS Storm Prediction Center Norman OK
0728 PM CDT Thu Aug 20 2026
Areas affected...portions of central Nebraska into far northwestern
Kansas
Concerning...Severe potential...Watch unlikely
Valid 210028Z - 210200Z
Probability of Watch Issuance...20 percent
SUMMARY...Isolated severe hail and wind may accompany the stronger
storms this evening. An instance of 2+ inch diameter hail is
possible with any longer-lasting, discrete supercells.
DISCUSSION...A long-lived thunderstorm cluster with transient
supercell characteristics and a history of producing severe gusts
continues to propagate southward along/ahead of a surface trough,
where MLCINH is minimal. Latest MRMS MESH depicts a potential
increase in hail size with an embedded supercell structure.
Furthermore, additional storms also initiating ahead of the surface
trough, along a confluence zone in southwestn NE into far northwest
KS. In this region, 3000+ J/kg MLCAPE is in place, along with at
least 40 kts of effective bulk shear per 00Z mesoanalysis. The
latest GLD shows an elongated hodograph, indicative of splitting
supercell structures with a continued severe hail/gust threat. When
also considering 7-8 C/km mid-level lapse rates in place (per
regional 00Z observed soundings), an instance of 2+ inch diameter
hail cannot be ruled out with mature supercells at their peak
intensity.
..Squitieri/Guyer.. 08/21/2026
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...GID...LBF...GLD...
LAT...LON 39620205 40460141 41500077 41780052 41840007 41649975
41129957 40419958 39799990 39470044 39280113 39260165
39620205
MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 90 MPH
MOST PROBABLE PEAK WIND GUST...65-80 MPH
MOST PROBABLE PEAK HAIL SIZE...1.50-2.50 IN
MD 2060 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR PARTS OF NORTHERN AL...MIDDLE TN...AND FAR NORTHEAST MS
Mesoscale Discussion 2060
NWS Storm Prediction Center Norman OK
0725 PM CDT Thu Aug 20 2026
Areas affected...Parts of northern AL...Middle TN...and far
northeast MS
Concerning...Severe potential...Watch possible
Valid 210025Z - 210300Z
Probability of Watch Issuance...40 percent
SUMMARY...The risk of damaging wind gusts should increase over the
next few hours. While a watch is not currently expected, trends will
be monitored.
DISCUSSION...Isolated thunderstorms are evolving within a zone of
broad low-level confluence extending from parts of Middle/western TN
into far northern MS. Over the next few hours, increasing
large-scale ascent preceding a midlevel wave moving across the lower
OH Valley could support an increase in thunderstorm coverage within
this zone. Ahead of this activity, a warm and very moist PBL (upper
70s to near 80 dewpoints) are yielding a corridor of strong
surface-based buoyancy. While modest deep-layer flow/shear and lack
of a LLJ should tend to limit convective organization, some
strengthening of midlevel northwesterly flow accompanying the
midlevel wave (sampled by upstream VWP) could favor a loosely
organized cluster of storms. If this evolution occurs, damaging wind
gusts will be the primary concern. While a gradual increase in
nocturnal static stability and the modest deep-layer shear may
temper the overall severe risk, convective trends will be monitored.
..Weinman/Guyer.. 08/21/2026
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...MRX...OHX...BMX...HUN...MEG...
LAT...LON 34468820 34748839 35028832 35358815 35568778 35688713
35588634 35398583 35038562 34648557 34228586 34058643
34028727 34168781 34468820
MOST PROBABLE PEAK WIND GUST...55-70 MPH
MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN
MD 2059 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR PORTIONS OF SOUTHEASTERN SOUTH DAKOTA TO THE NEBRASKA AND IOWA BORDERS
Mesoscale Discussion 2059
NWS Storm Prediction Center Norman OK
0713 PM CDT Thu Aug 20 2026
Areas affected...portions of southeastern South Dakota to the
Nebraska and Iowa borders
Concerning...Severe potential...Watch possible
Valid 210013Z - 210115Z
Probability of Watch Issuance...40 percent
SUMMARY...An isolated severe hail threat will persist for a few more
hours. However, storms will move into stronger MLCINH, which may
limit the spatial and temporal extent of the severe threat.
