Mesoscale Precipitation Discussion 0833
NWS Weather Prediction Center College Park MD
500 AM EDT Thu Aug 08 2024

Areas affected...Northern SC...Central and Southern NC...Southwest
to South-Central VA

Concerning...Heavy rainfall...Flash flooding likely

Valid 080900Z - 081500Z

SUMMARY...T.S. Debby will continue to weaken this morning as it
advances further inland across the coastal plain of the Southeast,
but will continue to promote extremely heavy rainfall. Numerous to
widespread areas of flash flooding are expected to continue in
association with Debby, with considerable to locally catastrophic
impacts.

DISCUSSION...The early morning GOES-E IR satellite imagery in
conjunction with radar and surface observations shows T.S. Debby
moving northwest and inland across the SC coastal plain. Cold
convective tops are noted across the northern semicircle of the
storm with multiple bands of strong convection continuing to
produce extremely heavy rainfall rates that are occasionally on
the order of 1 to 3 inches/hour.

Much of this is occurring over central to southeast NC and is
aligned with a corridor of strong moisture flux convergence with
the aid of a southeast low-level jet of 50+ kts. Coinciding with
this is also the transport of increasing buoyancy in the boundary
layer with MLCAPE values across southeast NC of 1000 to 1500 J/kg.
There is also a fair amount of low-level shear which has been
fostering these organized convective bands with embedded
mesocyclone activity which is further enhancing the rainfall
efficiency and related rates.

Debby is increasingly coming under the influence of shortwave
energy dropping down across the TN Valley and the upper-level flow
is becoming increasingly divergent across the southern
Mid-Atlantic region which should help favor the poleward advance
of heavy rainfall with Debby going through the morning hours. This
will allow for the heavy rains and embedded stronger convective
elements over central NC to begin overspreading southwest to
south-central VA by later this morning.

Rainfall rates will remain maximized in the stronger convective
bands around the northeast quadrant of Debby's circulation, and
there will continue to be significant concerns for cell-training
that will favor enhanced rainfall amounts. Given the rain rates of
1 to 3 inches/hour, and the concentrated corridors of
cell-training, some additional rainfall amounts by late this
morning may reach 3 to 6 inches, with isolated heavier totals not
out of the question.

Therefore, numerous to widespread areas of flash flooding are
expected to continue this morning in association with Debby, with
considerable to locally catastrophic impacts where the heaviest
rains occur. This will include a significant urban flash flood
threat from Greensboro to the Raleigh-Durham area, with areas near
and to the north of Wilmington also at risk.

Orrison

ATTN...WFO...AKQ...CAE...GSP...ILM...LWX...MHX...RAH...RNK...

ATTN...RFC...MARFC...OHRFC...SERFC...NWC...

LAT...LON   37757991 37587868 36797769 35777694 34497664
            33727731 33567830 34087933 33838017 33748078
            34008139 34718177 36038163 37178084