303
AWUS01 KWNH 300750
FFGMPD
NDZ000-MTZ000-301300-

Mesoscale Precipitation Discussion 1149
NWS Weather Prediction Center College Park MD
350 AM EDT Sun Aug 30 2026

Areas affected...northeastern MT into ND

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

Valid 300748Z - 301300Z

SUMMARY...A few slow moving thunderstorms could produce localized
areas of flash flooding across portions of northeastern MT into a
sizable portion of ND through 13Z. Hourly rainfall of 1 to 2+
inches could result in isolated storm total rainfall maxima
of/over 3 inches through 13Z, although these higher totals are
expected to remain isolated.

DISCUSSION...0730Z GOES East water vapor imagery showed
southwesterly flow aloft over the Dakotas with an embedded
shortwave near the central ND/SD border, just upstream of the
ridge axis located north/south over western MN. The shortwave
along the ND/SD border has been associated with scattered strong
to severe thunderstorms across northern SD while another impulse
on water vapor imagery was associated with weaker and scattered
showers/thunderstorms near the northern MT/ND border in the
vicinity of a pair of outflow boundaries.

RAP and VAD wind data showed a well defined 850 mb low in
west-central SD, with a northwestward extending trough axis into
eastern MT and southwestern Saskatchewan. A zone of modest 850 mb
confluence/convergence was in place over ND where MLCAPE was
estimated to be 1000 to 2000+ J/kg via 07Z SPC mesoanalysis data,
with little to no CIN extending from near Williston to Devils Lake
and as far south as I-90. An anomalous plume of moisture was also
over ND with PWs ranging from 1.2 inches across the northwestern
part of the state to 1.7 inches in the southeastern part.

Expectations are for lift tied to the impulse(s) on water vapor
imagery to combine with lower level ascent focused near 850 mb to
result in at least a modest increase in thunderstorm activity over
the next few hours across northwestern to east-central ND. There
remains some uncertainty in the coverage of storms however, given
poor model handling of this region of the U.S. so far and only
modest low level convergence in place. Should thunderstorms
develop and become more numerous overnight, high hourly rainfall
will be possible with slow moving cells given ND was located
within a weakness in the mean steering flow with 0-6 km mean layer
winds of only 5 to 15 kt. 1 to 2 inches of rain in an hour
(locally higher) may develop, resulting in potential for isolated
rainfall maxima over 3 inches through 13Z.

Otto

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

ATTN...WFO...BIS...FGF...GGW...

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

LAT...LON   48970194 48780015 48179827 47399781 46709829
            46559925 46630087 47020231 47550358 48010494
            48850499