618 
FXUS63 KBIS 210222
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
922 PM CDT Sun Mar 20 2022

.UPDATE...
Issued at 921 PM CDT Sun Mar 20 2022

For this update, have blended in current conditions and adjusted 
pops a little on the western border. Regional radar mosaic shows 
the stronger returns in eastern Montana, and a few reporting 
locations (Wolf Point, Miles City) have reported light rain in the
past hour under those stronger reflectivities. High resolution 
model solutions continue to suggest the best precipitation 
chances initially will be along the Montana border, so increased 
pops a bit in my west to better align with my neighbors. We also
brought in small pops to the southwest a bit faster based on
light returns moving north out of South Dakota on the Bowman 
radar.

Winds have begun to increase from the northwest in the western 
part of the state. KXWA has gusted to around 35 mph which is in 
line with some of the higher gusts being reported in eastern 
Montana. The current forecast has that covered well, so only made 
minor adjustments. 


UPDATE Issued at 642 PM CDT Sun Mar 20 2022

Late afternoon surface analysis placed low pressure across
northwest/north central South Dakota with an inverted trough into
western North Dakota. The low is expected to gradually move east 
tonight into Monday. This could bring a chance of rain/snow to 
western North Dakota later this evening. The main change for this 
forecast update was to add small pops to the far northwest corner 
of the state a couple hours earlier than in the previous forecast.
Hi-resolution model solutions have been fairly consistent in 
suggesting at least a small chance in that area in the coming 
hours. Otherwise, the timing still looks good with the best 
chances for most areas holding off until after midnight. 

In regards to snow amounts, the current forecast again looks to 
be on track. NBM 4.1 snow amounts over the 24 hours ending at 00Z
Tuesday are generally in line with the current forecast, showing
the higher amounts towards the Turtle Mountains. The 90th 
percentile has less than an inch for most locations with again the
higher amounts of an inch or two towards the Turtle Mountains. 
Looking at the 10th percentile, it basically shows a dry outcome. 
It's entirely possible some locations don't get much at all from 
this system, espcially with the fairly dry looking 90th percentile
in the far south central towards the James River Valley (south of
Jamestown).

Winds are a bit tricky with them weakening in the inverted 
trough, but they are gusty in the stronger pressure gradient 
ahead and behind it. In general the stronger gusts have been 
around 35 mph which is covered well by the going forecast. 

&&

.SHORT TERM...(This evening through Monday)
Issued at 131 PM CDT Sun Mar 20 2022

The main forecast issue in the short term period will be
precipitation chances and winds tonight and Monday.

Currently, low pressure was situated over northwest South Dakota
with an inverted trough north northwest into far northeast
Montana. A rather tight pressure gradient extended east across 
the forecast area with winds around 20 mph with gusts up to 
around 35 mph over central ND. Winds have been diminishing over 
western ND closer to the inverted trough. Skies were partly to 
mostly sunny across the area with mainly high thin clouds.

Tonight. the surface low and inverted trough will propagate slowly
eastward, with the inverted trough situated around the Highway 83
corridor by around midnight. The strong southeast winds will
slowly diminish over central ND this evening. In western ND there
will be a period of stronger northwest winds this evening on the
back side of the inverted trough. These stronger northwest winds
could sneak into central ND later this evening as well. All of
these winds are expected to remain below advisory criteria. 

Precipitation chances finally arrive late tonight with the mid 
and upper level trough. Small precipitation chances arrive in the
far west late this evening, with better chances holding off until
after midnight, then crossing the Highway 83 corridor early 
Monday morning, and moving into the Turtle Mountains and James 
River Valley by mid to late morning Monday and tapering there by 
mid afternoon. Precipitation will start out as rain this evening, 
but as temperatures drop later tonight, expect mostly a mix of 
rain and snow, with more rain west and south central and more snow
north central. These precipitation amounts are going to be light 
too. Most areas will see less than a tenth of an inch, and many 
seeing only a trace to a couple hundredths. The Turtle Mountains 
area might see some of the higher qpf totals Monday and they 
should be cold enough for all snow early then a rain snow mix late
morning and on. This area could around an inch of snow, most 
areas that get any snow only receiving a trace to a few tenths of
an inch. 

It will be noticeably colder and breezy Monday. After lows tonight
in the low to middle 30s, highs will only climb into the mid 30s
around the Turtle Mountains, to near 50 along the South Dakota 
border.

.LONG TERM...(Monday night through Sunday)
Issued at 131 PM CDT Sun Mar 20 2022

If precipitation hasn't already ended over eastern portions of
central ND by Monday evening, it will end early Monday evening.

Otherwise mainly dry conditions are expected Tuesday through
Thursday. Another wave moves through the Northern Plains during 
the Thursday night through Friday timeframe bringing a small 
chance of precipitation. This is followed by upper level ridging 
through next weekend. After temperatures mainly in the 30s and 40s
for Tuesday and Wednesday, we rise into the 50s on Thursday ahead
of the aforementioned wave that cools us back down into the 40s 
on Friday. We then warm back into the upper 40s and 50s for most 
areas by Sunday, with lower 60s possible over the far southwest.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 642 PM CDT Sun Mar 20 2022

An area of low pressure moving across South Dakota will bring a
chance of rain/snow to western and central North Dakota tonight 
and Monday. The precipitation will move from west to east, so the 
first TAF locations to have precipitation chances will be in the 
west. Confidence in fairly low in regards to precipitation 
intensity and potential visibility restrictions. For now, will 
generally suggest P6SM, but monitor as things develop. More 
confidence comes in the potential for lower (MVFR and perhaps IFR)
ceilings. Winds will turn to a northwesterly direction as the low
crosses the region. 


&&

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

$$

UPDATE...King
SHORT TERM...TWH
LONG TERM...TWH
AVIATION...King