AWUS01 KWNH 260652
FFGMPD
VAZ000-NCZ000-SCZ000-GAZ000-TNZ000-261045-

Mesoscale Precipitation Discussion 1062
NWS Weather Prediction Center College Park MD
252 AM EDT Thu Sep 26 2024

Areas affected...central/northern GA into the southern to central
Appalachians

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

Valid 260651Z - 261045Z

SUMMARY...Areas of heavy rain with south to north training to
build northward through GA into the southern and central
Appalachians through the morning. Rainfall rates of 1-2 in/hr will
be likely, but isolated 2+ in/hr cannot be ruled out.

DISCUSSION...Regional radar imagery across the Southeast at 0630Z
showed a "Y" shaped appearance in reflectivity with a branch of
heavier rainfall extending northeastward from the FL Panhandle
into central GA, co-located with a remnant outflow/effective
frontal boundary. A second axis of higher reflectivity extended
northwestward across the GA coast into central GA and a broken
axis of higher reflectivity values was located from central GA
into western NC. These axes of higher reflectivity/heavier
rainfall aligned fairly well with the leading edge of low level
(0-3 km AGL) moisture flux where a plume of 2+ inch precipitable
water values was building northward across GA via southeasterly
low level winds of 20-30 kt. Mesoscale areas of rotation were
embedded within the precipitation shield, associated with enhanced
convergence and higher reflectivity along with with south to north
training following the deeper layer steering flow.

Short term RAP forecasts showed an axis of low level moisture flux
convergence focusing from central GA into the southern
Appalachians through 11Z along with gradually strengthening
925-850 mb winds as Hurricane Helene continues to advance north
from the southern Gulf of Mexico, increasing the low level height
gradient across the Southeast. Flow is expected to be especially
focused along the northern GA/SA border with RAP forecasts of 40
kt by 12Z. The increased low level flow into and perpendicular to
the axis of terrain, coupled with lift within the right entrance
region of a 110-120 kt jet max aloft, should allow for
steady/periods of heavy rain with rainfall rates of 1-2 in/hr. The
flash flood threat will also exist farther north toward the
upslope regions of the central Appalachians into western NC and
southwestern VA where heavy rain has already fallen over the past
1-2 days, although reduced instability/moisture with northern
extent may temper rainfall rates compared to those farther south.

Otto

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!_mf8Di26G500TgTbBXssuA17EmMKPTbty_iVZuLEhVaiDzKYKRNhX8wlFaPb9Hk6zscb=
hHKQLgLumB83leSZcQ8gS-g$  for graphic product...

ATTN...WFO...CAE...CHS...FFC...GSP...MRX...RNK...

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

LAT...LON   36958081 36798069 36308087 35898114 35198192=20
            34738225 34178229 32608194 32398331 32648457=20
            33238469 34088456 34588434 35168392 35948323=20
            36168293 36418229 36588189 36758143 36938111=20
=20=20=20=20=20=20=20=20=20=20=20=20

=3D =3D =3D
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