862
FXUS63 KBIS 011459
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
959 AM CDT Wed May 1 2024

.KEY MESSAGES...

- Another round of rain showers and low stratus will push into
  the southwest around noon mountain time before expanding
  across central North Dakota later this afternoon through the
  evening.

- Daily chances (low to medium) for rain (and maybe an isolated
  thunderstorm or two) through the rest of the week, with
  temperatures slightly below normal.

- Breezy to windy across the forecast area on Friday.

&&

.UPDATE...
Issued at 959 AM CDT Wed May 1 2024

Little needing updating this morning. Most of the CWA is
currently experiencing clear skies, except across the far northeast
and far southwest. Clouds will go on the increase from the
southwest today, with scattered showers returning this afternoon
in the west. An isolated thunderstorm is still possible,
although instability looks limited for today. More organized and
widespread showers are still expected this evening into tonight.
Overall the forecast remains on track with little updates at
this time.

UPDATE
Issued at 630 AM CDT Wed May 1 2024

Made some slight changes to the sky grids to account for some
redevelopment of low stratus on the back end of the original
deck across the north, otherwise the forecast remains on track
at this time. Some showers linger across the far north central
this morning, but are expected to push out of the forecast area
by the mid morning. What will become the next round of rain is
beginning to develop downstream in southeastern Montana. Winds
are generally light and variable, while current temperatures
range from the lower 20s in the far southwest where the sky is
clear, up to the lower 40s in the northeast where the stratus
deck remains.

&&

.DISCUSSION...
Issued at 405 AM CDT Wed May 1 2024

Today, the region remains under the influence of a fast approaching
upper level low moving into the southern Canadian Prairies out of the
Pacific Northwest. An associated surface low center continues to be
parked over southern Saskatchewan, and is responsible for the light
showers and low stratus that continues to pivot northward out of the
area at this time. The upper level low will stall out over the
southern Canadian Prairies late today, and allow a shortwave trough
to push another round of rain showers and low stratus into the
southwest later this morning. Lows this morning are in the upper 20s
west to upper 30s east. Highs today are expected to be a little
warmer as a weak ridge is pushed ahead of the shortwave trough,
from the lower 50s west to the lower 60s east.

Rain showers will slowly expand to the northeast through the day
today as the surface low in southern Saskatchewan dips into northern
Montana and begins to mature, with the highest chances (40 to 80
percent) presently expected across the south central. Modest
instability over the southwest and portions of the south central
will allow for an isolated thunderstorm or two to potentially
develop this afternoon and again on Thursday (10 to 20 percent
chance), though these are not expected to become severe at this
time. The surface low will then become mature as it pushes
across the International Border late Wednesday and through the
day Thursday, with rain chances becoming widespread (60 to 80
percent) across the forecast area as the showers again begin to
pivot northward throughout the day. Rain totals for this whole
period will vary across western and central North Dakota. The
west will only see limited chances for showers, mainly on
Thursday, and thus has the lowest expected totals from the trace
(southwest) to a quarter of an inch (northwest) range. With
more consistent showers expected in central North Dakota along
with some enhanced rainfall rates where isolated thunderstorms
do develop, rainfall totals here are favored (50 to 60 percent)
to exceed one half inch by late Thursday, with the ensemble
hinting that some locations could even exceed one inch overall
(20 percent chance). Behind this system on Friday, some light
wrap around showers could persist across the forecast area while
modest CAA promotes breezy to windy conditions. Temperatures
through Friday are expected to be below normals, with highs in
the 50s and lows in the lower 30s to mid 40s.

Upper level ridging will begin to intrude into the west late
Thursday and into early Saturday, allowing conditions to dry out and
begin to warm up into the upper 60s and 70s by Sunday afternoon.
Another upper level low will move over the Pacific Coast on Saturday
before supplanting the ridge late Sunday into Monday, again
establishing an active pattern for the early portions of next week.
CSU Machine Learning has begun to paint the southern portions of the
state with severe weather potential Monday and Tuesday. Uncertainly
remains with regards to this system as the ensemble remains
discordant at this time, with the deciding factor appearing to a
minority cluster (~15% membership) resolving on the sufficient
instability for initiation. In any scenario, this pattern again
bring widespread chances for showers across western and Central
North Dakota through early next week.

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 630 AM CDT Wed May 1 2024

Mainly VFR conditions to begin the 12Z TAF period, though what
remains of the previous rain showers and low stratus deck
lingers across the north. Another round of rain showers and MVFR
to IFR ceilings are anticipated to push into the southwest late
this morning and then expand across central North Dakota
through the TAF period, with the northwestern terminal of KXWA
currently expected to remain mostly clear. Isolated
thunderstorms may develop this afternoon over the south, though
not with enough certainty to place it at any given TAF site at
this time. Light winds this morning will temporarily become
moderate through the afternoon as a weak front passes through
the forecast area, then diminish overnight and by the end of the
TAF period. Winds may become strong and erratic where
thunderstorms do develop.

&&

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

&&

$$

UPDATE...Anglin
DISCUSSION...Adam
AVIATION...Adam