SPC MD 1399

MD 1399 CONCERNING SEVERE POTENTIAL…WATCH POSSIBLE FOR SOUTHEAST NEBRASKA INTO CENTRAL IOWA AND NORTHERN MISSOURI

Mesoscale Discussion 1399
NWS Storm Prediction Center Norman OK
0847 PM CDT Fri Aug 31 2018

Areas affected...southeast Nebraska into central Iowa and northern
Missouri

Concerning...Severe potential...Watch possible 

Valid 010147Z - 010345Z

Probability of Watch Issuance...60 percent

SUMMARY...Scattered storms capable of large hail are expected to
develop this evening.

DISCUSSION...An very unstable air mass currently resides along and
west of a warm front roughly along the MO River. The 00Z OAX and TOP
soundings both show MLCAPE in excess of 3000 J/kg, with MUCAPE of
4000-5000 J/kg. In addition, low level shear near the warm front is
strong, owing to large looping hodographs in a warm advection
regime.

Although the air mass is largely capped, a southwesterly low-level
jet increasing to around 50 kt will maintain lift, while the
presence of steep lapse rates aloft support strong updrafts capable
of hail. Overall, convection may remain disorganized, but the amount
of available instability will likely support large to damaging hail
in some of the cells. Therefore, a watch cannot be ruled out this
evening if storm trends suggest more than an isolated severe threat.

..Jewell/Thompson.. 09/01/2018

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

ATTN...WFO...DMX...EAX...FSD...OAX...GID...

LAT...LON   39649467 40019525 40159633 40419735 40859759 41389725
            41969637 42229572 42229461 41999385 41589315 40959266
            40359249 39849267 39589301 39479367 39649467 

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