|Mesoscale Discussion 908|
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Mesoscale Discussion 0908
NWS Storm Prediction Center Norman OK
0256 PM CDT Thu Jun 10 2021
Areas affected...far northeast MT...western ND
Concerning...Severe potential...Tornado Watch likely
Valid 101956Z - 102130Z
Probability of Watch Issuance...95 percent
SUMMARY...Convective initiation is expected between 20-21 UTC along
the dryline over eastern MN near the ND border. Explosive growth
into significant-severe producing supercells is forecast late this
afternoon into the early evening.
DISCUSSION...Visible-satellite imagery shows a swelling band of
agitated cumulus along the dryline over far eastern MT near Sydney.
Temperatures immediately east of the dryline have warmed into the
lower 80s with a deepening boundary layer featuring low to mid 60s
deg F dewpoints. The 18 UTC Glasgow, MT raob showed a very steep
700-500 mb lapse rate (8.6 deg C/km). Modifying the raob for 19 UTC
surface conditions east of the dryline near the ND/MT border (i.e.,
Sydney, MT) yielded 3300 J/kg MLCAPE with very little convective
inhibition remaining. As the cap erodes, expecting explosive
updraft growth quickly evolving into a few discrete supercells.
Giant hail (3+ inches in diameter) is possible with the stronger
storms as the organize and move northeast into a less deeply mixed
and more moisture rich environment near the warm front. Supercell
tornadoes will be possible in vicinity of the warm front, in
addition to the hail/severe gust hazard. Other isolated storms are
forecast to eventually develop southward along the dryline into
parts of southwest ND and northwest SD. Large to giant hail will be
the primary hazard with these storms before additional thunderstorm
development into a severe squall line evolves later this evening.
...Please see www.spc.noaa.gov for graphic product...
LAT...LON 48980713 48560749 48100717 48090558 47640477 45790370
45970205 48380212 48970265 48980713
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