|Mesoscale Discussion 1004|
< Previous MD Next MD >
Mesoscale Discussion 1004
NWS Storm Prediction Center Norman OK
0902 PM CDT Mon Jun 12 2017
Areas affected...Portions of western/central NE...northeastern into
east-central WY...and western/central SD
Concerning...Tornado Watch 317...320...
Valid 130202Z - 130300Z
The severe weather threat for Tornado Watch 317, 320 continues.
SUMMARY...A threat for a few tornadoes and scattered large
hail/damaging winds continues across valid portions of WW 317/320.
Parts of WW 317 have been locally extended in time until 03Z based
on latest radar trends.
DISCUSSION...Two semi-discrete supercells continue across western NE
as of 02Z. The southernmost storm has had multiple tornado and large
hail reports associated with it over the past several hours. A
strongly unstable airmass into central NE/southern SD, where MLCAPE
ranges from 2500-3500 J/kg per 01Z mesoanalysis, will very likely
support continued severe-caliber storms into the late evening.
Strong effective bulk shear values of 50-60+ kt owing to a
northeastward- moving upper low over the northern Great Basin will
also contribute to robust updraft organization, with all severe
hazards remaining possible. A short-term (next hour or two) tornado
threat should be maximized across parts of western NE into far
southwestern SD with the previously mentioned semi-discrete
supercells. Across this area, strongly veering/strengthening
low-level winds are contributing to a relative maximum in effective
SRH values (300-500+ m2/s2).
Additional convection has recently formed along northern portions of
the Laramie Mountains in east-central WY, and this activity may also
pose some severe risk, although instability is weaker with northward
extent. Current expectations are still for ongoing storms to grow
upscale into one or more bowing line segments as they move into
north-central NE and western/central SD later this evening. If this
were to occur, then damaging winds would likely become the primary
...Please see www.spc.noaa.gov for graphic product...
LAT...LON 41020272 41100329 41900340 42350351 42600475 42540599
44910592 44930127 44280046 43679980 42150023 41020272
Top/All Mesoscale Discussions/Forecast Products/Home