Alert archive / Indiana / Mesoscale Discussions in 2011

Mesoscale Discussion 635

April 27, 201113 counties in Illinois; 59 counties in Indiana; 6 counties in Kentucky

The Storm Prediction Center issued this mesoscale discussion at Apr 27, 2011, 5:27 PM CDT for 13 counties in Illinois; 59 counties in Indiana; 6 counties in Kentucky. It was in force for 63 min.

The area

The outline as issued.

The facts

Issued
Apr 27, 2011, 5:27 PM CDT (22:27 UTC)
Expired
Apr 27, 2011, 6:30 PM CDT
In force
63 min
Issued by
the Storm Prediction Center
All 78 counties

Clark County, IL, Crawford County, IL, Edwards County, IL, Gallatin County, IL, Hamilton County, IL, Hardin County, IL, Lawrence County, IL, Pope County, IL, Richland County, IL, Saline County, IL, Wabash County, IL, Wayne County, IL, White County, IL, Bartholomew County, IN, Blackford County, IN, Boone County, IN, Brown County, IN, Clark County, IN, Clay County, IN, Clinton County, IN, Crawford County, IN, Daviess County, IN, Dearborn County, IN, Decatur County, IN, Delaware County, IN, Dubois County, IN, Fayette County, IN, Floyd County, IN, Franklin County, IN, Gibson County, IN, Grant County, IN, Greene County, IN, Hamilton County, IN, Hancock County, IN, Hendricks County, IN, Henry County, IN, Jackson County, IN, Jay County, IN, Jefferson County, IN, Jennings County, IN, Johnson County, IN, Knox County, IN, Lawrence County, IN, Madison County, IN, Marion County, IN, Martin County, IN, Monroe County, IN, Montgomery County, IN, Morgan County, IN, Ohio County, IN, Orange County, IN, Owen County, IN, Parke County, IN, Perry County, IN, Pike County, IN, Posey County, IN, Putnam County, IN, Randolph County, IN, Ripley County, IN, Rush County, IN, Scott County, IN, Shelby County, IN, Spencer County, IN, Sullivan County, IN, Switzerland County, IN, Tipton County, IN, Union County, IN, Vanderburgh County, IN, Vigo County, IN, Warrick County, IN, Washington County, IN, Wayne County, IN, Crittenden County, KY, Daviess County, KY, Henderson County, KY, Trimble County, KY, Union County, KY, Webster County, KY

The radar

The Indianapolis radar (KIND), 94 km from the middle of the area, began a volume at 22:29 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.

The nearest sounding before it

Lincoln, IL (KILX), launched 12:00Z, 10.5 hours before the alert went out and 225 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, Lincoln, IL at 12:00Z on 2011-04-27Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Lincoln, IL at 12:00Z on 2011-04-27The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 64 square meters per square second.1939587897117136Sfc1 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
791 m above ground
0-6 km bulk shear
56 kt
0-1 km storm-relative helicity
64 m²/s²
0-3 km storm-relative helicity
93 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

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

638 
ACUS11 KWNS 272227
SWOMCD
SPC MCD 272227 
OHZ000-KYZ000-INZ000-ILZ000-272330-

MESOSCALE DISCUSSION 0635
NWS STORM PREDICTION CENTER NORMAN OK
0527 PM CDT WED APR 27 2011

AREAS AFFECTED...SERN IL...CNTRL/SRN IND

CONCERNING...TORNADO WATCH 237...239...

VALID 272227Z - 272330Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 237...239...CONTINUES.

A NEW TORNADO WATCH WILL LIKELY BECOME NECESSARY N OF WW/S 237/239
INTO PORTIONS OF CNTRL/SRN IND BY 00Z.

