Colorado Mesoscale Discussion

Areas affected…eastern CO/southwest NE/western KS

Concerning…Heavy rainfall…Flash flooding possible

Valid 132025Z – 140225Z

Summary…Rainfall rates of 1-2 in/hr, locally higher, will pose a
flash flood threat from slow moving thunderstorms this afternoon
over portions of the central High Plains. A transition to
increased forward propagation is expected near 00Z which should
limit any additional flash flooding to storm mergers and brief
repeating of cells.

Discussion…Regional radar imagery from 20Z showed a broken line
of slow moving, discrete thunderstorms over eastern CO. Meanwhile,
a growing cluster of storms over far northeastern CO into western
Nebraska was beginning to forward propagate and drop southward.
Surface observations showed a upslope flow regime with dewpoints
in the upper 50s to upper 60s across the region and the SPC
mesoanalysis estimated MLCAPE of 2000-3000 J/kg from northeastern
CO into southwestern NE. Slow movement of heavy rain cores, some
of which will contain large hail, are capable of rainfall rates of
1-2 in/hr, with a recent observation in eastern
Sedgwick county reporting 1.9 in/hr ending 20Z.

While the early stages of development will favor slow moving
thunderstorms capable of flash flooding rainfall, wind shear
between the lower and mid-levels of the troposphere supports an
eventual propagation of any organized clusters off toward the
southeast, along and into the greatest axis of instability
extending into west-central KS. At this point, flash flooding
should be limited to storm mergers and/or brief repeating of heavy
rain cores. Given a large section of northwestern KS into eastern
CO has received 300 percent of normal rainfall over the past
week, soils are less absorbent than normal and more prone to flash
flooding. Area Flash flood Guidance values of 1.5 inches in 3
hours will have the potential to be exceeded both early on and
later in the forecast period as anomalous moisture continues to
feed into the thunderstorm cluster from the southeast.


…Please see for graphic product…



LAT…LON 41140186 40660081 39889991 39159920 38699907
38239915 37859989 37720138 38200269 39590302

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