921
FXUS63 KBIS 081751
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
1251 PM CDT Wed May 8 2024

.KEY MESSAGES...

- Low to medium chances for rain showers remain in the forecast
  today, highest in western North Dakota.

- A transition to warmer and drier weather is expected Thursday
  through the weekend.

&&

.UPDATE...
Issued at 1251 PM CDT Wed May 8 2024

As expected, a few more showers are starting to develop in the
west and are mainly visible on the Williston and Bowman radars.
These showers remain very isolated in nature, however, coverage
should increase a bit this afternoon especially in the
northwest. CAMs are starting to back off on the idea of
thunderstorms reaching the southern James River Valley of ND
this afternoon. Nevertheless, there`s still a low chance a
rumble or two of thunder could occur.

UPDATE
Issued at 907 AM CDT Wed May 8 2024

Patchy fog remains in the southwest, although based on the
latest webcams and observations, if any dense fog persists, it
is very limited in areal coverage. A few very isolated showers
are present mainly in the western half of the state. Therefore,
reduced PoPs to a 20 percent slight chance through the morning
hours to reflect this.

UPDATE
Issued at 657 AM CDT Wed May 8 2024

Early morning satellite shows cloud cover slowly eroding from east
to west over south central North Dakota. While sunshine could be
more plentiful there this morning, diurnal cumulus is likely to
develop in the afternoon. Back to the west, a localized area of
dense fog has developed over Stark and southern Dunn Counties.
Confidence on the duration of this fog remains low, as it is
associated with a low cloud deck and commenced when northeast
surface winds began increasing.

Recent high-resolution guidance shows a slightly increased chance of
a few thunderstorms near the South Dakota boarder in Dickey and
McIntosh Counties during the late afternoon and early evening, which
is forecast to lie in the northeast quadrant of the surface low. RAP
guidance shows up to around 500 J/kg CAPE with effective bulk shear
decreasing with time. A stronger storm or two cannot be completely
ruled out in this part of the state later today, but severe weather
is not expected. However, there is also a signal in RAP guidance for
funnel clouds/landspouts, with forecast non-supercell tornado
parameter values as high as 3. Will not be strongly messaging this
potential yet, but mesoscale features will bear watching later
today. It appears though that the highest NST potential will
remain south of the stateline.

&&

.DISCUSSION...
Issued at 355 AM CDT Wed May 8 2024

An occluded surface cyclone is centered near Dickinson early this
morning, with the parent upper low having retrograded back closer to
the MT/ND/SD border intersection. While widespread cloud cover
continues to circulate around the low, shower activity overnight has
been confined to only far western parts of the state, and even there
it is becoming more isolated early this morning. The low is forecast
to gradually weaken and slowly drift southward into western South
Dakota throughout the day today. The continued presence of cyclonic
vorticity rotating around the top of the low keeps a 20 (central ND)
to 40 (western ND) percent chance of showers in the forecast for
today. Temporally, there are higher chances for showers in the
afternoon than the morning, owing to the diurnally-driven
destabilization of the boundary layer. Model soundings in south
central North Dakota show some deeper buoyancy potential, but this
is where the lowest shower chances are located spatially, and the
moisture profile is drier there. Elsewhere, the depth of the buoyant
layer is projected to be much shallower. Therefore, the probability
for a thunderstorm across all of western and central North Dakota
this afternoon is quite low. The positioning of the surface low will
bring breezy northeast winds to northern and western North Dakota
today, with lighter winds elsewhere. An overall decreasing trend in
loud cover should allow for a slightly warmer afternoon, with highs
forecast in the mid 50s southwest to mid 60s central and east.

Low chances for isolated showers remain in the forecast overnight
into Thursday morning, but diminish from north to south over time.
The influence of the low will finally depart the local area on
Thursday as a west-east oriented upper ridge slides in. This should
allow temperatures to rebound to near normals for this time of year,
with low NBM spread implicating high confidence in highs on Thursday
around 65 to 70. A weak mid to lower level trough coming down from
Saskatchewan could bring some isolated showers into the state late
Thursday afternoon and evening, as a handful of CAMs are projecting.
But the rising heights aloft are likely to greatly limit this
potential.

A clipper-like system remains on track to dig into the Upper
Mississippi River Valley and western Great Lakes regions on Friday,
though its forecast track has consolidated a little farther to the
east. Western and central North Dakota are now less likely to see
diurnally driven showers Friday afternoon, but breezy conditions can
still be expected. The high temperature forecast for Friday is very
similar to Thursday at around 65 to 70.

While ensembles strongly favor a northwest flow pattern over the
weekend, there still uncertainty on whether any disturbances will
bring any showers or storms through the area. There is growing
confidence in above normal highs well into the 70s on Saturday as a
stronger wave farther north over Canada ushers a thermal ridge into
the Northern Plains. Confidence in the synoptic pattern begins to
lower considerably as early as Monday, with signs of a more active
quasi-zonal pattern that could potentially be followed by a larger
central CONUS trough mid next week. The ensemble consensus
temperature outlook maintains near to above normal temperatures
through the middle of next week, but there is a minority outcome for
cooler temperatures by the end of this time period.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1251 PM CDT Wed May 8 2024

MVFR ceilings continue to prevail primarily over western ND at
this time. That said, ceilings should improve to VFR over the
next few hours and remain that way through the rest of the
period. The one exception is that isolated to scattered showers
are possible mainly through this evening. The best chances are
a 30 to 40 percent chance in the northwest this afternoon.
Either way, brief reductions in ceilings and visibility are
possible under any passing showers.

&&

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

&&

$$

UPDATE...Telken
DISCUSSION...Hollan
AVIATION...Telken