Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 082038

National Weather Service Sioux Falls SD
238 PM CST Mon Mar 8 2021

.SHORT TERM...(This Evening through Tuesday)
Issued at 238 PM CST Mon Mar 8 2021

Strong southerly flow will keep very mild temperatures in place
through the night. In fact low temperatures tonight will be about 10
degrees above the normal highs for this time of year. With the
stronger winds in place will lean on the warmer guidance which
should yield roughly mid 40s to lower 50s in most locations given
the expected 925 mb temperatures.

Tuesday will be a very warm day ahead of an incoming cold front.
This will set up an environment conducive to fire weather concerns,
but we may struggle a bit to reach red flag conditions as the major
fire weather components, low humidity and strong winds, may not come
together in any one location for 3 hours or longer. It does look
like the better chance will be near the James River. West of there
the cold front moves in by mid afternoon and will likely stabilize
temperatures and possible cause a drop of a few degrees. East of the
James River southerly winds will be strong in the morning and
gradually decrease through the afternoon as the pre frontal trough
moves in. Plus with a fairly strong inversion east of the James
River dew points will likely remain on the higher side. Highs should
be in the 70s in most locations.

.LONG TERM...(Tuesday Night through Monday)
Issued at 238 PM CST Mon Mar 8 2021

Tuesday night will see cooler air spill into the area as a northern
stream jet moves by to the north and winds to to the north at the
surface. While this is happening a southern stream jet will move
into KS which should begin to spin up a surface low pressure in
southern NE by about early Wednesday morning. Clouds and
precipitation chances will gradually increase through the night
which will keep mild temperatures in place, so will be a rain
threat. There will be some minor elevated instability around roughly
750 mb into far northeast NE and northwest IA which may allow for
some showers with isolated thunder to develop around about 3-6z,
with flow becoming more broadly warm advective and the instability
diminishing later in the night which should bring a larger area of
possible rainfall with only a minor threat for thunder in northwest
IA. As this first shot of lift moves through the upper level jet
remains to the southwest of the area which will allow mid level
winds to remain backed into Wednesday evening. The thermal profile
aloft become more favorable for precipitation production, with the
main concern during much of the day Wednesday that the more
favorable combination of lift, moisture and thermal structure is
just north of the area. Model soundings do hint at some very weak
very elevated instability along and north of I-90 which could bring
some showery activity and the soundings do indicate a good chance
for snow by afternoon as colder temperatures remain in place and
cool a bit more. Amounts of snow and rainfall still very much up in
the air with low confidence on forcing, instability and location of
the two areas of lift.

The chances for precipitation late Wednesday night into Thursday is
pretty low. There will be a trailing area of lift from near Sioux
City to Storm Lake that could produce a little snowfall but only a
low chance for now. Otherwise as the system shifts east cooler air
will be in place, but still mild for this time of year. Highs
generally in the mid to upper 40s barring any unexpected snow depth.

Friday into Saturday will see the area between low pressure to the
northeast and developing low pressure over the desert southwest.
This should bring quiet and seasonally mild weather. Basically
looking at highs in the 40s and lows in the 20s.

More agreement on deepening low pressure aloft over the Rockies but
not much agreement on when/where some of this energy will eject onto
the Plains. So , at this time nothing more than a heads up that some
busy weather will be possible next week.


.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1104 AM CST Mon Mar 8 2021

VFR through the period. Southeast winds may gust to 25 to 30 knots
today, then a fairly steady southerly wind of 10 to 20 mph is
expected tonight. By morning, southerly winds east of the James
River may gust to 30 to 35 knots at times, especially across
southwest MN.




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