531
FXUS63 KBIS 130825
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
325 AM CDT Mon May 13 2024

.KEY MESSAGES...

- There will be daily chances for showers and thunderstorms
  through the week. A few storms may become strong this
  afternoon and evening in the west.

- Near average temperatures are expected this week, with highs
  in the mid 60s to mid 70s and lows in the 40s.

&&

.DISCUSSION...
Issued at 318 AM CDT Mon May 13 2024

Presently, a surface low sits across Montana, while mid-level
ridging is present across much of the Rocky Mountains and Northern
Plains.  At the moment, much of the area is under clear skies and
calm winds, with widespread temperatures in the upper 30s to lower
40s. Some areas may see temperatures in the mid 30s, though the
areal extent of these cold patches aren`t large enough to warrant
issuing a Frost Advisory. The near-surface smoke from the Canadian
wildfires has exited the area for the most part, with any remaining
smoke only present in the upper atmosphere.

As the day progresses, a shortwave trough riding the top of the
aforementioned ridge will bring about the next chance of
precipitation for much of the area. Some showers and thunderstorms
have already developed along the associated surface boundary across
parts of northern Montana and southern Saskatchewan. As such,
chances for precipitation will arrive in the northwestern portions
of the state in the early morning hours, slowly spreading east
throughout the rest of the morning as the trough continues moving
east. These chances will remain rather low, around 20%, due to the
relatively dry air near the surface, as indicated by forecasted
dewpoint depressions in the 20 to 30 degree range.

Through the afternoon and early evening hours, there will be a
slight chance for some thunderstorms, due to a very narrow
corridor of instability entering the state from the west.
However, most recent deterministic guidance suggests instability
maxing out around 500 J/kg, mostly across the border with
Montana. As a result, the likelihood of any thunderstorms being
strong to severe is rather low. While there will be plenty of
0-3 km shear across the north central portion of the state, this
shear maximum will be displaced from the instability maximum.
The threat for any strong storm will be highly conditional, and
will likely only be possible in the very narrow region where
these two maximums overlap. For now, the SPC has placed us in a
General Thunderstorm risk area. Warm temperatures are expected
again today, with widespread highs in the upper 60s and 70s.

Showers will continue overnight as the shortwave moves east, with
chances for rain increasing into the overnight hours. Most of the
area will see a 50 to 70% chance for rain tonight, with chances
decreasing to the southeast and into the southern James River
Valley. Overnight lows will mostly be in the 40s and lower 50s.

A surface low is forecast to develop across South Dakota early
Tuesday morning, moving east with the previously mentioned shortwave
trough. This may bring continued showers along the northern
periphery of the low, keeping chances for rain across the area in
the 40 to 70% range through the day Tuesday. The highest chances
look to be in the southwest and central areas of the state, with
chances decreasing to around 20% in the northwest. There`s a slight
chance (roughly 15 to 30%) for some thunderstorms associated with
these showers. Severe storm potential is currently minimal.

This active showery pattern is then expected to continue through the
rest of the week, as multiple shortwaves and disturbances pass
across the Northern Plains. Near daily chances for showers and
thunderstorms persist into the weekend. High temperatures for each
day will remain firmly in the mid 60s to mid 70s.

&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1229 AM CDT Mon May 13 2024

VFR conditions are present across all terminals at the moment, with
light winds generally out of the east. Clear skies are expected
through the night, with some high clouds filtering into the state
from the west. Winds will shift to be more southeasterly during the
afternoon on Monday, with speeds increasing at the same time. Winds
will increase to the 10 to 15 mph range, with some gusts up to 20
mph possible near the end of the TAF period. A front will bring
about some showers from west to east, arriving in the west at around
00z, expanding east through the end of the TAF period.

&&

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

&&

$$

DISCUSSION...Besson
AVIATION...Besson