AWUS01 KWNH 290808
FFGMPD
MNZ000-NDZ000-291400-

Mesoscale Precipitation Discussion 1394
NWS Weather Prediction Center College Park MD
407 AM EDT Tue Sep 29 2026

Areas affected...North Dakota into northern Minnesota

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

Valid 290806Z - 291400Z

Summary...Showers and thunderstorms will continue to develop and
train along a stationary front through the early morning. Rainfall
rates of 1-2"/hr, at times potentially greater, will create an
additional 2-3" of rainfall with isolated higher amounts. This may
cause instances of flash flooding.

Discussion...The regional radar mosaic tonight shows an expansion
of high reflectivity across North Dakota associated with
strengthening convection along a stationary front analyzed by WPC.
This activity is developing in response to an impressive overlap
of ascent and moisture as low-level convergence and upper
diffluence merge within an extreme moisture plume reflected by
LPWs that are above the 95th percentile according to CIRA from New
Mexico all the way to North Dakota. Although MUCAPE has remained
modest (around 500 J/kg), the extreme PWs and ample deep layer
ascent are sufficient to negate the relative dearth of
instability, and recent MRMS hourly rainfall has been above 2
inches leading to FLASH unit streamflow responses of 200-500
cfs/smi across parts of Stutsman, Barnes, and Griggs counties, ND.

Moisture advection will remain impressive into the morning as the
850mb LLJ, measured around 30 kts on regional VWPs, only slowly
veers from S to SW. This will maintain an impressive draw of rich
low-level theta-e air and sufficient instability out of NE/SD to
support efficient rainfall as reflected by both HREF and REFS
probabilities for 1"/hr rates remaining 20-40% for several more
hours. Additional convective development should primarily occur in
the immediate vicinity of the stationary front as it lifts slowly
northeast, and with 0-6km mean winds aligned to both this front
and the accompanying Corfidi vectors, training of echoes from WSW
to ENE is likely. Where the most prolonged training occurs, total
rainfall of 2-3" is expected, with locally higher totals possible
(10-30% chance of more than 3").

As already experienced tonight, through training, these efficient
rainfall rates can quickly lead to rapid runoff and elevated
streamflow responses. Any additional heavy rain will only
exacerbate this concern, and as FFG falls in response (it is now
as low as 0.75"/3hrs in some areas), instances of flash flooding
may result until activity begins to more steadily move eastward in
response to more rapid veering of the LLJ by late morning.


Weiss

ATTN...WFO...BIS...DLH...FGF...

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

LAT...LON 48889484 48849369 48679313 47819331 46779525
46089731 45959915 46000034 46340126 46870118
46970111 47680006 48459747

$$
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