Mesoscale Discussion 87

Issued

Feb 15, 2021, 9:28 AM CST (15:28 UTC)

Expired

Feb 15, 2021, 3:30 PM CST

In force

6 hr

Issued by

the Storm Prediction Center

Concerning

Freezing rain

The Northeast Alabama radar (KHTX), 105 km from the middle of the area, began a volume at 15:30 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.

593 
ACUS11 KWNS 151528
SWOMCD
SPC MCD 151528 
KYZ000-TNZ000-ALZ000-MSZ000-LAZ000-152130-

Mesoscale Discussion 0087
NWS Storm Prediction Center Norman OK
0928 AM CST Mon Feb 15 2021

Areas affected...southeastern Louisiana...eastern
Mississippi...western Alabama...middle Tennessee...and
central/eastern Kentucky

Concerning...Freezing rain 

Valid 151528Z - 152130Z

SUMMARY...A relatively narrow band of freezing rain will persist for
several hours across the discussion area.  The onset of freezing
rain will occur in portions of Tennessee in the next hour or so and
in Kentucky after around 18-19Z.

DISCUSSION...Recent radar mosaic imagery and observations indicate
areas of moderate to occasionally heavy freezing rain along an axis
from BTR/HUM to HSV.  The precipitation was being enhanced by strong
ascent associated with an upstream mid-level wave centered over
Oklahoma and Texas.  Impressive hourly freezing rain rates have been
observed - including 0.11 inch per hour at BTR as of 1453Z.  Weak
mid-level instability was allowing for localized enhancement of
precipitation rates in a few areas due to the convective processes. 
A few lightning flashes have also been observed across Mississippi.

Over time, the band of heavier precipitation will migrate
northeastward, with freezing rain becoming increasingly likely
across Tennessee and Kentucky.  Accumulations of 0.05-0.20 inch per
3 hours are possible (locally heavier near convection).  Current
observations/models indicate that areas of freezing rain have
already begun south/southeast of Nashville, and heavier
precipitation will begin in the Nashville area in the next hour or
so.  3-6 hours of freezing rain is expected.  The onset of heavier
freezing rain will spread from southwest to northeast across
central/eastern Kentucky beginning after around 18-19Z.  The axis of
heavier freezing rain will shift eastward out of southeastern
Louisiana and southern Mississippi this morning (in the next hour or
two), though lighter accumulations of freezing drizzle/rain and
sleet may continue throughout the afternoon.

..Cook.. 02/15/2021

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

ATTN...WFO...MRX...JKL...LMK...OHX...BMX...HUN...MOB...MEG...
JAN...LIX...

LAT...LON   37758493 37948406 37778341 37198342 36128436 35528574
            34268720 33718767 32738800 31588852 30638946 30269026
            30479102 31559060 33378919 35268762 36148674 37758493

Mesoscale Discussions in Mississippi, 2021Mesoscale Discussions in Tennessee, 2021Mesoscale Discussions in Kentucky, 2021Every mesoscale discussion in 2021

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.