Flash Flood Guidance
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Issued by NWS
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AWUS01 KWNH 241335
FFGMPD
NCZ000-SCZ000-GAZ000-TNZ000-ALZ000-241930-
Mesoscale Precipitation Discussion 0838
NWS Weather Prediction Center College Park MD
934 AM EDT Fri Jul 24 2026
Areas affected...Northern AL...Northern GA...Adj Souitheast TN,
Western NC, Far Upstate SC...
Concerning...Heavy rainfall...Flash flooding possible
Valid 241335Z - 241930Z
SUMMARY...Scattered, slow moving thunderstorms capable of intense
focused heavy rainfall (2-2.5"/hr rates) support widely scattered
incidents of possible flash flooding.
DISCUSSION...13z surface analysis shows a weak surface wave along
the TN/AL/GA intersection just west of Chattanooga which as arched
the front northeastward across far SE TN before northeasterly CAD
flow along the eastern lee of the southern Appalachians have
anchored the front from GVL to LZU to CPP before angling
northeastward near the Fall-line in central SC near HQU. The
upstream portion of the front is dropping southward into northern
AL and is denoted best in the Visible imagery with some weak
northerly flow to help convergence south of the front.
Tds along and west remain well into the mid-70s with some
temperature separation from some weak early morning insolation;
though with broad weak 10-15kts of westerly low level flow, there
are some bubbling convective areas where MUCAPE has risen to over
1000, nearing 1250 J/kg. Orthogonal isentropic ascent to the
front has been the most effective in stronger and broader ascent
with a few cells being efficient enough for a localized 2"/hr
rate/total. However, moving off the front has resulted in
weakening into SC, though the persistent location of the ascent is
supportive of redevelopment and therefore increased potential of
repeating over the next few hours.
The increasing insolation through the morning coupled with weak
capping should see both an increase in coverage as well as
convective vigor, as MLCAPEs reach 1500 J/kg by late morning,
early afternoon hours. Upstream shortwave energy will provide
some dPVA and area (especially GA into the Carolinas will remain
in diffluent flow aloft to support some increased
divergence/outflow for convection. Total PWat values of 2 will
slightly increase toward 2.25" and deep layer steering flow will
remain slightly confluent (increasing to ~20kts) but mostly west
to east to allow for localized repeating/training especially as
the CAD erodes and the front lifts but remains fairly parallel to
the mean flow. Isolated spots of 2-3.5" remain possible, but most
should fall quickly and be in the range of the 1-3 hr FFG values
suggestive of widely scattered to scattered incidents of
focused/localized possible flash flooding. This would only
increase in potential if cells can intersect the prone urban
centers, especially Birmingham and Atlanta.
Gallina
...Please see www.wpc.ncep.noaa.gov for graphic product...
ATTN...WFO...BMX...FFC...GSP...HUN...MRX...
ATTN...RFC...ALR...ORN...NWC...
LAT...LON 35448404 35308326 34808281 34008267 33498285
33398363 33438491 33208708 33818794 34358802
34658775 34858644 35398491