901
AWUS01 KWNH 012126
FFGMPD
NEZ000-SDZ000-NDZ000-020325-

Mesoscale Precipitation Discussion 0534
NWS Weather Prediction Center College Park MD
525 PM EDT Mon Jul 01 2024

Areas affected...Central ND...Central/Southwest SD...Far Northwest
NE

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

Valid 012125Z - 020325Z

SUMMARY...Developing and expanding clusters of strong convection
with high rainfall rates going into the evening hours may pose a
few instances of flash flooding where any cell-mergers or
cell-training activity occurs.

DISCUSSION...Radar and satellite imagery show rapidly developing
and expanding clusters of heavy showers and thunderstorms across
portions south-central ND down through central SD and into
northwest NE. The activity is organizing in response to a strong
shortwave trough and associated frontal zone ejecting east out
across the northern Plains while interacting with a very moist and
unstable airmass lifting north through the central and northern
Plains.

A north/south axis of MLCAPE values reaching 1500 to 2500 J/kg are
focused along the frontal occlusion and especially the cold front
extending south-southwest of a wave of low pressure situated east
of Hettinger, ND. The instability is being aided by a southerly
low-level jet of 30 to 40 kts and this strong warm air advection
and moisture transport is also combining with as much as 40 to 50
kts of effective bulk shear for organized convective line segments
and some supercell activity.

Over the next few hours, convection should continue to grow
further in coverage and organization as height falls/forcing
associated with the shortwave trough ejects farther east out
across the northern Plains and interacts with the moist/unstable
low-level jet. The PWs are running quite high with magnitudes of
1.5 to 1.75 inches which are a solid 1.5 to 2 standard deviations
above normal. This will support some of the stronger convective
cells attaining rainfall rates that could reach 2 inches/hour
which is supported by the 18Z HREF guidance.

Some localized concerns for some cell-merger and cell-training
activity will exist, and the 18Z HREF does favor some potential
for isolated 3 to 4+ inch totals going through the late evening
hours. A few instances of flash flooding cannot be ruled out as a
result where these heavier totals materialize.

Orrison

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

ATTN...WFO...ABR...BIS...CYS...FGF...LBF...UNR...

ATTN...RFC...MBRFC...NCRFC...NWC...

LAT...LON   48889986 48799842 47899805 46409829 45009902
            43500034 42830154 42700295 43300330 45120194
            46820146 47890136 48540074