523
FXUS63 KBIS 242345
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
645 PM CDT Fri May 24 2024

.KEY MESSAGES...

- Rain and snow showers central east, gradually tapering off
  from west to east this evening. Chance (30%) of showers and
  thunderstorms again in the southwest overnight.

- Winds gusting to 45 mph in portions of south central North
  Dakota including parts of the James River Valley. A Wind
  Advisory is in effect until this evening.

- Areas of frost over much of western and central North Dakota.

- Active weather pattern continues with rain chances over much
  of the area through Monday, then again Thursday to Saturday.

&&

.UPDATE...
Issued at 627 PM CDT Fri May 24 2024

The wind advisory has been cancelled over the south central but
remains in effect for the James River Valley. As of 6 PM winds
were still gusting to 43 mph at Jamestown. Expect these winds to
diminish a bit later this evening. Clouds were diminishing over
western ND with some sunshine, but showers were over eastern
Montana, and have already pushed into the southwest. Expect
showers to move into the northwest in the next hour or so. There
has been some lightening associated with this activity but
there has been a decrease in lightning in the past 1-2 hours.
Expect mainly scattered shower activity but a few rumbles of
thunder can`t be ruled out this evening as this activity moves
into western ND.

In eastern portions of central ND, precipitation has ended over
all but the far eastern portions of the CWA. Also, snow
continues in and around the Turtle Mountains, but is expected to
taper off this evening.

&&

.DISCUSSION...
Issued at 305 PM CDT Fri May 24 2024

The stacked low pressure system continues to slowly move east
across the North Dakota Minnesota border. In our area,
temperatures have remained much cooler than first forecasted in
the central and north on the backside of the low. This is
allowing snow to mix with the rain falling. The Turtle Mountains
area has received around 6 inches of snow so far! A rain/snow
mix has been reported in the southern James River Valley and
into South Dakota as well. Our forecast challenge of the day
has been this, where will the rain snow mix be the rest of the
day? We have adjusted from the NBM to have a rain snow mix the
rest of of the day where precipitation is falling. This area is
between Bismarck and Jamestown, up to the Canadian Border and
east. The Wind Advisory is still in effect west of the river
until 23z, and east of the river until 01z. Although they will
most likely be cancelled early as the tight pressure gradient is
over the James River Valley right now and moving east.

In the cyclonic flow around the upper low, showers and maybe a
thunderstorm are possible across the west and southwest for a
few hours tonight, about a 30 percent chance. Lows overnight
across the area will dip into the mid-30s with light winds. A
Frost Advisory has been issued until 13z Saturday for this
reason. Localized lower elevations could drop near or below
freezing. The rest of Saturday will be drier, with highs still
slightly below average in the upper 60s and lower 70s. The
Turtle Mountains will be 50 degrees or cooler, especially with
the snow on the ground, so this could be over forecasted. Frost
is most likely again Saturday night in the northeast with
temperatures in the mid 30s again. The pattern aloft Saturday
has a brief weak ridge moving through before another upper low
and shortwave move in Sunday.

Sunday will still be below average temperatures with showers and
thunderstorms (non-severe) likely, moving west to east. The
highest chances move to the east by 00z as the next ridge
pushes into the west. The chances of rain look to continue all
night and into Monday afternoon. This ridge will continue until
Wednesday night when another big low digs south through the
Pacific Northwest. This puts us back into the active southwest
flow with plenty of diffluence aloft for thunderstorms through
Friday. Temperatures all week will remain just below average as
our cooler Spring continues into June.

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 627 PM CDT Fri May 24 2024

Rain exiting the forecast area east, showers moving into the
forecast area west.

Low pressure over far northeast North Dakota will lift northeast
this evening. Strong winds over eastern portions of central will
diminish in the next 1-2 hours, including KJMS. Scattered MVFR
ceilings will also exit this area this evening. Elsewhere,
expect mostly low VFR conditions this evening with scattered
showers moving into the west. Included a VCSH at KXWA and KDIK
this evening. Patchy fog is possible later tonight in the west,
but too much uncertainty at this time to include at any TAF
site. A west to northwest surface flow is expected through
tonight over the area.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
Frost Advisory from midnight CDT /11 PM MDT/ tonight to 8 AM
CDT /7 AM MDT/ Saturday for NDZ001>005-009>013-018>023-025-
033>037-041-042-044>048-050-051.
Wind Advisory until 8 PM CDT this evening for NDZ036-037-
046>048-050-051.

&&

$$

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