AWUS01 KWNH 220952
FFGMPD
FLZ000-GAZ000-221500-

Mesoscale Precipitation Discussion 0918
NWS Weather Prediction Center College Park MD
551 AM EDT Thu Aug 22 2024

Areas affected...southeastern GA into northeastern FL

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

Valid 220950Z - 221500Z

SUMMARY...Slow moving showers/thunderstorms, capable of localized
rainfall rates over 3 in/hr will likely continue for another few
hours in the vicinity of the GA/FL border near the coast.
Localized flash flooding will be possible, especially with any
overlap of urban areas.

DISCUSSION...0930Z radar imagery from KJAX showed a small region
of slow moving showers and thunderstorms located between I-95 and
the coast in Camden and Nassau counties (southern GA/northern FL).
Local Wunderground.com reporting stations showed agreement with
KJAX rainfall estimates showing hourly rainfall of 2 to 3 inches
associated with cells observed on radar. This region was located
just north of a stationary front with 0-1 km AGL flow from the
east between 10-20 kt, advecting warm moist air in from the
Atlantic. SPC mesoanalysis data from 09Z showed SBCAPE over 2000
J/kg just offshore and a narrow axis of weaker but sufficient and
uninhibited instability inland, straddling the GA/FL border. Area
surface observations showed a convergence axis located near or
just east of I-95, coincident with the ongoing slow moving showers/thunderstorms.

There is little change to the overall setup expected over the next
3 to 6 hours, although the onset of daytime heating after sunrise
may disrupt the existing gradient/convergence axis in place.
Nonetheless, some degree of frictional convergence with continued
low level onshore flow within the instability axis is expected to
continue a threat for slow moving showers and thunderstorms in the
vicinity of the GA/FL border. There is some concern for the
ongoing activity to build south toward the Jacksonville metro
region which would have greater sensitivity to flash flood impacts
due to the urban nature compared to surrounding, more rural area.
Within the slow moving areas of heavy rain, hourly rainfall of 2-3
inches is expected but values could surpass 3 inches in an hour in
the more persistent activity with 6-hr rainfall totals possibly
exceeding 6 inches in some locations. Flash flooding will be
possible as a result.

Otto


ATTN...WFO...CHS...JAX...

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

LAT...LON 31458177 31308115 30838124 29898118 29728169
29918219 30348235 30918221
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