298
AWUS01 KWNH 140421
FFGMPD
MNZ000-SDZ000-NDZ000-140857-

Mesoscale Precipitation Discussion 0931
NWS Weather Prediction Center College Park MD
1220 AM EDT Thu Aug 14 2025

Areas affected...Northeast SDak...Southeast NDak...Far
West-central MN...

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

Valid 140417Z - 140857Z

SUMMARY...Regenerative warm-air advection thunderstorms will be
slow to move initially resulting in spots of 2-3.5" and possible
localized flash flooding, before shifting east-northeast toward
early morning.

DISCUSSION...GOES-E 10.3um and KABR RADAR show a few bands of
thunderstorms across northeast South Dakota into far southeast
North Dakota with downstream cirrus and lighter showers extending
into western Minnesota.  GOES-E WV and RAP analysis shows an
exiting and flattening shortwave within synoptic scale ridging
across south central MN into northeast IA, while a stronger
shortwave and associated linear convective complex along the
southern flank of the wave starting to reach central SDak and Sand
Hills of NEB.  The low-level jet has responded while recently
strengthening to 45-50kts at 850mb with solid veered 925-700mb
profile along/ahead of the approaching wave.  This is obliquely
intersecting the lingering boundary left in the wake of the prior
wave.  Recent strengthening and increasing deeper layer moisture
with total PWat values up to 1.75" helps to differentiate the
isentropic boundary across the southern portion of the Red River
Valley; and given increasing core of the unstable air north-south
axis generally along 98-99W with values of 2000-2500 J/kg MUCAPEs.
  The stronger moisture flux convergence is increasing rainfall
efficiency for the thunderstorms.  Rates of 1.5-2"/hr are starting
to become more common with the recent cooling noted in the
convective tops.

Along with the strengthening flux convergence, the veered inflow
is also supporting southwestward upwind propagation and given the
sharpness of the ridging between the two mid-level waves, the
deeper layer steering is also slackened to reduce eastward cell
motions as well.  This has resulted in back-building and localized
training of downdrafts locally along the best isentropic upglide
ascent plane to increase duration over an hour with repeating that
may allow for localized 2-3.5" totals over the next few hours.
Hourly rates are near the hourly FFG, but those locally higher
totals have a good potential to exceed the 3hr FFG values which
range from 1.5-2.5" across the area of concern.  As such,
localized flash flooding is considered possible for the next few
hours.   As the MCS/shortwave passes, winds will remain strong,
but likely veer further and increase forward propagation into
northwest and west-central MN...but with the decrease in local
duration potential for exceedance will diminish.

Gallina

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

ATTN...WFO...ABR...FGF...MPX...

ATTN...RFC...KRF...MSR...NWC...

LAT...LON   46839674 46239622 45649600 45059601 44669643
            44739700 44939737 45409775 45799795 46059800
            46439794 46819753