Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 130526 AAB
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1126 PM CST Thu Dec 12 2019

.UPDATE...
Issued at 526 PM CST Thu Dec 12 2019

Expanded the mention of fog to cover Pierre this evening. Also
started the mention this hour instead of 3z given recent
observations.

&&

.SHORT TERM...(This Evening through Friday Night)
Issued at 259 PM CST Thu Dec 12 2019

Forecast challenges revolve around p-type tonight/Friday along with
strength of post cold-fropa northwest winds Friday afternoon/night.

Currently, most of the forecast area is enshrouded in cloud-cover.
This has kept the temperature from moving all that much...readings
generally between 10 degrees above zero (far northeast) and the
mid 20s (far southwest). That being said, low level waa has begun
across the central part of the state, and will continue to advect
north and east overnight into Friday morning, in advance of the
next pseudo-clipper low pressure system.

Later tonight into early Friday morning, within the strongest
pocket(s) of low to mid-level forcing and lift, there could be some
radar returns for light snow showing up on regional 88D`s. Far north
central and northeast South Dakota counties could see a light
dusting for snow accumulation through Friday morning. It`s also
possible that prior to the strong cold frontal passage progged for
Friday/night, enough saturation loss within the DGZ could lead to a
change from snow p-type potential to patchy/scattered pockets of
freezing drizzle p-type potential, mainly across and east of the
Prairie Coteau from late Friday morning through Friday afternoon.
But, once the cold front sweeps through, the primary p-type of
concern switches back to snow (showers) as low level lapse rates
steepen within the cooling low level airmass Friday afternoon/night.

Temperatures will be warmest on Friday prior to the cold frontal
passage. Breezy/windy north-northwest post cold-frontal mixing winds
will advect another arctic cold airmass down into the region, with
temperatures by late Friday night likely falling back down into the
low single digits above zero.

.LONG TERM...(Saturday through Thursday)
Issued at 259 PM CST Thu Dec 12 2019

The models and most ensembles show good agreement in the Saturday
through Thursday time period for our region and the U.S. The period
starts out with a split flow regime over the country with a strong
jet stream coming off the Pacific into California and across the
southern U.S. with another branch of northwest flow coming in from
western Canada and over our region. Each branch has a strong short
wave trough moving through it from Saturday into Monday. The
southern branch short wave will steal any moisture from making it to
the northern branch short wave trough. These two branches of flow
will phase together early in the week with continued cold northwest
flow dominating our region. There is an indication that heights will
build over our region towards the middle of the week. The
model consensus shows it dry through the entire long term period.

Much below normal temperatures are expected on Saturday and Sunday
with mainly single digits and teens for highs. Monday and Tuesday
will still be below normal with highs mainly in the teens and 20s.
At this time, Wednesday looks to warm up a little more closer to
normal with 20s and 30s. We will see if this warm up continues into
Thursday or not if upper heights continue to rise or fall back down.

&&

.AVIATION...(For the 06Z TAFS through 06Z Friday Night)
Issued at 1126 PM CST Thu Dec 12 2019

MVFR/IFR stratus will remain over the region through Friday
evening.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
&&

$$

UPDATE...Wise
SHORT TERM...Dorn
LONG TERM...Mohr
AVIATION...Wise


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