Mesoscale Precipitation Discussion 0092
NWS Weather Prediction Center College Park MD
109 AM EST Sat Mar 09 2024

Areas affected...Southern AL...Southwest to Central GA...Florida
Panhandle...

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

Valid 090610Z - 091200Z

SUMMARY...A few more hours of potential back-building and training
thunderstorms capable 2"/hr rates and isolated spots of flash
flooding or re-aggravation of ongoing flooded/saturated grounds.

DISCUSSION...06z surface analysis denotes a pair of surface waves
along a relatively stationary frontal zone from central AL back
toward southeast LA.  A very subtle low to mid-level wave is
riding northeastward along this boundary at the lead edge of a mid
to upper level speed max ahead of the positively tilted synoptic
long wave over the mid to lower Mississippi River Valley.  Spurred
by weak divergence aloft, this 925-850 wave is providing a
short-term increase in warm advective response off the high
Theta-E air mass of the central Gulf where Tds remain in the low
70s.  CIRA LPW notes that the sfc-850 layer is highly anomalous
and near 1" total across SE LA into southern AL ahead of this
front.  Combined with confluent 850-700 (.5-.66") and exiting
pocket of 700-500 (.25-.33) values combine to 1.75-2" total PWat
across Mobile Bay.   Modestly unstable MLCAPEs to 1500 J/kg will
provide ample buoyancy for the warm sector for stronger efficient
thunderstorms with rates of 2"/hr likely.

However, the overall flow continues to become increasingly
unidirectional through depth, limiting convergence for convective
initiation.  Surface convergence has been weak enough to spur
occasional cells/weak clusters that train across the warm sector
until reaching the warm front that cross SE AL into the eastern FL
Panhandle.  Afterward, isentropic ascent is strong with 50+kt of
ascent over the cooler/stable air in GA, but providing strong
moisture flux for broad shield precipitation.  While rates
decrease to .5"/hr with some embedded convective elements
occasionally up to 1" randomly scattered through GA...adding to
moderate rainfall that has already fallen over the last few hours.
  As the mid-level wave/upper-level speed max moves through,
height-falls will increase  movement of the cold front from
west-east reaching the western FL panhandle by 12z.  As such,
streaks of 2-4" totals in short 1-2hr durations remain possible
across the warm sector in S AL/FL panhandle with broad 2-3" of
shield precip across areas of GA which may still result in
flooding, but less likely flashy in nature.  In either scenario,
flooding is considered possible though 12z.

Gallina

ATTN...WFO...BMX...FFC...MOB...TAE...

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

LAT...LON   33878368 33728300 33238250 32678235 31998275
            31608325 31238371 30358496 30208724 30348824
            30968820 31408750 32008652 32708559 33108518
            33628438