ACUS11 KWNS 210149
SWOMCD
SPC MCD 210148=20
KYZ000-TNZ000-MOZ000-MSZ000-ARZ000-210315-

Mesoscale Discussion 0508
NWS Storm Prediction Center Norman OK
0848 PM CDT Sun Apr 20 2025

Areas affected...east Arkansas...west Tennessee...far west Kentucky

Concerning...Tornado Watch 156...

Valid 210148Z - 210315Z

The severe weather threat for Tornado Watch 156 continues.

SUMMARY...Thunderstorms continue to move east across Arkansas. A
tornado threat will continue through the evening before beginning to
lessen toward midnight. Trends will be monitored for potential watch
across far west Tennessee and Kentucky

DISCUSSION...A broken line of thunderstorms, many exhibiting at
least transient supercellular characteristics, will continue to move
east this evening. Recent VAD wind profiles from NQA (Memphis 88D)
show the low-level jet (as proxied by the 0-1 km shear value) has
increased from around 15-20 knots three hours ago to nearly 35 knots
at present. Additionally, the VAD profile shows considerable
clockwise turning below three kilometers, with much of that in the
lowest one kilometer AGL (0-1 km SRH of nearly 350 m2/s2).

Presently, SPC mesoanalysis shows a significant reduction in
instability across eastern Arkansas as compared to areas to the
west. However, given the upstream airmass remains moist and the
strength of the low-level jet, an axis of instability up to 1000
J/kg of MLCAPE should be maintained for at least another couple of
hours.=20

With time, large-scale ascent and the low-level jet across Arkansas
should weaken as the main short-wave trough moves away from the
area. The weakening low-level jet should result in increased
difficulty maintaining low-level instability. This combined with
increasing convective inhibition from the loss of diurnal heating
should result in a decrease in convective intensity through the
evening hours. However, storm-scale processes (e.g. mesoscyclones)
will allow thunderstorms to persist for at least a couple of hours
into the less favorable environment. Thus, western Tennessee and
Kentucky will be monitored for the need of a tornado watch.

..Marsh.. 04/21/2025

...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!8_T1m5MORGs0l0Z-5WGqutFYUDyDPW5hOzNVDMen_h1FVd-IURQPN6fqJb5j_Q4Dn7rEUks0N= 3bbFi4yf76gjQ-GDsI$ for graphic product...

ATTN...WFO...PAH...MEG...JAN...LZK...SHV...

LAT...LON 36449104 36788802 33889070 33069332 36449104=20

MOST PROBABLE PEAK TORNADO INTENSITY...85-115 MPH
MOST PROBABLE PEAK WIND GUST...55-70 MPH
MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN


=3D =3D =3D
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