Alert archive / Michigan / Severe Thunderstorm Watches in 2011

Severe Thunderstorm Watch 697

July 29, 20115 counties in Indiana; 15 counties in Michigan; Fulton County, Williams County, Ohio

The Storm Prediction Center issued this severe thunderstorm watch at Jul 29, 2011, 2:15 AM EDT for 5 counties in Indiana; 15 counties in Michigan; Fulton County, Williams County, Ohio. It was in force for 6 hr.

The area

The outline as issued.

The facts

Issued: Jul 29, 2011, 2:15 AM EDT (06:15 UTC)
Expired: Jul 29, 2011, 8:06 AM EDT
In force: 6 hr
Issued by: the Storm Prediction Center
Largest hail expected: 0.5 in
Strongest gust expected: 60 kt

All 22 counties

Elkhart County, IN, LaGrange County, IN, LaPorte County, IN, Saint Joseph County, IN, Steuben County, IN, Berrien County, MI, Branch County, MI, Calhoun County, MI, Cass County, MI, Hillsdale County, MI, Jackson County, MI, Lenawee County, MI, Livingston County, MI, Macomb County, MI, Monroe County, MI, Oakland County, MI, Saint Clair County, MI, Saint Joseph County, MI, Washtenaw County, MI, Wayne County, MI, Fulton County, OH, Williams County, OH

The radar

The Northern Indiana radar (KIWX), 109 km from the middle of the area, began a volume at 06:18 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 SPC expected

The probabilities SPC published with the watch, for the watch area over its life.

Two or more tornadoes: 10%
One or more EF2 to EF5 tornadoes: 2%
Ten or more severe wind reports: 30%
One or more gusts of 65 knots or more: 10%
Ten or more severe hail reports: 10%
One or more hailstones of 2 inches or more: 5%
Six or more combined severe hail and wind reports: 60%

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
Jul 29, 2:30 AM EDT	Severe Thunderstorm Warning	IWX	Berrien, Cass	30 min

Discussions around it

SPC mesoscale discussions over the same counties from four hours before the watch to its end.

The nearest sounding before it

Detroit, MI (KDTX), launched 00:00Z, 6.3 hours before the alert went out and 133 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: 2191 J/kg
Mixed-layer CIN: -1 J/kg
Mixed-layer LCL: 825 m above ground
0-6 km bulk shear: 33 kt
0-1 km storm-relative helicity: 87 m²/s²
0-3 km storm-relative helicity: 99 m²/s²
Significant tornado parameter: 0.7
Supercell composite: 3.4

Open this sounding in Storm Lab

The text

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

475 
WWUS20 KWNS 290619
SEL7
SPC WW 290619
INZ000-MIZ000-OHZ000-LEZ000-LHZ000-LMZ000-291400-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 697
NWS STORM PREDICTION CENTER NORMAN OK
215 AM EDT FRI JUL 29 2011

THE NWS STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

       FAR NORTHERN INDIANA
       SOUTHERN LOWER MICHIGAN
       FAR NORTHWEST OHIO
       FAR WESTERN LAKE ERIE
       FAR SOUTHERN LAKE HURON
       FAR SOUTHEASTERN LAKE MICHIGAN

EFFECTIVE THIS FRIDAY MORNING FROM 215 AM UNTIL 1000 AM EDT.

HAIL TO 0.5 INCH IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70
MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 80
STATUTE MILES EAST AND WEST OF A LINE FROM 35 MILES EAST
SOUTHEAST OF SOUTH BEND INDIANA TO 20 MILES NORTHEAST OF MOUNT
CLEMENS MICHIGAN.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU7).

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.

DISCUSSION...SMALL SCALE BOWS WITH LOCALLY DMGG WIND MAY OCCUR OVER
WW THIS MORNING...WHERE ZONE OF JET ENTRANCE REGION ASCENT AND LOW
LVL WAA WILL REMAIN COINCIDENT WITH CORRIDOR OF 2.25 INCH PW AND
MODERATE...DEEP UNIDIRECTIONAL FLOW.  MID LVL WLY WINDS MAY INCREASE
TO AROUND 50 KTS OVER SE LWR MI BY DAWN...AND COULD EXTEND RISK FOR
BOWING STRUCTURES/SPORADIC HIGH WIND EWD INTO LK ERIE.

AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 0.5 INCH. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60
KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM
MOTION VECTOR 26030.


...CORFIDI

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 29, 12:51 AM EDT	Mesoscale Discussion	SPC	Elkhart, Lake, LaPorte, Porter, Saint Joseph	84 min
Jul 29, 3:31 AM EDT	Mesoscale Discussion	SPC	DeKalb, Elkhart, LaGrange, Steuben	89 min
Jul 29, 4:51 PM EDT	Mesoscale Discussion	SPC	Bartholomew, Blackford, Boone, Brown, Clay, Clinton and 31 more	84 min
Jul 29, 3:56 AM EDT	Severe Thunderstorm Watch	SPC	Ashtabula, Cuyahoga, Erie, Geauga, Lake, Lorain and 4 more	5 hr
Jul 29, 2:06 PM EDT	Mesoscale Discussion	SPC	Ashland, Belmont, Carroll, Champaign, Clark, Columbiana and 35 more	84 min

Nearby

Severe Thunderstorm Watches in Michigan, 2011 Severe Thunderstorm Watches in Indiana, 2011 Severe Thunderstorm Watches in Ohio, 2011 Every severe thunderstorm watch in 2011

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.