227
FXUS63 KBIS 230305
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
1005 PM CDT Wed May 22 2024

.KEY MESSAGES...

- Scattered to numerous showers are expected tonight across
  western and central North Dakota. A stray rumble of thunder is
  possible.

- A low pressure system moves into the region Thursday, bringing
  chances for strong to severe thunderstorms to portions of the
  area. Gusty winds, large hail, and one or two tornadoes will
  be possible, particularly for areas along the ND/SD state
  line.

- Periodic showers and thunderstorms are expected over the
  holiday weekend.

- Drier weather and a warm up are in store heading into the
  middle of next week.

&&

.UPDATE
Issued at 952 PM CDT Wed May 22 2024

Scattered to numerous showers continue their march across the
state with the heaviest showers currently located along a line
from around Washburn, through far eastern McLean county, up into
McHenry county, and then arching over to the northwest through
Kenmare and into Burke county. For these areas and east, we did
introduce some likely precipitation chances (~70 percent) over
the next few hours. Elsewhere, activity will be more scattered
through the night with generally low to medium chances of rain
(20 to 50 percent). Thunder chances continue to diminish but SPC
mesoanalysis does suggest there is still potentially some very
weak instability out there. Thus, a stray bolt of lightning or
two can`t be ruled out.

UPDATE
Issued at 635 PM CDT Wed May 22 2024

Widely scattered showers continue to move in/develop across the
west. The area with the most widespread showers thus far has
been across the northwest and the showers are now starting to
move into the north central. Every once in a while we see a
lightning strike or two out of the heaviest showers but
instability is limited. Current SPC mesoanalysis shows MLCAPE
only maxing out around 100 to 250 J/kg and MUCAPE around 500
J/kg. There is some decent effective shear in place a bit
further south of the heaviest showers so if more development
occurs to the south, there could be a conditional chance for a
stronger storm or two through the evening hours. However, this
is a low confidence solution for the moment. No major changes
were needed for this update. Just blended in the latest
observations to the going forecast.

&&

.DISCUSSION...
Issued at 408 PM CDT Wed May 22 2024

Visible satellite shows a few clouds moving across the northwestern
corner of North Dakota as a surface ridge moves over the center of
the state.  Winds have slackened west to east over the past few
hours as a closed low has lifted to the northeast, over portions of
Minnesota, the UP of Michigan, and Canada.  Expect light and
variable winds to continue for the rest of the afternoon.  A few
showers and thunderstorms have developed across northern Montana and
are starting to move toward the Montana/North Dakota state line.
There is a 20-50% chance of a few scattered showers and/or weak
thunderstorms expected, particularly for the northwestern and north
central part of the state this evening and tonight.  At this time,
severe storms are not expected.

Tonight, a shortwave trough will move from the PACNW to the
Bighorns.  A low pressure system is expected to develop as the
system comes over the Black Hills and West River region of South
Dakota Thursday afternoon.  A warm front is expected to develop over
tomorrow, with still some uncertainty as to where it will set up.
Locations range from northern South Dakota to central North Dakota.
Instability will increase heading into the afternoon, with the warm
front in place.  Thunderstorms are expected to develop along the
front and within the warm sector, which again brings some
uncertainty into which areas may see the best chance for storms and
possible severe weather.  Any thunderstorms that are able to develop
tomorrow in the southeastern part of the area where the warm front
will be and a cold front moves through will have the potential of
becoming strong to severe.  The Storm Prediction Center has placed
this area in a Marginal (1/5) to Slight (2/5) Risk for severe
storms.  The main hazards with any storms will be winds gusting to
60 mph and hail up to ping pong ball size. An isolated tornado or
two cannot be entirely ruled out.  Overnight, temperatures will fall
into the mid-30s in a few locations, bringing a chance of a
rain/snow mix to portions of the area.

Friday, the low will continue to lift to the northeast, with wrap
around moisture expected.  Rain chances will continue through the
daytime hours and into the evening, eventually ending west to east
across the region.  Afternoon highs will be slightly warmer than the
previous day, at least in the west, climbing into the mid to upper
50s.  Heading toward the central part of the state, expect highs in
the low to mid-50s.

Expect a warm up over the holiday weekend as the are comes under
westerly to northwesterly flow.  Temperatures will return to the mid
to upper 60s for highs and the low to mid-40s for lows.  There are
some low end chances (20-30%) for showers and thunderstorms
Saturday, with a better chance on Sunday (30-50%).  The best chances
for precipitation will be on Sunday, particularly for the southern
half of the state.

Memorial Day, a closed low remains in Canada, bringing the
possibility for some more wrap around moisture moving into the
region.  Although chances remain fairly low (20-30%) for showers and
storms, this may put a bit of a damper on outdoor holiday or travel
plans.

An upper ridge moves over the Dakotas heading into mid-week.  Dry
conditions are expected along with a return of temperatures to the
70s.

&&

.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 635 PM CDT Wed May 22 2024

A complicated aviation forecast is on tap tonight through
Thursday. Isolated to scattered showers will continue to spread
across western and central North Dakota this evening and into
the overnight hours. The heaviest showers could lead to brief
MVFR visibilities and maybe a lightning strike our two.
Widespread MVFR ceilings should move into the west and north
Thursday morning (impacting KXWA/KDIK/KMOT) and spread into the
central by the early afternoon (impacting KBIS). Some of the
higher resolution models are suggesting some ceilings dipping
into IFR categories but confidence is too low this far out to
include mention in any site specific forecast at this time.

More showers and thunderstorms will develop Thursday afternoon
across the southwest and into the central. A few of these storms
across the south could become strong to severe. If one of the
strongest storms move overhead, they could produce hail to the
size of ping pong balls and winds to 60 mph. A tornado or two is
possible as well. Winds may become gusty and erratic in and
around any showers or thunderstorms. KJMS may remain in VFR
categories through the period, but they should at least see low
VFR ceilings in the afternoon.

&&

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

&&

$$

UPDATE...ZH
DISCUSSION...Wekesser
AVIATION...ZH