DISCUSSION...Multiple splitting supercells have developed over the
last couple of hours, with an instance of golfball hail recently
reported on a storm in Minnehaha County, SD. These storms are
benefiting from 3000+ J/kg MLCAPE and 50 kts of effective bulk shear
in place. Nonetheless, these storms are also approaching a region of
appreciable MLCINH. The current thinking is that these storms should
gradually weaken as they move off of the surface trough/boundary and
move into the inhibition. As such, while a few more instances of
severe hail could occur, the severe threat should remain confined
along the surface trough for just a few more hours.
..Squitieri/Guyer.. 08/21/2026
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...FSD...OAX...LBF...
LAT...LON 42619823 42829877 42999891 43109886 43149818 43279774
43529727 43839692 43899669 43889644 43849622 43709612
43249616 42859627 42639654 42579705 42619823
MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 90 MPH
MOST PROBABLE PEAK WIND GUST...55-70 MPH
MOST PROBABLE PEAK HAIL SIZE...1.50-2.50 IN
MD 2058 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PARTS OF SOUTHEAST OK...SOUTHWEST AR...AND FAR NORTHEAST TX
Mesoscale Discussion 2058
NWS Storm Prediction Center Norman OK
0607 PM CDT Thu Aug 20 2026
Areas affected...Parts of southeast OK...southwest AR...and far
northeast TX
Concerning...Severe potential...Watch unlikely
Valid 202307Z - 210130Z
Probability of Watch Issuance...20 percent
SUMMARY...Thunderstorms will be capable of producing strong to
locally damaging wind gusts for the next few hours. A watch is not
currently expected, though convective trends are being monitored.
DISCUSSION...Thunderstorms are increasing in coverage along a
stationary boundary draped across southeast OK and southwest AR.
Along/south of the boundary, temperatures have warmed to near 105 F
amid lower/middle 60s dewpoints -- resulting in a strongly unstable
air mass. This activity is largely displaced from a midlevel trough
and enhanced flow aloft moving across the lower OH Valley, which
should tend to reduce overall convective organization. Nevertheless,
around 25 kt of midlevel northwesterly flow oriented perpendicular
to the stationary boundary and evolving cluster of storms could
support a loosely organized cluster capable of producing locally
damaging wind gusts for the next few hours.
..Weinman/Guyer.. 08/20/2026
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...LZK...SHV...TSA...FWD...
LAT...LON 33729526 34039560 34349570 34669553 34799505 34629348
34429306 34089284 33579283 33249314 33179369 33299431
33729526
MOST PROBABLE PEAK WIND GUST...55-70 MPH
MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN
SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0255 PM CDT Thu Aug 20 2026
Valid 202000Z - 211200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
THE MID-ATLANTIC...PARTS OF THE SOUTHEAST...AND FROM THE CENTRAL
PLAINS INTO THE UPPER MISSISSIPPI VALLEY...
...SUMMARY...
Scattered severe storms are possible this afternoon into this
evening across parts of the Mid Atlantic, posing a risk for a couple
of tornadoes and damaging wind gusts. Large hail and isolated wind
damage will be possible late today into tonight with severe storms
from Nebraska into northwest Wisconsin. Scattered damaging gusts
are possible over parts of the Deep South this afternoon into the
early evening.
...20z Update...
The previous forecast largely remains on track with only minor
adjustments made based on recent convective trends and recent
guidance. Regional radar mosaics show the development of discrete
and semi-discrete supercells across the northern MD into southern PA
ahead of a mid-level perturbation and weak cold front. The recent 18
UTC IAD sounding sampled modest buoyancy (around 1000 J/kg MLCAPE),
which seems to be more marginal compared to recent RAP mesoanalysis
MLCAPE depictions. Nonetheless, strong shear was sampled by this
RAOB, including just under 200 m2/s2 effective SRH. This environment
likely exists downstream into far southeast PA and western NJ and
warranted a slight northward expansion of the CIG1 tornado contour.
