Marine Thunderstorm Winds in Lake St. Clair, May 18, 2026

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
337 PM EDT Mon May 18 2026

.KEY MESSAGES...

- Warm and humid conditions exist today and Tuesday which support
the risk of severe thunderstorms each day, mainly during the
afternoon and evening hours. The strongest storms are capable of
damaging wind, large hail, and isolated tornadoes.

- A cold front Tuesday night ushers in dry and cooler weather for
Wednesday and Thursday.

- The next chance of rain arrives Friday and Friday night.

&&

.DISCUSSION...

Severe Thunderstorm Watch 221 is in effect until 800 pm for the
mature MCS inbound into SE Mi. Damaging wind gusts of 70 mph or
greater have been reported and remain the primary hazard as the line
tracks across SE Mi. Instability trends remain on track as full
morning to early afternoon sun lifted temperatures to near 90 all
areas. Model MLCAPE up around 2000 J/kg in HREF mean and RAP
projections of hourly mesoanalysis add confidence to persistence.
The system is already demonstrating benefits of the locally enhanced
wind shear profile supplied by the parent MCV resulting in a mature
linear convective mode now expected to maintain organization while
crossing SE Mi. Storms exit eastward into Ontario by 00Z at or
before watch expiration.

Another round of severe thunderstorm potential for Tuesday is set up
by Midwest low pressure as it moves into upper Michigan while
pulling a cold front through the central Great Lakes. SE Mi remains
firmly in the warm sector of this system throughout the day with
early to mid evening cold front timing offering time for instability
to become sufficient. Morning clouds and a stray shower likely slow
the pace of surface heating compared to today, however model
projections of MLCAPE place 2000 J/kg in reach by 21Z Tuesday
afternoon, especially toward the Ohio border. This occurs in a very
similar wind profile compared to today in terms of moderate
unidirectional shear except with a deeper 40-45 knot layer through
500 mb. Storm initiation timing is the primary uncertainty as shown
in the wide range of hi-res model solutions that collectively
suggest a later afternoon consensus. Later timing equates to less
impact to SE Mi in terms of coverage area and also a more isolated
severe threat before storms can better organize while the cold front
moves through the area.

Frontal passage Tuesday night, before midnight, sweeps storms out of
SE Mi and sweeps in cooler air for the mid week period. A broad area
of surface high pressure and short wave ridging ensures below normal
temperatures but dry weather during this time period as well.
Central Plains to Ohio valley low pressure then brings the next
round of showers into Lower Mi later Friday and Friday night.

&&

.MARINE...

Attention to the near-term forecast will focus on the ongoing line of
thunderstorms that extend across central Michigan. This line will
pass across the eastern Great Lakes this evening and will bring
heavy downpours, frequent lightning, and strong to severe weather.
Strong to severe thunderstorms will be capable of producing wind
gusts aoa 50 knots for all of the open water locations. Hail to an
inch and/or a waterspout cannot be ruled out but are secondary
hazards for severe weather. Prior to this line of thunderstorm
arriving, isolated to scattered thunderstorm activity will be
possible. A Severe Thunderstorm Watch is in effect until 8 PM EDT.

Outside of any thunderstorm activity, breezy southwest to south flow
will persist, bringing non-thunderstorm gusts on the order of 20 to
25 knots. The main line of storms will exit late tonight but
isolated to scattered showers and thunderstorms will be possible
overnight. Renewed strong to severe thunderstorm chances will again
be possible tomorrow afternoon and evening which will bring
additional chances to see all storm hazards included wind gusts aoa
50 knots. These stronger storms will be most favorable from central
Lake Huron and locations south. Outside of thunderstorms, gusts to
25 knots will again be possible during daylight hours. Re-issuance
of Small Craft Advisories will be likely.

&&

.PREV DISCUSSION...
Issued at 158 PM EDT Mon May 18 2026

AVIATION...

Conditions deteriorate this afternoon and evening as a line of
strong to severe thunderstorms moves through the airspace. VFR
ceilings and visibilities drop sharply along the interface of the
convective line with temporary IFR conditions likely. Upstream
observations and local storm reports indicate gusts in excess of 70
mph are possible with this organized line. Current trajectories
reveal storm motion of approximately 45 mph, forecast to move
through the terminals between 20Z and 23Z. A conditionally unstable
airmass is allowing for a few pre-trough storms to develop ahead of
the line with low confidence that these storms survive across the
airfields. However, did move up the TEMPO period for the Metro
terminals to account for the possibility of slightly earlier
discrete activity. Limited model signal for widespread redevelopment
late this evening behind the line, although better chances exist at
MBS. Winds decrease slightly overnight, holding from the southwest
into Tuesday with a mainly dry start and

D21/DTW Convection...Most likely time-frame for thunder will be from
20-22Z. A period of IFR visibility will accompany the line of
storms. Potential for additional thunderstorms has decreased for
Tuesday afternoon/evening, but a chance remains.

