Alert archive / Michigan / Flash Flood Warnings in 2021

Flash Flood Warning 6, NWS Detroit, MI

August 12, 2021Macomb County, Oakland County, Wayne County, Michigan

NWS Detroit, MI issued this flash flood warning at Aug 12, 2021, 5:41 AM EDT for Macomb County, Oakland County, Wayne County, Michigan. It was in force for 3 hr. 10 reports came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued
Aug 12, 2021, 5:41 AM EDT (09:41 UTC)
Expired
Aug 12, 2021, 8:42 AM EDT
In force
3 hr
Issued by
NWS Detroit, MI
Area
Storm-based polygon
Flood severity
None

Counties Macomb County, MI, Oakland County, MI, Wayne County, MI

The radar

The Detroit radar (KDTX), 37 km from the middle of the area, began a volume at 09:43 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.

What was reported inside it

TimeReportWhereRemark
Aug 12, 6:00 AM EDTHEAVY RAIN 2.7Garden City, MI6 HOUR RAINFALL.
Aug 12, 7:00 AM EDTFLOOD4 Nw St. Clair Shores, MIFLOODED ROADWAYS AROUND 13 MILE AND GROESBECK HIGHWAY.
Aug 12, 7:00 AM EDTHEAVY RAIN 1.072 Sw Shelby Township, MI24 HOUR RAINFALL.
Aug 12, 7:00 AM EDTHEAVY RAIN 2.21Bloomfield Hills, MI24 HOUR RAINFALL.
Aug 12, 7:00 AM EDTHEAVY RAIN 2.324 S Detroit, MI24 HOUR RAINFALL.
Aug 12, 7:00 AM EDTHEAVY RAIN 2.4Canton, MI24 HOUR RAINFALL.
Aug 12, 7:30 AM EDTFLOOD5 Nw St. Clair Shores, MIROADWAY FLOODED AND CARS STRANDED.
Aug 12, 7:30 AM EDTHEAVY RAIN 2.3Beverly Hills, MI24 HOUR RAINFALL.
Aug 12, 8:00 AM EDTHEAVY RAIN 2.154 E White Lake, MI24 HOUR RAINFALL TOTAL AT THE NWS DETROIT/PONTIAC OFFICE.
Aug 12, 8:30 AM EDTHEAVY RAIN 2.62Farmington, MI24 HOUR RAINFALL.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Detroit, MI (KDTX), launched 00:00Z, 9.7 hours before the alert went out and 36 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 00:00Z on 2021-08-12Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 12 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Detroit, MI at 00:00Z on 2021-08-12The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 243 square meters per square second.19395878Sfc1 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
12 J/kg
Mixed-layer CIN
-458 J/kg
Mixed-layer LCL
1474 m above ground
0-6 km bulk shear
39 kt
0-1 km storm-relative helicity
243 m²/s²
0-3 km storm-relative helicity
373 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

087 
WGUS53 KDTX 120941
FFWDTX
MIC099-125-163-121300-
/O.NEW.KDTX.FF.W.0006.210812T0941Z-210812T1300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Detroit/Pontiac MI
541 AM EDT Thu Aug 12 2021

The National Weather Service in Detroit/Pontiac has issued a

* Flash Flood Warning for...
  Southern Macomb County in southeastern Michigan...
  Southern Oakland County in southeastern Michigan...
  Northern Wayne County in southeastern Michigan...

* Until 900 AM EDT.

* At 541 AM EDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 1 and 2 inches of rain 
  have fallen. Additional rainfall amounts of 1 to 2 inches are 
  possible in the warned area. Flash flooding is ongoing or expected 
  to begin shortly.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Radar.

  IMPACT...Flash flooding of small creeks and streams, urban
           areas, highways, streets and underpasses as well as
           other poor drainage and low-lying areas.

* Some locations that will experience flash flooding include...
  Warren, Livonia, Troy, Southfield, St. Clair Shores, Pontiac, 
  Novi, Mount Clemens, Milford, Grosse Pointe, Downtown Detroit, 
  Canton, Detroit, Sterling Heights, Dearborn, Royal Oak, 
  Birmingham, South Lyon, Northville and Clinton.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don't drown when encountering flooded roads. Most flood 
deaths occur in vehicles.

&&

LAT...LON 4266 8368 4266 8271 4263 8277 4260 8274
      4256 8274 4252 8283 4245 8283 4236 8288
      4232 8306 4227 8311 4227 8354 4243 8355
      4244 8366

FLASH FLOOD...RADAR INDICATED

$$

AM
2 follow-up statements
779 
WGUS73 KDTX 121048
FFSDTX

Flash Flood Statement
National Weather Service Detroit/Pontiac MI
648 AM EDT Thu Aug 12 2021

MIC099-125-163-121300-
/O.CON.KDTX.FF.W.0006.000000T0000Z-210812T1300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Macomb MI-Oakland MI-Wayne MI-
648 AM EDT Thu Aug 12 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 9 AM EDT THIS MORNING 
FOR SOUTHERN MACOMB, SOUTHERN OAKLAND AND NORTHERN WAYNE COUNTIES...

