Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 300825
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
325 AM CDT Mon Mar 30 2020

.SHORT TERM...(Today and tonight)
Issued at 325 AM CDT Mon Mar 30 2020

The short term forecast is highlighted by warm and breezy
conditions, with a chance for rain showers late.

Early this morning, a shortwave embedded in southwest flow aloft
was moving through the forecast area, with some scattered clouds
but otherwise quiet conditions. A surface trough was located over
central Montana, with high pressure to our east.

As upper-level ridging continues to build to our east, southwest
flow aloft will persist throughout the day, with southeasterly flow
at the surface. Expecting quite a breezy day today, with a
tightening pressure gradient ahead of the pre-frontal surface
trough, as well as modest mixing per BUFR soundings. Highs will be
the warmest we`ve seen in the past few days, with low to mid 60s
across much of the forecast area, and mid to upper 50s from the
Turtle Mountains through the James River Valley.

Fire weather could be a concern today in the west, with very low
RH values along with the breezy winds. RAP is showing a
significant dry layer at 925 mb ahead of the prefrontal trough,
with winds shifting to the west this afternoon. Downsloping winds
should lead to this dry air mixing out and dropping RH values
pretty significantly, so have them bottoming out to around 15
percent in the southwest late this afternoon. Used the HRRR for
guidance, which has been doing well the past few days compared to
the national blend. For now, looking like the strongest winds will
be in central ND where RH is just a bit higher, but still
something to keep an eye on if the stronger winds can overlap with
the very low RH values.

As a weak shortwave moves through the Dakotas tonight, there is a
chance for some scattered rain showers to push northeast this
evening and overnight. Guidance continues to show only 100 to 200
J/kg of instability, and SPC outlook has general thunder just
south of the ND/SD border. Can`t rule out a few flashes of
lightning, but otherwise sticking with the previous forecast of
just rain showers and not thunderstorms in the forecast for
tonight, due to the limited spatial coverage.

.LONG TERM...(Tuesday through Sunday)
Issued at 325 AM CDT Mon Mar 30 2020

An active weather pattern and cooler temperatures highlights the
extended forecast.

A deep upper low moving through southern Canada will propagate
east on Tuesday, with a surface low staying north of the
International Border. A secondary surface low will be moving
northeast through South Dakota. A potent cold front extending from
the northern surface low is expected to move into northwestern
North Dakota Tuesday afternoon, sweeping southeast throughout the
evening and night. Compared to today, there is a better chance of
a thunderstorm on Tuesday along/ahead of this front. GFS
advertising up to 500 J/kg of instability in the south central and
James River Valley, along with moderately steep lapse rates and
dew points in the 40s. SREF has this area highlighted, and
although opted to not include thunder in the grids with this
update, could see this being added in with future updates.
Regardless of any thunder/lightning, could be some modest rain
showers Tuesday afternoon/night along with gusty winds, with a
transition to snow likely overnight and into early Wednesday
morning, although little to no accumulations are expected.

Wednesday through the rest of the week, things still look messy,
with not much of a break in precipitation before the next wave comes
through.

Colder on Wednesday in the wake of the cold front, with temperatures
even lower on Thursday (highs in the 30s). Model guidance continues
to show the large upper low remaining somewhat stationary up in
southern Canada, with a strong trough rotating around it and
bringing the chance for precipitation back through the Northern
Plains. GFS continues to be the northernmost solution, and there is
still plenty of spread in QPF amounts between various model guidance
as well as GEFS plumes. However, increasing confidence in the
overall synoptic setup, with this main wave of precipitation pushing
into southwest North Dakota overnight Wednesday and slowly
expanding northeast through Thursday. Accumulating snow is
certainly possible with this round of precipitation since temps
will hover around freezing / mid 30s for basically all of the
forecast area on Thursday. Current forecast from the blend is a
widespread swath of 1 to 3 inches for all but the far northwest,
so certainly not a major snowstorm, but still a hard transition
from how mild it has been lately.

Precipitation could linger into Friday morning before we finally
clear out some, with quasi-zonal flow aloft and temperatures
beginning a slow warming trend through the weekend.

&&

.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1225 AM CDT Mon Mar 30 2020

VFR conditions expected at all terminals for the 06Z TAF cycle.
Some patchy fog is possible in eastern North Dakota tonight but
should stay east of KJMS. Southeasterly winds will increase to 15
to 20 knots during the afternoon, with gusts up to 30 knots
possible. Some rain showers are possible towards the end of the
TAF cycle, but low confidence in timing and location, so not
included at any terminal.


&&

.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...MJ
LONG TERM...MJ
AVIATION...MJ


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