Donnybrook, North Dakota Weather Forecast Discussion

357
FXUS63 KBIS 241135
AFDBIS
Area Forecast Discussion
National Weather Service Bismarck ND
635 AM CDT Wed Sep 24 2025
.KEY MESSAGES...
- Above average temperatures and dry conditions are expected
  through the end of the month.
&&
.UPDATE...
Issued at 633 AM CDT Wed Sep 24 2025
Patchy fog has developed across parts of central North Dakota.
Other than at Linton, where sensors have consistently reported
zero visibility for several hours, the fog appears to be shallow
and spatially limited, with varying visibility over time. Since
dense fog appears to remain very isolated, no plans for any
enhanced messaging at this time. But there is still an hour or
two to go for further fog development until radiative cooling
ceases.
&&
.DISCUSSION...
Issued at 338 AM CDT Wed Sep 24 2025
An oblong, highly-tilted upper level ridge axis extends from the
Pacific waters off northern California to just south of Hudson Bay
early this morning, with a surface ridge axis extending from
northern Colorado through the western Dakotas and curved into the
northern Red River Valley. Monitoring for the potential development
of patchy dense fog across central North Dakota, with quarter mile
visibility observed as far west as Devils Lake and Cooperstown.
Temperatures this morning are in the 40s and 50s, with high spatial
variability caused by terrain and sheltering.
A mid level shortwave ejecting off the Canadian Rockies is forecast
to induce surface cyclogenesis over the southern prairie provinces
today. The upper ridge axis will barely be tilted clockwise while
the deepening surface low shunts the surface ridge axis
southeastward. Expect a breezier day in western parts of the state,
particularly the northwest where southwesterly winds could gust to
around 25 mph this afternoon. It will otherwise remain quiet today,
with plentiful sunshine and high temperatures around 75 to 85. As
the mid level shortwave tracks eastward across central Canada
tonight into Thursday, the cold front attendant to its surface low
will plunge into northern North Dakota before stalling and
retreating with the trailing surface high that is forecast to
maintain a steady eastward progression across southern Saskatchewan
and Manitoba. This brings cooler afternoon temperatures into the
forecast for Thursday, especially across the far north. Highs on
Thursday could be limited to the mid and upper 60s in the Turtle
Mountains and Devils Lake Basin areas while still approaching 80
degrees along the South Dakota border.
A more potent shortwave trough is forecast to land on the Pacific
Northwest coast by Thursday evening and quickly traverse the Rockies
along the international border early Friday before lifting toward
Hudson Bay later on Friday. The shortwave should briefly amplify a
meridional upper ridge axis over the Northern Plains Thursday night,
with the underlying low level thermal ridge translating through the
region Friday morning and afternoon. The timing of the cold frontal
passage attendant to the shortwave and its surface cyclone is likely
to play a role in high temperatures on Friday. This is reflected in
the latest NBM guidance, with values as cool as the lower 70s in the
northwest corner of the state to lower 80s south central and
southeast. This system is more likely to bring windier conditions to
the region on Friday, both in the warm sector and with and trailing
the frontal passage. Deterministic guidance shows strong cold air
advection and pressure rises with the cold front, as well as steep
mid level lapse rates given the time of the day. However, forecast
ensemble mean boundary layer winds do not exceed 25 kts, which would
limit the surface gust potential to well below the advisory criteria
of 45 mph. Despite the synoptic scale lift from both the cold front
and upper shortwave, the atmosphere is not projected to carry enough
moisture to support measurable precipitation at this time.
The departing system on Friday is forecast to leave behind a broad
subsidence regime to start the weekend. Highs on Saturday look to be
slightly cooler in the lower to mid 70s for central and eastern
North Dakota, but the progressive nature of the pattern could allow
upper 70s to near 80 back into western parts of the state. From
Sunday through early next week, there is strong ensemble consensus
in highly amplified ridging over the Upper Midwest as longwave
troughing deepens along the Pacific coast. This should result in a
southwesterly flow aloft regime over the Northern Plains with strong
low level/surface southerly return flow, although cluster analysis
reveals minor discrepancies on finer-scale details. This favored
pattern would prolong the stretch of seasonably warm and dry weather
through the end of the month, although there are some hints in
guidance that lower amplitude waves embedded in the southwest flow
could eventually introduce chances for rain as early as Monday
night. For now though, the forecast remains dry for all but the far
north into the first day of October next Wednesday. The NBM
temperature distribution remains well above normal for high
temperatures through Tuesday, with 70s and 80s remaining in the
forecast. A distinct cool down can be seen in NBM data by the end of
next week, but not any colder than around average.
One final note about the forecast through the end of the month is
that the odds for sub-freezing low temperatures are very low. Only
Friday night/Saturday morning has even a 5 to 10 percent chance for
sub-freezing temperatures, and only for low-lying sheltered areas
across the west and north central. All other days through next
Tuesday carry negligible to zero chances. Low temperatures are more
likely to remain in the 40s and 50s through the middle of next week,
and in fact could be near record-warm values around 60 during the
period of strong southerly return flow early next week.
&&
.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 633 AM CDT Wed Sep 24 2025
Patchy fog has developed across central and eastern North Dakota
early this morning. KJMS may continue to experience periods of
visibility restrictions until around 15Z, when all fog should
dissipate. VFR conditions are otherwise expected through the
forecast period. Winds today will generally become southwesterly
around 5 kts at KBIS and KJMS, 10 kts from KDIK to KMOT, and 15
kts with gusts to around 25 kts at KXWA. A light southwesterly
breeze will continue across all of western and central North
Dakota tonight. By early Thursday morning, a cold front is
forecast to enter northwest and north central North Dakota,
turning winds to the north-northwest around 10-15 kts.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Hollan
DISCUSSION...Hollan
AVIATION...Hollan

NWS BIS Office Area Forecast Discussion