DTW THRESHOLD PROBABILITIES...

* High for thunderstorms this afternoon and early evening, then low-
  medium for thunderstorms Tuesday afternoon/evening.

* Medium for ceilings at or below 5000 ft with thunderstorms this
  afternoon and evening.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...

MI...None.

Lake Huron...Small Craft Advisory until 10 PM EDT this evening for LHZ421-422-
     441>443.

Lake St Clair...Small Craft Advisory until 10 PM EDT this evening for LCZ460.

Michigan waters of Lake Erie...None.

&&

DISCUSSION...BT
MARINE.......BT
AVIATION.....KGK

You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.

Hazardous Weather Outlook
National Weather Service Detroit/Pontiac MI
345 AM EDT Mon May 18 2026

MIZ047>049-053>055-060>063-068>070-075-076-082-083-190745-
Midland-Bay-Huron-Saginaw-Tuscola-Sanilac-Shiawassee-Genesee-Lapeer-
St. Clair-Livingston-Oakland-Macomb-Washtenaw-Wayne-Lenawee-Monroe-
345 AM EDT Mon May 18 2026

This hazardous weather outlook is for southeast Michigan.

.DAY ONE...Today and Tonight

The potential exists for severe thunderstorms to develop mainly
between 3 and 9 pm today. Storms will be capable of producing
damaging wind gusts to 60 mph, hail to one inch in diameter and
isolated tornadoes. Storms will track from west to east at 45 to 50
mph.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday

The risk for severe weather exists again Tuesday mainly during the
afternoon and evening hours, with strong winds, large hail and heavy
rainfall possible.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed late this afternoon and evening.

LCZ460-LEZ444-LHZ361>363-421-422-441>443-462>464-190745-
Lake St Clair-
Michigan Waters of Lake Erie from Detroit River to North Cape MI-
Lake Huron from 5NM east of Mackinac Bridge to Presque Isle Lt
beyond 5 NM off shore-
Lake Huron from Presque Isle Light to Sturgeon Point MI beyond 5NM
off shore-
Lake Huron from Sturgeon Point to Alabaster MI beyond 5NM off shore-
Outer Saginaw Bay SW of Alabaster to Port Austin MI to Inner Saginaw
Bay-Inner Saginaw Bay SW of Point Au Gres to Bay Port MI-
Port Austin to Harbor Beach MI-Harbor Beach to Port Sanilac MI-
Port Sanilac to Port Huron MI-
Lake Huron from Port Austin to Harbor Beach beyond 5NM Off Shore-
Lake Huron from Harbor Beach to Port Sanilac beyond 5NM Off Shore-
Lake Huron from Port Sanilac to Port Huron beyond 5NM Off Shore-
345 AM EDT Mon May 18 2026

This hazardous weather outlook is for portions of Lake Erie, Lake
Huron and Lake St Clair.

.DAY ONE...Today and Tonight

The potential exists for severe thunderstorms to develop mainly
between 3 and 9 pm today. Storms will be capable of producing
damaging wind gusts to 50 knots, hail to one inch in diameter and
isolated tornadoes. Storms will track from west to east at 40 to 45
knots.

A small craft advisory is in effect through this evening. Refer to
the latest marine forecast for details.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday

The risk for severe weather exists again Tuesday mainly during the
afternoon and evening hours, with strong winds, large hail and heavy
rainfall possible.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed late this afternoon and evening.

You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.

MR

Special Weather Statement
National Weather Service Detroit/Pontiac MI
300 PM EDT Mon May 18 2026

MIZ069-181930-
Oakland MI-
300 PM EDT Mon May 18 2026

...A STRONG THUNDERSTORM WILL IMPACT SOUTHEASTERN OAKLAND COUNTY
THROUGH 330 PM EDT...

At 300 PM EDT, Doppler radar was tracking a strong thunderstorm near
Livonia, moving northeast at 30 mph.

HAZARD...Wind gusts of 50 to 55 mph.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects.

Locations impacted include...
Troy, Southfield, Pontiac, Novi, Royal Oak, Birmingham, Rochester,
Northville, Detroit Zoo, West Bloomfield, Farmington Hills, Rochester
Hills, Madison Heights, Oak Park, Auburn Hills, Ferndale, Hazel Park,
Berkley, Wixom, and Clawson.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

A Severe Thunderstorm Watch remains in effect until 800 PM EDT for
southeastern Michigan.

