WW 505 SEVERE TSTM MI LH LM LS 202350Z - 210600Z
URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 505
NWS Storm Prediction Center Norman OK
750 PM EDT Mon Jul 20 2026
The NWS Storm Prediction Center has issued a
* Severe Thunderstorm Watch for portions of
Northern Lower Michigan
Lake Huron
Lake Michigan
Lake Superior
* Effective this Monday night and Tuesday morning from 750 PM
until 200 AM EDT.
* Primary threats include...
Scattered damaging wind gusts to 70 mph possible
Isolated very large hail events to 2 inches in diameter possible
A tornado or two possible
SUMMARY...Widely scattered intense storms over Upper Michigan and
northern Wisconsin will track southeastward into the watch area this
evening, posing a risk of damaging winds and hail. A tornado or two
is possible.
The severe thunderstorm watch area is approximately along and 55
statute miles east and west of a line from 15 miles southeast of
Manistee MI to 40 miles north northeast of Pellston MI. For a
complete depiction of the watch see the associated watch outline
update (WOUS64 KWNS WOU5).
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 500...WW 501...WW 504...
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
28030.
...Hart
WW 504 SEVERE TSTM IA IL MO 202240Z - 210400Z
URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 504
NWS Storm Prediction Center Norman OK
540 PM CDT Mon Jul 20 2026
The NWS Storm Prediction Center has issued a
* Severe Thunderstorm Watch for portions of
East Central Iowa
Northwest Illinois
Northeast Missouri
* Effective this Monday afternoon and evening from 540 PM until
1100 PM CDT.
* Primary threats include...
Scattered damaging winds and isolated significant gusts to 80
mph likely
Isolated very large hail events to 2 inches in diameter possible
SUMMARY...A fast-moving bowing line of thunderstorms over eastern
Iowa will track southeastward across the watch area this evening,
with a risk of severe wind gusts and hail.
The severe thunderstorm watch area is approximately along and 55
statute miles either side of a line from 45 miles north northwest of
Burlington IA to 15 miles east southeast of Peoria IL. 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.
&&
OTHER WATCH INFORMATION...CONTINUE...WW 500...WW 501...
AVIATION...A few severe thunderstorms with hail surface and aloft to
2 inches. Extreme turbulence and surface wind gusts to 70 knots. A
few cumulonimbi with maximum tops to 500. Mean storm motion vector
30035.
...Hart
WW 501 TORNADO MI WI LM LS 202050Z - 210400Z
URGENT - IMMEDIATE BROADCAST REQUESTED
Tornado Watch Number 501
NWS Storm Prediction Center Norman OK
350 PM CDT Mon Jul 20 2026
The NWS Storm Prediction Center has issued a
* Tornado Watch for portions of
The Upper Peninsula of Michigan
Northeast Wisconsin
Lake Michigan
Lake Superior
* Effective this Monday afternoon and evening from 350 PM until
1100 PM CDT.
* Primary threats include...
A few tornadoes likely with a couple intense tornadoes possible
Scattered damaging winds and isolated significant gusts to 75
mph likely
Scattered large hail and isolated very large hail events to 2.5
inches in diameter possible
SUMMARY...Scattered supercell development is expected late this
afternoon into early tonight across north central/northeast
Wisconsin and the Upper Peninsula of Michigan. The storm
environment favors the potential for a few tornadoes, including a
couple of strong (EF2+) tornadoes, as well as isolated very large
hail of 2-2.5 inches in diameter. As storms cluster by late
evening, the threat for wind damage will increase, with a few
significant (75+ mph) gusts possible.
The tornado watch area is approximately along and 75 statute miles
east and west of a line from 35 miles west northwest of Marquette MI
to 45 miles west southwest of Green Bay WI. For a complete depiction
of the watch see the associated watch outline update (WOUS64 KWNS
WOU1).
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 500...
AVIATION...Tornadoes and a few severe thunderstorms with hail
surface and aloft to 2.5 inches. Extreme turbulence and surface wind
gusts to 65 knots. A few cumulonimbi with maximum tops to 550. Mean
storm motion vector 30035.
...Thompson
WW 500 TORNADO IA WI 202005Z - 210300Z
URGENT - IMMEDIATE BROADCAST REQUESTED
Tornado Watch Number 500
NWS Storm Prediction Center Norman OK
305 PM CDT Mon Jul 20 2026
The NWS Storm Prediction Center has issued a
* Tornado Watch for portions of
Northeast and central Iowa
Extreme southwest Wisconsin
* Effective this Monday afternoon and evening from 305 PM until
1000 PM CDT.
* Primary threats include...
