Area Forecast Discussion
Issued by NWS Aberdeen, SD

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000
FXUS63 KABR 182142
AFDABR

Area Forecast Discussion
National Weather Service Aberdeen SD
342 PM CST Sun Feb 18 2018

.SHORT TERM...(This Evening through Monday)
Issued at 342 PM CST Sun Feb 18 2018

The low pressure system/cold front has been able to sink southeast
of the forecast area this afternoon, with temperatures slowly
falling throughout the day behind this boundary. The coldest air
will remain over our northwest counties, where 850mb temps fall to
around -18C by daybreak Monday. This area will have a better chance
of falling below 0F, while the rest of the area stays mainly in the
single digits above zero.

The 500mb low deepening over the Pacific Northwest will push a large
trough across the western half of the nation tonight into Monday
morning, with plenty of moisture overspreading the area. Already
seeing snow at MBG and north of PIR this afternoon, with some
flurries at NWS ABR around 20Z. This lines up well with some of the
CAM solutions. Have sped up the onset of snow for this event. Still
feel that the headlines (Winter Storm Warning for much of our
southwest) is in good shape timing and amount wise. Continue to
highlight a long term event, with 2 distinct periods of interest
across the forecast area. For the HWO it ends up being 3 periods of
snow amounts mentioned, due to the different temporal breakdown
needed for that product. The focus for tonight through Monday should
be Stanley and Jones (and surrounding areas) with 3 to 8 inches of
snow possible. The combination of this snow (with ratios around near
18:1) and winds gusting around 25kts have been productive in
reducing visibility to 2-4SM at MBG. This will likely be common
through the night. Expect snow ratios to increase in the cooling air
to closer to 22:1 by the end of the afternoon Monday. The focus for
stronger winds will likely be over the eastern half of the forecast
area, where lighter snow is anticipated. With plenty of cold air
sinking in, temperatures will remain in the single digits to teens
above zero for highs Monday.


.LONG TERM...(Monday Night through Sunday)
Issued at 342 PM CST Sun Feb 18 2018

Light snow will likely be ongoing across the area at the beginning
of the period (Monday evening), with another round of somewhat
heavier snow approaching from the west. The models remain in decent
agreement that a moderate to heavy band or two will set up, but
continue to differ on strength and exact location. The boundary
south of the region will be continuing to drop south, so will lean
toward the southern parts of the CWA likely seeing the highest
amounts of snow. An additional 2 to 5 inches looks possible during
the Monday night/Tuesday morning time frame. Winter Storm Warnings
and/or Winter Weather Advisories will remain in effect through
Monday night into Tuesday morning.

High pressure moves in behind the exiting system on Tuesday, and
will result in dry, but cool, conditions across the area through the
latter part of the week. A system tracking from the Southern Plains
to the eastern Great Lakes may bring some light snow to the
southeastern part of the area Thursday night, then another high
pressure system will bring back dry conditions for the weekend.

Temperatures will be below normal early in the period, with highs in
the single digits and teens Tuesday and Wednesday. Will see near to
slightly above normal temperatures for the remainder of the period,
with highs in the 20s to lower 30s.


&&

.AVIATION...(For the 18Z TAFS through 18Z Monday Afternoon)
Issued at 1125 AM CST Sun Feb 18 2018

MBG has been stuck under a 015-020 deck since 1537Z, with no signs
of VFR ceilings and vis at all getting out of it through the
period. These mid clouds will sink across the rest of the forecast
area today, within the next couple of hours at PIR and ABR. Expect
much of the impact snow wise to slide into PIR, with snow starting
this evening and continuing through at least the morning hours
Monday.


&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...Winter Weather Advisory from 3 PM Monday to 6 AM CST Tuesday for
     SDZ005-009-010.

     Winter Weather Advisory from 6 PM Monday to noon CST Tuesday for
     SDZ006>008-011-018>023.

     Winter Storm Warning until 6 AM CST /5 AM MST/ Tuesday for
     SDZ015>017-033>037-045-048-051.

MN...Winter Weather Advisory from 6 PM Monday to noon CST Tuesday for
     MNZ039-046.

&&

$$

SHORT TERM...KF
LONG TERM...Parkin
AVIATION...KF


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