Area Forecast Discussion
Issued by NWS Aberdeen, SD

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000
FXUS63 KABR 152129
AFDABR

Area Forecast Discussion
National Weather Service Aberdeen SD
329 PM CST Thu Feb 15 2018

.SHORT TERM...(This Evening through Friday)
Issued at 326 PM CST Thu Feb 15 2018

As the banded snow feature has weekend and move south, we are
replaced with widespread stratus light snow. The back edge is
nearing Mobridge and extends northeast towards Jamestown, ND.
Tracking the clearing we can expect it to cross the CWA through the
remainder of the afternoon into the early evening. A 1035mb high
pressure follows, with the center of the high tracking across
western/central South Dakota. This puts the James valley/northeast
South Dakota/western Minnesota in westerly flow all night which may
help limit our temperature drop. The flow becomes more
south/southwest for Friday. Snow free areas will happily rebound,
with mixed temperatures from 900mb yielding around 30 degrees.


.LONG TERM...(Friday Night through Thursday)
Issued at 326 PM CST Thu Feb 15 2018

When the period begins, one preliminary mid-level impulse riding
through northwest flow aloft could bring a quick shot (light
dusting) of snow to portions of central and north central South
Dakota late friday night into early Saturday. Not a lot of
confidence right now in that scenario generating much in the way of
measurable snow.

The focus then turns to early Sunday morning through early Tuesday
morning. On Sunday, over far north central into far northeastern
South Dakota and west central MN, the flow pattern is zonal for a
short time as it transitions into southwest flow aloft. Within the
zonal flow pattern decent low to mid level waa-forcing and synoptic
scale lift develops, with a small portion of this cwa being included
in "ground zero" for snow-genesis. Basically, measurable snow is
possible along and north of U.S. Highway 12 from early Sunday
morning through early Sunday evening, with generally a trace to
around an inch of snow thought to be possible, per the going
qpf/snow-ratio values, with higher amounts possible further north
and east across portions of North Dakota and the northern half of
Minnesota. The newest forecast wrinkle is that models are now
beginning to hint at the potential for some ice/saturation loss in
the clouds where it`s needed to produce snow p-type. As such, a
little freezing drizzle has crept into the Sunday forecast now.

Stepping forward in time some more, from late Sunday night through
early Tuesday morning, while the cwa is under southwest flow aloft,
more shortwave energy is expected to lift out of the broad western
CONUS longwave trof being carved out by jet stream winds aloft.
Energy is currently expected to move out across portions of the
central/northern plains, including this cwa from late Sunday night
through early Tuesday morning. Generally speaking, looking at a
prolonged (24 to 30 hours) period of light snow potential, and there
could even be a couple of brief breaks in the snow throughout that
timeframe. Most of the forecast area could see light to moderate
snow accumulations, if QPF guidance, which for the past couple of
days has been holding steady between appx 0.20 and 0.40 inches of
water-equivalent precipitation, continues to maintain similar
forecast QPF amounts and models continue to maintain that there is
sufficient ice present to produce snow p-type. Snowfall amounts will
begin to be fine-tuned over the next couple of days.

No changes of significance to note in the temperature forecast.
Deterministic and ensemble output still maintain that minimal low
level thermal advection is occurring between Friday evening and
Saturday evening (highs and lows running generally near to above
climo normal). Then, from Sunday through Tuesday night, low level
caa takes over and high/low temperatures fall to ranges well below
normal. But, perhaps by mid-week, a little bit of a warming trend
may be developing.


&&

.AVIATION...(For the 18Z TAFS through 18Z Friday Afternoon)
Issued at 1125 AM CST Thu Feb 15 2018

A mix of MVFR/IFR CIGS/VISBY with snow centered around the KPIR
terminal. KMBG should begin improving with higher CIGS/improved
VISBY upstream. KABR/KATY will see much more showery type
snowfall with off and on reduced VISBY, though CIGS remain MVFR at
KABR and IFR at KATY until stratus breaks up around late
afternoon/evening.


&&

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

$$

SHORT TERM...Connelly
LONG TERM...Dorn
AVIATION...Connelly



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