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000
FXUS63 KBIS 260007
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
707 PM CDT Thu Apr 25 2024

.KEY MESSAGES...

- Strong southeast winds are likely across the southeast this
  evening.

- Showers and thunderstorms are likely (60-90%) this evening
  through Friday, with the highest probabilities across the
  southern half of the state.

- Cooler temperatures on Saturday and Sunday, with low to medium
  chances of rain showers across southern and central North
  Dakota.

- Temperatures warm up back to above normal next work week, with
  low chances for showers most days.

&&

.UPDATE...
Issued at 705 PM CDT Thu Apr 25 2024

Limited updates needed so far this evening. In the east near to
isolated advisory winds are being reported. Coverage was more
isolated to scattered thus held off on an advisory at this time.
These winds could gust 45 to 50 MPH this evening, diminishing
around sunset. Meanwhile in the west and south central, continue
to monitor thunderstorm development. Pockets of MUCAPE near 1000
J/KG remain, although shear values of 20 to 25 knots are proving
to be not enough to sustain severe thunderstorms in ND at this
time. That being said, still cannot rule out an isolated strong
storm through the evening. Hail and perhaps gusty winds would be
the main threat, although still expecting storms to be sub
severe. Brief heavy rain could also be possible as precipitable
water values are currently above normal for this time of year.
Overall will continue to monitor winds and thunderstorms with
little updates needed at this time.

&&

.DISCUSSION...
Issued at 304 PM CDT Thu Apr 25 2024

Currently, mostly mid to high level clouds are present across the
area, with widespread temperatures in the low to mid 70s. There is
still the potential for some areas out west to reach 80 within the
next few hours, however the intrusion of thicker clouds from Montana
and western South Dakota may limit those chances. Some cumulus has
begun to form across the border in eastern Montana as well. Winds
across the area are out of the south southwest, with some places in
the James River Valley reaching sustained wind speeds in the 20 to
30 mph range, with occasional gusts nearing 35 mph. These winds are
expected to decrease near sunset, when mixing weakens.

We are still on track to receive our first real chance at some
convection and the development of thunderstorms. Recent
deterministic guidance indicates a corridor of 1000 - 2000 J/kg of
MUCAPE, along with modest lapse rates, supporting the potential for
the development of thunderstorms. However, shear continues to be the
main limiting factor, with 0-6 km shear maxing out at 15 to 20 kts
across the region with highest instability. Should any storms
develop, small hail and gusty winds will likely be the main
concerns, as these storms will not be able to sustain themselves
without the shear. Gusty winds from these storms may continue as the
storm collapses as well. Initially, these storms will begin to
develop across the southwest during the late afternoon and early
evening hours, before spreading across the rest of the area after
sunset. CSU machine learning continues to advertise a low chance for
severe hail during this period, mostly across western portions of
the state. Our area is still only in a general thunder risk from the
SPC, but the Marginal Risk (level 1 of 5) has been expanded up to
our southern border.

Following this round of thunderstorms, a warm season Colorado Low is
forecast to move to the south of the area through Friday, bringing
much of the area a period of showers. Wrap around moisture long the
northern periphery of the surface low will make its way into the
southern half of the state late tonight, expanding northward through
the day Friday. Chances for precipitation at its peak will range
from 20 to 30% across the far northwest, to 80 to 95% for nearly the
entirety of central North Dakota and the James River Valley.
Precipitable water values are forecast to be near 1.00", which
approaches the 90th percentile of the precipitable water
climatology. Parts of south central and the southern James River
Valley currently have a 45 to 75% chance of exceeding 0.50" of rain,
while the chances for exceeding 1.00" remain rather low, at around
10 to 20% for the same area. Most of the area is expected to see at
least some rain through the day Friday, with chances tapering off
overnight and into Saturday as the surface low pushes out into the
Great Lakes region.

A cold front is forecast to drop down across the area from the north
this weekend, with high temperatures on Saturday and Sunday forecast
to be a bit cooler than what we have been seeing lately. Widespread
highs are forecast to be in the upper 40s to the upper 50s, with
overnight lows in the 30s to lower 40s. While some areas may see
temperatures below freezing, precipitation is unlikely to occur in
those areas, so any concerns for snowfall are minimal. As that cold
front moves through, a secondary, weaker low pressure system is
forecast to take a similar path to the previous Colorado low, just
displaced a bit further south. Moisture associated with this system
are expected to be reduced, with chances for precipitation mostly
displaced further southeast. Chances for exceeding 0.50" will be
rather low, only maxing out around 20 to 30% in the far southern
James River Valley, with most locations remaining lower than 10%.

After these systems move through, upper level flow is expected to be
a bit more zonal, with an upper level ridge moving into the area
from the west. Temperatures are forecast to increase Monday and
through the rest of the week, increasing into the 60s to lower 70s.
However, there is still some disagreement in the placement and
strength of this ridge, which would affect how active the pattern
becomes. Current WPC cluster analysis suggests two separate
scenarios: 60% of members suggest a stronger ridge, leading to a
warmer, less active, and therefore drier pattern, with only
occasional daily chances for afternoon and evening showers. The
other 40% of members suggest a more southward displaced ridge,
leading to a more active and wet pattern, with the potential for
greater chances for showers and thunderstorms. Either way, next work
week is looking to be a bit warmer than the weekend that
precedes it.

&&

.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 705 PM CDT Thu Apr 25 2024

Periods of showers and thunderstorms will bring MVFR to IFR conditions
at times through the forecast period. This evening, showers and
thunderstorms will push into western North Dakota. These could
bring periods of MVFR conditions. Meanwhile breezy winds and
increasing clouds could be found across the central and east.
Tonight, showers and thunderstorms transition to more widespread
showers that then look to linger across much of the forecast
area through Friday. Prevailing showers are in most TAF sites as
a result, with the exceptions being in northwestern North Dakota
including KXWA. These widespread showers could bring MVFR to
IFR ceilings. Breezy southeast winds could linger across the
east tonight into Friday. Meanwhile a breezy northeast wind
could develop across the west on Friday.


&&

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

&&

$$

UPDATE...Anglin
DISCUSSION...Besson
AVIATION...Anglin