Confidence in convective coverage with southwestward extent into
southern VA and NC remains limited based on trends in
radar/satellite trends and latest high-res guidance. Other forecast
thoughts outlined in the previous discussion below remain on track.
...Northern MS/AL...
Convection is developing along/ahead of a weak surface front and
mid-level wave across southeast AR into northern MS. This aligns
well with recent guidance, especially RRFS solutions, which depict
increasing thunderstorm coverage through early evening. Wind and
hail probabilities have been adjusted slightly across northern
AL/southern TN to reflect these solutions and capture areas where
air mass recovery continues.
...Northern MN...
A surface low is becoming apparent in surface observations and GOES
visible imagery across northern MN with early stages of convection
noted over the past 45 minutes. With 64-66 F dewpoints spreading
north towards north-central MN, some potential exists for more
robust convection than previously depicted by guidance. Recent
RRFS/HRRR time-lagged ensembles have also trended slightly north
with the strongest UH signals, which matches these recent
observations and warranted a northward expansion of probabilities.
Elsewhere, the forecast outlined below remains on track. See MCD
#2053 for additional short-term details regarding the near-term
severe threat across north-central NE.
..Moore.. 08/20/2026
.PREV DISCUSSION... /ISSUED 1133 AM CDT Thu Aug 20 2026/
...Central Appalachians into the Mid-Atlantic...
Radar mosaic late this morning showed a couple of weak convectively
related vorticity maxima moving east across the central and southern
Appalachians (i.e., southwest PA, eastern KY). One of these lead
disturbances was sampled by the WSR-88D VAD at Jackson, KY, with an
upstream shortwave trough over the OH Valley moving towards the
Mid-Atlantic states.
The airmass across the Mid-Atlantic into the Carolinas will continue
to heat amid patchy but thinning cloud cover. Model guidance shows
moderate buoyancy developing by early to mid afternoon from the
southern Appalachians northward into the northern Mid-Atlantic
region. A belt of stronger 700-500 mb westerly flow (30-45 kt) will
overspread the northern half of VA northward into PA/NJ. Beneath
this stronger flow, southerly low-level flow veering and
strengthening with height will support hodographs favorable for
organized severe storms, including supercells and organized line
segments. The latest model guidance shows a few simulated
supercells developing in the area centered over MD and the upper
Chesapeake Bay vicinity during the 20-00z timeframe. This scenario
seems plausible given some low-level enlargement to the hodograph
and effective shear around 40 kt. A tendency for upscale growth
into a line segment is expected as this activity moves east towards
the coast during the evening. A couple of supercell tornadoes are
possible with this activity, in addition to a line-embedded
mesovortex and scattered damaging gusts.
...Carolinas into the TN Valley and lower MS Valley...
Ample low-level moisture and strong heating will result in an
unstable airmass from the Carolinas into much of the Southeast.
Low-level convergence along a cold front that will extend from the
western Carolinas into AR this afternoon will result in scattered
thunderstorm coverage as 2500-4000 J/kg MLCAPE develops by mid
afternoon. High PW (in excess of 2 inches) and steep 0-3 km lapse
rates and modest westerly to west-northwesterly flow will favor
damaging downbursts with the stronger southeast-moving clusters.
...Central Plains into the Upper MS Valley...
A tongue of relatively rich low-level moisture (mainly 60s F surface
dewpoints) will extend from the central Great Plains northward ahead
of a cold front, which is forecast to be draped from western MN into
western NE this afternoon. Thunderstorm initiation is anticipated
first across the Upper MS Valley before expanding southwestward.
