FXUS63 KBIS 050009
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
609 PM CST Mon Mar 4 2024

.KEY MESSAGES...

- Increasing chances for snow (50 to 80 percent) over south
  central North Dakota late tonight through Tuesday morning.
  This may include pockets of heavier snowfall rates.

- Another system will bring medium chances (40 to 60 percent)
  for snow across northern, central, and eastern parts of the
  state Tuesday night through Wednesday night, with the highest
  probabilities for accumulating snow north central and
  northeast.

- Near to below normal temperatures expected this week, perhaps
  warming later in the week into the upcoming weekend.

&&

.UPDATE...
Issued at 608 PM CST Mon Mar 4 2024

The forecast for this evening is in good shape. A cloud free sky
over fresh snow pack across northern North Dakota should allow
overnight temperatures to fall near, if not below zero.

Confidence continues to increase in a mesoscale 700 mb wave bringing
an area of snow to south central parts of the state late tonight
into Tuesday afternoon. The highest probabilities for accumulating
snow are enclosed by Interstate 94, the James River, the South
Dakota border, and the Missouri River. Some, but not all
deterministic guidance advertise strengthening Q-vector convergence
over this wave. There is greater model consensus though in steep mid
to upper level lapse rates exceeding 8 C/km and near zero to
negative EPV implying the presence of conditionally symmetric
instability. These parameters all fit the conceptual model for this
types of system. This could result in very small pockets of heavier
snow accumulation much greater than the general 1 to 2 inches
favored by the current suite of ensemble guidance, with the 12Z HREF
maximum snowfall showing as high as 6 inches. We will continue to
evaluate arriving model guidance for this potential, and may need to
introduce some enhanced messaging for a higher-impact but very low-
predictability event.

&&

.DISCUSSION...
Issued at 241 PM CST Mon Mar 4 2024

Current surface places departing low along the Manitoba/Ontario
border while high settles in over our area. At the upper levels,
west to southwest flow remains over our area with a variety of
waves noted upstream. Over our neck of the woods, skies are
mostly clear over northern areas, with some upper level clouds
on the increase over southern portions of the area.

For tonight, quiet weather starts off the evening, but the next
short wave moves over the Bighorns and approaches our area as a
surface low spins up over the Black Hills area and tracks east.
This will bring increasing snow chances over south central North
Dakota late tonight.

On Tuesday, aforementioned system will continue to expand
chances (around 40 to 70 percent chance) over south central
North Dakota into the James River Valley, before gradually
dissipating in the afternoon. An inch or two over parts of south
central North Dakota appears likely, with NBM showing a low
chance (15-30 percent) of seeing 3 inches.

In the meantime, a closed upper low along the
Saskatchewan/Manitoba border swings east-southeastward and tries
to open up, with snow chances (30-50 percent, highest east
approaching 60 percent) spreading through most of the area
Tuesday night into Wednesday. What gets a little tricky is
guidance continues to show an area of elevated frontogenesis
Wednesday, primarily over eastern portions of the area. Thus,
some banded snowfall will be a possibility.

System makes its departure Wednesday night, though a little snow
may linger on Thursday over far southeastern portions of the
area. Quiet weather then expected through the weekend into the
start of the upcoming work week. Temperatures attempt to warm
through this period, but a big fly in the ointment will be how
much snowpack remains, and how much has melted off. Thus
temperature forecast remains quite tricky.

&&

.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 608 PM CST Mon Mar 4 2024

VFR conditions and light winds are expected through tonight. An area
of snow is expected to move into south central North Dakota Tuesday
morning, with the greatest aviation impacts likely to stay away from
KBIS and KJMS. MVFR ceilings are likely to develop from KBIS to KXWA
late Tuesday morning through the afternoon, and may spread toward
KJMS to KMOT by the end of the day. At KDIK, there is low confidence
in an IFR/LIFR ceiling developing Tuesday afternoon, with VFR
otherwise expected. East to southeast winds around 10 kts are
expected on Tuesday.

&&

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

&&

$$

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