SPC MD 2209

SPC MD 2209


Mesoscale Discussion 2209
NWS Storm Prediction Center Norman OK
0241 PM CDT Mon Oct 02 2023

Areas affected…northeastern Colorado into western Nebraska

Concerning…Severe potential…Watch possible

Valid 021941Z – 022145Z

Probability of Watch Issuance…40 percent

SUMMARY…Intensifying thunderstorms, including isolated supercells
and/or small organizing clusters posing increasing risk for
marginally severe hail and strong surface gusts, appears
increasingly probable through 4-6 PM MDT. It is not yet clear that
a watch is necessary, but trends will continue to be monitored for
this possibility.

DISCUSSION…As modest mid-level height falls overspread the
Colorado and Wyoming Rockies this afternoon, models suggest that
strongest surface pressure falls will become concentrated from the
lee of the Colorado Front Range into western Nebraska by 22-00Z.
Low-level lapse rates are already rapidly steepening along this
corridor, and it appears that boundary-layer moisture advection
during the next few hours will contribute to appreciable
destabilization, including CAPE increasing up to 1500 J/kg.

The latest Rapid Refresh suggests that cooling of an initially warm
corridor around 700 mb may already be underway across this region,
which may lead to the initiation of thunderstorms across northeast
Colorado during the next hour or so. Once this occurs, activity is
likely to intensify while tending to develop north-northeastward
through western Nebraska. Beneath 40-50 kt south-southwesterly 500
mb flow, strengthening southerly flow (to 30+ kt) in the 850-700 mb
layer may contribute to organizing convection with increasing
potential to produce strong surface gusts (aided by evaporative
cooling in downdrafts associated with sizable sub-cloud
temperature-dew point spreads), in addition to marginal severe hail.

..Kerr/Grams.. 10/02/2023

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


LAT…LON 41350367 42440328 42290132 40320182 39010330 40100397

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