Alert archive / Kentucky / Mesoscale Discussions in 2021

Mesoscale Discussion 67

February 10, 20214 states

The Storm Prediction Center issued this mesoscale discussion at Feb 10, 2021, 11:18 AM CST for 4 states. It was in force for 4 hr.

The area

The outline as issued.

The facts

Issued: Feb 10, 2021, 11:18 AM CST (17:18 UTC)
Expired: Feb 10, 2021, 3:15 PM CST
In force: 4 hr
Issued by: the Storm Prediction Center
Concerning: Freezing rain

All 78 counties

Alexander County, IL, Edwards County, IL, Franklin County, IL, Gallatin County, IL, Hamilton County, IL, Hardin County, IL, Jackson County, IL, Jefferson County, IL, Johnson County, IL, Lawrence County, IL, Massac County, IL, Perry County, IL, Pope County, IL, Pulaski County, IL, Saline County, IL, Union County, IL, Wabash County, IL, Wayne County, IL, White County, IL, Williamson County, IL, Clark County, IN, Crawford County, IN, Daviess County, IN, Dubois County, IN, Floyd County, IN, Gibson County, IN, Harrison County, IN, Jackson County, IN, Jefferson County, IN, Knox County, IN, Lawrence County, IN, Martin County, IN, Orange County, IN, Perry County, IN, Pike County, IN, Posey County, IN, Scott County, IN, Spencer County, IN, Vanderburgh County, IN, Warrick County, IN, Washington County, IN, Anderson County, KY, Ballard County, KY, Breckinridge County, KY, Bullitt County, KY, Butler County, KY, Caldwell County, KY, Carroll County, KY, Crittenden County, KY, Daviess County, KY, Edmonson County, KY, Grayson County, KY, Hancock County, KY, Hardin County, KY, Hart County, KY, Henderson County, KY, Henry County, KY, Hopkins County, KY, Jefferson County, KY, Larue County, KY, Livingston County, KY, Lyon County, KY, Marion County, KY, McCracken County, KY, McLean County, KY, Meade County, KY, Muhlenberg County, KY, Nelson County, KY, Ohio County, KY, Oldham County, KY, Shelby County, KY, Spencer County, KY, Trimble County, KY, Union County, KY, Washington County, KY, Webster County, KY, Cape Girardeau County, MO, Perry County, MO

The radar

The Evansville,IN radar (KVWX), 66 km from the middle of the area, began a volume at 17:16 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

Nashville Metro, TN (KBNA), launched 12:00Z, 5.3 hours before the alert went out and 194 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: 631 m above ground
0-6 km bulk shear: 74 kt
0-1 km storm-relative helicity: 456 m²/s²
0-3 km storm-relative helicity: 455 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

593 
ACUS11 KWNS 101718
SWOMCD
SPC MCD 101718 
KYZ000-INZ000-ILZ000-MOZ000-102115-

Mesoscale Discussion 0067
NWS Storm Prediction Center Norman OK
1118 AM CST Wed Feb 10 2021

Areas affected...Lower Ohio River Valley

Concerning...Freezing rain 

Valid 101718Z - 102115Z

SUMMARY...Freezing rain is expected to expand in coverage and
intensity across portions of the Ohio river valley this afternoon.
Freezing rain rates approaching 0.05 to 0.1 inches per hour will be
possible.

DISCUSSION...12z upper-air observations showed broad cyclonic flow
across the northern 3rd of the CONUS with several small shortwave
troughs embedded within this flow. Over the last 2 hours, radar data
shows stratiform precipitation across portions of southern Illinois
and eastern Missouri increasing in coverage/intensity likely due to
increased isentropic and large scale ascent from one of the
approaching shortwave troughs. Surface observations under the
developing band of precipitation indicate freezing rain/ mist as the
primary precipitation type across the area.

Hi-res model guidance and observational data suggest that rain rates
will gradually increase through the afternoon as isentropic ascent
continues to strengthen along and north of the surface front. A few
thunderstorms my also develop across the region with guidance
indicating MUCAPE around 100-150 J/kg aloft. Rates may approach 0.1
in/hr in the heaviest cores through this afternoon. Additional
precipitation will likely expand southwestward as greater forcing
for ascent develops aloft. Freezing rain and occasional sleet appear
to be the most likely precipitation types through the next several
hours given upstream and downstream RAOBS showing fairly uniform
+1-2 C warm layers atop sub freezing surface layers.

..Lyons/Goss.. 02/10/2021

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

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

LAT...LON   36968841 37008932 37509009 38058982 38718792 39058618
            39048576 38678499 38118491 37648511 37258574 37148708
            37008803 36968841

Nearby

Mesoscale Discussions in Kentucky, 2021 Mesoscale Discussions in Indiana, 2021 Mesoscale Discussions in Illinois, 2021 Every mesoscale discussion in 2021

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.