22Z SURFACE ANALYSIS PLACED A 995 MB SURFACE LOW IN EXTREME SRN IL
AND A QUASI-STATIONARY FRONT EXTENDING NEWD BISECTING IND. ONGOING
CONVECTIVE CLUSTER/NARROW QLCS COINCIDENT WITH THE SURFACE LOW HAS
HAD A HISTORY OF EMBEDDED ROTATIONAL SIGNATURES WITHIN A VERY
STRONGLY SHEARED ENVIRONMENT...0-1 KM SRH AROUND 300 M2/S2 SAMPLED
BY PAH VWP DATA. AFTERNOON MODEL GUIDANCE IS CONSISTENT IN TRACKING
THE SURFACE LOW NEWD ALONG THE QUASI-STATIONARY FRONT THROUGH THE
EVENING HOURS. ALTHOUGH DESTABILIZATION AHEAD OF THE CYCLONE SHOULD
REMAIN WEAK...ENOUGH OF A BREAK BETWEEN THE PRIMARY
STRATIFORM/CONVECTIVE REGION IN SERN IND/CNTRL KY MAY BE SUFFICIENT
TO MAINTAIN TSTM INTENSITY TO THE NE. ISOLATED TORNADOES AND
DAMAGING WINDS WILL REMAIN THE MAIN THREATS.

..GRAMS.. 04/27/2011

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

ATTN...WFO...ILN...LMK...IWX...IND...PAH...ILX...

LAT...LON   37298795 37208863 38098889 39518772 40238688 40638558
            40518488 40008477 39488460 39078465 38488554 37788699
            37298795

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 26, 8:35 PM CDTMesoscale DiscussionSPCCrawford, Edwards, Gallatin, Lawrence, Wabash, White55 min
Apr 26, 9:13 PM CDTMesoscale DiscussionSPCAlexander, Gallatin, Hardin, Johnson, Massac, Pope and 5 more62 min
Apr 27, 12:42 PM CDTSevere Thunderstorm WatchSPCAlexander, Hardin, Johnson, Massac, Pope, Pulaski and 1 more5 hr
Apr 27, 3:06 PM CDTMesoscale DiscussionSPCAlexander, Edwards, Franklin, Gallatin, Hamilton, Hardin and 10 more54 min
Apr 27, 3:29 PM CDTTornado WatchSPCAlexander, Edwards, Franklin, Gallatin, Hamilton, Hardin and 13 more5 hr
Apr 26, 7:33 PM CDTMesoscale DiscussionSPCAdams, Allen, Blackford, Boone, Carroll, Cass and 35 more57 min
Apr 26, 9:58 PM CDTTornado WatchSPCClark, Crawford, Dubois, Floyd, Harrison, Jefferson and 4 more7 hr
Apr 27, 4:38 PM CDTMesoscale DiscussionSPCClark, Crawford, Floyd, Harrison, Jefferson, Ohio and 4 more37 min
Apr 27, 4:44 PM CDTTornado WatchSPCClark, Crawford, Dubois, Floyd, Harrison, Jefferson and 5 more7 hr
Apr 27, 6:22 PM CDTTornado WatchSPCAdams, Bartholomew, Blackford, Boone, Brown, Carroll and 49 more8 hr
Apr 27, 4:33 AM CDTMesoscale DiscussionSPCAdair, Barren, Boyle, Casey, Clinton, Cumberland and 12 more57 min
Apr 27, 5:07 AM CDTTornado WatchSPCAdair, Allen, Anderson, Barren, Bourbon, Boyle and 28 more5 hr
Apr 27, 7:34 AM CDTTornado WatchSPCBath, Bell, Breathitt, Clay, Elliott, Estill and 21 more4 hr
Apr 27, 8:39 AM CDTMesoscale DiscussionSPCBoyd, Carter, Greenup, Lewis66 min
Apr 27, 2:22 PM CDTMesoscale DiscussionSPCBell, Breathitt, Clay, Floyd, Harlan, Jackson and 11 more83 min

Nearby

Mesoscale Discussions in Indiana, 2011Mesoscale Discussions in Illinois, 2011Mesoscale Discussions in Kentucky, 2011Every mesoscale discussion 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.