Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 220920
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
320 AM CST Sun Jan 22 2017

.SHORT TERM...(Today and Tonight)
Issued at 319 AM CST Sun Jan 22 2017

Persistent stratus will continue to blanket much of the forecast
area today, in the wake of slowly departing upper low. One last lobe
of vorticity swinging through lingering cyclonic flow aloft could
produce enough weak lift for patchy light precip across eastern
portions of our area. CAMs have picked up on this with some splotchy
very light QPF, and seeing some very light echoes develop on
regional radar north of Sioux Falls, so will carry some low pops
from east of Brookings to Orange City line through this morning.
Lack of mid level/ice-bearing moisture layer evident on satellite
and in forecast soundings, so drizzle/freezing drizzle should be the
dominant precip type. With stratus expected to remain extensive,
expect another day with highs generally in the mid-upper 30s.

Could see some clearing work as far east as the James Valley or
possibly lower portions of the I-29 corridor by sunset. Model RH
progs indicate stratus could remain pretty stubborn across southwest
MN/northwest IA through tonight, though fog does not appear as
likely, as continued westerly low level flow should allow some drier
near-surface air to work eastward. The lack of stratus and light
winds in our west should allow temperatures to fall into the lower
20s tonight, while eastern areas hold in the mid-upper 20s under the
lingering stratus.


.LONG TERM...(Monday through Saturday)
Issued at 319 AM CST Sun Jan 22 2017

Focus in the long term will be on snow chances Mon night through Wed.

As a longwave trough approaches the plains on Monday GFS/ECM are in
fair agreement on strength and timing of the H5 low and associated
surface features.  Moisture is readily available throughout the
duration as evidenced by soundings and time/height sections. Daytime
warming on Tues will allow for some RA/SN mix with a period of all
rain to the south around SUX before changing over to snow by Tuesday
evening.

Because of the duration of this event, going from late Monday night
with snow finally tapering off by Wed morning, 3-6" storm total is
still a good possibility.  Best chances/timing of snow looks to be
from late Tues night into Wed morning as the ECM is showing some
negative tilt and deepening of the H5 low (GFS not so much on the
tilt but does show some deepening) as well as a stronger shortwave
passing through around 00z.  It`s still a bit early to get too
specific on where exactly the higher snow amounts will fall so I
didn`t make huge changes from the previous forecast.

After this system moves off to the east by Wed, temps will go back
to at or below freezing for highs and teens for lows.  Also in it`s
wake will be increased wind as surface gradient remains tight until
at least Wed night.  This will allow for blowing snow and have kept
a mention of this in the forecast.


&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1036 PM CST Sat Jan 21 2017

IFR conditions along and north of Interstate 90 will sink south
and southeast through the next several hours. LIFR conditions
appear as though they will be more isolated and possibly confined
to locations along the southern and western fringes of the stratus
field. Conditions will again improve along the southern edges and
advect northward during the day Sunday but many locations will
remain MVFR or IFR through the period.


&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
IA...None.
NE...None.
&&

$$

SHORT TERM...JH
LONG TERM...Sally
AVIATION...08


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