141
FXUS63 KBIS 081157
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
657 AM CDT Wed May 8 2024

.KEY MESSAGES...

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

- Low chance for a few thunderstorms, possibly strong, in
  McIntosh and Dickey Counties during the late afternoon and
  early evening hours today.

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

&&

.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 /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 657 AM CDT Wed May 8 2024

Dense fog with an LIFR ceiling has once again developed at KDIK
early this morning. The most likely outcome is for visibility to
improve and ceilings to slowly lift by late morning, but forecast
confidence is low. Across the rest of the western half of the state,
mostly MVFR ceilings with periodic IFR ceilings are observed at the
start of this forecast period, with VFR conditions at KJMS. The
overall expectation is for a gradual improvement to VFR ceilings
this afternoon. Isolated to widely scattered showers remain possible
this forecast period, mainly across the west and north central. The
strongest winds for this forecast period will be across northwest
and north central North Dakota, with east to northeast winds around
15-20 kts. South central North Dakota (KBIS to KJMS) will see
lighter southeast winds this morning, turning to the east later in
the day. At KDIK, northeast winds will increase to near 15 kts this
afternoon. All terminals should see decreasing winds become more
northerly this evening through tonight.

&&

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

&&

$$

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