SPC MD 1743

MD 1743 CONCERNING SEVERE THUNDERSTORM WATCH 500... FOR EASTERN NEBRASKA AND FAR WESTERN IOWA

Mesoscale Discussion 1743
NWS Storm Prediction Center Norman OK
0902 PM CDT Sun Oct 11 2020

Areas affected...eastern Nebraska and far western Iowa

Concerning...Severe Thunderstorm Watch 500...

Valid 120202Z - 120400Z

The severe weather threat for Severe Thunderstorm Watch 500
continues.

SUMMARY...The potential for severe wind will continue for portions
of central Minnesota as well as eastern Nebraska and far western
Iowa through at least 03 UTC.

DISCUSSION...Recent radar trends from MN show an organized squall
line, which suggests that 40-45 knot effective bulk shear is
compensating for relatively weak (around 500 J/kg MLCAPE)
instability. Convection will likely begin to diminish as it moves
eastward into the cool side of a diffuse surface warm front, but
will continue to pose a severe wind potential in the near term
(through at least 03 UTC) for central MN. With temperatures in the
mid 60s (and dewpoints in the 40s) across eastern MN, a downstream
watch is not anticipated at this time. 

Further south, the cold front has overtaken the main line of storms
per recent surface and radar observations from KOAX. This will
further favor a linear storm mode for the rest of the evening.
Despite increasing inhibition from nocturnal cooling, stronger
ascent associated with the cold front should maintain convection for
the next few hours. Downward trends in MRMS vertically integrated
ice and warming IR cloud top temperatures, combined with a
transition to a linear storm mode, suggest a downward trend in the
hail potential overall, though a few instances of severe hail can
not be ruled out with any stronger updraft pulses. Although severe
wind is possible along the entirety of the line, portions of
southeast NE may see a locally higher wind threat associated with
accelerating convection along the cold frontal surge.

..Moore/Dial.. 10/12/2020

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

ATTN...WFO...MPX...DMX...FSD...OAX...GID...

LAT...LON   40979791 42009666 42409634 42849593 43769563 44629550
            45269523 45759511 45929479 45859429 45329389 44969383
            44489390 43889416 43149459 42549494 41999520 41659539
            41169556 40739560 40459611 40429688 40569759 40979791 

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