Mesoscale Discussion 182

Issued

Mar 15, 2021, 11:44 PM CDT (04:44 UTC)

Expired

Mar 16, 2021, 1:15 AM CDT

In force

91 min

Issued by

the Storm Prediction Center

Concerning

Severe potential...watch unlikely

Chance of a watch

20%

The Columbus AFB radar (KGWX), 60 km from the middle of the area, began a volume at 04:47 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.

004 
ACUS11 KWNS 160444
SWOMCD
SPC MCD 160444 
ALZ000-MSZ000-160615-

Mesoscale Discussion 0182
NWS Storm Prediction Center Norman OK
1144 PM CDT Mon Mar 15 2021

Areas affected...parts of north central Mississippi through central
and northern Alabama

Concerning...Severe potential...Watch unlikely 

Valid 160444Z - 160615Z

Probability of Watch Issuance...20 percent

SUMMARY...Thunderstorms are expected to undergo a gradual increase
in coverage and intensity during the next few hours. Some threat
will exist for mainly a few instances of large hail and strong wind
gusts, but a tornado cannot be ruled out. A WW will probably not be
needed in the near term unless trends dictate otherwise.

DISCUSSION...Showers and thunderstorms have shown an increase in
coverage during the past hour from north central MS into northern
AL, and this trend is expected to continue during the next couple
hours. Activity is developing within a moderately unstable
environment (1000-1500 J/kg MUCAPE) north of an old outflow
boundary, and fostered by what appears to be deeper but modest
forcing for ascent accompanying a weak impulse moving rapidly
eastward through the area. Vertical wind profiles through a deep
layer exhibit strong effective bulk shear (50+ kt). While 0-2 km
hodographs are not particularly large, magnitudes of storm relative
helicity from 150-250 m2/s2 are common in this region, conditionally
sufficient for low-level mesos. The transient deeper forcing for
ascent attending the progressive impulse may serve to weaken the
mid-level inversion, and this may contribute to an increase in
coverage and intensification of convection next few hours. Storms
will probably remain slightly elevated north of the boundary where
surface temperatures are in the low to mid 60s F. The primary threat
should therefore be a few rotating updrafts capable of isolated
large hail and a few strong wind gusts, but a brief tornado or two
cannot be ruled out if any storm manages to become surface based.
With time however, the low-level winds are forecast to gradually
veer and weaken later tonight.

..Dial/Hart.. 03/16/2021

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

ATTN...WFO...BMX...HUN...MEG...JAN...

LAT...LON   33499003 34418812 34748647 34528571 33778552 33238619
            32838797 32878951 33499003

Mesoscale Discussions in Alabama, 2021Mesoscale Discussions in Mississippi, 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.