Mesoscale Precipitation Discussion 0132
NWS Weather Prediction Center College Park MD
1108 PM EDT Tue Apr 02 2024

Areas affected...portions of Alabama, Georgia, and western South
Carolina

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

Valid 030307Z - 030907Z

Summary...Convective coverage was expanding across Alabama and
west-central Georgia, and 1+ inch/hr rain rates were beginning to
approach urbanized areas near Atlanta, GA and south of Birmingham,
AL.  Isolated instances of flash flooding are possible through 09Z.

Discussion...The combination of broad low-level confluence across
the discussion area and upper difluence was resulting in maturing
convection across southwestern/central Alabama and west-central
Georgia over the past couple of hours.  SPC mesoanalyses indicated
that storms were located in an unstable, yet weakly capped
environment characterized by ~1500 J/kg SBCAPE, 1.5-2 inch PW
values, and strong vertical shear/flow aloft.  The flow aloft was
keeping most convection progressive in nature, although convective
orientation (more parallel to flow aloft) in a couple areas was
resulting in training and rain rates exceeding 1 inch/hr - 1) west
of Atlanta Metro (near Carrollton, GA) and 2) over Talladega
National Forest near west of Selma, AL.  FFG thresholds are
generally in the 2.5 inch/hr range across most of the discussion
area (locally lower in urban areas), suggestive of an isolated
flash flood threat where ground conditions are relatively
sensitive in the short term.

Over time, three factors should contribute to a continued, gradual
expansion of convective coverage through the night, including 1)
an approaching mid/upper jet stream across currently across
southeast Texas, 2) increasing low-level flow/persistent low-level
confluence across the unstable airmass in place across the
discussion area, and 3) destabilization into portions of northern
Georgia and upstate South Carolina, where ground conditions are
somewhat more sensitive for flash flood potential (lower FFGs). 
Each of these factors suggest a continued risk of areas of rain
rates approaching 2 inches/hr (especially where training is
pronounced) along with a gradually increasing, yet isolated flash
flood risk.  Again, this risk is focused mainly from central Al
into the Atlanta Metro area in the near term, but should spread
northeastward into more of the southern Appalachians over the next
3-6 hours.

Cook

ATTN...WFO...BMX...CAE...FFC...GSP...HUN...MOB...MRX...TAE...

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

LAT...LON   35258189 35078113 34448096 33768130 32828228
            31998411 31338615 31358751 31598812 32118815
            33078753 33818682 34658598 34928464 35218307