Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 241151

Area Forecast Discussion
National Weather Service Sioux Falls SD
651 AM CDT Sat Mar 24 2018

.SHORT TERM...(Today and Tonight)
Issued at 410 AM CDT Sat Mar 24 2018

Very active forecast across the area with one system currently
working through the area and a second expected to impact the area
late in the weekend.  Prevailing precipitation type is transitioning
into snow across the area.  Expect snow to linger through mid day in
the east with weak isentropic lift on the 290K surface.  As the lift
dies away and transitions to downglide expect precipitation to come
to an end.  Have extended the Winter Storm Warning through 18Z in
southwest Minnesota. Expect precipitation to be winding down in the
mid day hours, but brisk easterly flow will still make conditions
far from desirable.

With that said, expect clouds to hang tough across the
area keeping temperatures cool today.  As easterly flow takes on a
slightly more southerly component, temps warm slightly at 925 mb but
only a degree or so.

Inherited pops tonight across central South Dakota, but wasn`t
overly excited about precipitation potential.  Forecast soundings
suggest stratus would not be overly thick, only 1000-1500 feet
making it difficult to produce drizzle.  Above that, the atmosphere
appears to not be saturated.  Therefore, limited pops to near 30
percent or less and tried to break down the time resolution on the
limited potential for drizzle.

.LONG TERM...(Sunday through Friday)
Issued at 410 AM CDT Sat Mar 24 2018

Better set up for drizzle on Sunday night as stronger warm air
advection sets up across the area.  Am concerned about the icing
potential across the northeast section of the forecast
area...basically northeast of a line from Huron to Storm Lake.
00Z run of the NAM has cooled 2-3 C in the 925-850 mb layer
suggesting the entire profile would remain below freezing, while the
GFS continues to maintain the warm nose in this layer. ECMWF remains
with temperatures near 0C at both 925 and 850 mb, still hinting at
icing potential.  The problem is that the dendritic layer appears to
remain unsaturated through much of the day Monday, making it
difficult to get anything but drizzle/freezing drizzle. Have
continued to keep icing potential in the forecast, especially east
of the Huron to Storm Lake line.

With active forecast, have not made any changes to the extended but
appears to be largely characterized with cooler than normal
temperatures as northwest flow prevails.


.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
Issued at 650 AM CDT Sat Mar 24 2018

Widespread IFR or worse conditions prevail this morning, with the
main snowband now retreated to areas east of I-29. As it dries out
aloft, there is a chance that there could be a brief period of
freezing drizzle for KHON or KFSD, but have not explicitly
mentioned at this point. Persistent easterly flow will not allow
ceilings to improve much through today or tonight with inversion
in place, other than to find some lower level dry air pushing
westward through southern MN and northern IA.


SD...Winter Weather Advisory until 10 AM CDT this morning for SDZ040-

MN...Winter Weather Advisory until 10 AM CDT this morning for MNZ089-

     Winter Storm Warning until 1 PM CDT this afternoon for MNZ071-

IA...Winter Weather Advisory until 10 AM CDT this morning for IAZ002-

     Winter Storm Warning until 1 PM CDT this afternoon for IAZ003.



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