A few tornadoes likely with a couple intense tornadoes possible
Scattered damaging winds likely with isolated significant gusts
to 75 mph possible
Scattered large hail and isolated very large hail events to 2.5
inches in diameter possible
SUMMARY...Supercell development is underway across northern Iowa and
these storms will spread southeastward through this evening. The
storm environment favors a few strong-intense tornadoes (EF2+), very
large hail (up to 2.5 inches in diameter) and isolated significant
severe gusts (75+ mph), especially where the supercells interact
with a modifying outflow boundary.
The tornado watch area is approximately along and 85 statute miles
east and west of a line from 10 miles west of Knoxville IA to 70
miles north northeast of Waterloo IA. For a complete depiction of
the watch see the associated watch outline update (WOUS64 KWNS
WOU0).
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.
&&
AVIATION...Tornadoes and a few severe thunderstorms with hail
surface and aloft to 2.5 inches. Extreme turbulence and surface wind
gusts to 65 knots. A few cumulonimbi with maximum tops to 600. Mean
storm motion vector 33030.
...Thompson
WW 0505 Status Updates
STATUS REPORT ON WW 505
THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA.
..MEAD..07/21/26
ATTN...WFO...APX...GRR...
STATUS REPORT FOR WS 505
SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS
MIC009-019-029-031-035-039-047-055-079-085-089-097-101-105-113-
119-133-137-141-165-210140-
MI
. MICHIGAN COUNTIES INCLUDED ARE
ANTRIM BENZIE CHARLEVOIX
CHEBOYGAN CLARE CRAWFORD
EMMET GRAND TRAVERSE KALKASKA
LAKE LEELANAU MACKINAC
MANISTEE MASON MISSAUKEE
MONTMORENCY OSCEOLA OTSEGO
PRESQUE ISLE WEXFORD
LHZ345-346-347-361-LMZ323-341-342-344-345-346-362-364-366-849-868-
LSZ322-210140-
CW
. ADJACENT COASTAL WATERS INCLUDED ARE
GRAND TRAVERSE BAY SOUTH OF A LINE GRAND TRAVERSE LIGHT TO
NORWOOD MI
SEUL CHOIX POINT TO 5NM WEST OF MACKINAC BRIDGE
WW 0504 Status Updates
STATUS REPORT ON WW 504
SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 35 SSE CID
TO 35 NE PIA.
..MEAD..07/21/26
ATTN...WFO...DVN...ILX...
STATUS REPORT FOR WS 504
SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS
ILC017-057-067-071-095-107-109-113-123-125-129-131-143-167-169-
175-179-187-203-210140-
IL
. ILLINOIS COUNTIES INCLUDED ARE
CASS FULTON HANCOCK
HENDERSON KNOX LOGAN
MCDONOUGH MCLEAN MARSHALL
MASON MENARD MERCER
PEORIA SANGAMON SCHUYLER
STARK TAZEWELL WARREN
WOODFORD
MOC045-199-210140-
MO
. MISSOURI COUNTIES INCLUDED ARE
CLARK SCOTLAND
THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE
REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL
WW 0501 Status Updates
STATUS REPORT ON WW 501
SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 30 WNW RHI
TO 20 NW IMT TO 30 ENE MQT.
..MEAD..07/21/26
ATTN...WFO...MQT...GRB...
STATUS REPORT FOR WT 501
SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS
MIC003-041-043-109-153-210140-
MI
. MICHIGAN COUNTIES INCLUDED ARE
ALGER DELTA DICKINSON
MENOMINEE SCHOOLCRAFT
WIC009-015-029-037-041-061-067-069-071-073-075-078-083-085-087-
097-115-135-137-139-141-210140-
WI
. WISCONSIN COUNTIES INCLUDED ARE
BROWN CALUMET DOOR
FLORENCE FOREST KEWAUNEE
LANGLADE LINCOLN MANITOWOC
MARATHON MARINETTE MENOMINEE
OCONTO ONEIDA OUTAGAMIE
PORTAGE SHAWANO WAUPACA
WAUSHARA WINNEBAGO WOOD
LMZ221-248-250-521-522-541-542-543-LSZ249-250-210140-
WW 0500 Status Updates
STATUS REPORT ON WW 500
SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 25 SSW FOD
TO 30 SSW ALO TO 30 NNE OTM TO 30 SSE CID.
