[BNAWX] Severe Storm Outlook Narrative

[EMWIN Server]

ACUS11 KWNS 092249
SWOMCD
SPC MCD 092248
TNZ000-ALZ000-MSZ000-ARZ000-100015-

Mesoscale Discussion 0575
NWS Storm Prediction Center Norman OK
0548 PM CDT Sun May 09 2021

Areas affected...Far Eastern Arkansas...Northern
Mississippi...Northwest Alabama...and Southwestern/Central Tennessee

Concerning...Severe Thunderstorm Watch 158...

Valid 092248Z - 100015Z

The severe weather threat for Severe Thunderstorm Watch 158
continues.

SUMMARY...Semi-discrete storms capable of large hail, damaging wind
gusts, and a few tornadoes remain possible this evening across WW
158.

DISCUSSION...Regional radar shows a segmented line of convection
moving southeast through WW 158, extending northeast into portions
of southwestern Tennessee. Storms thus far have been able to
maintain semi-discrete within the line, likely attributable to
strong deep layer shear (effective shear near 50 kt) and decent
low-level shear (20-25 kt 0-1 km shear) amid modest instability that
ranges from 2000 J/kg in northern Mississippi to near 1000 J/kg
across southwest Tennessee. In particular, mid-level lapse rates of
7-8 C in the 700-500 mb layer will continue to support a large hail
threat, as indicated in RAP forecast soundings.

Given the persistence of the semi-discrete mode in the short term,
embedded supercells capable of large hail, damaging wind gusts, and
a few tornadoes will remain possible during the next couple of
hours. As the low-level jet begins to strengthen this evening,
increasing low-level theta-e advection and destabilization should
allow storms to transition to a linear mode after the 00z-01z time
frame. Given uncertainty in convective evolution the next few hours,
downstream watch issuance across portions of central Tennessee and
northwest Alabama remains unclear, and thus, trends will continue to
be monitored.

..Karstens.. 05/09/2021

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

ATTN...WFO...OHX...BMX...HUN...MEG...JAN...LZK...

LAT...LON   35449034 35868940 36188778 36108684 35358659 34508707
            34168841 34109065 34489129 35129094 35449034
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