Mesoscale Precipitation Discussion 0128
NWS Weather Prediction Center College Park MD
915 AM EDT Sat Apr 05 2025

Areas affected...Arklatex...Lower MS Valley...Mid-South...Lower OH
Valley

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

Valid 051315Z - 051915Z

SUMMARY...Training areas of very heavy showers and thunderstorms
over the next several hours are expected across large areas of
central and eastern AR and also parts of western TN. High-end
flash flooding with life-threatening and locally catastrophic
impacts will likely set up over the next several hours across
these areas. This is a particularly dangerous situation.

DISCUSSION...A particularly dangerous situation is expected to
begin to unfold over the next several hours across areas of
central and eastern AR and potentially into western TN as a band
of slow-moving and training showers and thunderstorms with high
rainfall rates impacts this region. Already the mid-morning GOES-E
IR satellite imagery and area dual-pol radars show an extensive
area of convection impacting large areas of the Arklatex with an
eastward extension of this into portions of the Mid-South and
Lower OH Valley.

The convection continues to be driven by the gradual ejection of
mid-level troughing/height falls across the southern Plains with
downstream interaction with a moist and unstable 30 to 40+ kt
southerly low-level jet and proximity of a strong frontal zone.
Multiple waves of low pressure continue to transit the front which
is yielding locally focused areas of low-level convergence and
forcing and this is with an already divergent flow pattern aloft.
MUCAPE values along the front which extends from southwest to
northeast AR are on the order of 1000 to 2000 J/kg along with a
substantial block of vertical shear with effective bulk shear
values of 50+ kts overrunning large areas of the Lower MS Valley
and Mid-South.

The HRRR guidance shows the low-level jet becoming increasingly
convergent and strengthening to 50+ kts by late this morning from
far eastern TX up through southern AR with a substantial corridor
of speed convergence suggested along the nose of this across
central and eastern AR and into western TN. The moisture transport
will be very strong, and the latest CIRA-ALPW data shows very
strong SFC/850 mb LVT (Layered Vapor Transport) values of 320+
kg/m/s lifting up across the western Gulf Coast region which will
advance north through the Lower MS Valley by midday and through
this afternoon. The PWs are forecast to be 1.75+ inches and the
level of forcing, moisture transport and instability should
support locally extreme rainfall rates of 2 to 3+ inches/hour.

Extensive cell-training with these high rainfall rates is the
major concern over the next several hours, with potential
additional rainfall totals of as much as 4 to 6+ inches possible
by mid-afternoon. Saturated soil conditions included areas that
are already flooded will see enhanced impacts from these rains
which may include multiple large cities extending from Texarkana,
AR northeastward to Dyersburg, TN. This is particularly dangerous
situation with with concerns for Flash Flood Emergency level
impacts going through mid-afternoon.

Orrison

ATTN...WFO...LSX...LZK...MEG...OHX...PAH...SGF...SHV...

ATTN...RFC...ABRFC...LMRFC...OHRFC...NWC...

LAT...LON   37508810 36988764 35838834 34759000 34229102
            33379260 32569373 32739468 33249472 34499433
            35429358 36019280 37149070 37488942