..MEAD..07/21/26
ATTN...WFO...DMX...ARX...DVN...
STATUS REPORT FOR WT 500
SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS
IAC001-007-015-049-051-057-073-077-087-099-101-107-111-115-117-
121-123-125-127-135-139-153-157-169-177-179-181-183-185-
210140-
IA
. IOWA COUNTIES INCLUDED ARE
ADAIR APPANOOSE BOONE
DALLAS DAVIS DES MOINES
GREENE GUTHRIE HENRY
JASPER JEFFERSON KEOKUK
LEE LOUISA LUCAS
MADISON MAHASKA MARION
MARSHALL MONROE MUSCATINE
POLK POWESHIEK STORY
VAN BUREN WAPELLO WARREN
WASHINGTON WAYNE
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.
MD 1681 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR SOUTHWEST WISCONSIN...FAR SOUTHEAST MINNESOTA...AND NORTHEAST IOWA
Mesoscale Discussion 1681
NWS Storm Prediction Center Norman OK
0720 PM CDT Mon Jul 20 2026
Areas affected...southwest Wisconsin...far southeast Minnesota...and
northeast Iowa
Concerning...Severe potential...Watch unlikely
Valid 210020Z - 210215Z
Probability of Watch Issuance...20 percent
SUMMARY...Storm development south of Tornado Watch 501 is appearing
less likely. Based on current observations, an additional watch is
not expected.
DISCUSSION...Over the past hour, visible satellite and radar data
have shown several attempts at storm initiation along a weakly
convergent surface front. Short parcel residence time within the
frontal zone coupled with a warm nose in the 700-800 mb layer, per
00Z MPX sounding, appears to limiting storm development. In
addition, convectively processed air spreading north into the area
from ongoing storms across IA is resulting in an increasingly narrow
warm sector ahead of the front. Given these observations and the
absence of storms in latest CAM guidance, an additional watch is not
currently expected to the south of Tornado Watch 501.
..Mead.. 07/21/2026
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...GRB...MKX...DVN...ARX...MPX...
LAT...LON 43699265 44399165 44619095 44369048 43878951 43398895
42488974 42889202 43699265
MOST PROBABLE PEAK WIND GUST...UP TO 60 MPH
MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN
MD 1679 CONCERNING SEVERE POTENTIAL...WATCH LIKELY FOR EASTERN U.P. OF MICHIGAN AND NORTHERN LOWER MICHIGAN
Mesoscale Discussion 1679
NWS Storm Prediction Center Norman OK
0617 PM CDT Mon Jul 20 2026
Areas affected...eastern U.P. of Michigan and northern lower
Michigan
Concerning...Severe potential...Watch likely
Valid 202317Z - 210115Z
Probability of Watch Issuance...80 percent
SUMMARY...Severe weather potential is expected to increase across
the discussion area this evening with the primary hazards being
damaging winds and large hail. A watch will likely be required prior
to 01Z.
DISCUSSION...Within the exit region of an upper-level jet streak
advancing into WI, large-scale forcing for ascent will overspread
the region from the west this evening. In response, a southwesterly
low-level jet will strengthen from southern WI into lower MI, which
in turn will enhance the flux of an increasingly moist and unstable
air mass into the region from the west. That destabilization process
will allow ongoing storms, including supercells, to spread southeast
across Lake Michigan into northern lower MI later this evening.
Inspection of forecast soundings suggests that storms may be
slightly elevated atop a shallow, near-surface inversion, which may
tend to mitigate a more robust tornado threat, despite strengthening
low-level shear. Nonetheless, the presence of seasonably strong
deep-layer shear will support the continuation of organized storm
modes, including supercells and bowing structures, with the primary
hazards being large hail and damaging wind gusts.
..Mead.. 07/20/2026
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...APX...GRR...MQT...
LAT...LON 44568687 45558617 46368511 46208385 45618344 45108332
44558440 44048628 44168674 44568687
MOST PROBABLE PEAK TORNADO INTENSITY...85-110 MPH
MOST PROBABLE PEAK WIND GUST...55-70 MPH
MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN
SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0800 PM CDT Mon Jul 20 2026
Valid 210100Z - 211200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE UPPER GREAT LAKES INTO THE LOWER MISSOURI VALLEY...
