417 
FXUS63 KFSD 130908
AFDFSD

AREA FORECAST DISCUSSION
National Weather Service Sioux Falls SD
308 AM CST Fri Dec 13 2019

.SHORT TERM...(Today through Saturday Afternoon)
Issued at 308 AM CST Fri Dec 13 2019

Moisture starved short wave moving into central South Dakota as of 
08Z, and will quickly move across the area through the morning. 
Despite being a fairly robust mid level wave, not expecting much in 
the way of precipitation west of I-29; however, as the wave 
encounters deeper moisture, it may produce some light precipitation 
across northwest Iowa and portions of southwest Minnesota. Certainly 
good jet dynamics with the forecast area in the left exit region of 
185+ knot jet streak over the intermountain west. 

Precipitation type is quite tricky, with warm yet 
unsaturated layer ahead of the wave.  Warm layer is most pronounced 
across northwest Iowa, and may lead to a little sleet or freezing 
rain prior to more intense precipitation to saturate the column. 
Precipitation band should be relatively compact, keeping amounts 
fairly limited.  Expanded pops a bit on the back edge as models are 
hinting at some instability aloft.  Forecast soundings hint that ice 
within the dendritic zone becomes difficult to come by on the 
western edge of the precipitation shield, and may see precipitation 
try to switch back to freezing rain/drizzle.  

Secondary wave slides across the Central Plains late this afternoon 
into tonight, and the Missouri River Valley has an outside chance of 
getting skimmed by light snow.  Of greater concern will be the 
increasing northerly wind drawing cooler air into the region tonight 
into Saturday.  Models show 925 temperatures plummeting well into 
teens below zero, potentially near -20 C north of I-90 leading to 
highs in the single digits.   

.LONG TERM...(Saturday Evening through Thursday)
Issued at 308 AM CST Fri Dec 13 2019

With clearing skies and light winds as surface ridge slides 
southwest of the area, temperatures have the potential of getting 
quite cold Saturday night.  

Models are hinting that temperatures may try to moderate through the 
first half of next week, but will be a slow progression with the jet 
remaining well south of the area.  As mid level flow turns more 
westerly midweek, temperatures may warm more significantly.

&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1106 PM CST Thu Dec 12 2019

Widespread MVFR-IFR stratus to start the period will lower further
through Friday morning, with IFR-LIFR conditions appearing likely
for many areas north of the Missouri River Valley into the early
afternoon before slight improvement. Areas of IFR visibility in 
fog most likely near and west of the James River Valley, including
at KHON prior to 18Z Friday. At the same time, a relatively narrow
band of light snow will lift through eastern parts of the region,
mainly impacting areas east of the I-29 corridor Friday morning.

Winds remain relatively light for much of the period, but will
increase from the northwest after 14/00Z, behind a cold front 
pushing through the area.


&&

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

$$

SHORT TERM...BT
LONG TERM...BT
AVIATION...JH