291
AWUS01 KWNH 260721
FFGMPD
MOZ000-ARZ000-OKZ000-KSZ000-261200-

Mesoscale Precipitation Discussion 0325
NWS Weather Prediction Center College Park MD
320 AM EDT Sun May 26 2024

Areas affected...much of MO...northeastern and eastern KS...far
northern AR...far northeastern OK

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

Valid 260720Z - 261200Z

Summary...Isolated to scattered instances of flash flooding
becoming more likely through dawn with upscale growth and training
of convection resulting in 1-3"/hr rainfall rates.

Discussion...Deep convective activity late tonight remains
somewhat scattered at this hour across eastern portions of the
central/southern Plains into the Mid-MS Valley, though there are a
couple of distinct areas where organized activity is starting to
take shape: 1) over northeastern KS where semi-discrete cells are
becoming more numerous in a west-to-east training orientation),
and 2) with ongoing supercells just to the south, near the
MO/KS/AR/OK border region, which have tended to remain more
discrete and separated (thus far). The broader mesoscale
environment is characterized by MUCAPE of 1500-3000 J/kg (with an
interesting pocket of more stable air near the KS/MO border),
PWATs of 1.3-1.6" (between the 90th percentile and max moving
average, per SPC sounding climatology), and effective bulk shear
of 30-60 kts. A very strong LLJ (40-60 kts) from the SSW is
resulting in strong moisture transport/flux into the region, which
should continue to organize convection due to further
destabilization amid ongoing height falls from the approaching
potent shortwave trough.

Taking a look at the hi-res guidance, the activity farther south
was largely missed by the entire 00z HREF suite, and only the
latest runs of the HRRR (04z/05z/06z runs) have begun to properly
assimilate and initialize these storms in the MO/KS/AR/OK border
region. This has resulted in an altered depiction of QPF through
early morning, with the 05z/06z HRRR suggesting that short-term
localized totals will be limited to 1-3" for the northern swath.
Earlier runs of the HRRR suggested higher amounts (locally 3-5"),
as do the 00z HREF 40-km neighborhood probabilities for 3"
exceedance (which are as high as 20-40%). But this development
makes sense, as observational trends support a secondary swath of
higher QPF to the south in association with upscale growth of
convection and training of supercells (which have been capable of
2-3"/hr rainfall rates, compared to only 1-2"/hr with the swath
farther north). Therefore the preference is towards the 06z HRRR
as it has caught up with these trends, which suggests localized
totals of 3-5" with the swath farther south (and is consistent
with the exceedance probabilities from the HREF, though displaced
just a bit south). As a result, expect for isolated to scattered
instances of flash flooding to become more likely through dawn.

Churchill

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...EAX...ICT...LSX...LZK...MEG...PAH...SGF...TOP...
TSA...

ATTN...RFC...ABRFC...LMRFC...MBRFC...NCRFC...NWC...

LAT...LON   39929744 39629524 39399318 39259217 38649135
            37929091 37618981 36558956 36049027 35859243
            35989486 36719629 37989659 38589727 39209783