Alert archive / Arkansas / Mesoscale Discussions in 2021
Mesoscale Discussion 69
The Storm Prediction Center issued this mesoscale discussion at Feb 11, 2021, 4:02 AM CST for 20 counties in Arkansas; 4 counties in Mississippi; 19 counties in Tennessee. It was in force for 5 hr.
The area
The outline as issued.
The facts
- Issued
- Feb 11, 2021, 4:02 AM CST (10:02 UTC)
- Expired
- Feb 11, 2021, 9:00 AM CST
- In force
- 5 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Freezing rain
All 43 counties
Arkansas County, AR, Cleveland County, AR, Craighead County, AR, Crittenden County, AR, Cross County, AR, Grant County, AR, Jackson County, AR, Jefferson County, AR, Lee County, AR, Lincoln County, AR, Lonoke County, AR, Mississippi County, AR, Monroe County, AR, Phillips County, AR, Poinsett County, AR, Prairie County, AR, Pulaski County, AR, St. Francis County, AR, White County, AR, Woodruff County, AR, Coahoma County, MS, DeSoto County, MS, Tate County, MS, Tunica County, MS, Benton County, TN, Carroll County, TN, Chester County, TN, Crockett County, TN, Decatur County, TN, Dyer County, TN, Fayette County, TN, Gibson County, TN, Hardeman County, TN, Haywood County, TN, Henderson County, TN, Henry County, TN, Houston County, TN, Humphreys County, TN, Lauderdale County, TN, Madison County, TN, Shelby County, TN, Tipton County, TN, Weakley County, TN
The radar
The Memphis radar (KNQA), 10 km from the middle of the area, began a volume at 10:07 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
Little Rock, AR (KLZK), launched 00:00Z, 10.0 hours before the alert went out and 62 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.
- Mixed-layer CAPE
- 13 J/kg
- Mixed-layer CIN
- 0 J/kg
- Mixed-layer LCL
- 403 m above ground
- 0-6 km bulk shear
- 51 kt
- 0-1 km storm-relative helicity
- 174 m²/s²
- 0-3 km storm-relative helicity
- 206 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.1
The text
As transmitted.
627
ACUS11 KWNS 111002
SWOMCD
SPC MCD 111002
TNZ000-MSZ000-MOZ000-ARZ000-111500-
Mesoscale Discussion 0069
NWS Storm Prediction Center Norman OK
0402 AM CST Thu Feb 11 2021
Areas affected...eastern Arkansas...northwest Mississippi through
western Tennessee
Concerning...Freezing rain
Valid 111002Z - 111500Z
SUMMARY...Areas of freezing rain will continue through eastern
Arkansas, west Tennessee and northwest Mississippi through the early
morning hours before gradually diminishing after 14Z. Rainfall rates
occasionally from 0.05 to 0.1 inch per hour remain likely.
DISCUSSION...Isentropic ascent and low-level theta-e advection above
a cold, stable surface layer associated with the leading edge of
arctic air will maintain areas of scattered showers and
thunderstorms early this morning. RAP analysis indicates MUCAPE from
200-400 J/kg in the convective layer where 6.5-7 C/km mid-level
lapse rates exist. Surface temperatures are generally in the upper
20s to around 30F. The low-level jet will maintain a large melting
layer aloft, likely resulting in freezing rain as the dominant
precipitation type for the duration of the event. Rates will
occasionally reach 0.1 inch per hour within the deeper convective
elements. A weak, progressive mid-level impulse and the accompanying
low-level jet will continue east of this region through the morning.
This should result in a gradual decrease in precipitation after 14Z.
..Dial.. 02/11/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...OHX...MEG...JAN...LZK...
LAT...LON 36009038 36368872 36338769 35798772 35098917 34039065
33809262 35069238 36009038SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Feb 10, 10:36 PM CST | Mesoscale Discussion | SPC | Arkansas, Cleveland, Crittenden, Cross, Dallas, Desha and 15 more | 5 hr |
Nearby
Mesoscale Discussions in Arkansas, 2021Mesoscale Discussions in Tennessee, 2021Mesoscale Discussions in Mississippi, 2021Every 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.