258
AWUS01 KWNH 282046
FFGMPD
MNZ000-SDZ000-NDZ000-290244-

Mesoscale Precipitation Discussion 1386
NWS Weather Prediction Center College Park MD
445 PM EDT Mon Sep 28 2026

Areas affected...Eastern North Dakota

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

Valid 282044Z - 290244Z

SUMMARY...Linear thunderstorms developing along a slow moving warm
front will increase in coverage into this evening over eastern
North Dakota into South Dakota and east into western Minnesota.
Rainfall rates of 2"/hr are likely to continue in the stronger
cells. Increased duration of heavy rain from the slow motion could
allow rainfall totals of 2 to 3 inches to 03Z.

DISCUSSION...As of 2030Z...Strong SSWly low level flow around 30kt
continues to stream up the Great Plains and converge on a warm
front over southern North Dakota in the wake of an MCV now
tracking east over north-central MN. Moisture is pooling around
1.5" along this front which is about 3 standard deviations above
normal. Sufficient instability (SBCAPE of 1000 to 1500 J/kg) is
present south of the front and is aiding redevelopment of the
frontal line. Rain rate estimates from nearby radars peak at
2"/hr. Much of this area has been dry recently with drought
conditions. So flash flooding should be limited to areas with the
highest rainfall. Instability decreases east into MN and
increasing toward northwest South Dakota. Therefore the main focus
for expanded development should be to the southwest while current
activity develops as it drifts north. Another discussion farther
southwest into WY may be needed.

The 19Z HRRR and 18Z RRFS runs have a decent handle on this
activity with the RRFS really favoring western development while
the HRRR has heavy rain into MN. The discussion area is a bit of a
compromise from ongoing activity and consideration of these two
models. Maxima of 2 to 3 inches and localized flash flooding are
considered possible through 02Z. The threat for heavy
thunderstorms refocuses over similar areas overnight as the LLJ
further increases and possibly becomes more oriented with the
front, so subsequent discussions and increasing flash flood
coverage can be expected overnight.

Jackson

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

ATTN...WFO...ABR...BIS...FGF...

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

LAT...LON   47939591 46749558 46059695 45450144 46150150
            46909991 47769748