977
FXUS63 KBIS 071918
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
218 PM CDT Sun Jul 7 2024

.KEY MESSAGES...

- Another round of scattered showers and thunderstorms is
  expected this afternoon and early evening. Some storms may
  once again produce funnel clouds, with a weak landspout
  tornado possible.

- The daily potential for showers and storms will focus more
  over eastern North Dakota Monday and Tuesday, with coverage
  becoming more isolated.

- A warming trend is expected this week, with widespread highs
  in the 90s likely on Friday.

&&

.DISCUSSION...
Issued at 216 PM CDT Sun Jul 7 2024

A persistent cyclonic flow pattern continues to sit over the
Northern Plains this afternoon, with embedded mid to upper level
circulations rotating around the base of a longer wave trough.
While the longwave trough axis has shifted slightly eastward,
now from central Nebraska to western Ontario, western and
central North Dakota still lie under the influence of the
embedded impulses which have generated yet another round of
afternoon showers and thunderstorms. As has been the case for
the past several days, atmospheric conditions including an
unstable and buoyant boundary layer, very weak deep layer shear,
and surface vorticity are once again favorable for the
development of funnel clouds, with a brief weak landspout
tornado possible. The highest chance for funnel clouds and a
landspout are shifted farther east, but they still cannot be
ruled out with any storm across the entire state. Showers and
storms should gradually dissipate through the evening. Highs
this afternoon are forecast around 75 to 80, with northwest
winds around 10 to 15 mph.

We will finally start to see a more notable pattern shift Monday and
Tuesday as the downstream trough slides further east and deamplifies
over the Great Lakes while a strong western CONUS ridge begins to
expand and tilt eastward. Diurnally driven showers and storms remain
in the forecast along and east of Highway 83 on Monday and Tuesday,
but with lower coverage expected and possibly (hopefully) a lower
risk for funnel clouds. This pattern shift will allow temperatures
to begin warming back closer to normal, especially in the west. By
Tuesday, highs in the 80s are forecast for all of western and
central North Dakota. Ensemble guidance shows the upper ridge
continuing to build over the Rockies and High Plains Wednesday and
Thursday, with a weak surface flow pattern. This should promote a
break from daily showers and thunderstorms and continue the warming
trend. By Thursday, the NBM is advertising mid 80s east to mid 90s
southwest.

For Friday into next weekend, ensembles are pointing toward a
possible flattening of the ridge that could result in an active
zonal flow over the Northern Plains. The NBM favors Friday to be the
hottest day of the week as the ridge flattening process is just
beginning, with current projections around 90 to 95 statewide and
possibly approaching 100 in the far southwest. But Friday could also
mark the return of thunderstorm chances lasting through the weekend.
This may include prospects for severe weather given the enhanced
flow aloft, warm surface temperatures, and NBM dewpoints in the 60s.
CSU machine learning guidance confirms this thinking, with low
severe probabilities spread across the state Friday through Sunday.
Given timing and spatial uncertainty, the NBM is only carrying low
PoPs for now. Temperatures are likely to remain above normal (which
is mid 80s for highs) next weekend, but there is larger ensemble
spread due to lower confidence in the evolution of a closed upper
low moving across central Canada.

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 1243 PM CDT Sun Jul 7 2024

Scattered showers and thunderstorms are likely to develop once again
this afternoon and evening. The highest confidence in coverage of
showers and storms is from around KBIS to KJMS, where VCTS has been
included. Elsewhere, coverage is likely to be more widely
scattered to isolated, and far western North Dakota could
remain completely dry. Any heavier shower or storm could produce
brief periods of MVFR to IFR visibility. Otherwise, VFR
conditions are likely through the forecast period. Some patchy
fog could develop late tonight into Monday morning, but
confidence on exact location is low. Northwest winds around
10-15 kts this afternoon will become light after sunset.

&&

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

&&

$$

DISCUSSION...Hollan
AVIATION...Hollan