Mesoscale Precipitation Discussion 0890
NWS Weather Prediction Center College Park MD
547 AM EDT Mon Sep 24 2018

Areas affected...Far northeast AR...western TN...far western KY

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

Valid 240947Z - 241547Z

Summary...Additional heavy rain expected to expand this morning
across area of the lower Tennessee and lower Ohio River where
flash flood guidance values have lowered from recent heavy
precipitation.  This will increase potential for local runoff
issues through this morning.

Discussion...Stream flow anomalies as per the National Water Model
are high across the lower Tennessee and lower Ohio Valley region
from recent heavy rains.  There is a strong model signal for
precipitation to continue to enhance this morning over this area
of high stream flow/saturated soils in a region of well defined
upper difluence associated with shortwave energy pushing
northeastward across these areas.  With pw values forecast to
remain anomalous in the 2.0 to 2.5+ standard deviation above the
mean range...deep saturated warm cloud layer...approximately 13000
feet as per regional 0000 utc soundings...heavy rains are possible
with uvv enhancement in the region of defined upper difluence. 
Rainfall rates of 1-2" per hour possible across these area this
morning.

The latest href probabilities for 2 and 3 inches in a six hour
period are showing max values over far northeast AR and western
TN...with probabilities in the 50-70% range for 2 inches and
40-60% for 3 inches. These areas match well with the latest hrrr
six hour qpf axis along the AR/TN border region..with max hrrr
amounts of 5"+.

Oravec

ATTN...WFO...LMK...MEG...OHX...PAH...

ATTN...RFC...LMRFC...OHRFC...

LAT...LON   38258745 38148628 37848619 37348640 36968667
            35998719 35268836 34688976 34729002 34829043
            35379058 36159008 36768931 37718823