At 648 AM EDT, Doppler radar indicated scattered thunderstorms 
producing heavy rain across the warned area. Between 2 and 3 inches 
of rain have fallen. Flooding has been reported on I-94 and the 
Davison Freeway. Additional rainfall amounts of 1 to 2 inches are 
possible in the warned area this morning.

HAZARD...Flash flooding caused by thunderstorms.

SOURCE...Radar.

IMPACT...Flash flooding of small creeks and streams, urban areas,
         highways, streets and underpasses as well as other poor
         drainage and low-lying areas.

Some locations that will experience flash flooding include...
  Warren, Livonia, Troy, Southfield, St. Clair Shores, Pontiac, 
  Novi, Mount Clemens, Milford, Grosse Pointe, Downtown Detroit, 
  Canton, Detroit, Sterling Heights, Dearborn, Royal Oak, 
  Birmingham, South Lyon, Northville and Clinton.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don't drown when encountering flooded roads. Most flood 
deaths occur in vehicles.

&&

LAT...LON 4266 8368 4266 8271 4263 8277 4260 8274
      4256 8274 4252 8283 4245 8283 4236 8288
      4232 8306 4227 8311 4227 8354 4243 8355
      4244 8366

FLASH FLOOD...RADAR INDICATED

$$

MR
817 
WGUS73 KDTX 121242
FFSDTX

Flash Flood Statement
National Weather Service Detroit/Pontiac MI
842 AM EDT Thu Aug 12 2021

MIC099-125-163-121252-
/O.CAN.KDTX.FF.W.0006.000000T0000Z-210812T1300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Macomb MI-Oakland MI-Wayne MI-
842 AM EDT Thu Aug 12 2021

...FLASH FLOOD WARNING FOR SOUTHERN MACOMB, SOUTHERN OAKLAND AND 
NORTHERN WAYNE COUNTIES HAS BEEN REPLACED WITH A FLOOD ADVISORY...

Heavy rain has ended, however it will take time for flood waters to 
recede. A flood advisory is in effect through this morning. Please 
continue to heed remaining road closures.

LAT...LON 4266 8368 4266 8271 4263 8277 4260 8274
      4256 8274 4254 8281 4252 8283 4245 8283
      4236 8288 4232 8306 4227 8311 4227 8354
      4243 8355 4244 8366

$$

KDK

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 11, 10:42 PM EDTSpecial Weather StatementDTXGenesee, Lapeer, Livingston, Oakland, Shiawassee63 min
Aug 11, 11:00 PM EDTSpecial Weather StatementDTXLenawee, Washtenaw60 min
Aug 11, 11:34 PM EDTSpecial Weather StatementDTXMacomb, Monroe, Saint Clair, Wayne56 min
Aug 12, 12:47 AM EDTSpecial Weather StatementDTXTuscola43 min
Aug 12, 1:14 AM EDTSpecial Weather StatementDTXGenesee, Shiawassee46 min
Aug 12, 2:04 AM EDTAreal Flood AdvisoryDTXLivingston2 hr
Aug 12, 2:36 AM EDTSpecial Weather StatementDTXWayne54 min
Aug 12, 3:08 AM EDTAreal Flood AdvisoryDTXWayne4 hr
Aug 12, 4:33 AM EDTFlash Flood WarningDTXLivingston2 hr
Aug 12, 5:18 AM EDTAreal Flood AdvisoryDTXMacomb, Oakland3 hr
Aug 12, 6:31 AM EDTSevere Thunderstorm WarningDTXLenawee, Livingston, Monroe, Washtenaw59 min
Aug 12, 6:43 AM EDTAreal Flood WarningDTXLivingston2 hr
Aug 12, 7:09 AM EDTSevere Thunderstorm WarningDTXMacomb, Monroe, Oakland, Wayne45 min
Aug 12, 7:18 AM EDTSpecial Weather StatementDTXMonroe42 min
Aug 12, 7:27 AM EDTSpecial Marine WarningDTX34 min
Aug 12, 7:35 AM EDTRiver Flood WarningDTXLivingston18 days
Aug 12, 8:42 AM EDTAreal Flood AdvisoryDTXMacomb, Oakland, Wayne3 hr
Aug 12, 11:53 AM EDTRiver Flood WarningDTXMacomb7 hr
Aug 12, 6:08 PM EDTRiver Flood WarningDTXWayne15 hr

Nearby

Flash Flood Warnings in Michigan, 2021Every flash flood warning 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.