Alert archive / Illinois / Mesoscale Discussions in 2016

Mesoscale Discussion 29

January 19, 20164 states

The Storm Prediction Center issued this mesoscale discussion at Jan 19, 2016, 8:21 PM CST for 4 states. It was in force for 3 hr.

The area

The outline as issued.

The facts

Issued: Jan 19, 2016, 8:21 PM CST (02:21 UTC)
Expired: Jan 19, 2016, 11:15 PM CST
In force: 3 hr
Issued by: the Storm Prediction Center

All 77 counties

Bond County, IL, Champaign County, IL, Christian County, IL, Clark County, IL, Clay County, IL, Clinton County, IL, Coles County, IL, Crawford County, IL, Cumberland County, IL, DeWitt County, IL, Douglas County, IL, Edgar County, IL, Edwards County, IL, Effingham County, IL, Fayette County, IL, Franklin County, IL, Gallatin County, IL, Greene County, IL, Hamilton County, IL, Hardin County, IL, Jackson County, IL, Jasper County, IL, Jefferson County, IL, Jersey County, IL, Johnson County, IL, Lawrence County, IL, Macon County, IL, Macoupin County, IL, Madison County, IL, Marion County, IL, Montgomery County, IL, Morgan County, IL, Moultrie County, IL, Perry County, IL, Piatt County, IL, Pope County, IL, Pulaski County, IL, Randolph County, IL, Richland County, IL, Saint Clair County, IL, Saline County, IL, Sangamon County, IL, Scott County, IL, Shelby County, IL, Union County, IL, Wabash County, IL, Washington County, IL, Wayne County, IL, White County, IL, Williamson County, IL, Clay County, IN, Crawford County, IN, Daviess County, IN, Dubois County, IN, Gibson County, IN, Greene County, IN, Knox County, IN, Lawrence County, IN, Martin County, IN, Monroe County, IN, Orange County, IN, Owen County, IN, Parke County, IN, Pike County, IN, Posey County, IN, Putnam County, IN, Spencer County, IN, Sullivan County, IN, Vanderburgh County, IN, Vermillion County, IN, Vigo County, IN, Warrick County, IN, Henderson County, KY, Union County, KY, Bollinger County, MO, Cape Girardeau County, MO, Perry County, MO

The radar

The Evansville,IN radar (KVWX), 107 km from the middle of the area, began a volume at 02:24 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

Lincoln, IL (KILX), launched 00:00Z, 2.4 hours before the alert went out and 172 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: 879 m above ground
0-6 km bulk shear: 47 kt
0-1 km storm-relative helicity: 85 m²/s²
0-3 km storm-relative helicity: 193 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

137 
ACUS11 KWNS 200221
SWOMCD
SPC MCD 200221 
INZ000-KYZ000-ILZ000-MOZ000-200515-

MESOSCALE DISCUSSION 0029
NWS STORM PREDICTION CENTER NORMAN OK
0821 PM CST TUE JAN 19 2016

AREAS AFFECTED...CNTRL/SRN IL AND ADJACENT PORTIONS OF SE MO...WRN
KY...W CNTRL/SW IND

CONCERNING...HEAVY SNOW 

VALID 200221Z - 200515Z

SUMMARY...SNOW...INCLUDING AT LEAST A COUPLE HOUR PERIOD OF HEAVY
SNOW RATES IN EXCESS OF 1 INCH PER HOUR...WILL OVERSPREAD MUCH OF
CENTRAL AND SOUTHERN ILLINOIS AND PORTIONS OF ADJACENT STATES
THROUGH 03-06Z...BEFORE DIMINISHING.  HEAVIEST SNOW RATES MAY IMPACT
THE I-64 CORRIDOR NEAR MT. VERNON IL THROUGH THE EVANSVILLE IND
AREA.

DISCUSSION...AN AREA OF DEVELOPING SNOW ACROSS THE MIDDLE
MISSISSIPPI VALLEY APPEARS LARGELY IN RESPONSE TO FORCING ASSOCIATED
WITH LOW-LEVEL WARM ADVECTION...IN ADVANCE OF A COUPLE OF SHORT WAVE
TROUGHS PROGRESSING INTO/THROUGH THE MISSISSIPPI VALLEY.  AS A
SOUTHWESTERLY 850 MB SPEED MAXIMUM STRENGTHENS EAST OF THE I-44
CORRIDOR OF SOUTH CENTRAL MISSOURI...TOWARD SOUTHERN ILLINOIS...
HOURLY SNOW RATES APPEAR TO BE INCREASING SOUTH THROUGH EAST OF THE
GREATER ST. LOUIS METROPOLITAN AREA.  SNOW RATES MAY INTENSIFY
FURTHER THROUGH THE 03-06Z TIME FRAME...WITH INCREASING LARGE-SCALE
ASCENT AND LOW-LEVEL MOISTURE RETURN ACROSS AND SOUTH OF THE I-64
CORRIDOR OF SOUTHERN ILLINOIS INTO SOUTHERN INDIANA.

ANOTHER RELATIVE MAXIMUM IN SNOWFALL RATES APPEARS TO BE DEVELOPING
ALONG A LOWER/MID TROPOSPHERIC THERMAL GRADIENT ACROSS THE
SPRINGFIELD/DECATUR IL AREA TOWARD TERRE HAUTE IN.  THIS MAY PERSIST
AND INTENSIFY FURTHER THROUGH LATE EVENING...BEFORE DIMINISHING
AFTER 06Z AS LARGE-SCALE ASCENT SHIFTS EASTWARD INTO THE OHIO VALLEY
AND WEAKENS.

GIVEN THE RELATIVELY HIGH SNOW TO LIQUID WATER RATIOS ASSOCIATED
WITH THE COLD LOW-LEVEL ENVIRONMENT...AND THE PLUME OF PRECIPITABLE
WATER ON THE ORDER OF ONE-HALF INCH OVERSPREADING THE REGION...LIFT
APPEARS SUFFICIENT TO SUPPORT AT LEAST A COUPLE HOUR PERIOD OF SNOW
RATES IN EXCESS OF 1 INCH PER HOUR.

..KERR.. 01/20/2016

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

ATTN...WFO...LMK...IND...PAH...ILX...LSX...

LAT...LON   38398991 39059054 39749073 40278867 39998724 39238627
            38208643 37618751 37158893 37269027 38149000 38398991

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jan 19, 9:36 PM CST	Mesoscale Discussion	SPC	Butler, Carter, Dunklin, Howell, New Madrid, Oregon and 5 more	5 hr

Nearby

Mesoscale Discussions in Illinois, 2016 Mesoscale Discussions in Indiana, 2016 Mesoscale Discussions in Missouri, 2016 Every mesoscale discussion in 2016

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.