Moderate northwesterly flow aloft will support supercell wind
profiles, with elongated/straight hodographs, and the threat for all
severe hazards. Large to very large hail (i.e. greater than 2 inch
diameter) will be the primary severe hazard, particularly during the
early evening as the storms move into greater instability. Isolated
strong to severe gusts (i.e. 55 to 75 mph) are possible as well.
Given the supercellular storm mode and low-level southerly flow, a
low-probability tornado risk also exists. Some risk for isolated
damaging gusts may persist into the early overnight across southern
NE and northern KS if clustering can
occur.
...AZ...
Not much change from prior forecast thinking in that isolated to
widely scattered storms are forecast but a generally lower risk for
severe gusts is anticipated later today into this evening. Steep
lapse rates and inverted-V profiles will support an isolated risk
for severe gusts with the more intense downdrafts.
SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0453 PM CDT Thu Aug 20 2026
Valid 221200Z - 281200Z
...Synopsis...
The trough will begin to lift northeastward as it becomes slightly
negatively-tilted going into Day 3/Saturday. High pressure remains
in place over much of the southwestern half of the CONUS with
shortwave trough passages periodically moving across the crest of
the high through the northern states. While slight differences in
timing of the aforementioned trough remain, the overall pattern
evolution remains similar amongst various ensemble forecast
guidance. As we turn the corner toward next week, the ridge broadens
and builds over the Intermountain West once again. Forecast
certainty in any particular solution decreases thereafter given
greater ensemble spread.
...Pacific Northwest/Northern California/Great Basin...
The Pacific Northwest and immediately neighboring areas of northern
CA and the Great Basin will remain a focus through at least the
first half of the extended forecast. Expect gusty southwesterly
winds combined with dry weather to continue into Day 3/Saturday.
Cooler conditions will arrive as the trough approaches and moves
onshore Day 3/Saturday. Given the jet aloft and surface conditions
that would support deep daytime mixing, a favorable pattern remains
in place for dry and breezy weather to overlap very dry fuels across
northeastern CA, southern OR, and northwestern NV. Thus, 40%
Critical probabilities were maintained on Day 3/Saturday.
Additionally, where winds appear strongest (sustained at 20-25 mph
from the southwest amid RHs near 10-15%) ahead of an approaching
cold front over the tri-state CA, OR, NV area, 70% Critical
probabilities were maintained on Day 3/Saturday.
Lift associated with the upper-level jet max approaching the region,
limited but adequate (precipitable water values near 0.6-0.8")
moisture, fast-moving (25-35 mph) storms, and dry fuels (ERCs near
the 80-95th percentile) remains in place on Day 3/Saturday as
convection is expected to become more widespread. With minimal
precipitation expected from the previous day, the existing area of
10% Dry Thunderstorm risk was expanded to include a larger areal
extent of the eastern Pacific Northwest and nearby northern Great
Basin and western MT. Central ID and northeastern WA will be closely
monitored for a potential increase in thunderstorm coverage.
Additional 10% Dry Thunderstorm risk areas were added over far
northeastern WA on Day 4/Sunday as convection lingers and again on
Day 5/Monday over the area of southwest ID, southeast OR, and
portions of northern NV as monsoonal moisture continues to meander
further west.
...Southern Plains...
On Day 4/Sunday and Day 5/Monday, a cold front will move across the
southern Plains, increasing fire weather risk in southwesterly flow
ahead of the front as it progresses southeastward. Current ensemble
forecast guidance suggests sustained 10-20 mph south to
southwesterly winds will combine with afternoon RHs near 15-20%
across the TX/OK Panhandles and surrounding areas with critically
dry fuels.
...Northern Plains...
Post-frontal northwesterly winds over the northern High Plains and
portions of the northern Rocky Mountains remains a concern on Day
4/Sunday. Across much of central MT, sustained northwesterly winds
of 10-20 mph will occur amid afternoon RHs of 15-25%. The existing
40% Critical probabilities were adjusted slightly westward on Day
4/Sunday.
..Stearns.. 08/20/2026
...Please see www.spc.noaa.gov/fire for graphic product...
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