Alert archive / Michigan / Mesoscale Discussions in 2007

Mesoscale Discussion 2016

September 25, 200714 counties in Illinois; 11 counties in Indiana; 19 counties in Michigan

The Storm Prediction Center issued this mesoscale discussion at Sep 25, 2007, 1:36 PM CDT for 14 counties in Illinois; 11 counties in Indiana; 19 counties in Michigan. It was in force for 84 min.

The area

The outline as issued.

The facts

Issued: Sep 25, 2007, 1:36 PM CDT (18:36 UTC)
Expired: Sep 25, 2007, 3:00 PM CDT
In force: 84 min
Issued by: the Storm Prediction Center

All 44 counties

Cook County, IL, DuPage County, IL, Ford County, IL, Grundy County, IL, Iroquois County, IL, Kane County, IL, Kankakee County, IL, Kendall County, IL, Lake County, IL, LaSalle County, IL, Livingston County, IL, Putnam County, IL, Will County, IL, Woodford County, IL, Elkhart County, IN, Jasper County, IN, LaGrange County, IN, Lake County, IN, LaPorte County, IN, Marshall County, IN, Newton County, IN, Porter County, IN, Pulaski County, IN, Saint Joseph County, IN, Starke County, IN, Allegan County, MI, Barry County, MI, Berrien County, MI, Branch County, MI, Calhoun County, MI, Cass County, MI, Clinton County, MI, Eaton County, MI, Gratiot County, MI, Ingham County, MI, Ionia County, MI, Jackson County, MI, Kalamazoo County, MI, Kent County, MI, Montcalm County, MI, Ottawa County, MI, Saint Joseph County, MI, Shiawassee County, MI, Van Buren County, MI

The radar

The Northern Indiana radar (KIWX), 100 km from the middle of the area, began a volume at 18:37 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 watches that followed

Watches SPC issued over any of the same counties within four hours of this discussion.

Severe Thunderstorm Watch 689Sep 25, 3:00 PM CDT

The nearest sounding before it

Lincoln, IL (KILX), launched 12:00Z, 6.6 hours before the alert went out and 250 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: 1485 J/kg
Mixed-layer CIN: -24 J/kg
Mixed-layer LCL: 726 m above ground
0-6 km bulk shear: 38 kt
0-1 km storm-relative helicity: -76 m²/s²
0-3 km storm-relative helicity: -22 m²/s²
Significant tornado parameter: -0.4
Supercell composite: -2.3

Open this sounding in Storm Lab

The text

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

000 
ACUS11 KWNS 251837
SWOMCD
SPC MCD 251836 
MIZ000-INZ000-ILZ000-252000-

MESOSCALE DISCUSSION 2016
NWS STORM PREDICTION CENTER NORMAN OK
0136 PM CDT TUE SEP 25 2007

AREAS AFFECTED...NERN IL / NWRN IND / PORTIONS OF SRN AND CNTRL
LOWER MI

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

VALID 251836Z - 252000Z

TSTMS ARE EXPECTED TO INCREASE IN BOTH COVERAGE AND INTENSITY BY MID
TO LATE AFTERNOON ACROSS DISCUSSION AREA.  POTENTIAL WILL EXIST FOR
A FEW SEVERE STORMS CAPABLE OF MAINLY DAMAGING WINDS AND A WW MAY
BECOME NECESSARY.

BREAKS IN THE MID AND HIGH-LEVEL CLOUDS HAVE ALLOWED FOR LOCALLY
STRONGER DIABATIC HEATING TO OCCUR TODAY IN PRE-FRONTAL WARM SECTOR
FROM W-CNTRL IL NEWD INTO SRN LOWER MI WHERE TEMPERATURES HAVE
WARMED TO 80-85 F.  THIS HEATING COUPLED WITH A MOIST BOUNDARY LAYER
ARE CONTRIBUTING TO A MODERATELY UNSTABLE /MLCAPES OF 1000-1500 J
PER KG/ AND VERY WEAKLY CAPPED ENVIRONMENT AS OF 18Z.  BOTH VISIBLE
SATELLITE AND REGIONAL RADAR IMAGERY CONFIRM TSTMS DEVELOPING ALONG
MULTIPLE PRE-FRONTAL CONFLUENCE ZONES...NAMELY OVER PORTIONS OF
CNTRL AND NRN IL.

INSPECTION OF AREA VWPS SHOWS THAT THE STRONGER MID AND HIGH-LEVEL
WIND FIELDS AND RESULTANT DEEP LAYER VERTICAL SHEAR EXISTS FROM THE
CHICAGO AREA NWD.  LARGELY UNIDIRECTIONAL DEEP LAYER WIND FIELDS
ORIENTED PARALLEL TO THE INITIATING BOUNDARIES SUGGESTS THAT STORMS
SHOULD GRADUALLY GROW UPSCALE INTO MULTIPLE LINE SEGMENTS.  WHILE
SOME HAIL WILL BE POSSIBLE...IT APPEARS THAT LOCALLY DAMAGING WINDS
WILL BE THE PRIMARY SEVERE WEATHER HAZARD.

..MEAD.. 09/25/2007

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...DTX...IWX...GRR...LOT...ILX...DVN...

40698932 41528929 43118665 43568500 43268407 42638392
41918469 41138631 40278828

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Sep 25, 2:59 PM CDT	Severe Thunderstorm Watch	SPC	Ford, Iroquois, Kankakee, Will	6 hr
Sep 24, 7:37 PM CDT	Mesoscale Discussion	SPC	Baraga, Dickinson, Iron	83 min

Nearby

Mesoscale Discussions in Michigan, 2007 Mesoscale Discussions in Illinois, 2007 Mesoscale Discussions in Indiana, 2007 Every mesoscale discussion in 2007

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.