WW 603 SEVERE TSTM KY TN 200510Z - 201100Z
URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 603
NWS Storm Prediction Center Norman OK
1210 AM CDT Thu Aug 20 2026
The NWS Storm Prediction Center has issued a
* Severe Thunderstorm Watch for portions of
Western Kentucky
Middle Tennessee
* Effective this Thursday morning from 1210 AM until 600 AM 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...A cluster of storms including embedded supercells will
continue east-southeastward across the region overnight, with
damaging winds, large hail possible, and potentially a tornado risk.
The severe thunderstorm watch area is approximately along and 40
statute miles north and south of a line from 35 miles west southwest
of Fort Campbell KY to 35 miles south southeast of Bowling Green KY.
For a complete depiction of the watch see the associated watch
outline update (WOUS64 KWNS WOU3).
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 601...WW 602...
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
28025.
...Guyer
WW 602 SEVERE TSTM AR IL KY MO TN 200245Z - 200800Z
URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 602
NWS Storm Prediction Center Norman OK
945 PM CDT Wed Aug 19 2026
The NWS Storm Prediction Center has issued a
* Severe Thunderstorm Watch for portions of
Northern Arkansas
Southern Illinois
Western Kentucky
Southern Missouri
Western Tennessee
* Effective this Wednesday night and Thursday morning from 945 PM
until 300 AM 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 storms including some supercells will continue
to develop and spread generally eastward, with a clustering of
storms possible later this evening into the overnight.
The severe thunderstorm watch area is approximately along and 50
statute miles north and south of a line from 35 miles west of West
Plains MO to 50 miles southeast of Cape Girardeau MO. For a complete
depiction of the watch see the associated watch outline update
(WOUS64 KWNS WOU2).
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 601...
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
28025.
...Guyer
WW 601 SEVERE TSTM AZ 192140Z - 200600Z
URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 601
NWS Storm Prediction Center Norman OK
240 PM MST Wed Aug 19 2026
The NWS Storm Prediction Center has issued a
* Severe Thunderstorm Watch for portions of
Southern Arizona
* Effective this Wednesday afternoon and evening from 240 PM
until 1100 PM MST.
* Primary threats include...
Scattered damaging wind gusts to 70 mph possible
SUMMARY...Strong to severe storms will continue to develop
especially over the mountains, with some storm organization and
aggregating outflows expected to reach the desert floor, with
severe-caliber wind gusts and blowing dust possible through at least
early/mid-evening.
The severe thunderstorm watch area is approximately along and 95
statute miles east and west of a line from 60 miles northeast of
Phoenix AZ to 35 miles west southwest of Sierra Vista AZ. 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 600...
AVIATION...A few severe thunderstorms with hail surface and aloft to
0.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A
few cumulonimbi with maximum tops to 550. Mean storm motion vector
03020.
...Guyer
WW 0603 Status Updates
STATUS FOR WATCH 0603 HAS NOT BEEN ISSUED YET
WW 0602 Status Updates
STATUS REPORT ON WW 602
SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 25 SSE FLP
TO 10 W FAM.
..BUNTING..08/20/26
ATTN...WFO...LZK...MEG...PAH...SGF...LSX...
STATUS REPORT FOR WS 602
SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS
ARC021-049-055-065-075-121-135-200640-
AR
. ARKANSAS COUNTIES INCLUDED ARE
CLAY FULTON GREENE
IZARD LAWRENCE RANDOLPH
SHARP
ILC003-069-087-127-151-153-181-200640-
IL
. ILLINOIS COUNTIES INCLUDED ARE
ALEXANDER HARDIN JOHNSON
MASSAC POPE PULASKI
UNION
KYC007-033-035-039-047-055-075-083-105-107-139-143-145-157-177-
219-221-200640-
KY
. KENTUCKY COUNTIES INCLUDED ARE
WW 0601 Status Updates
STATUS REPORT ON WW 601
SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 50 NNE PHX
TO 50 SE SAD.
..THORNTON..08/20/26
ATTN...WFO...TWC...PSR...
STATUS REPORT FOR WS 601
SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS
AZC003-013-019-021-023-200440-
AZ
. ARIZONA COUNTIES INCLUDED ARE
COCHISE MARICOPA PIMA
PINAL SANTA CRUZ
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.
No Mesoscale Discussions are in effect as of Thu Aug 20 05:45:25 UTC 2026.SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0800 PM CDT Wed Aug 19 2026
Valid 200100Z - 201200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE MID
MISSISSIPPI AND OHIO VALLEYS AND SOUTHERN ARIZONA...
...SUMMARY...
Thunderstorms capable of severe wind gusts and hail remain possible
this evening across the mid Mississippi and lower Ohio Valleys and
southern Arizona. More isolated strong storms are possible through
the evening across parts of the central/southern High Plains and
parts of the Southeast.
...Mid MS Valley to the lower OH Valley.
