418
FXUS63 KBIS 031753
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
1253 PM CDT Mon Jun 3 2024

.KEY MESSAGES...

- Another round of thunderstorms this afternoon through Tuesday
  morning. A few storms could be severe this afternoon and
  this evening.

- Strong northwest winds Tuesday through Thursday.

- Temperatures will be near to slightly above average early in
  the week, then return back to below average.

&&

.UPDATE...
Issued at 1227 PM CDT Mon Jun 3 2024

Well just like clockwork SPC upgraded the west to a marginal
severe threat just after the last discussion. Overall our
thinking really hasn`t changed. We think most will see showers
and scattered thunderstorms this afternoon through tonight as
they track across the state. However, this afternoon will bring
the greatest risk for isolated strong to severe storm when the
instability is maximized over the west. Then potentially a
strong to severe storm then track into the central portion of
the state, given the strength of the upstream shortwave, but we
are far more uncertain with the potential for storms to maintain
their strength as they move into central ND. The most likely
threat looks to be strong winds to 60 mph. If a rotating updraft
is maintained long enough hail to the size of a quarter would
be possible, but as mentioned earlier the CAPE profile in
general is not conducive to large hail. Updated text products
out shortly.

UPDATE Issued at 1112 AM CDT Mon Jun 3 2024

Fog is dissipating over the James River Valley and the Dense Fog
Advisory has been allowed to expire. The narrow band of showers
working into the west has dropped some light precip as it moved
through the southwest. Hettinger had a hundredth of an inch.
Short term models are having a hard time picking up on this so
just added and area of slight chance pops late morning and early
afternoon north of its current location. Better precip chances
move into the area mid to late afternoon. The chance of severe
storms looks minimal this afternoon in the west but there is a
small window of modest instability with good bulk shear. The NAM
which is the most generous depicts some tall skinny cape of
around 500-1000J/KG and around 30 knots of bulk shear from
around Hettinger up to Dickinson and Watford City. GFS/RAP
bufkit soundings are not as impressive with very little CAPE
this afternoon. Did advertise a few strong storms possible with
some small hail and locally gusty winds. Updated text products
will be transmitted shortly.

UPDATE
Issued at 900 AM CDT Mon Jun 3 2024

We extended the dense fog advisory on the western fringes
through 11 AM. Dense fog remains mainly along the western edge
of the stratus from Jamestown northwest to Harvey and the north
to the Turtle Mountains. Southern portions of the Advisory were
allowed to expire. Shower activity over eastern Montana may
push into western ND before noon. This will be very light but
will take a look and may add some slight chance pops to the far
west late morning. Updated text products will be transmitted
shortly.


UPDATE Issued at 637 AM CDT Mon Jun 3 2024

A dense fog advisory has been issued until 9am CT east of the
river. Advection fog moved in a few hours ago, but now that the
sun is up, it should burn off in the next 2 hours. The advisory
expires at 9am. High clouds from the incoming wave are already
over the western half of the state, with light showers in
eastern Montana already. The CAMs still have the forecasted
timing of this afternoon.

&&

.DISCUSSION...
Issued at 330 AM CDT Mon Jun 3 2024

In the wake of last evening`s convection, calm winds and clear
skies has allowed fog to form in a moist lower atmosphere. So
far, we do not need a Fog Advisory. Fog is very dense in the
Devil`s Lake Basin so we will keep an eye on it. As always,
the fog should burn off as the sun rises.

We are currently in between two waves. The shortwave from
yesterday and the incoming upper low. As of 3am the positive
vorticity side of the wave is in central Montana with a few
showers. By late morning that should advect into the state, with
a surface low pressure in southeast Montana. Showers and
thunderstorms should wait to form until the afternoon when
diurnal heating and diffluence aloft increase. They`ll move west
to east out of Montana just like yesterday. Temperatures will
also be increasing at 850mb with a thermal ridge which will help
not produce severe storms making the rising air parcels slow
down. A cold front, located at the leading edge of the trough
axis will move through after midnight. It will move through our
east around sunset Tuesday, ending our chances for rain. The
upper low will continue to spin up in Canada, filtering cooler
air down backing the cold front. Tuesday`s highs will be much
cooler in the low 70s. Winds on the backside of the front will
be breezy but sub-advisory level. We stay in cyclonic flow
through Wednesday, before a large western CONUS ridge moves in,
drying our weather pattern until next week maybe. Wednesday
another cold front drops in from Canada with a stronger high pressure
bubble. We will most likely need a Wind Advisory then. Our
confidence in this is high as this signal has been there the
last few days. Early next week another upper low might develop
and move in, bringing the showers back to North Dakota.
Temperature for the next 6 days will be at or below average
(average is mid 70s).

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1227 PM CDT Mon Jun 3 2024

Fog has finally dissipated at KJMS and VFR conditions to begin
the 18Z TAF period at all TAF sites.

Thunderstorms will be the main forecast issue later this
afternoon and tonight as a potent upper level wave moves through
the region. Isolated thunderstorms are expected to develop this
afternoon over eastern MT/western ND and then become more
numerous as they spread east tonight and Tuesday morning. At
this time we focused mainly on the initial line of thunderstorms
that move through this evening and into the early overnight
hours, but there may be a couple rounds of convection. Any
storms would have the potential for MVFR-IFR visibilities and
MVFR ceilings in addition to strong wind gusts. In addition to
the convection, areas of fog are possible over eastern portions
of central ND, ahead of the convection. Then once convection
exits patchy fog could be possible at any TAF site. Tuesday
morning lingering showers and isolated thunder will exit from
west to east with strong west to northwest winds developing
towards the end of the TAF period.

&&

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

&&

$$

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