Alert archive / Indiana / Mesoscale Discussions in 2017

Mesoscale Discussion 849

May 26, 20179 counties in Illinois; 31 counties in Indiana

The Storm Prediction Center issued this mesoscale discussion at May 26, 2017, 6:30 PM CDT for 9 counties in Illinois; 31 counties in Indiana. It was in force for 90 min.

The area

The outline as issued.

The facts

Issued: May 26, 2017, 6:30 PM CDT (23:30 UTC)
Expired: May 26, 2017, 8:00 PM CDT
In force: 90 min
Issued by: the Storm Prediction Center

All 40 counties

Champaign County, IL, Clark County, IL, Coles County, IL, Cumberland County, IL, Douglas County, IL, Edgar County, IL, Moultrie County, IL, Piatt County, IL, Vermilion County, IL, Bartholomew County, IN, Boone County, IN, Brown County, IN, Clay County, IN, Clinton County, IN, Decatur County, IN, Fayette County, IN, Fountain County, IN, Franklin County, IN, Hamilton County, IN, Hancock County, IN, Hendricks County, IN, Henry County, IN, Johnson County, IN, Madison County, IN, Marion County, IN, Monroe County, IN, Montgomery County, IN, Morgan County, IN, Owen County, IN, Parke County, IN, Putnam County, IN, Rush County, IN, Shelby County, IN, Tippecanoe County, IN, Tipton County, IN, Union County, IN, Vermillion County, IN, Vigo County, IN, Warren County, IN, Wayne County, IN

The radar

The Indianapolis radar (KIND), 82 km from the middle of the area, began a volume at 23:34 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 270May 26, 7:10 PM CDT

The nearest sounding before it

Lincoln, IL (KILX), launched 12:00Z, 11.5 hours before the alert went out and 124 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 1724 m above ground
0-6 km bulk shear: 34 kt
0-1 km storm-relative helicity: 151 m²/s²
0-3 km storm-relative helicity: 131 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

496 
ACUS11 KWNS 262331
SWOMCD
SPC MCD 262330 
OHZ000-INZ000-ILZ000-270100-

Mesoscale Discussion 0849
NWS Storm Prediction Center Norman OK
0630 PM CDT Fri May 26 2017

Areas affected...East-central IL...Central into southeast IN

Concerning...Tornado Watch 269...

Valid 262330Z - 270100Z

The severe weather threat for Tornado Watch 269 continues.

SUMMARY...The threat for large hail, damaging wind, and perhaps a
tornado continues across valid portion of Tornado Watch 269. A
downstream severe thunderstorm watch is possible for
central/southeast IN and perhaps southwest OH.

DISCUSSION...At 2330Z, a thunderstorm cluster with an embedded
intense supercell is moving into west-central IN. In the short term,
the threat for large hail and damaging wind will continue with this
cluster, with at least some tornado threat associated with the
long-lived mesocyclone currently moving into Warren and Fountain
counties in Indiana.  

The downstream airmass across central IN is not as moist and
unstable as areas further west, but steep midlevel lapse rates and
ascent attendant to the MCV that initiated this cluster will likely
result in maintenance of the convective system for the next few
hours. The tornado threat will tend to diminish with time as the
environment for surface-based convection becomes more hostile, but
some hail and wind threat may persist into this evening into
central/eastern IN and perhaps southwest OH. 

Depending on convective trends over the next hour, downstream severe
thunderstorm issuance is possible. Local extension of WW 269 is also
possible if the threat primarily appears to be in the short term.
Meanwhile, redevelopment north of the trailing outflow cannot be
ruled out across portions of central IL, though this risk will
decrease with time this evening.

..Dean/Guyer.. 05/26/2017

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...ILN...IND...LOT...ILX...

LAT...LON   40378879 40518789 40468661 40238561 39908473 39258473
            39058566 39078659 39168739 39268826 39488855 39668878
            39978895 40378879

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 26, 1:25 PM CDT	Mesoscale Discussion	SPC	Champaign, Coles, DeWitt, Douglas, Edgar, Ford and 8 more	3 hr
May 26, 2:45 PM CDT	Tornado Watch	SPC	Champaign, DeWitt, Ford, Fulton, Iroquois, Kankakee and 10 more	5 hr
May 26, 4:31 PM CDT	Mesoscale Discussion	SPC	Champaign, DeWitt, Ford, Fulton, Iroquois, Kankakee and 12 more	59 min

Nearby

Mesoscale Discussions in Indiana, 2017 Mesoscale Discussions in Illinois, 2017 Every mesoscale discussion in 2017

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.