Severe Storm Outlook Narrative (AC)
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000
ACUS11 KWNS 191712
SWOMCD
SPC MCD 191711
IAZ000-MNZ000-SDZ000-191915-

Mesoscale Discussion 1347
NWS Storm Prediction Center Norman OK
1211 PM CDT Wed Jul 19 2017

Areas affected...Portions of eastern SD...southern MN...northern IA

Concerning...Severe Thunderstorm Watch 419...

Valid 191711Z - 191915Z

The severe weather threat for Severe Thunderstorm Watch 419
continues.

SUMMARY...A small, organized cluster of thunderstorms producing
severe wind gusts is expected to continue moving through the
remaining portions of the Watch through 18z.  A Watch will be needed
soon into the MN/IA portions of the MCD area.

DISCUSSION...A cluster of thunderstorms continues moving south and
east across eastern SD around 50 kt and has been producing severe
wind gusts, some significant, the last few hours. Latest radar
trends show indications of a mesoscale convective vortex/bookend
vortex developing over western Kingsbury County that is likely
contributing to the uptick in convective intensity/coverage.
Although a capping inversion remains across the region, and the main
lifting associated with the right-entrance region of the upper jet
streak is lifting farther north away from the east-southeastward
propagating system, rapid destabilization along/south of the warm
front amidst low-mid 70s surface dewpoints is ongoing. Moreover, a
significant cold pool is developing -- a 7-mb pressure jump was
noted at KHON -- that should allow for continuation and
intensification of the system in the next few hours.  Given the
expected movement of the current system into MN by 18z, and the
potential for new convective development farther east along the warm
front in IA, a Watch downstream of the current Watch is likely.

..Coniglio/Cohen/Hart.. 07/19/2017

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

ATTN...WFO...ARX...MPX...DMX...FSD...

LAT...LON   42889668 43629758 44149743 44519641 44479473 44179310
            43589175 42899194 42599299 42519418 42709571 42889668




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