Mesoscale Precipitation Discussion 1083
NWS Weather Prediction Center College Park MD
135 PM EDT Tue Sep 19 2023

Areas affected...eastern Kansas, eastern Oklahoma

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

Valid 191733Z - 192300Z

Summary...Areal coverage of locally heavy rain (and spots of 1+
inch/hr rain rates) has persisted over the past couple hours. 
Isolated/marginal flash flood potential exists, but should
gradually increase over the next 3-6 hours (through 23Z).

Discussion...Scattered, slow-moving convection continues across
much of the discussion area currently.  Individual cells moving at
10-20 mph were prolonging rain rates in a few spots, with 1-2.5
inch/hr rain rates noted per MRMS over the past couple hours.  The
storms are being supported by an axis of 1.2-1.5 inch PW values
collocated with appreciable (20-30 kt) southerly low-level flow
from the OK/TX Red River northward through eastern Kansas. 
Additionally, steep mid-level lapse rates along and west of the
discussion area were also supporting deep convection, and should
continue to do so as modest westerly flow aloft maintains those
lapse rates and weak shortwave troughs aloft traverse the
discussion area over the next 3-6 hours.  This pattern will
support continued thunderstorm development across the discussion
area over the next 3-6 hours (and likely beyond), with slow storm
motions and sufficient instability/moisture resulting in
occasional 1-2 inch/hr rain rates at time.

The main limiting factor for a more robust flash flood risk in the
short term (through 18Z) is dry antecedent conditions and
relatively high FFG thresholds.  Latest FFGs are in the 2.5-3
inch/hr range (locally lower closer to I-35/135 in central
Oklahoma/Kansas), suggesting that any flash flood risk will likely
be tied to where heavier rainfall can materialize over sensitive
and/or low-lying areas.  Latest thinking is that as persistent,
slow-moving storms continue over the discussion area, soils will
gradually moisten and result in locally increased sensitivity to
heavy rainfall over time.  A gradual increase in flash flood
potential is expected through 23Z or so, although a more robust
flash flood risk may hold off until around that time or later.

Cook

ATTN...WFO...EAX...ICT...OUN...SGF...TOP...TSA...

ATTN...RFC...ABRFC...MBRFC...NWC...

LAT...LON   39609592 39219528 37789494 35269504 34349603
            34259758 35449818 37849775 39139722 39539682