063
FXUS63 KBIS 301819
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
119 PM CDT Mon Jun 30 2025

.KEY MESSAGES...

- Breezy today with high temperatures around 80.

- Dry through the day Tuesday, with only low chances for
  overnight showers and storms Tuesday night through Wednesday
  night.

- Warmer and more humid Wednesday and Thursday, with highs
  around 85 to near 95.

- Increasing chances for showers and thunderstorms Thursday
  through Independence Day. Widespread severe storms are not
  expected at this time.

&&

.UPDATE...
Issued at 116 PM CDT Mon Jun 30 2025

Fair weather clouds are developing over the area with the
daytime heating in very modest cyclonic flow. Will have to keep
an eye over central North Dakota to see if any little very light
showers develop from this, but will keep the forecast dry for
now.

UPDATE
Issued at 1005 AM CDT Mon Jun 30 2025

Quiet weather continues over the area with only a few clouds
sliding through parts of north central North Dakota through the
James River Valley.

UPDATE
Issued at 621 AM CDT Mon Jun 30 2025

Isolated to scattered showers have shifted into the Devils Lake
Basin and northern Red River Valley. Although we can`t completely
rule out a stray shower in the northern James River Valley this
afternoon, dry weather is expected through tomorrow.

It is a cooler start to the day in the southwest, where a few
locations have fallen into the mid 40s. Temperatures should
quickly warm through the morning, reaching the upper 70s and
lower 80s this afternoon.

&&

.DISCUSSION...
Issued at 429 AM CDT Mon Jun 30 2025

A mid/upper level trough axis extends from Hudson Bay through North
Dakota early this morning. This feature is responsible for scattered
showers moving across north central and into northeast parts of the
state. A thunderstorm was briefly observed near Rolla just before 4
AM CDT, but that has been the only lightning noted in our forecast
area. The showers should shift off to the south east by mid morning,
following the base of the mid/upper trough.

Northwest flow aloft will transition from cyclonic to anticyclonic
today as surface high pressure from eastern Montana to the Black
Hills nudges eastward. The position of the surface high to the west
will result in another breezy day for most of the state, with the
strongest northwest winds of around 25 mph gusting to 35 mph
expected east of Highway 83 and south of Highway 200. Temperatures
will remain seasonably pleasant, with highs around 80.

Quiet weather should continue tonight through Tuesday as the surface
high slides southeastward into the Great Plains and the upstream
thermal ridge expands eastward. This raises the high temperature
forecast into the mid and upper 80s for Tuesday. From Tuesday
evening through the night, there are two separate areas with low
probabilities for shower and thunderstorm development. One is in
southwest North Dakota near the top of a poleward advecting plume of
higher theta-e. The other is near the Canadian border where an axis
of low level moisture convergence is forecast along a baroclinic
zone. In northern North Dakota, CAPE is forecast to diminish to
negligible values through the late evening and overnight. In the
southwest though, an elevated mixed layer could yield MUCAPE
increasing to as high as 1000-1500 J/kg, with effective bulk shear
possibly exceeding 40 kts. This means that a stronger storm cannot
be ruled out. But with models soundings showing a shallow depth to
the layer of increasing moisture, it may be difficult for rising air
parcels to be sustained above the LFC, and the probability of any
showers or storms forming at all is only around 20 percent.

The upstream upper level ridge axis is forecast to shift eastward
into the High Plains on Wednesday and approach the Mississippi River
Valley on Thursday. This is expected to bring warmer temperatures
and higher dewpoints back into the state. Forecast highs are mostly
around 85 to 90 on Wednesday and in the upper 80s to near 95 on
Thursday. These are still skewed to the cooler side of the NBM
distribution, but forecast east to southeast surface winds combined
with increasing moisture are not favorable for strong mixing of the
boundary layer. Dry weather is expected during the day Wednesday.
For Wednesday evening/night, there is a 20 to 30 percent chance of
showers and storms entering the state from Montana. Deterministic
models do show falling mid level heights spreading eastward, but
there is notable ensemble spread for both CAPE and shear, and any
convection moving in would almost certainly be elevated. By Thursday
evening, much stronger buoyancy is forecast under an established
southwest flow aloft on the backside of the upper ridge. Chances for
thunderstorms increase from around 20 percent Thursday afternoon to
around 50 percent by midnight. Deep layer shear looks to be either
weak or displaced from the pool of buoyancy where it is stronger.
This may prevent any storms that do form on Thursday from becoming
severe, at least on a widespread basis.

Southwest flow aloft is favored to remain in place through the
Fourth of July, and ensembles are now showing signs for the passage
of a deeper shortwave. While the entire holiday is unlikely to be a
washout, the chance of showers and thunderstorms at any given point
in the day/evening has certainly increased from previous forecast
iterations. Ensemble deep layer shear is not indicative of a larger-
scale severe threat at this time, but heavy rain could be a concern
as ensembles are showing precipitable water above the 95th
percentile of climatology. Ensemble spread in most fields begins to
grow rapidly through the holiday weekend, but the NBM distributions
of maximum and minimum temperatures do shift slightly cooler, and
chances for showers and storms are only around 20 to 30 percent.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 116 PM CDT Mon Jun 30 2025

VFR conditions are expected to prevail through the forecast
period.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

UPDATE...JJS
DISCUSSION...Hollan
AVIATION...JJS