SPC MD 1485

MD 1485 CONCERNING SEVERE THUNDERSTORM WATCH 510... FOR PORTIONS OF SOUTHERN SOUTH DAKOTA INTO NORTHERN NEBRASKA
MD 1485 Image


Mesoscale Discussion 1485
NWS Storm Prediction Center Norman OK
1014 PM CDT Mon Jul 15 2019

Areas affected...Portions of southern South Dakota into northern
Nebraska

Concerning...Severe Thunderstorm Watch 510...

Valid 160314Z - 160445Z

The severe weather threat for Severe Thunderstorm Watch 510
continues.

SUMMARY...Severe threat continues for the remainder of Severe
Thunderstorm Watch 0510. Severe wind gusts will be the main threat,
with occasional large hail possible. Trends are currently being
monitored for the potential of a downstream WW issuance.

DISCUSSION...Multicellular convection has gradually congealed into a
loosely organized MCS along the northwest NE/southwest SD border,
with a few severe wind reports noted within the past couple of
hours. While the overall kinematic fields are weak downstream of the
MCS (with no anticipated appreciable ramp up in a nocturnal
low-level jet), adequate buoyancy resides across all along the NE/SD
border, owing to steep lapse rates in the 700-300 mb layer, and rich
low-level moisture extending up to 850 mb (per latest RAP forecast
soundings). As such, ample elevated instability is expected
throughout the night in advance of the storms, even with a gradually
stabilizing boundary layer, which may sustain the MCS, as indicated
by several members of the 00Z HREF, and the last few runs of the
HRRR. Still, the marginal deep-layer and low-level shear environment
may also promote progressive cold pools, which may outrun the
antecedent convection, potentially weakening the MCS.

Given the uncertainty in MCS evolution within the ambient weakly
forced but highly buoyant environment, convective trends will
continue to be monitored for a potential downstream WW issuance.

..Squitieri/Grams.. 07/16/2019

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

ATTN...WFO...FSD...OAX...GID...LBF...UNR...CYS...

LAT...LON   41050128 42020215 42600255 43130287 43360279 43450236
            43349979 43129784 42199766 41849784 41509829 41269881
            41050128 

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