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000
FXUS63 KBIS 160000
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
700 PM CDT Mon Apr 15 2024

.KEY MESSAGES...

- Multiple rounds of showers are likely (60-80% chance) tonight through
  Tuesday night, with a few thunderstorms possible (30%
  chance). The highest precipitation chances are across central
  and eastern North Dakota. Severe weather is not expected.

- Low humidity and gusty southeast winds will lead to near
  critical fire weather conditions through the early evening
  across the south.

- Cooler temperatures start on Tuesday and will continue into
  the weekend. The coldest days will be Thursday and Friday when
  highs will mainly range from the mid 30s to mid 40s.

- Some light snow is possible Wednesday night through Friday,
  mainly across the north (30% chance). Little to no
  accumulation is expected.

&&

.UPDATE...
Issued at 700 PM CDT Mon Apr 15 2024

Little needing updating early this evening. Gusty winds continue
to be found across the area, with the highest winds still mainly
confined to those currently in the Wind Advisory. Thus no
changes to this advisory at the moment. Near critical fire
weather conditions could linger into the early evening across
the south, especially for areas that cleared out and warmed this
afternoon. This mornings showers and thunderstorms linger across
the north currently. The next round of showers and thunderstorms
will move northward from South Dakota tonight, and become
widespread for Tuesday. Currently, this disturbance is providing
for stronger storms in western SD. There will be some weak to
modest MUCape when these storms enter into ND tonight, although
they will have moved off from the stronger surface based cape
they are currently thriving on. Thus severe weather is overall
not expected tonight, although cannot rule out a strong wind
gust given the elevated nature of these expected storms. The
steep mid level lapse rates could perhaps provide for some small
hail if any stronger storms can develop. Confidence in this
remains low at this time.

&&

.DISCUSSION...
Issued at 254 PM CDT Mon Apr 15 2024

This afternoon, a deep upper low was moving across the Rockies,
while a surface low had formed on the lee side, in northeast
Colorado. A secondary low was analyzed in northeast Wyoming but
is starting to merge with the main low. There have been two main
rounds of precipitation that have come from the secondary low,
with a few marginal impulses moving through aloft. One area is
now in eastern North Dakota, while the second is moving through
central North Dakota. Although SPC mesoanalysis indicates
instability is quite low, we have had a few isolated
thunderstorms in this second area over the past couple of hours.

A Wind Advisory remains in effect for parts of southern North
Dakota, with sustained winds up to 30 mph and gusts up to 55.
Somewhat inverted V soundings and scattered rain showers are mixing
down stronger than expected wind gusts, with a few observed gusts in
excess of 60 mph earlier today. We did issue a Special Weather
Statement for counties surrounding the Wind Advisory for
occasional gusts up to 55 mph.

We are expecting a break in precipitation late this afternoon
and evening before showers and a few thunderstorms become more
widespread late tonight and through Tuesday as the deep Colorado
low pushes northeast. NBM QPF probabilities have stayed
relatively consistent over the past couple of days, with a high
probability of at least 0.50" of rain for areas from Bismarck
to Rolla and east. Probabilities quickly drop off the further
west you go, with only a low chance for even 0.10" in far
western North Dakota. The various deterministic models are
advertising pretty different solutions when it comes to the
environment tonight and tomorrow, but the general expectation is
for a few hundred J/kg of CAPE at most late tonight into
Tuesday which would support a few thunderstorms. High-res output
paints a similar picture, with potentially a few storms moving
north from South Dakota where the environment is more supportive
of convection. Any thunderstorms that do develop could lead to
locally higher rain amounts.

Precipitation chances taper off from west to east Tuesday night
into Wednesday as the Colorado low moves off to the northeast.
Meanwhile, a secondary deep trough and attendant low will drop south
from British Columbia and Alberta Tuesday into Wednesday. Ensemble members
continue to favor a slightly northern track to this system that
keeps the bulk of precipitation in the southern Canadian
Prairies. This system will also bring a push of colder air for
the end of the week, with 850mb temperatures cooling down to 5
to 10 degrees C below zero. This will translate to highs
Thursday and Friday in the mid 30s to mid 40s, with overnight
lows in the 20s, potentially even the teens in some of our
normal cold spots. We continue to carry a 20 to 30% chance of
precipitation across mainly northern North Dakota Wednesday
night into Friday, with snow the predominant expected
precipitation type. However, little to no accumulation is
expected.

Winds are expected to stay elevated through the week as the Colorado
low wraps up and deepens as it moves northeast, although the ECMWF
EFI is less bullish on the upper end potential compared to the past
few days. On both Wednesday and Thursday, strong northwest
winds are forecast, with sustained speeds in the 20 to 30 mph
range, potentially a little higher.

There is fairly good agreement on flow aloft turning more quasizonal
over the weekend and into next week, allowing warmer air to slowly
return to the region. NBM temperature percentiles show a steady
warming trend through Monday, with low chances of precipitation
returning to the forecast then as well.

&&

.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 700 PM CDT Mon Apr 15 2024

Developing showers, with a few thunderstorms at times, will
return MVFR to IFR conditions to the forecast area tonight into
Tuesday. This evening will see mainly VFR conditions, with a few
showers and isolated thunderstorms across the north. Later this
evening through tonight, showers and thunderstorms are expected
to develop across the south and push north and eastward. This
looks to return MVFR conditions to most sites. Widespread
showers then settle in for most ares Tuesday, bringing IFR
ceilings. The exception being the northwest including KXWA
where VFR to MVFR conditions may prevail. Gusty easterly winds
will be found through most of the night and into Tuesday.
Eventually winds look to become more northerly across most sites
later in the day Tuesday. LLWS is also possible tonight into
Tuesday morning, mainly from KBIS to KJMS and southward.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
Wind Advisory until 11 PM CDT /10 PM MDT/ this evening for
NDZ034>036-041-042-044>047-050.

&&

$$

UPDATE...Anglin
DISCUSSION...Jones
AVIATION...Anglin