Evening water vapor imagery showed a broad trough and enhanced
northwesterly mid-level flow stretching from the southern Dakotas
into the mid MS Valley. Downstream of a flattened upper ridge over
the Southwest, this trough and stronger flow aloft should continue
eastward this evening aiding in thunderstorm development across
parts of the Mid MS and lower OH valleys this evening.
Several clusters of storms are already ongoing this evening near a
diffuse frontal zone across MO and into southern IL and western KY.
As the upper trough approaches, ascent form a 30+ kt southwesterly
low-level jet may support an increase in storm coverage, possibly
along the flank of the exist cluster in MO and farther south along
the frontal zone later this evening. Moderate, and likely somewhat
elevated buoyancy (2000-3000 J/kg MUCAPE), and 40-50 kt of
deep-layer shear will favor organized clusters or supercell
structures. Hail is possible, along with some damaging winds and
perhaps a tornado, especially if storms can develop into a more
coherent MCS. These storms should spread eastward overnight into the
lower OH Valley with a continued severe risk.
...Central and southern High Plains...
Scattered thunderstorms, including a few supercells are ongoing
across the central and southern High Plains within a broad upslope
flow regime. Aided by an upper trough with moderate northwesterly
flow aloft, organized storms structures capable of large hail should
continue along the Foothills and adjacent high plains this evening.
Steep lapse rates and large temperature-dew point depressions may
also favor a few severe gusts with the more intense cores/clusters
that can develop.
...AZ...
Scattered storms across the higher terrain of southern AZ should
continue to move toward the southwest into the Lower Deserts this
evening. Adequate monsoon moisture amid very hot temperatures (100
F+) and steep low-level lapse rates will support strong downdrafts
with severe gusts of 60-75 mph possible.
...Southeast...
Scattered thunderstorms are ongoing early this evening from MS into
western/southern AL and across the FL Panhandle in association with
a weak MCV. A warm boundary layer and seasonably high moisture
content should continue to support scattered strong storms through
this evening. PWATs over 2 inches will favor strong water-loaded
downdrafts with isolated damaging gusts potential. Storms should
gradually diminish in coverage and intensity tonight as the boundary
layer stabilizes.
..Lyons.. 08/20/2026
SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
1238 AM CDT Thu Aug 20 2026
Valid 201200Z - 211200Z
...NO CRITICAL AREAS...
...Synopsis...
Upper-level troughing will persist over the northeastern CONUS
today, with an embedded mid-level shortwave yielding increased
precipitation chances over a drought-stressed environment in
northern Minnesota and Wisconsin. The established upper ridge over
the Great Basin will continue to amplify, delivering above normal
temperatures and dry conditions to the Interior West. Meanwhile, an
upper trough will deepen along the West Coast, ushering stronger
southwesterly flow into the northwestern CONUS. Only brief and
localized elevated fire environment conditions are expected over
much of the Intermountain West this afternoon.
..Elizalde-Garcia.. 08/20/2026
...Please see www.spc.noaa.gov/fire for graphic product...
SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
1242 AM CDT Thu Aug 20 2026
Valid 211200Z - 221200Z
...Synopsis...
The established upper ridge over the Great Basin will continue to
amplify as an upper trough strengthens along the West Coast on Day
2/Friday. A mid-level low pressure system will near the Pacific
Northwest coast as the upper-level jet max peaks over
southern/central Oregon, providing a favorable setup for
thunderstorms along/east of the Cascades. Farther south, increasing
southwesterly flow over the western Great Basin will promote gusty
surface winds within a warm and dry airmass, yielding elevated fire
weather concerns.
...Central-eastern Oregon/Washington...
As the mid-level low nears the Oregon/Washington coastline, synoptic
scale forcing will overspread the Pacific Northwest late
afternoon/overnight. As a result of afternoon vertical mixing, some
isolated dry thunderstorms are possible (5-15% chance) before better
moisture is ushered in by the upper trough late evening. However,
widespread cloud cover during the day may inhibit solar insolation,
thus limiting greater instability. While some timing disparity is
portrayed in recent guidance on the approach of the upper trough,
the overall pattern is favorable for thunderstorm potential
overnight. Forecast soundings depict 0.8-1.0" PWATs, 30-35 kt LCL-EL
winds, and a dry sub-cloud layer, indicating higher rainfall
accumulation will likely remain localized (or within areas that see
multiple rounds of storms). A drought-stressed and recently
receptive fuel environment will raise concerns for new lightning
ignitions; thus, an Isolated Dry Thunderstorm risk area was
introduced across the region to capture the expanse of thunderstorm
potential in the afternoon and the overnight hours. Highlights may
need to be confined in future outlooks as the pattern is better
resolved.
...Northeastern California, northwestern Nevada, and southern
Oregon...
Daytime high temperatures will be slightly cooler on Day 2/Friday as
compared to previous days, but will still range from 90-100 F. At
peak heating, sustained southwesterly winds of 10-15 mph (gusts up
to 25 mph) and 10-15% RH will allow elevated fire weather conditions
to evolve where fuels have grown increasingly more receptive.
..Elizalde-Garcia.. 08/20/2026
...Please see www.spc.noaa.gov/fire for graphic product...
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