Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

000 
FXUS63 KFSD 131127
AFDFSD

AREA FORECAST DISCUSSION
National Weather Service Sioux Falls SD
527 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 12Z TAFS through 12Z Saturday morning)
Issued at 522 AM CST Fri Dec 13 2019

IFR to VLIFR conditions expected through the morning as deep low
lying stratus across the area. Could also see areas of fog
reducing visibility. Expect visibilities to slowly improve through
the morning hours on Friday, settling in the 2-4 sm range where
fog remains. Could also see mixed precipitation mainly across
northwest Iowa through 15Z this morning. Best chances are mainly
east of highway 60, so have not included mention in KSUX at this
time. 


Fog is expected to lift into a stratus deck this
evening as cold front moves through the region. Gusty northwest
winds are expected tonight, though ceiling heights will improve
into the MVFR range with the gusty winds. 

&&

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

National Weather Service Glossary of Abbreviations