182
FXUS63 KBIS 311950
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
250 PM CDT Fri May 31 2024

.KEY MESSAGES...

- Seasonably cool temperatures today with scattered afternoon
  showers and thunderstorms.

- Dry Saturday, then chances for showers and thunderstorms
  return later Saturday night through the first half of next
  week. Near or slightly above normals highs in the 70s and 80s
  through much of the work week.

- Isolated to scattered severe storms will be possible over
  central North Dakota into the James River Valley Sunday
  afternoon and evening.

&&

.DISCUSSION...
Issued at 250 PM CDT Fri May 31 2024

The dominate feature for the forecast period is a blocking upper
level low that will establishing it and linger over the Canadian
Prairies today through the middle of next week. A series of
shortwaves tracking around or below this low through this period
will promote periods of showers and thunderstorms over North Dakota
when their influence enters the northern Plains.

Today, a surface high pressure center lingers over northern South
Dakota. Conditions remain primarily clear, though an incoming bundle
of shortwave energy aloft will allow for showers and potentially an
isolated thunderstorm or two to develop across portions of the
northwest and north central this afternoon. There is some modest
instability developing over portions of the southwest and south
central by the mid afternoon, however model soundings reveal a
distinct lack of sufficient moisture that is unfavorable for even
isolated convection over this area. High temperatures today are
forecast broadly from the mid 60s west and the lower 70s east, still
somewhat cool for the season. Winds are out of the southwest from 10
to 15 mph, with some gusts up to 25 mph across the north, but are
anticipated to generally diminish through the rest of afternoon and
evening. Lows tonight are forecast broadly in the 40s across the
forecast area, a little warmer compared to yesterday.

Saturday is looking to be another pleasant day, with primarily dry
and calm conditions expected across the forecast area. Sky cover
will diminish through the afternoon, becoming mostly sunny through
the afternoon and evening. Winds will turn to the west through the
morning and remain fairly light, though breezy conditions with
sustained speeds from 15 to 20 mph will be possible across the
International Border as an upper level jet pushes across the
southern Canadian Prairies. Highs on Saturday return to near or
slightly above normal, in the 70s across all of North Dakota.
Overnight lows are forecast in the 50s.

Saturday night into early Sunday, the more energetic shortwave
trough and associated surface low center will push into the forecast
area from the south. With highs forecast in the 70s and 80s,
rebounding low level moisture levels, and steep lapse mid-level
lapse rates over much of the central North Dakota, the environment
ahead of this system will be fairly buoyant. Current model MUCAPE
across the south central by the early Sunday afternoon range in the
1000-2000 J/KG along with 30 - 35 knots of shear, increasing to 2000-
3000 J/KG and 35 to 40 knots of shear over the James River
Valley by the mid afternoon. As such, widespread showers and
thunderstorms are expected on Sunday, with window where strong
to severe storms will possible over the south central. At it
stands, the SPC have placed much of the James River Valley in a
Slight (level 2 of 5) risk for severe thunderstorms on Sunday,
with much of central North Dakota in a Marginal (level 1 of 5)
risk as well. There still remain questions as to how long these
stronger storms will be viable, by the late afternoon and early
evening MUCAPE drops off considerably, and the potential for
early convection may exhaust the atmosphere prematurely.

For early next week, off and on chances for showers and
thunderstorms will continue as more shortwaves travel along the
stationary upper level low, with the highest chances for showers (50-
80%) and thunderstorms (20-40%) on Tuesday as another energetic
pacific shortwave arrives into the northern Plains. By Wednesday,
longwave ridging pushing over the rockies will displace the block
low and eastward and promote drier conditions through the remainder
of the week. Highs through the first half next week remain at or
above seasonal normals, broadly in 70s and 80s, before returning to
the upper 60s and 70s by the end of the workweek.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 250 PM CDT Fri May 31 2024

VRF conditions are mainly expected throughout the 18Z TAF
period. Some diurnal showers and an isolated thunderstorm or two
are expected to develop across the northwest and north central
this afternoon through the evening which may briefly introduce
some MVRF ceilings, though there is not enough confidence to place
it any given TAF site at this time. Winds are expected to be
out of the southwest this afternoon, with the northern terminals
of KXWA and KMOT moderate speeds up to 15 knots and gusts up to
25 knots through the early afternoon. Winds will diminish
through the late afternoon, and remain light overnight while
becoming more westerly.

&&

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

&&

$$

DISCUSSION...Adam
AVIATION...Adam