SPC 2000Z Day 1 Outlook

Day 1 Outlook Image

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0148 PM CST Tue Nov 10 2020

Valid 102000Z - 111200Z


Thunderstorms capable of producing damaging to severe winds and a
few tornadoes will remain possible this afternoon and evening from
parts of Missouri northeastward into portions of far eastern Iowa,
Illinois, and Wisconsin.

...20Z Update...
A QLCS will continue moving northeastward across IL and into
southern WI this afternoon and evening in tandem with a progressive
shortwave trough over the Upper Midwest. Damaging winds will remain
a concern given the linear mode and strength of the low/mid-level
flow per area VWPs. There is also some potential for a few tornadoes
with embedded circulations within the line, particularly in close
proximity to a deepening surface low that will develop from far
eastern IA into WI through this evening. For more information on the
near-term severe threat across this area, see Mesoscale Discussion

..Gleason.. 11/10/2020

.PREV DISCUSSION... /ISSUED 1015 AM CST Tue Nov 10 2020/

...Mid MS Valley...
Water vapor loop shows a strong shortwave trough and associated
mid-level speed max rotating across the central Plains into MO/IA. 
This feature will result in strong surface cyclogenesis as a surface
low deepens along a cold front extending from northern MO into WI. 
The corridor along and just east of the low/front will be the area
of concern for strong/severe thunderstorms today.

Thunderstorms are ongoing this morning along the front over MO. 
Convection is expected to intensify and build northward toward the
surface low by early afternoon.  CAM solutions indicate that the
bowing convective structures will not be substantially undercut by
the front, suggesting the activity will remain primarily
surface-based.  This supports a risk of damaging wind gusts in the
stronger cores.  Forecast soundings show strengthening low-level
shear across the threat area through the afternoon as the deepening
low helps to back/enhance near-surface winds.  This could promote
the development of a few semi-discrete supercells along the line,
posing a risk of a few tornadoes.

The activity will track northeastward across Lake MI this evening
and eventually into northern Lower MI.  Thermodynamic parameters
will be rather weak over this area, but there is some potential for
a lingering risk of locally strong/damaging wind gusts.  

Relatively strong deep southeasterly flow is present today across
the FL peninsula.  A moist and moderately unstable air mass is also
in place across the region, with broken sunshine this afternoon
helping to steepen low-level lapse rates.  Local VAD profiles show 
25-35 knot winds in the 0-3km layer.  Most CAM solutions show
relatively fast-moving thunderstorms affecting the region, posing a
risk of locally gusty/damaging wind gusts.

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