SPC MD 1418


MD 1418 Image

Mesoscale Discussion 1418
NWS Storm Prediction Center Norman OK
0230 PM CDT Fri Aug 07 2020

Areas affected...Portions of far eastern ND...extreme northeastern
SD...and northern/central MN

Concerning...Severe potential...Watch possible 

Valid 071930Z - 072200Z

Probability of Watch Issuance...60 percent

SUMMARY...An increasing threat for large hail, severe wind gusts,
and perhaps a tornado should occur this afternoon and evening. Watch
issuance may be needed.

DISCUSSION...A well-defined MCV is ongoing near the ND/MN border
this afternoon. Modest ascent associated with a mid-level vorticity
maximum related to the MCV and persistent low-level warm advection
will likely encourage robust convective initiation across far
eastern ND into western MN within the next couple of hours. Some
clearing of low clouds to the east of the MCV, coupled with
increasing low-level moisture and steepening mid-level lapse rates,
are contributing to an increase in buoyancy across parts of
southeastern ND into central MN and vicinity. Current expectations
are for MLCAPE to reach 1500-2500 J/kg by peak afternoon heating,
and for convective inhibition to become negligible in the vicinity
of the MCV around 21-22Z.

A veering/strengthening wind profile with height through mid levels
will likely support storm organization, with around 30-35 kt of
effective bulk shear probable. Initial storm development along/near
the ND/MN border may be supercellular, with a threat for both large
hail and severe wind gusts. In addition, a tornado or two also
appears possible with this initially discrete convection, as
low-level winds and related effective SRH will be modestly enhanced
by the close proximity of the MCV. Later this afternoon and into the
evening, storms may have a tendency to grow upscale into a small
bowing line as a south-southwesterly low-level jet modestly
strengthens over southern/central MN. The threat for severe/damaging
winds would potentially increase across parts of northern/central MN
if storms evolve as forecast. The potential for additional storms to
develop across the warm sector to the south/southwest of the MCV
remains unclear, as a low-level temperature inversion may inhibit
updrafts. Regardless, watch issuance may be needed in the next
couple of hours pending signs of surface-based convective initiation
near the MCV.

..Gleason/Kerr.. 08/07/2020

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


LAT...LON   45599629 45869692 46599732 47169718 47509642 47459444
            47299355 46889238 46329240 45869281 45559331 45359462

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