400
FXUS63 KBIS 181935
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
235 PM CDT Thu Jul 18 2024

.KEY MESSAGES...

- High temperatures warm into the 80s today through the weekend.
  This is near to slightly above average for mid to late July. A
  few readings in the low 90s are expected in the southwest
  today.

- Chances for showers and thunderstorms increase this evening
  and overnight, with a 20 to 50 percent chance of showers and
  thunderstorms Friday and then a 20 to 30 percent chance
  Saturday.

- Severe weather chances are very low through this weekend,
  though a strong storm or two isn`t out of the question on
  Friday.

&&

.DISCUSSION...
Issued at 235 PM CDT Thu Jul 18 2024

Today, a persistant upper level ridge lingers over to the west
of the forecast area, with the associated thermal ridge
progressing a little further eastward this afternoon. As such,
at or above normal high temperatures are forecast, broadly in
the 80s in the north and central while portions of the west are
expected to see temperatures break into the lower 90s. A weak
impulse of energy will traverse down the ridge and approach our
west this afternoon and evening, promoting chances (10 to 20%)
for showers and possibly even some thunderstorms later this
afternoon and evening. While moisture returns are beginning to
increase across the northern Plains, the environment will remain
dry enough that strong to severe storms are not expected. Cloud
cover will generally increase across North Dakota this evening,
becoming partly cloudy in the north to mostly cloudy in the
south. Winds are anticipated to remain generally light, though
could become gusty where thunderstorms do develop.

A more substantial shortwave disturbance will dig into the
forecast area late tonight and into early Friday, expanding the
chances (30 to 40%) across much of the state. The best forcing
will push through the forecast area through the mid morning
hours, promoting some chances for isolated thunderstorms across
portions of the southwest and south central. While model bulk
shear values do lie in the 25 to 35 knot range at this time,
strong capping will is currently expected to inhibit the
development of stronger storms at this point. Later in the
afternoon, the erosion of the cap over portions of the south
central and James River Valley, moderate low level saturation
ahead of the trough, and some bonus forcing from low level
convergence could allow a stronger storm or two to develop
across this region. Were stronger storms do develop, we could
see some strong gusts approaching 45 to 55 mph and small hail.
Our current expectation for severe weather remains low, however,
as model bulk shear values steadily decrease to around or even
below 20 to 25 knots by the early afternoon period which, when
paired with a fairly skinny CAPE profile in model Soundings and
a moderately dry mid level forecast at around 50% humidity,
indicates that any stronger storms will likely have trouble
sustaining themselves. This expectation is reflected by both the
SPC and CSU keeping the severe potentially mainly across the
South Dakota border, where the ingredients are somewhat more
favorable. The showers and thunderstorms that do develop should
move southeast out of our area by the early evening hours.
Partly to mostly cloudy skies will linger through much of
Friday, before beginning to clear in late evening once the
showers and storms move off to the southeast. Otherwise, highs
on Friday are forecast broadly in the 80s, though some locations
in the far west could approach the lower 90s.

This weekend, chances for showers and thunderstorms will be
possible in the afternoon hours as the occasional shortwave
travels down the approaching upper level ridge. Then, mainly
dry conditions are anticipated through much of next week. Highs
each day through the weekend and into early next week are
expected to be fairly seasonable, broadly in the 80s through
Monday. By Tuesday, the development of another ridging pattern
across the western CONUS will begin to promoting highs from the
mid 80s to the lower 90s across much of western and central
North Dakota through the later half of next week.

&&

.AVIATION /12Z TAFS THROUGH 12Z FRIDAY/...
Issued at 235 PM CDT Thu Jul 18 2024

VFR ceilings and visibility are expected at all terminals
throughout the 18Z TAF period. Low chances chances for showers
and potentially a thunderstorm will develop across portions of
the southwest and south central this afternoon, though
confidence is too low to place it at any given terminal at this
time. Chances for showers and isolated thunderstorms then
increase again across the south tomorrow morning, with light
rain currently anticipated at KJMS. These chances will become
more widespread beyond the end of the 18Z TAF period, mainly
through Friday afternoon and early evening. Winds are
anticipated to remain light, though where showers and
thunderstorms do develop gusty and erratic winds will be
possible.

&&

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

&&

$$

DISCUSSION...Adam
AVIATION...Adam