Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 141747 AAA
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1147 AM CST Thu Dec 14 2017

.UPDATE...
Issued at 1139 AM CST Thu Dec 14 2017

Light precipitation will continue sliding southward across the
region over the next few hours. Based on a report in our
northeast, plus a webcam observation, have added patchy freezing
drizzle in the far northeast portion of the CWA. The rest of the
forecast for today looks good overall.

&&

.SHORT TERM...(Today and Tonight)
Issued at 400 AM CST Thu Dec 14 2017

Another day, another 500mb embedded wave sining in from the
northwest. This one is just to our northwest early this morning, and
will sink southeast through mid afternoon. Current sfc set up shows
a stationary front over our eastern counties, extending from 1016-
1018mb pressure center over eastern ND/northeastern SD and much of
MN. This feature will slide east as a ridge of high pressure
temporarily builds overhead through this evening, before becoming
surpressed to our south as the next trough nears from the north
(extending from the low over northwestern Canada).

Went closer to the RUC13 with the top down method, which reduced the
probability of ice over our eastern counties shortly past 12Z, and
kept a higher chance of freezing drizzle with any of the light radar
returns shown over that area. Even through we seem to be in a lull,
it looks to be temporary as additional light precipitation slides
in from western SD and ND. Continue to monitor upstream observations
where have been mainly reporting SN, although the Glen Allin
station did briefly report UP. Extended the Winter Weather
Advisory until 9am for the lingering freezing drizzle with icy
conditions on untreated roadways. After 9am there will be a better
chance of mainly snow. Total snowfall amounts today should be
around an inch or less, with the best chance of accumulation over
our southwestern counties. Couldn`t rule out some lingering
flurries over the east (mainly Sisseton Hills) tonight. Another
concern today will be the breezy winds developing west of the
Missouri River. Winds are expected to stay below advisory
criteria.

.LONG TERM...(Friday through Wednesday)
Issued at 400 AM CST Thu Dec 14 2017

It appears a pattern change will likely take place in the long term,
particularly toward the middle and end of next week. The recent west
conus ridge and east conus trof is forecast to retrograde with
troffing gradually taking shape over the western conus as mid level
ridge develops over the eastern Pacific. Most models, especially
ensembles, indicate as much. Deterministic runs offer less
confidence, but that`s probably to be expected at this time range.

During the long term, probably the best chc for measurable pcpn will
occur Saturday and Saturday night as a system tracks across the
region; and again by the middle to latter part of next week as the
mid level pattern goes through some sort of re-alignment.

Temperatures overall will favor near to above normal for the vast
majority of the forecast.  But, a change to colder temps is likely
toward the end of next week.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday Afternoon)
Issued at 1139 AM CST Thu Dec 14 2017

Light precipitation will continue sliding southward across the
region through mid afternoon. Visibility will be impacted briefly
with heavier snowfall rates. Otherwise, expect MVFR cigs to
continue through this evening with a gradual improvement possible
tonight.

&&

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

$$

UPDATE...SD
SHORT TERM...KF
LONG TERM...TDK
AVIATION...SD



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