SPC MD 1061


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Mesoscale Discussion 1061
NWS Storm Prediction Center Norman OK
0525 PM CDT Tue Jun 30 2020

Areas affected...Southeast North Dakota and eastern South Dakota

Concerning...Severe potential...Watch likely 

Valid 302225Z - 010030Z

Probability of Watch Issuance...80 percent

SUMMARY...Numerous storms are expected along and ahead of a cold
front this evening. The primary threats will be large hail and
damaging winds.

DISCUSSION...22Z surface analysis shows a strong cold front from
southern North Dakota into central and east central South Dakota.
The environment ahead of this front is very moist and unstable with
dewpoints in the mid 70s and temperature in the upper 80s to near
90. This has yielded MLCAPE in excess of 5000 J/kg with CINH
recently eroded. Most of the upper-level forcing is farther west and
thus, storm development will likely be confined to low-level
boundaries. This includes the cold front which is surging eastward
across southern North Dakota and central South Dakota and a
confluence zone east of Aberdeen. Despite very strong instability,
storms may struggle to organize (similar to the storms in Brown
County, SD between 22Z and 2220Z) due to the warm nose around 700mb
(per RAP soundings) and relatively weak flow above 1-2 km (per ABR
VWP). In addition, storm motions may take some updrafts to the cool
side of the cold front rather quickly which may also limit the
duration of any severe threat. However, despite these negative
factors, storms are expected to be numerous along the front and
mid-level lapse rates are very steep (~8.5 C/km per SPC
mesoanalysis). Therefore, even if storms remain somewhat loosely
organized, there will be a threat for large hail and damaging winds
with the stronger updrafts which are able to realize faster
mid-level parcel accelerations associated with the steep lapse

..Bentley/Guyer.. 06/30/2020

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


LAT...LON   43889895 44829935 45870000 46520056 46800092 47010124
            47080091 47069974 47029859 46989730 46929710 46369692
            45079672 44109712 43759802 43699848 43549887 43889895 

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