Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 152113

Area Forecast Discussion
National Weather Service Sioux Falls SD
313 PM CST Fri Dec 15 2017

.SHORT TERM...(This evening through Saturday)
Issued at 306 PM CST Fri Dec 15 2017

A fractured cloud deck is present over the region with this
morning`s flurry activity shut off by drying of the lower levels.
Quiet weather continues into the overnight hours with northwesterly
becoming zonal flow aloft. Will see our cloud cover continue to
break up but with westerly flow and no real cold intrusion, will see
overnight lows remain well above normal.

A weak frontal boundary begins to nudge into the region Saturday and
will bring increasing cloud cover and a switch to
northerly/northwesterly winds. With 925 mb temperatures still in
the +1 to +5 C range, will keep high temperatures above normal
with fairly widespread 40s.

.LONG TERM...(Saturday night through Friday)
Issued at 306 PM CST Fri Dec 15 2017

Models  continue to advertise some very light and small precip
chances behind the front on Saturday night but struggle to show much
support in the way of forcing on the midlevel front. Thus will hold
only minimal chances right along the Missouri River near
Chamberlain. In fact, if any precipitation does occur, a potential
lack of saturation in the ice growth zone could just lead to some
patchy drizzle/freezing drizzle.

Sunday through Wednesday look fairly uneventful across our area as
we initially sit in between the southern and northern stream
before the jet slides overhead by Tuesday. Any vort maxes that do
slide through won`t have much in the way of moisture to work with
and thus will maintain a dry forecast. Will look for an uptick in
the winds by late Monday before turning northwesterly and breezy
Tuesday. Temperatures will continue to run anywhere from 10-20
degrees above normal with the coolest temperatures on Sunday,
closer to 5-10 degrees above normal.

Our big pattern change will come Thursday with a cold frontal
passage and arrival of much colder air bringing us back to near and
below normal temperatures. Any details regarding precipitation with
this system are still very murky as the ECMWF keeps the system as
an open wave slightly longer with a stronger northern energy where
as the latest GFS splits the system and cuts off a low over the
desert southwest sooner leaving us with weaker northern energy. For
this reason, will cap precipitation (snow) chances at 50 percent or
less until better model agreement arises one way or the other. For
now, all that can be said with confidence is the return of colder
temperatures with any snow chances very uncertain.


.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1114 AM CST Fri Dec 15 2017

Mid to high level clouds will continue to pass over the region
with winds generally under 10-15 kts. VFR conditions are expected
through the TAF period.




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