Alert archive / Indiana / Mesoscale Discussions in 2014

Mesoscale Discussion 1621

August 26, 201420 counties in Indiana; 19 counties in Michigan; 4 counties in Ohio

The Storm Prediction Center issued this mesoscale discussion at Aug 26, 2014, 1:49 PM EDT for 20 counties in Indiana; 19 counties in Michigan; 4 counties in Ohio. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued
Aug 26, 2014, 1:49 PM EDT (17:49 UTC)
Expired
Aug 26, 2014, 4:15 PM EDT
In force
2 hr
Issued by
the Storm Prediction Center
Chance of a watch
20%
All 43 counties

Allen County, IN, Carroll County, IN, Cass County, IN, DeKalb County, IN, Elkhart County, IN, Fulton County, IN, Grant County, IN, Howard County, IN, Huntington County, IN, Kosciusko County, IN, LaGrange County, IN, Marshall County, IN, Miami County, IN, Noble County, IN, Pulaski County, IN, Steuben County, IN, Wabash County, IN, Wells County, IN, White County, IN, Whitley County, IN, Barry County, MI, Branch County, MI, Calhoun County, MI, Clinton County, MI, Eaton County, MI, Genesee County, MI, Gratiot County, MI, Hillsdale County, MI, Ingham County, MI, Ionia County, MI, Jackson County, MI, Kalamazoo County, MI, Lenawee County, MI, Livingston County, MI, Oakland County, MI, Saginaw County, MI, Saint Joseph County, MI, Shiawassee County, MI, Washtenaw County, MI, Defiance County, OH, Fulton County, OH, Paulding County, OH, Williams County, OH

The radar

The Northern Indiana radar (KIWX), 64 km from the middle of the area, began a volume at 17:50 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 nearest sounding before it

Detroit, MI (KDTX), launched 12:00Z, 5.8 hours before the alert went out and 178 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 12:00Z on 2014-08-26Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 91 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 12:00Z on 2014-08-26The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 102 square meters per square second.1939Sfc1 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
91 J/kg
Mixed-layer CIN
-226 J/kg
Mixed-layer LCL
1506 m above ground
0-6 km bulk shear
25 kt
0-1 km storm-relative helicity
102 m²/s²
0-3 km storm-relative helicity
104 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.2

Open this sounding in Storm Lab

The text

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

938 
ACUS11 KWNS 261749
SWOMCD
SPC MCD 261749 
MIZ000-OHZ000-INZ000-262015-

MESOSCALE DISCUSSION 1621
NWS STORM PREDICTION CENTER NORMAN OK
1249 PM CDT TUE AUG 26 2014

AREAS AFFECTED...NORTHERN INDIANA...NORTHWEST OHIO...SOUTHERN LOWER
MICHIGAN

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

VALID 261749Z - 262015Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...THUNDERSTORMS CROSSING THE REGION THIS AFTERNOON MAY
PRODUCE LOCALIZED DMGG WIND GUSTS AND PERHAPS MARGINALLY SVR HAIL.
CONVECTIVE TRENDS WILL CONTINUE TO BE MONITORED...THOUGH WW ISSUANCE
IS CURRENTLY UNLIKELY.

DISCUSSION...MOSAIC RADAR LOOPS INDICATE LONGER-LIVED MULTICELL
CLUSTERS BECOMING LOOSELY ORGANIZED INTO A BROKEN SQUALL LINE FROM
SWRN LOWER MI TO E-CNTRL IL. THIS IS OCCURRING IN AN ENVIRONMENT
CHARACTERIZED BY WEAK SYNOPTIC FORCING FOR ASCENT. VWPS ACROSS THE
REGION SAMPLE ONLY MODEST MID-LEVEL FLOW -- E.G. 15-25 KT FROM 4 TO
6 KM AGL...STRONGEST IN LOWER MI. HOWEVER...THE AIR MASS CONTINUES
TO DESTABILIZE IN ADVANCE OF THE ONGOING ACTIVITY OWING TO DIURNAL
HEATING OF A MOIST BOUNDARY LAYER -- E.G. SFC DEWPOINTS IN THE UPPER
60S TO AROUND 70F -- YIELDING MLCAPE ON THE ORDER OF 1000-2000 J/KG.
THIS SHOULD ENCOURAGE FORWARD PROPAGATION OF THE ONGOING STORMS
EWD...AIDED BY 15-20 KT OF 1-3-KM-AGL FLOW FAVORING EWD SPREAD OF
COLD POOLS. ISOLATED MARGINALLY SVR WIND/HAIL MAY ACCOMPANY THE MOST
INTENSE STORMS. HOWEVER...WITHOUT STRONGER DEEP SHEAR...A MORE
ORGANIZED...FASTER-MOVING SYSTEM WITH A GREATER-COVERAGE SVR-TSTM
RISK IS NOT CURRENTLY ANTICIPATED. HOWEVER...CONVECTIVE TRENDS WILL
CONTINUE TO BE MONITORED.

..COHEN/MEAD.. 08/26/2014

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

ATTN...WFO...CLE...DTX...IWX...GRR...IND...LOT...

LAT...LON   40378738 41898600 43378495 43368347 42798307 41618378
            40478539 40378738

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 25, 8:45 PM EDTMesoscale DiscussionSPCBenton, Boone, Carroll, Cass, Clinton, Fountain and 17 more60 min
Aug 26, 10:34 AM EDTMesoscale DiscussionSPCLake, Porter116 min
Aug 26, 3:09 PM EDTMesoscale DiscussionSPCBartholomew, Blackford, Boone, Brown, Clay, Clinton and 33 more3 hr

Nearby

Mesoscale Discussions in Indiana, 2014Mesoscale Discussions in Michigan, 2014Mesoscale Discussions in Ohio, 2014Every mesoscale discussion in 2014

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.