363
FXUS63 KBIS 302356
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
656 PM CDT Thu May 30 2024

.KEY MESSAGES...

- Scattered showers with gusty winds and possibly a
  thunderstorm or two in the northwest this evening.

- Seasonably cool temperatures on Friday with areas of frost
  possible southwest early in the morning, then scattered
  afternoon showers and thunderstorms.

- Dry Saturday, then chances for showers and thunderstorms
  return later Saturday night through early next week.

&&

.UPDATE...
Issued at 655 PM CDT Thu May 30 2024

Shower activity is now confined to northwest North Dakota. One batch
of showers with occasional lightning has lifted into southeast
Saskatchewan, while another batch with no lightning observed is
entering from northeast Montana along and north of the Missouri
River. With up to 500 J/kg still present, will maintain a slight
chance of a thunderstorm in the forecast for the evening. All
showers are forecast to dissipate or lift north into Canada later
this evening.

We will continue to monitor satellite trends this evening for the
possible need of a Frost Advisory in southwest North Dakota later
tonight into early Friday morning. The main area of focus is a batch
of mountain wave clouds from the Bighorns to Black Hills, extending
north toward the ND/SD border. If these clouds remain south of the
state, which latest RAP guidance favors, temperatures could easily
fall into the mid 30s in low lying areas.


&&

.DISCUSSION...
Issued at 233 PM CDT Thu May 30 2024

A blocking upper level pattern will keep an upper level low situated
over the central Canadian Prairie Provinces through the weekend. A
combination of shortwaves rotating around this low, and impulses
coming off the Pacific, tracking across the Northern Rockies and
below the Canadian low will influence the weather over our area
through the weekend. This low eventually gets pushed east as a
stronger wave coming off the Pacific moves into the Region early
to mid next week.

Currently, showers and a few thunderstorms are lingering over
the far southern James River Valley but should exit the area
this afternoon. This activity is situated along a warm
front/trough that is currently exiting the JRV. Breezy westerly
winds behind this front have developed over most of western
and central North Dakota. A trailing cold front will sweep
through the area later this afternoon and tonight. There may be
a few showers trying to move into western ND late this
afternoon/early this evening, but with very dry air southwest,
the potential for shower activity will likely be limited to the
west central/northwest and any thunderstorm activity should be
limited to the far northwest corner.

Late tonight and early Friday the focus shifts to temperatures.
Current forecast trends clear out much of western and central ND
tonight. By 12Z Friday, surface high pressure is situated over
western SD with mid and high level clouds beginning to work back
into western ND from the southwest. However, very dry air is
situated over the area overnight. The NAEFS SA table shows a
signal for dry PWATs over western ND. IF winds drop off tonight,
which it looks like they may in the southwest, and skies remain
clear, we could see some temperatures in the middle 30s
southwest, resulting in Frost. Given our normally cool areas
west of the Missouri River extend north and east to the
Beulah/Hazen area and towards eastern Lake Sakakawea, the area
of mid 30s could extend even farther north and east than we are
currently advertising. NBM 10th percentile was only depicting
some upper 30s and no frost, so we combined some MOS based
guidance to trend temperatures down a bit over the southwest.
MET/MAV guidance for Hettinger is 34. There is the potential
that mid level clouds could move into the area, keeping
temperatures from dropping into the 30s at all. Will hedge
towards the cool side and pass along to the evening shift.
Potentially we could see a frost advisory if ideal conditions
are met.

After a cool start Friday, diurnal heating, combined with
another upper level impulse will fire afternoon showers and
thunderstroms. The lack of heating is expected to keep the
severe threat to a minimum and SPC is currently carrying a
general thunderstorm risk and this looks reasonable.

Saturday will bring mostly sunny skies with warmer temperatures.
Highs should be mainly in the 70s statewide. Late Saturday night
and Sunday, an impulse emanating from the Pacific will move
into the area bringing another round of showers and
thunderstorms, with a stronger wave moving into the Region early
next week. There is some some indication that the far southeast
could see a few stronger storms on Sunday but this remains
quite a ways out. Still something to monitor as we head into the
weekend. Uncertainty in the deterministic models and ensembles
increases as we head into next week, but the pattern will likely
remain active through at least Monday and Tuesday.

&&

.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 655 PM CDT Thu May 30 2024

VFR conditions are expected to prevail through the forecast period.
Scattered showers remain possible across northwest North Dakota this
evening, and another round of afternoon showers with a few
thunderstorms is possible across most of western and central North
Dakota on Friday. Strong westerly winds will diminish to around 10
kts later this evening and only increase slightly on Friday.

&&

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

&&

$$

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