Severe Storm Outlook Narrative (AC)
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000
ACUS11 KWNS 192336
SWOMCD
SPC MCD 192336
MNZ000-SDZ000-NDZ000-200130-

Mesoscale Discussion 1657
NWS Storm Prediction Center Norman OK
0636 PM CDT Tue Sep 19 2017

Areas affected...the eastern Dakotas and into western Minnesota

Concerning...Tornado Watch 487...

Valid 192336Z - 200130Z

The severe weather threat for Tornado Watch 487 continues.

SUMMARY...Severe/isolated tornado risk appears likely to increase
over the next 1-2 hours.

DISCUSSION...Latest visible satellite loop shows a field of
stable/billow-type clouds over eastern South Dakota transitioning on
the western edge toward deeper convective updrafts, with convection
also increasing across central North Dakota/north-central South
Dakota near the front over the past half hour.

While the initial cluster of strong/severe storms continues moving
east across east-central and southeast North Dakota, becoming more
elevated with time, the storms developing farther west near and
ahead of the cold front have access to greater CAPE (mixed-layer
values in the 1500 to 2500 J/kg range).  With amply strong/veering
flow with height across the area, and hints in VWP data of an
increase in low-level southeasterlies -- confirming model forecasts
of LLJ increase, expect severe/isolated tornado risk to increase in
tandem with ongoing convective development.

..Goss.. 09/19/2017

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

ATTN...WFO...MPX...FGF...FSD...ABR...BIS...

LAT...LON   43769683 43509856 43869984 44920038 47099984 48750005
            49019531 47389528 43799655 43769683



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