660
AWUS01 KWNH 142220
FFGMPD
TNZ000-ALZ000-MSZ000-150418-

Mesoscale Precipitation Discussion 1010
NWS Weather Prediction Center College Park MD
619 PM EDT Sat Sep 14 2024

Areas affected...portions of central and northern Alabama

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

Valid 142218Z - 150418Z

Summary...Extremely sensitive ground conditions still support a
continued flash flood risk through the night as scattered showers
migrate northwestward.

Discussion...Widespread convective overturning and cloud cover has
resulted in very modest surface-based instability profiles across
the discussion area (generally in the 500-1250 J/kg range).
Despite the weak instability, high moisture content (around 1.9
inch PW values) and sustained boundary layer convergence along a
general axis extending from far northeast Mississippi through
southeastern Alabama continues to support occasional
shower/thunderstorm development oriented in training,
northwestward-moving bands.  These band were producing occasional
rain rates between 0.5-1 inch/hr over ground conditions
characterized by FFG thresholds of nearly 0.  Even light rainfall
can exacerbate and cause new instances of flash flooding in this
scenario, which isn`t surprising given the estimated 3-8 inch
rainfall totals that have occurred in the past 48 hours.

Models continue to depict scattered shower activity developing
from southeast to northwest within this regime through the
overnight hours despite a gradual loss of surface-based
instability.  Areas of 0.25-1 inch/hr rain rates remain possible
with the more persistent activity.  Given the continued rainfall
threat, flash flooding remains possible.

Cook

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...BMX...HUN...JAN...MEG...OHX...

ATTN...RFC...LMRFC...SERFC...NWC...

LAT...LON   35338815 35138739 34748643 34258588 33538539
            32418517 32058627 32298752 33528815 34728889