SPC AC 180533
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1233 AM CDT Wed Sep 18 2019
Valid 191200Z - 201200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER THE
NORTHERN HIGH PLAINS...
At least isolated storms producing large hail are possible Thursday
evening and overnight across the northern High Plains.
An upper trough will swing east across the Great Basin, with
increasingly meridional upper-level winds into WY and MT. Ahead of
this trough, height rises will occur over the northern Plains, upper
MS Valley, and Great Lakes with the upper high centered over the
central Gulf Coast states. High pressure will remain at the surface
over much of the East as low pressure develops over the northern
High Plains. This will maintain southerly winds across the Plains
with a warm front lifting north across the Dakotas. The moistening
air mass along with cool temperatures aloft will result in moderate
destabilization over the northern Plains, and will support scattered
strong storms mainly late in the day and overnight from eastern MT
Elsewhere, the remnants of TC Imelda will bring heavy rain to parts
of east TX as it drifts north, with warm temperatures aloft
...Eastern MT/WY into the western Dakotas...
As low pressure deepens over WY and MT, southeast winds will
increase across the northern Plains, with 30 kt southeast flow at
850 mb by late afternoon. This will allow for moistening, but most
of the area will remain capped through the day. Steeper low level
lapse rates will exist over WY and eastern MT, and into far western
SD and NE closer to the surface trough. At least isolated late-day
storms are expected in this zone, with increasing storm coverage
through the evening due to warm advection with the low-level jet.
Cool temperatures aloft and marginal deep-layer shear will favor a
few cells capable of large hail. Winds aloft decrease with eastern
extent, but cool temperatures aloft and a persistent low-level jet
will likely support elevated hail into parts of ND overnight.
...MAXIMUM RISK BY HAZARD...
Tornado: 2% - Marginal
Wind: 5% - Marginal
Hail: 5% - Marginal
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NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 1730Z