423
FXUS63 KBIS 030310
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
1010 PM CDT Thu May 2 2024

.KEY MESSAGES...

- Scattered showers and a few isolated thunderstorms will
  continue across northern North Dakota tonight and through most
  of Friday. Some light snow could mix in with the rain in parts
  of western North Dakota.

- Temperatures will warm through the weekend, with windy
  conditions Sunday.

- Chances for rain return late Sunday night, becoming likely by
  Monday (60 to 80 percent). Monday may also bring a higher
  chance for some thunderstorms. Low to medium rain chances (20
  to 60 percent) continue into mid week.

&&

.UPDATE...
Issued at 1010 PM CDT Thu May 2 2024

Main low has progressed into northeast North Dakota late this
evening, with the primary area of rain still directly around
the low. Some scattered showers continue across mainly north
central North Dakota, but activity has been diminishing over the
past hour or so. A secondary low is centered in far southeast
Saskatchewan, with low clouds in northwest North Dakota wrapping
around the low. Additional rain showers are visible on radar
across much of northern Montana, generally moving southeast in
cyclonic flow.

The main change with this update was to freshen up POPs through
Friday morning with the latest blended guidance. We now have a
mention of snow potentially mixing in with rain in parts of
western North Dakota on Friday morning, with overnight lows in
the upper 20s to lower 30s. No accumulation is expected at this
time.

UPDATE
Issued at 659 PM CDT Thu May 2 2024

Surface analysis shows the center of a low in east central North
Dakota, with widespread, more stratiform rain wrapping around
the center of the low across the eastern part of state. A line
of thunderstorms has developed on a narrow low-level warm nose,
extending from the Bowbells area to just east of the
Bismarck/Mandan area. Directly behind this is an additional line
of primarily showers, with winds shifting to westerly and
increasing behind this second line. Ceilings are still modestly
high enough to where there is some virga present with these
radar returns, seen both from our office and on NDAWN cameras
across the area.

We did get a report of small hail from a cell that passed
through Strasburg. Low freezing levels do tend to drive small
hail, and the RAP-estimated 50dbz height for severe hail is
only around 13-15k feet, so would not be surprised if we got
additional reports of small hail as these thunderstorms move
through.

As the upper low exits to the northeast, expecting showery
activity to diminish across most of the area. There is
additional development upstream in eastern Montana so will have
to keep an eye on this to see if it persists over the next
couple of hours and expands into western North Dakota.

&&

.DISCUSSION...
Issued at 343 PM CDT Thu May 2 2024

Satellite observations show an upper level low located over the
northwest that will continue to push eastward this evening.
Wrap around showers will persist across the western and
northern half of the state. There is enough instability over the
west and south central for thunderstorms. Thunderstorms will
decrease later this evening as instability decreases. Overcast
skies have resulted in below normal temperatures in the lower
50s this afternoon.

The upper low will continue to push eastward Friday and cold
air advection on the backside of the low will mix stronger winds
down to the surface. In addition a surface pressure gradient
will lead to breezy winds across the state in the afternoon.
Temperatures will remain on the cooler side Friday as overcast
skies will linger for much of the day limiting warming.
Overnight lows could drop into the upper 20s across the
southwest as surface high pressure passes over Friday night.
Saturday temperatures will begin to trend upward to near normal
as surface high pressure clears out the clouds across region
and ridging begins to build out west over the Northern Rockies.
Sunday temperatures are forecast to climb into the 60 to 70s out
west as the upper level ridge pushes quickly through the
region. A strong surface pressure gradient will lead to windy
conditions across the western and south central North Dakota in
the afternoon. This short term warm up will be short lived as
another broad trough pushes across Western CONUS.

A strong upper level low pressure system will move up from the
Rocky Mountains Monday leading to widespread precipitation
across the Northern Plains. The NBM has 50 percent chance of 1
inch rain across the Northern half of the state. Thunderstorms
are possible as the system first moves into the region and there
is some instability around 500-1000 j/kg. CSU Machine Learning
Program has backed off on severe weather parameters due to the
ensembles having decreased instability, but there still is low
chance for severe weather Monday. In addition to rain, windy
conditions are expected Monday as a strong surface low with a
tight pressure gradient moves through the region. Wrap around
precipitation will continue through Wednesday leading to showers
and cooler conditions. Temperatures are forecast to sit in the
50s through the middle of the week. After this system there is a
ton of model uncertainty as ensembles want to wash the upper
low out over the plains while some solutions try to move it
eastward.

&&

.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 659 PM CDT Thu May 2 2024

VFR ceilings to start the TAF period, with intermittent MVFR
visibilities in any showers and thunderstorms. Lower ceilings
will be quickly moving into northwest North Dakota this evening,
expanding across western and northern North Dakota into Friday.
After a line of showers and thunderstorms moves through central
and eastern North Dakota this evening, scattered showers will
expand across the north through tonight and through the day
Friday, primarily impacting KXWA/KMOT. Breezy west to northwest
winds will continue across the area through the period. KBIS
and KJMS are expected to stay VFR through the TAF period outside
of any areas of precipitation.

&&

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

&&

$$

UPDATE...Jones
DISCUSSION...Johnson
AVIATION...Jones