...SUMMARY...
Severe thunderstorms capable of producing damaging wind gusts,
severe hail, and a couple of tornadoes will continue across portions
of the Upper Great Lakes and Lower Missouri Valley through late
tonight.
...01Z Update...
Water-vapor imagery and VWP data indicate a robust midlevel wave and
accompanying belt of 50-60-kt west-northwesterly flow overspreading
the Upper Midwest, and this feature will continue east-southeastward
across the Great Lakes region tonight. In the low-levels, an
attendant cold front will continue east-southeastward across this
region as well. In the Upper Great Lakes and Midwest, 50-60 kt of
deep-layer shear (sampled by regional VWPs) oriented perpendicular
to the cold front and a relatively narrow corridor of strong
pre-frontal buoyancy (around 3000 J/kg MLCAPE) will continue to
promote semi-discrete supercell structures. Locally damaging wind
gusts, severe hail, and a couple of tornadoes will be possible with
this activity, given ample low-level hodograph curvature (around 250
m2/s2 effective SRH) beneath the core of a 40-kt LLJ. This activity
will generally spread east-southeastward across parts of Lower MI
tonight, where a continued risk of damaging wind gusts, severe hail,
and a tornado or two will continue ahead of the cold front before
encountering increasingly stable air.
Farther south, a couple organized clusters are tracking southward
across parts of southern IA and western IL. Given strong cold pools
with this activity, the primary concern will be severe wind gusts
and isolated/sporadic hail. These storms will continue tracking
south-southeastward along a surface-based buoyancy gradient before
gradually weakening overnight.
..Weinman.. 07/21/2026
SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0441 PM CDT Mon Jul 20 2026
Valid 221200Z - 281200Z
Upper-level troughing off the West Coast will continue to bring
southerly flow and Pacific moisture, enhanced by Post Tropical
Cyclone Elida, into the northwest US. While the main upper low is
forecast to remain offshore of the Pacific Northwest, troughing will
move into the northwest US late this week, with enhanced mid-level
west-southwest flow across the region by the weekend. The Four
Corners High will persist through the outlook period with daily
monsoonal thunderstorms likely across much of the greater Four
Corners region.
...Day 3/Wednesday - Day 4/Thursday...
Isolated to scattered mixed wet/dry thunderstorms are expected
across portions of northern California, much of Oregon, and possibly
into the Washington Cascades Day 3/Wednesday, mostly during the
afternoon and evening. PWAT values of 0.9-1.25" are expected, but
20-30 knot storm motions and receptive fuels should result in
lightning ignitions. Scattered thunderstorms are likely across
central Oregon with 50-70% probabilities of rainfall exceeding 0.10"
amid surface dewpoints of 40-55F. Given the receptive fuels and fire
activity in the area, a subsequent outlook upgrade to a Scattered
DryT area is possible if the wetting rain footprint remains
relatively smaller to thunderstorm coverage.
Isolated to scattered mixed wet/dry thunderstorms are likely across
portions of central/eastern Washington, northeast Oregon, and the
Idaho Panhandle into northwest Montana Day 4/Thursday. The ambient
environment will dry slightly, but surface dewpoints of 40-50F and
PWAT values of 0.8-1.2" will still produce cores of wetting rain.
However, given the likely mixed wet/dry thunderstorm modes and
receptive fuels, a 10% area was introduced. Additionally, dry and
breezy west/southwest winds will begin to push inland across the
Inland Northwest into the northwest Great Basin as the onshore
pressure gradient tightens and stronger flow aloft arrives.
...Day 5/Friday - Day 8/Monday...
As the aforementioned stronger flow aloft moves over the northwest
and onshore pressure gradient tightens, dry and breezy conditions
will develop across much of the Inland Northwest, Idaho, Montana,
and northern Great Basin on Day 5/Friday. There remains some
uncertainty regarding the development of critical winds/RH, with
some guidance indicating areas in Idaho and Montana having the
highest probabilities of critical winds/RH over the least receptive
fuels in the region. Dry and breezy conditions will likely continue
across portions of the northwest US through the weekend, but too
much forecast uncertainty precludes any additional upgrades at this
time. Overall, lightning followed by multiple consecutive days of
dry and breezy conditions are expected across areas with ERCs > 90th
percentile and active large wildfires.
..Nauslar.. 07/20/2026
...Please see www.spc.noaa.gov/fire for graphic product...
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