Alert archive / Michigan / Special Weather Statements in 2021

Special Weather Statement, NWS Detroit, MI

July 20, 2021Sanilac County, Michigan

NWS Detroit, MI issued this special weather statement at Jul 20, 2021, 3:35 PM EDT for Sanilac County, Michigan. It was in force for 55 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued
Jul 20, 2021, 3:35 PM EDT (19:35 UTC)
Expired
Jul 20, 2021, 4:30 PM EDT
In force
55 min
Issued by
NWS Detroit, MI

County Sanilac County, MI

The radar

The Detroit radar (KDTX), 113 km from the middle of the area, began a volume at 19:35 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The nearest sounding before it

Detroit, MI (KDTX), launched 12:00Z, 7.6 hours before the alert went out and 109 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-pSkew-T log-p diagram, Detroit, MI at 12:00Z on 2021-07-20Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 151 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Detroit, MI at 12:00Z on 2021-07-20The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 24 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
151 J/kg
Mixed-layer CIN
-120 J/kg
Mixed-layer LCL
1105 m above ground
0-6 km bulk shear
19 kt
0-1 km storm-relative helicity
24 m²/s²
0-3 km storm-relative helicity
16 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

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What forecasters said that day

The local office's own words before this special weather statement went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Detroit, MI wrote its last area forecast discussion before this special weather statement went out at Jul 20, 3:30 PM EDT, 5 minutes earlier.

Area forecast discussion, Jul 20, 3:30 PM EDT, 5 minutes before
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Hazardous weather outlook, Jul 20, 8:11 AM EDT, 7 hours 24 minutes before
Hazardous Weather Outlook...CORRECTED
National Weather Service Detroit/Pontiac MI
811 AM EDT Tue Jul 20 2021

MIZ049-054-055-062-063-070-210815-
Huron-Tuscola-Sanilac-Lapeer-St. Clair-Macomb-
811 AM EDT Tue Jul 20 2021

This hazardous weather outlook is for portions of southeast
Michigan.

.DAY ONE...Today and Tonight

Isolated severe storms are possible this afternoon and evening.
Scattered to numerous thunderstorms will develop across the thumb
between 2 PM and 4 PM and will move south to Lake St Clair by 6 or 7
PM. The strongest storms will be capable of producing wind gusts to
60 MPH and hail to one inch in diameter. Individual storms will move
west to the east at 40 MPH while the main cluster of storms and/or
new storm development slowly tracks from north to south. A strong
cold front will be responsible for the thunderstorms.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday

Periodic chances for thunderstorms exist from Friday through Sunday.

.SPOTTER INFORMATION STATEMENT...
Dispatchers...please notify your emergency managers immediately.
Spotter activation may be needed this afternoon and evening.

MIZ047-048-053-060-061-068-069-075-076-082-083-210815-
Midland-Bay-Saginaw-Shiawassee-Genesee-Livingston-Oakland-Washtenaw-
Wayne-Lenawee-Monroe-
811 AM EDT Tue Jul 20 2021

This hazardous weather outlook is for portions of southeast
Michigan.

.DAY ONE...Today and Tonight

Scattered thunderstorms are expected this afternoon and evening. Some
storms may approach severe limits. The better chances for
thunderstorms will be along the Interstate 75 corridor and points
east. The strongest storms will be capable of producing wind gusts of
45 to 60 MPH and hail to one half inch in diameter. Storm motion will
be from west to east at 40 MPH. A strong cold front will be
responsible for the thunderstorms.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday

Periodic chances for thunderstorms exist from Friday through Sunday.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not anticipated today or tonight.

LCZ460-LEZ444-LHZ361>363-421-422-441>443-462>464-210815-
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-
811 AM EDT Tue Jul 20 2021

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

.DAY ONE...Today and Tonight

Strong thunderstorms are possible this afternoon and evening, mainly
across Lake Huron south of Sturgeon Point and down to Lake St Clair.
Thunderstorms are expected to develop over central and southern Lake
Huron this afternoon and move south into Lake St Clair and western
Lake Erie this evening. The strongest storms will be capable of
producing wind gusts in excess of 40 knots and hail in excess of a
half inch. Individual storm motion will be from west to east at 35
knots while storm clusters and new storm development will be oriented
from north to south.

Small craft advisories are in effect for the Lake Huron nearshore
waters from this afternoon through tonight.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday

Small craft advisories will remain in effect into Wednesday afternoon
for the southern Lake Huron nearshore waters.

Periodic chances for thunderstorms exist from Friday through Sunday.

.SPOTTER INFORMATION STATEMENT...
Dispatchers...please notify your emergency managers immediately.
Spotter activation may be needed this afternoon and evening.

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

SC

In the hours before

Special weather statement, Jul 20, 2:29 PM EDT, 1 hour 6 minutes before
Special Weather Statement
National Weather Service Detroit/Pontiac MI
229 PM EDT Tue Jul 20 2021

MIZ049-202000-
Huron-
229 PM EDT Tue Jul 20 2021

...A STRONG THUNDERSTORM WILL AFFECT NORTHERN HURON COUNTY...

At 229 PM EDT, a strong thunderstorm was located 8 miles northwest of
Port Austin, moving southeast at 25 mph.

Winds in excess of 40 mph and pea size hail are possible with this
storm.

This storm will be near...
  Port Austin around 245 PM EDT.
  Kinde around 300 PM EDT.
  Port Hope around 320 PM EDT.

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

Torrential rainfall is also occurring with this storm, and may cause
localized flooding. Do not drive your vehicle through flooded
roadways.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

LAT...LON 4400 8270 4386 8261 4387 8338 4392 8344
      4394 8342 4395 8334 4399 8329 4403 8310
      4407 8305 4407 8286
TIME...MOT...LOC 1829Z 310DEG 23KT 4414 8310

AM
Special weather statement, Jul 20, 3:35 PM EDT, 0 minutes before
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The office that day

Everything else NWS Detroit, MI issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jul 19, 9:54 PM EDTSmall Craft AdvisoryDTX42 hr
Jul 19, 9:59 PM EDTBeach Hazards StatementDTXBay, Huron, Saint Clair, Sanilac26 hr
Jul 20, 2:19 PM EDTSpecial Marine WarningDTX73 min
Jul 20, 2:29 PM EDTSpecial Weather StatementDTXHuron91 min
Jul 20, 2:57 PM EDTSevere Thunderstorm WarningDTXHuron51 min
Jul 20, 3:06 PM EDTSpecial Marine WarningDTX84 min
Jul 20, 4:27 PM EDTSpecial Weather StatementDTXLapeer93 min
Jul 20, 4:57 PM EDTSevere Thunderstorm WarningDTXLapeer63 min
Jul 20, 5:59 PM EDTSevere Thunderstorm WarningDTXLapeer, Macomb, Oakland, Saint Clair61 min
Jul 20, 6:43 PM EDTSevere Thunderstorm WarningDTXMacomb, Oakland62 min
Jul 20, 6:59 PM EDTSpecial Weather StatementDTXLivingston, Oakland61 min
Jul 20, 7:28 PM EDTSevere Thunderstorm WarningDTXOakland, Wayne62 min
Jul 20, 7:53 PM EDTSpecial Weather StatementDTXWashtenaw97 min

Nearby

Special Weather Statements in Michigan, 2021Every special weather statement in 2021

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.