648 
FXUS63 KBIS 192330
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
630 PM CDT Tue Oct 19 2021

.UPDATE...
Issued at 630 PM CDT Tue Oct 19 2021

Only minor changes were made with this update, mainly blending
observed trends into the the evening forecast. Satellite images
show continued southward advancement of the back edge of stratus
into southern and central ND, and early data from the 00 UTC RAOB
from Bismarck suggests the cloud layer is thin. However, guidance
suggests the stratus will develop back northward overnight, so we
will be monitoring its evolution after sunset. Otherwise, CAMs 
through the 22 UTC HRRR suggest the northern edge of precipitation
late tonight and Wednesday may remain further south than earlier 
anticipated. The exception is the 18 UTC NAM Nest, but that model 
core/configuration has a tendency to be too far north with its QPF
signature. Thus, if trends in successive guidance continue with 
the southward trend, our PoPs may follow suite in the next update.

&&

.SHORT TERM...(This evening through Wednesday)

Issued at 240 PM CDT Tue Oct 19 2021

Forecast highlights in the short term period will be lingering
clouds today/tonight, along with rain and snow chances south
tonight into early Wednesday.

Currently, upper level low centered along the Colorado/Wyoming
border area, with sfc high pressure to our north. Extensive cloud
cover across much of the state, with clearing from north to south
across the northwest and north central. Clouds associated with the
upper low streaming north towards our area. 

Model guidance continues to show the low clouds dissipating slowly
from north to south this afternoon into the evening to around the
I94 corridor, then halting/redeveloping back to the north later
tonight. Upper low moves into central South Dakota/Nebraska region
overnight, with chances for rain or snow developing across our far
south along the ND/SD border. Best chances for precpitation will
not arrive till after 09Z and last through the morning hours
before dissipating across the James River Valley during the day. 
Surface high pressure to the north will settle into western and
eventually central ND as well late tonight through Wednesday
morning, so how far north precip chances get to remain uncertain.
Latest NBM did lower QPF by about 30-50% compared to the forecast
issued earlier this morning. 

Precipitation type will depend on surface temperatures and how the
atmospheric profile cools with time. Expect a rain/snow mix
becoming mainly snow south central, possibly remaining all rain
across the southeast. Some potential for a mix of rain/snow/sleet
for a period around sunrise but not expecting any impacts from
this at this time. A few tenths of an inch of snowfall will be
possible dependent if we can get a snow band to develop. Global
models say maybe, CAMs keep best DivQ/frontogensis linkage to our
south. 

Another cool day tomorrow with highs in the 40s. Breezy south
central and east, but not as windy west closer to the surface
high.  

.LONG TERM...(Wednesday night through Tuesday)

Issued at 240 PM CDT Tue Oct 19 2021

Upper low continues to push to the east through the day 
Wednesday, pushing over the Iowa/Minnesota border by evening. This
allows surface high pressure to build across the Dakotas Wednesday
night, setting the stage for a widespread hard freeze for much of
western and central areas of the state, with forecast lows in the
lower to mid 20s. 

Mainly quiet weather expected through the rest of the work week
with northwest flow over the area. The southwest may push into the
50s for highs, 40s elsewhere. A weak clipper could bring some
light precip chances Thursday night-Friday morning, but opted to
maintain NBM and a dry forecast for now. 

A variety of systems off the west coast are expected to shift
upper level flow southwest for the weekend into the start of next
week, resulting in occasional precipitation chances. Should also
see a nice moderation in temperatures early next week (highs back
into the 60s) with all models showing strong WAA into the area.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 630 PM CDT Tue Oct 19 2021

MVFR ceilings in stratus are expected in southwest and south
central ND tonight, with local IFR ceilings possible. The main
uncertainty is how far north and west the low clouds may expand
back into areas they vacated earlier. Otherwise, rain and a low
chance of snow is possible near the ND-SD border overnight and 
Wednesday, with the highest probabilities of precipitation and 
related MVFR to IFR visibilities south of KJMS toward KABR.

&&

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

$$

UPDATE...CJS
SHORT TERM...NH
LONG TERM...NH
AVIATION...CJS