689
FXUS63 KBIS 020911
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
411 AM CDT Thu May 2 2024

.KEY MESSAGES...

- Widespread rain showers will continue through the morning and
  much of the day, mainly east of the Highway 83 corridor.

- Expect more hit and miss showers later this afternoon and
  evening across the west and central. A few isolated
  thunderstorms are possible. Chances for showers continue
  Friday.

- Chances for rain return Sunday night, becoming likely by
  Monday (60 to 70 percent). Monday may also bring a better
  chance for some thunderstorms. Low to medium rain chances (20
  to 60 percent) continue into mid week.

- Near to slightly below normal temperatures expected through
  Saturday, becoming near to above normal Sunday and Monday.

&&

.DISCUSSION...
Issued at 411 AM CDT Thu May 2 2024

An upper level low was located in the vicinity of the eastern
Montana/southern Saskatchewan border early this morning with a
surface low centered over southern Saskatchewan. Several
shortwaves will rotate around this low and into western and
central North Dakota, providing various chances for
precipitation through Friday night.

The initial impulse will continue to spread from south central
North Dakota and into the east. The heaviest precipitation
should remain mostly east of the Highway 83 corridor with the
exception of parts of the far south central. The latest NBM
shows continued medium to high chances (50 to 90 percent from
west to east) for a half inch or more of additional rainfall
over the aforementioned areas. While most of the rain from this
initial impulse will mainly move out of the area to the east by
the mid to late afternoon hours, the upper low is going to be
slow moving out. Another shortwave will rotate into our area
this afternoon and interact with a surface trough/frontal
boundary across portions of the west and central. The latest
CAMs suggest that we will see convective showers and isolated
thunderstorms developing in the mid to late afternoon hours
across the west, eventually spreading into the central. RAP
soundings suggest the potential for around 300 to 600 J/kg
MUCAPE so some thunder seems reasonable. There will be some
strong shear present, but mainly to the east of the instability
axis. Thus, severe weather is not expected.

On Friday, we could see a few more hit and miss wrap around
showers but this activity looks mainly focused across the
northern half of the forecast area for now. Instability will be
even weaker on Friday so thunder chances appear low at the
moment.

An upper ridge pops up to our west on Saturday with the axis
located over central Montana by the afternoon hours, placing
western and central North Dakota under northwest flow aloft.
After highs mainly in the upper 40s to the upper 50s today and
Friday, we start to clear out and warm on Saturday with forecast
highs in the lower 50s to lower 60s. The ridge then approaches
the Montana/North Dakota border late Saturday night and crosses
the state on Sunday. This will lead to even warmer temperatures
on Sunday, with highs forecast to be mainly in the upper 60s to
mid 70s.

By Sunday night, the ridge moves off to our east and we
transition into nearly meridional flow aloft as a strong
negatively tilted trough approaches. An upper low will close
off at the base of the trough and eventually swing up to the
North Dakota/South Dakota border by late Monday. Several rounds
of widespread precipitation appear to be in the cards Sunday
night through mid to late week as ensemble guidance suggests
this low will have a tough time getting kicked out of the
region. Monday may also bring a better chance for some
thunderstorms. Shear will be plenty strong, but instability is
likely to still be lacking a bit. That being said, CSU Machine-
Learning Probabilities suggest at least marginal chances for
some severe weather in the Sunday through Tuesday time frame so
it will be an interesting period to watch. Chances for showers
will linger mid to late week.

After Monday, temperatures will likely cool back to slightly
below normal categories through mid to late week with NBM highs
mainly into the lower 50s to lower 60s. It is worth noting that
ensembles continue to struggle with the pattern beyond Monday,
and this uncertainty is evident in significant high temperature
spread among NBM members. Thus, the temperature forecast next
week still includes quite a bit of uncertainty. As a final note,
periods of breezy conditions appear likely, mainly Friday and
then most of next week.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 1256 AM CDT Thu May 2 2024

A disturbance will continue to move from south central North
Dakota into eastern North Dakota through the night. Widespread
showers will be possible across much of the central and east
along with MVFR ceilings. Western North Dakota will likely
remain in VFR categories through the period, including the
terminals of KXWA and KDIK. KMOT may also remain in VFR
categories through the period, although ceilings here may come
close to MVFR categories Thursday morning at times. West winds
will become breezy Thursday afternoon across southwest North
Dakota, with some gusts up to 30 mph at KDIK. Winds will be
generally light elsewhere.

&&

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

&&

$$

DISCUSSION...ZH
AVIATION...ZH