FXUS63 KBIS 262045

AFDBIS



Area Forecast Discussion

National Weather Service Bismarck ND

345 PM CDT Thu Jun 26 2025



.KEY MESSAGES...



- An isolated strong to severe thunderstorm could impact far 

  northwest North Dakota this evening. Expected hazards include 

  hail as large as quarters and damaging wind gusts as high as 

  60 mph.



- Patchy fog is possible Friday morning over south central North

  Dakota into the James River Valley. 



- Scattered severe thunderstorms (risk level 2 out of 5) could 

  develop across central North Dakota Friday afternoon and 

  evening. Expected hazards include hail as large as tennis 

  balls, damaging winds as high as 70 mph, and a tornado or two 

  possible.



- Near to slightly above average high temperatures in the 80s

  are forecast Friday through next week. Friday will also be

  humid for all but far western North Dakota.



&&



.DISCUSSION...

Issued at 345 PM CDT Thu Jun 26 2025



The northern Plains falls under the influence of a transient 

upper level ridge passing through a much broader southwesterly 

low pattern. Downstream of this ridge, a shortwave trough 

continues to exit eastward into the Great Lakes region. This 

shortwave, in conjunction with ample moisture flowing into the 

region due to surface high pressure lingering over eastern 

Canada, promoted a layer of low stratus across much of the 

region earlier this morning. Along with the shortwave, this 

stratus layer continues to move eastward this afternoon. With 

thick cloud cover lingering across the eastern North Dakota, 

high temperatures in this area are slightly lower, forecast in 

the upper 60s and lower 70s, versus out west where clear skies 

have help push highs into the mid 70s to mid 80s. 



Later this afternoon, isolated to scattered thunderstorms are 

expected to develop over portions of eastern Montana as another 

weak shortwave and associated occluding low pressure system 

slowly makes its way eastward. Some of these storms may survive 

long enough to move into northwestern North Dakota later this 

evening. With moderate amount of instability across western 

North Dakota, with modeled MLCAPE values around 500 to 1000 

J/KG, and borderline sufficient bulk shear values around 30 to 

45 knots, a few of these storms may become strong to severe. 

With how borderline these values are, and how disorganized they 

become later in the evening, our expectation is that any severe 

storms that do develop would be relatively short lived, and 

would struggle to put down much more that base-line severe 

hazards of quarter sized hail and wind gusts up to 60 MPH at 

most. Clusters of showers and possible some thunderstorms may 

then linger across northwestern and central North Dakota 

overnight. 



Otherwise, for tonight, weak south to southeasterly winds and 

ample near surface moisture could promote patchy dog development

across portions of south central North Dakota into the James 

River Valley. An interrogation of BUFKIT model soundings during 

this period reveal a surface inversion very close to the 

surface, thus any patchy fog that does develop may be fairly 

shallow, and fairly quick to lift as we move into the mid 

morning hours. Low temperatures Friday morning are forecast in 

broadly from the mid 50s east up to around 60 west. 



Now on to Friday. With the Gulf essentially wide open to the 

northern Plains, the continued saturation the low to mid layers 

across western and central North Dakota will promote an 

increasingly unstable air mass Friday afternoon. With model 

surface dewpoint values peaking into the upper 60s and lower 70s

across central North Dakota, MUCAPE values approach the 3000 to

4000 J/KG range by the mid to late afternoon hours. While a 

strong forcing mechanism is not anticipated to present itself 

during this period, most likely to be associated with a broad by

shallow shortwave trough lofting a occluding low pressure 

system across North Dakota, the continued saturation of the mid 

layer is expected to help erode any lingering CIN across the 

forecast area, and thus CI can still be anticipated by the mid 

to late afternoon. With such weak forcing, these initial storms 

are anticipated to discrete in nature. Model shear values are 

somewhat all over the place, but broadly range from the lower 40

knot range all the up to around 55 knots just behind these 

initial storms. With this, supercellular development is entirely

possible which, along with the abundant cape across the area, 

could promote hail up to the size of tennis balls (2.5 inches). 

Another thing to consider is the potential for tornadic 

development during this period. While CAMs continue to capture 

more than sufficient near surface SRH values peaking into the 

100-200 M2/S2 range tomorrow afternoon, less agreement can be 

found regarding near surface shear. Even the RAP and NAMNEST, 

which have been most aggressively championing the potential for 

tornadoes, promote SFC-1km shear values just around 15 knots at

most which, while climatologically sufficient for tornado 

genesis, is not very high. Other models, such as the HRRR and 

HREF, are much more conservative with values around 10 knots or 

so. Overall, I think that the overall message is that a tornado 

or two is possible tomorrow afternoon, and would be associated 

with any potential supercell. Otherwise, an interrogation of 

BUFKIT model soundings reveals moderate DCAPE values across 

central North Dakota in the 1000-1500 J/KG range late Friday 

afternoon and evening, signaling the potential for strong wind 

gusts during this period. This would especially be true if a 

general conversion from a discrete storm mode into a more 

clustered or linear mode occurs, which can be anticipated with 

both the weak forcing mechanisms and is climatologically the 

norm as we head into the late evening and overnight period.

Thus, we are also advertising wind gusts up to 70 MPH as well.

Storms are expected to continue pushing eastward through the

late evening and overnight, by which time it is expected to have

started diminishing and clustering together. 



Beyond Friday, near zonal to slightly southwesterly flow is 

expected to persist over the forecast area through the weekend. 

With this pattern, near daily low to medium chances for showers 

and possible some thunderstorms can be expected. CSU machine 

learning continues to highlight southeastern North Dakota for 

severe weather potential on Saturday, though this is likely the 

remnants of the system passing through the northern Plains from 

Friday night. Temperatures during this period are advertised to 

be near to slightly above normal by the NBM, in broadly in the 

80s, though this deterministic output remains around the 25th 

percentile of the ensemble as a whole. Looking ahead into next 

week, there is moderate to strong agreement in the ensemble in a

switch to northwesterly flow aloft as broad upper level ridging

builds in the from the west. In this pattern, we could 

anticipate relatively dry weather during this period. The 

aforementioned ridge does begin to squish down by the midweek, 

turning flow more zonal and thus could allow for more chances 

for widespread rain. 



&&



.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...

Issued at 345 PM CDT Thu Jun 26 2025



Low stratus is causing MVFR to IFR ceilings across the forecast

area at the time of this mid day update. As this stratus deck 

continues to move eastward through the afternoon, ceilings are 

expected to broadly improve to VFR conditions from west to east.

KJMS may remain under MVFR ceilings through the early evening 

hours. Later this evening, chances for showers and thunderstorms

are expected to increase across northwestern North Dakota, 

including around the KXWA terminal. Some of these storms may 

become strong to severe, with large hail up to quarters (1 inch)

in size and wind gusts up to 60 MPH. These thunderstorms 

expected to generally diminishing through the late evening into 

the early overnight period, though scattered showers may linger 

across the north. Confidence is too low to include mentions of 

showers or thunderstorms anywhere except for KXWA at this time. 

Friday morning, patchy fog is possible across portions of south 

central North Dakota into the James River Valley. Have included 

visibility reductions at KJMS with this update. Currently, this 

fog is expected to be somewhat shallow, and should readily lift 

by the mid morning hours. Otherwise, Light east to southeasterly

winds are anticipated throughout the TAF period.



&&



.BIS WATCHES/WARNINGS/ADVISORIES...

None.



&&



$$



DISCUSSION...Adam

AVIATION...Adam

