..EXCESSIVE RAINFALL OUTLOOK MAY 12, 2023..

 Mesoscale Precipitation Discussion 0271

NWS Weather Prediction Center College Park MD
747 AM EDT Fri May 12 2023

Areas affected...southwestern NE into extreme northwestern KS

Concerning...Heavy rainfall...Flash flooding possible

Valid 121146Z - 121745Z

SUMMARY...A localized flash flood threat will continue for extreme
northwestern KS into southwestern NE over the next 3-6 hours with
peak rainfall rates of 1 to 1.5 in/hr and additional totals up to
2 or 3 inches through 18Z.

DISCUSSION...GOES East water vapor imagery continued to show a
slow moving closed mid-level low over the western NE/KS border at
11Z, with slow movement toward the NNE. Local radar imagery from
KGLD showed a narrow band of thunderstorms extending from Decatur
County, KS into southwestern NE, with a small
deformation/convergence axis of stratiform rainfall over Dundy,
Chase and Perkins counties in western NE. Within the convective
band, KGLD 1-hr rainfall estimates have been about 1 to 1.5 inches
since about 09Z but over a fairly localized region of the High
Plains. Farther west within the stratiform region, rain rates have
peaked generally in the 0.5 to 1.0 in/hr range.

Slow movement of the mid-level low and continued southerly to
easterly flow just ahead of the low will allow for locally heavy
rain to continue over the next few hours, with 500-1000 J/kg
MLCAPE along the far eastern portion of the MPD threat area
supporting rainfall rates of 1 to 1.5 in/hr at times with training
and slow moving convection. Additional peak storm totals up to 2
or 3 inches will be possible through 18Z, falling on top of a
region of the Great Plains that has seen 4-8 inches of rain over
the past 72 hours. Localized flash flooding will remain possible
given the saturated to nearly saturated conditions on the ground.
Farther north, the Sand Hills region of NE contains higher FFG and
more permeable soil types, where the flash flood threat is
expected to be lower and is therefore not included in this MPD.

Otto

DAYS 1-5 EXCESSIVE RAINFALL OUTLOOK

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