Alert archive / Michigan / Tornado Watches in 2002

Tornado Watch 720

October 4, 200221 counties in Michigan

The Storm Prediction Center issued this tornado watch at Oct 4, 2002, 4:00 PM EDT for 21 counties in Michigan. It was in force for 4 hr.

The area

The outline as issued.

The facts

Issued: Oct 4, 2002, 4:00 PM EDT (20:00 UTC)
Expired: Oct 4, 2002, 8:00 PM EDT
In force: 4 hr
Issued by: the Storm Prediction Center

All 21 counties

Alcona County, MI, Alpena County, MI, Arenac County, MI, Bay County, MI, Genesee County, MI, Huron County, MI, Iosco County, MI, Jackson County, MI, Lapeer County, MI, Lenawee County, MI, Livingston County, MI, Macomb County, MI, Monroe County, MI, Oakland County, MI, Saginaw County, MI, Saint Clair County, MI, Sanilac County, MI, Shiawassee County, MI, Tuscola County, MI, Washtenaw County, MI, Wayne County, MI

The radar

The Detroit radar (KDTX), 46 km from the middle of the area, began a volume at 20:03 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.

Warnings issued inside it

1 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.

Issued	Product	Office	Counties	Lasted
Oct 4, 4:58 PM EDT	Severe Thunderstorm Warning	GRR	Ingham, Jackson	47 min

The nearest sounding before it

Detroit, MI (KDTX), launched 12:00Z, 8.0 hours before the alert went out and 44 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 309 J/kg
Mixed-layer CIN: -61 J/kg
Mixed-layer LCL: 502 m above ground
0-6 km bulk shear: 48 kt
0-1 km storm-relative helicity: 198 m²/s²
0-3 km storm-relative helicity: 230 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 1.8

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

000 
WWUS20 KWNS 042003
SEL0  
SPC WW 042000
MIZ000-LEZ000-LHZ000-050000-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 720
STORM PREDICTION CENTER NORMAN OK
400 PM EDT FRI OCT 4 2002

THE STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF

   EASTERN LOWER MICHIGAN                           
   WESTERN LAKE ERIE                          
   WESTERN LAKE HURON                         

EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 400 PM UNTIL 800
PM EDT.

TORNADOES...HAIL TO 1 INCH IN DIAMETER...THUNDERSTORM WIND GUSTS TO
80 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE TORNADO WATCH AREA IS ALONG AND 45 STATUTE MILES EAST AND WEST
OF A LINE FROM 35 MILES SOUTH OF ANN ARBOR MICHIGAN TO 45 MILES
EAST NORTHEAST OF ALPENA MICHIGAN.

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 719...

DISCUSSION...STRONG LOW TO MID LEVEL SHEAR WILL REMAIN FAVORABLE
FOR UPDRAFT ROTATION WITH CONVECTION ALONG LINE OF FORCED ASCENT
MOVING E FROM WRN LWR MI.  WHILE LOW LEVEL LAPSE RATES REMAIN WEAK
ACROSS ERN LWR MI /PER 18Z DTX RAOB/...SUFFICIENT CAPE APPEARS
PRESENT TO SUPPORT BOWS SEGMENTS/POSSIBLE TORNADOES ALONG
CONVECTIVE BAND. 

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 1 INCH...EXTREME TURBULENCE AND SURFACE WIND
GUSTS TO 70 KNOTS.  A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 450. 
MEAN STORM MOTION VECTOR 21045.

...CORFIDI

451,0814 414,0825 414,0843 451,0833

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Oct 4, 1:10 PM EDT	Tornado Watch	SPC	Allegan, Antrim, Barry, Benzie, Berrien, Branch and 43 more	5 hr

Nearby

Tornado Watches in Michigan, 2002 Every tornado watch in 2002

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.