Mesoscale Precipitation Discussion 0645
NWS Weather Prediction Center College Park MD
229 PM EDT Fri Jul 11 2025

Areas affected...central MS

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

Valid 111828Z - 112228Z

Summary...Convection is growing in scale and could align along a
west-northwest to east-southeast axis shortly.  Hourly rain
amounts to 3" with local totals to 5" are possible, which could
lead to flash flooding in urban areas.

Discussion...Thunderstorms across MS over the past couple hours
have been forming in a very moist and unstable environment, with
precipitable water values of 2-2.25" and ML CAPE in western MS
above 3500 J/kg.  Westerly flow in the low-levels has been
steering convection generally west to east, but radar imagery is
implying the beginning of a cold pool forming across east-central
MS.  Effective bulk shear is 15-20 kts, which appears sufficient
to lead to loose organization.

The expectation is for an outflow boundary to shift south and
somewhat westward with time, which should lead to a more northwest
to southeast alignment with time downwind of the instability pool,
which should retrograde somewhat farther in the next several
hours.  While hourly rain totals to 3" are possible, there's
evidence that at least one location near Louisville MS managed 2"
in 26 minutes, likely due to the strong instability present, which
would bring instantaneous rain rates to 5"+. The 12z HREF
probabilities of 0.5"+ appears to be doing a much better job than
the 06z RRFS probs in this area.  Hourly amounts to 3" with local
amounts to 5" could cause flash flooding, particularly within
urban areas.

Roth

ATTN...WFO...JAN...MOB...

ATTN...RFC...ALR...ORN...NWC...

LAT...LON   33298971 32788860 31748855 31488939 31799030
            32519079 33139051