232 
FXUS63 KFSD 102351
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
651 PM CDT Sun Mar 10 2019

.SHORT TERM...(This evening through Monday)
Issued at 357 PM CDT Sun Mar 10 2019

Clouds will increase this evening into the overnight as the tail end 
of an upper level trough grazes the area. Flurries are possible from 
midnight through sunrise for a portion of the area. The best chance 
for this light precipitation is currently south of I-90 and north of 
NE & IA State Hwy 20. Only a dusting if any accumulation is 
expected. Patchy fog is also possible overnight, as winds will 
remain calm and the boundary layer will be fairly moist due to 
daytime snow melt.

Monday will be a quiet weather day overall, with partly cloudy skies 
and high temperatures about 5 degrees warmer than Sunday, 
which will generally be within a few degrees of freezing.

.LONG TERM...(Monday night through Sunday)
Issued at 357 PM CDT Sun Mar 10 2019

A very significant weather system is expected for the middle of the 
week. This system will bring abundant rainfall, with 1 to 2 inch 
rain amounts expected. This amount of rain with frozen ground and 
abundant snowpack will likely lead to widespread water issues.

On Tuesday, a deep upper level-trough will be situated over the 
Western CONUS. A leading shortwave will move northeast Tuesday 
morning bringing chances for light rain during the day. Surface 
temperatures quickly increase to above freezing during the daytime 
hours on Tuesday, with highs near 40 for many in the tri-state area.

Tuesday night into Wednesday, a much stronger and robust wave will 
intensify over the Plains, during the day Wednesday, this system 
will bring a steady stream of Gulf moisture northward. Strong 
synoptic lift along with intense frontogenesis will lead to ample 
forcing for a sustained period of moderate rain Wednesday into 
Thursday. Models are fairly consistent on this overall scenario, 
despite a shift of about 50 miles to the southeast with the axis 
of heaviest rain. There is currently high confidence in 
significant rain over much of the region. Additionally, above 
freezing overnight temperatures Wednesday into Thursday, high dew 
points, and abundant snowpack will increase the risk of widespread
water-related issues, such a flooding, street flooding, and 
ponding of water in low spots. The heaviest rain currently looks 
to fall in the Wednesday afternoon through Thursday morning 
period.

Given the strength of the surface low pressure, winds will be very 
strong with this system. Thursday looks to have the highest winds, 
with gusts in the 40 to 50 mph range. Another threat on Thursday 
will be blizzard conditions in central SD, as cold air advection 
increases in the northwest quadrant of the system, with rain 
changing to snow. The details are still low confidence, and likely
to change many times before Thursday, but the takeaway for now is
that Wednesday and Thursday will be very active weather-wise, so 
those with travel plans should closely monitor the forecast and 
prepare to make alternate plans to avoid traveling during the most
dangerous time periods.

The weather system will be exiting the area on Friday. Winds will 
still likely be breezy, but not nearly as strong as Thursday. The 
colder Canadian air mass will lead to highs mainly in the 20s to 
around 30. Dry conditions persist into the weekend, with 
northwesterly flow aloft and slowly warming surface temperatures.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 650 PM CDT Sun Mar 10 2019

Largest question tonight will be the degree of fog which may
develop after a day of melting snow. Moist layer is fairly
shallow, which brings up concern that moisture will effectively
deposit out on surfaces with light winds rather than lead to fog,
or perhaps a fairly shallow fog. Have maintained some ideas in the
higher resolution models which suggest that the James River 
valley and west would seem to the most favored for potential fog 
formation tonight. Will also see increasing mid-level clouds
pressing mainly near and south of I-90 which could bring a small
area of light snowfall tonight with brief MVFR visibility.

&&

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

$$

SHORT TERM...VandenBoogart
LONG TERM...VandenBoogart
AVIATION...Chapman