156
FXUS63 KBIS 290241
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
941 PM CDT Mon Sep 28 2026

.KEY MESSAGES...

- Excessive rainfall could cause localized flooding from south
  central North Dakota to the James River Valley through
  tonight.

- Mostly dry with near normal temperatures from Tuesday into
  the weekend.

&&

.UPDATE...
Issued at 910 PM CDT Mon Sep 28 2026

Convection continues over portions of western ND this evening,
from around Stanley to Killdeer. This is within an area of
surface convergence just north of the surface low. This
convection is pushing eastward into a more stable environment.
If it holds together, it would reach the Minot area around 10
PM. There is some uncertainty as to whether it will maintain its
strength, but we did bump up pops north central this evening
with a PROB30 for the Minot TAF 03-05Z.

Farther to the south, an E-W line of convection from just east
of Bismarck to just north of Jamestown, is lifting to the north.
This is near a warm front, currently analyzed from east of the
surface low in southern Dunn County, east into Foster County.
This convection formed just north of the previous convection
this afternoon and is lifting away from the Flood Watch area.
Water Vapor imagery shows an area of weak shortwave impulsed
tracking through a southwest upper flow from western SD into
southeast ND. There are some CAMS that show convection
developing in the next 1-2 hours and lifting through the Flood
Watch area. There are also some that show little if any
convection in the Flood Watch. The max PWATs have shifted
southeast of the Flood Advisory and moisture transport vectors
are also becoming less favorable, especially for eastern Sioux
and Emmons counties. We should know in the next 1-2 hours if we
can cancel the Flood Watch. Will hold on to it for now though.

Main change to the forecast was updating pops based on latest
radar.


UPDATE
Issued at 638 PM CDT Mon Sep 28 2026

The main forecast update was to clean up pops this evening.
Thunderstorms are currently exiting the far southeast Stutsman
county. A few thunderstorms were also pushing into the far south
central, from north central SD. A couple storms were also
firing over western ND where we had some daytime sunshine. Don`t
think these will last too long. The main area of concern is the
far south central into the JRV, where we issued the Flood
Watch. However, we are in a bit of a lull before the next wave
provides the forcing for additional showers and thunderstorms
over south central ND. The main limiting factor is the
convective potential. Most of the instability is in the
southwest and with the loss of heating, expect CIN to be on the
increase. If we get more stratiform rain with embedded some
embedded thunder, the potential for excessive rain will be less.
We we can get the forcing to get another round of thunderstorms
in this same general area, the potential for excessive rain
increases, especially for those areas that had a round of rain
this afternoon. Guidance suggest rain/thunderstorms will be on
the increase over south central ND this evening. Will continue
to monitor.

UPDATE
Issued at 544 PM CDT Mon Sep 28 2026

We have issued a Flood Watch for a portion of south central ND,
including the James River Valley. This narrow area received
anywhere for 1-3 inches of rain this afternoon. A warm front
remains situated over the area, and another round of
thunderstorms, some with very heavy rain, is possible again this
evening into early Tuesday morning. Flooding of urban and low
lying areas will be possible tonight, especially for those that
received an earlier round of heavy rain this afternoon. The
Flood Watch does include Stutsman county, but far southern
Stutsman is the area that received the heavy rain, in fact it`s
still raining in far southeast Stutsman attim, so the far
southern portion of the county is our main concern.

&&

.DISCUSSION...
Issued at 150 PM CDT Mon Sep 28 2026


Currently a very deep trough in Nevada is causing southwest flow
over the Northern Plains. East of the Mississippi River is
a ridge pattern. At the surface a low pressure system is
working into the western Dakotas, with widespread rain to its
east along a stationary front. This front is located just south
of Interstate 94 from west to east. Along the frontal zone,
several inches of rain has fallen between the Missouri River and
Ashley, ND. For this reason a Flood Advisory has been issued
until 3pm. Western North Dakota is now in the dry slot of the
low.

This evening model guidance suggests a redevelopment of showers
and maybe a thunderstorm in the south central and east. Models
have very little MUCAPE, less than 400 J/kg, this evening and
overnight. The rain shower development will likely be along that
stationary front as it slowly slides north in the surface
cyclonic flow. On the backside of the low, fog may be possible
across the forecast area until the late morning.

The rest of this week the pattern will change to zonal flow
over the Northern Plains, allowing all this rain that just fell
to dry out. No rain is then in the forecast until this weekend
when an Alberta Clipper slides into the state Friday night.
Temperatures through the week will stay near normal in the 60s
to lower 70s as the zonal flow keeps things steady.

&&

.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 638 PM CDT Mon Sep 28 2026

Isolated thunderstorms are possible this evening in western ND.
Showers and thunderstorms, some with very heavy rain, area
expected to move across far south central ND and into the James
River Valley. In this area, expected MVFR-IFR ceilings and
visibilities in thunderstorms with heavy rain this evening into
the early overnight hours. Elsewhere areas of fog are possible
across all of western and central ND tonight into Tuesday
morning. A cold front will move west to east through the state
Tuesday, turning winds west to northwest, ending any
precipitation and clearing skies.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
Flood Watch until 7 AM CDT Tuesday for NDZ037-046>048-050-062.

&&

$$

UPDATE...TWH
DISCUSSION...Smith
AVIATION...TWH