&&

LAT...LON 4244 8354 4266 8351 4273 8310 4245 8309
TIME...MOT...LOC 1900Z 222DEG 25KT 4244 8335

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...55 MPH

SF

Special Weather Statement
National Weather Service Detroit/Pontiac MI
342 PM EDT Mon May 18 2026

MIZ049-182030-
Huron MI-
342 PM EDT Mon May 18 2026

...A STRONG THUNDERSTORM WILL IMPACT CENTRAL HURON COUNTY THROUGH 430
PM EDT...

At 341 PM EDT, Doppler radar was tracking a strong thunderstorm over
Gagetown, or 7 miles northwest of Cass City, moving north at 40 mph.

HAZARD...Wind gusts up to 50 mph and half inch hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

This strong thunderstorm will be near...
  Owendale around 345 PM EDT.
  Pigeon and Elkton around 350 PM EDT.
  Port Austin around 420 PM EDT.

Other locations impacted by this storm include Pinnebog, Port
Crescent State Park, Redman, Filion, Huron City, Ivanhoe, and
Grindstone City.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

A Severe Thunderstorm Watch remains in effect until 800 PM EDT for
southeastern Michigan.

&&

LAT...LON 4401 8271 4368 8310 4367 8334 4400 8328
      4403 8310 4407 8305 4407 8285
TIME...MOT...LOC 1941Z 200DEG 34KT 4368 8327

MAX HAIL SIZE...0.50 IN
MAX WIND GUST...50 MPH

Mann

Preliminary Local Storm Report
National Weather Service Detroit/Pontiac MI
413 PM EDT Mon May 18 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0400 PM     Tstm Wnd Gst     Tri Cities Intl Airport 43.53N  84.08W
05/18/2026  M56 mph          Saginaw            MI   ASOS

            Measured at KMBS - MBS International Airport

&&

Event Number DTX2600463

AM

Preliminary Local Storm Report
National Weather Service Detroit/Pontiac MI
433 PM EDT Mon May 18 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0324 PM     Tstm Wnd Dmg     1 NW Rochester Hills    42.66N  83.17W
05/18/2026                   Oakland            MI   Trained Spotter

            Report of large tree limb down on house causing damage
            to roofing

0412 PM     Tstm Wnd Gst     Tri Cities Intl Airport 43.53N  84.08W
05/18/2026  M63 mph          Saginaw            MI   ASOS

            Measured at KMBS - MBS International Airport

0417 PM     Tstm Wnd Gst     Dundee                  41.96N  83.66W
05/18/2026  M81 mph          Monroe             MI   Trained Spotter

            Measured on a handheld anemometer

&&

Event Number DTX2600464
Event Number DTX2600465
Event Number DTX2600466

AM

Preliminary Local Storm Report
National Weather Service Detroit/Pontiac MI
508 PM EDT Mon May 18 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0400 PM     Tstm Wnd Dmg     2 E Hemlock             43.42N  84.19W
05/18/2026                   Saginaw            MI   Trained Spotter

            24 inch diameter healthy tree down

0405 PM     Tstm Wnd Dmg     3 SW Barton Hills       42.28N  83.80W
05/18/2026                   Washtenaw          MI   Emergency Mngr

            report of multiple power lines down

0418 PM     Tstm Wnd Dmg     Saginaw Harry Browne Ai 43.43N  83.86W
05/18/2026                   Saginaw            MI   Trained Spotter

            Report of multiple trees down near Harry Brown Airport

0426 PM     Tstm Wnd Dmg     1 NE Essexville         43.62N  83.83W
05/18/2026                   Bay                MI   Amateur Radio

            Report of 10 to 12 inch tree limbs down

0445 PM     Tstm Wnd Gst     Oakland County Intl Air 42.66N  83.41W
05/18/2026  M58 mph          Oakland            MI   ASOS

            Measured at KPTK Pontiac Airport

0450 PM     Tstm Wnd Dmg     2 E Otter Lake          43.22N  83.43W
05/18/2026                   Lapeer             MI   Trained Spotter

            Report of 3ft diameter pine tree down

&&

Event Number DTX2600467
Event Number DTX2600468
Event Number DTX2600469
Event Number DTX2600470
Event Number DTX2600471
Event Number DTX2600472

AM

Preliminary Local Storm Report
National Weather Service Detroit/Pontiac MI
514 PM EDT Mon May 18 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0403 PM     Tstm Wnd Dmg     3 SE Antrim Center      42.79N  84.06W
05/18/2026                   Shiawassee         MI   Public

            Photo of a healthy tree down across road. Estimated 1
            ft diameter.

&&

Event Number DTX2600473

AM