Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 282048

Area Forecast Discussion
National Weather Service Sioux Falls SD
348 PM CDT Fri Apr 28 2017

.SHORT TERM...(This evening through Saturday)
Issued at 347 PM CDT Fri Apr 28 2017

Other than areas of sub-freezing temperatures again tonight, not
much to worry about with the weather in the short term. Lows tonight
will be warmer than last night due to widespread cloud cover and
winds staying up closer to 10 mph through the night, but areas along
and north of I90 will still drop to around 30. Not expecting much in
the way of frost due to stronger winds and drier low levels
persisting to the north. For Saturday, upper level wave kicking out
ahead of main upper low will bring another chance of scattered
showers to the far southern areas, mainly in the afternoon.
Continued cool and breezy with highs below normal in the upper 40s
to lower 50s.

.LONG TERM...(Saturday night through Friday)
Issued at 347 PM CDT Fri Apr 28 2017

On Saturday night the upper level low over eastern New Mexico
begins to lift into the Central Plains, with increasing midlevel
theta e advection and frontogenesis across the southeastern half of
our CWA. With that, precipitation chances will ramp up overnight,
especially in areas from the lower MO River Valley, into
northwestern IA, and the lower portions of our MN zones.
Temperatures aloft will be supportive of snow over all but the far
southeast, and as readings fall into the mid 30s over east central
SD and southwestern MN, could see some snow mix in with the rain
late at night. Any accumulation would be negligible.

On Sunday the upper level lows lifts into eastern NE/KS by late in
the day, with the surface low tracking off to the southeast of our
area. Rainfall chances continue to increase for all but the
Chamberlain to Huron corridor. With a tightening gradient,
northeasterly winds will increase through the day, blowing 20 to 30
mph by afternoon. Highs will only top out in the upper 30s over
northwestern IA and much of southwestern MN where rainfall will be
the greatest, to the lower 50s through the Chamberlain to Huron
areas where rainfall chances are small and there may be breaks in
the clouds.

Still looking for a risk of accumulating snow over portions of the
area by later on Sunday night into Monday morning. Again,
temperatures aloft are supportive of snow, so any snow accumulation
is going to come down to the near surface temperatures. Soundings
are suggesting that readings will fall into the lower 30s through
east central SD into southwestern MN after 06Z, and this is the area
most at risk of accumulating snow. As has been well advertised, the
totals are going to be determined by the snow fall rates and how
close to freezing surface temperatures are, and will be somewhat
elevation dependent. One thing of note, some of the models are
suggesting drying out within the dendritic layer for part of the
night, especially over southwestern MN, so that will be something to
keep an eye on as far as precipitation type goes, and could have
some impact on projected snowfall totals. At this point, preliminary
snowfall totals range from 2 to 4 inches through east central SD
into parts of southwestern MN, then taper down rapidly outside of
this area.

The system pulls off into the western Great Lakes region by Monday
afternoon, so precipitation chances will drop off significantly by
Monday afternoon. Coldest areas on Monday will be in our east where
clouds will persist, with highs remaining only a degree or two
either side of 40. With decreasing clouds in our west, highs will
climb into the mid 50s.

With the near term issues, changed little in the extended period.
The overall trend will be for gradually warming temperatures through
the remainder of next week. There does not appear to be any
significant systems through the period, with minor precipitation
chances sometime in the Wednesday time frame.


.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1153 AM CDT Fri Apr 28 2017

Areas of MVFR ceilings and scattered showers will persist into the
early afternoon around SUX. Otherwise, VFR visibilities and
ceilings through the period.




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