831 FXUS63 KFSD 160905 AFDFSD Area Forecast Discussion National Weather Service Sioux Falls SD 305 AM CST Wed Jan 16 2019 .SHORT TERM...(Today and Tonight) Issued at 253 AM CST Wed Jan 16 2019 Colder air continues to sink southward into the area this morning, marking the beginning of an extended period of near to below normal temperatures through the upcoming 7 day forecast. In addition to the colder temperatures, there's no shortage of impactful weather through the forecast, with at least three chances for snow ahead. Today: Stratus will attempt to clear the CWA this morning, but should be replaced by mid and upper clouds through the day. Most should at least see filtered sunshine. Temperatures will only reach near or just below the seasonal normals. The good news at least is that winds will be diminishing slightly through the day. Tonight: A nuisance wave emanating out of northern Utah will drift eastward overnight quickly pushing stratus back northward this evening. Models have trended towards a slightly stronger 700 mb wave, with most models showing a period of saturation in the soundings later this evening and into the early overnight hours. QPF amounts won't be very high, but consensus suggests the possibility for a quick dusting to half inch of snow. A little bit of freezing drizzle may mix with the snow at times, especially on the back edge of the shortwave. Have boosted PoPs in most areas. .LONG TERM...(Thursday through Tuesday) Issued at 253 AM CST Wed Jan 16 2019 Thursday-Thursday Night: Despite the lingering cloud cover, temperatures may climb back near or slightly above the seasonal normals. It's possible to have a bit of fog early Thursday. Another surge of dry and cold air arrives Thursday night, setting the stage for a widespread snow on Friday. Friday-Friday Night: Overall, minimal changes to the ongoing forecast as model guidance remains consistent in bringing a progressive wave through the Central Plains on Friday. This wave will track eastward out of the traffic jam of disturbances visible on WV satellite imagery over the Pacific this morning. Warm advection associated with this wave is expected to begin early Friday morning over western and central South Dakota, slowly spreading eastward by daybreak Friday as dry air is overtaken. Confidence is a bit higher on a few items for this event. 1. There will be a very sharp northern and northeastern snow gradient due to the influence of cold and dry air. 2. Despite the broad nature of the warm advection, there will likely be a more narrowed and focused corridor of moderate snows on Friday. Soundings within this band suggest a rather deep dendritic layer, so when it snows, it will be efficient. Not a ton of instability within the soundings, but certainty something to monitor. 3. SLR will be increasing as Friday wears on, and influence of colder air arrives. Snow should trend towards the lighter and fluffier variety. 4. Driving around the region on Friday, will be messy. Regarding QPF, in coordination with surrounding offices have used a 50/50 blend of WPC guidance and Superblend. This does a bit better job accounting for the higher ensemble numbers, but won't go as far as the much higher ECMWF QPF. The end result is a fairly wide area of 2-6" snowfall, with the potential for locally higher amounts, especially in the initial development areas of central South Dakota, where amounts closer to 5- 8" may be possible. A fairly small winter storm watch could be considered later today for central South Dakota, if confidence in higher amounts grows. Saturday-Tuesday: After the snow, a burst of arctic air is expected to move southward bringing very cold temperatures to the area for Saturday along with wind chill advisory conditions. However this morning, we're seeing signs that the extreme drop in temperatures Saturday night into Sunday may be subdued a bit by increasing warm advection aloft, mid-level cloud cover and even a bit of light snow. Lows may still fall into the teens below zero, but they may also warm through the night from west to east. Rather extreme differences in extended guidance develops after Sunday, so confidence remains low. The GFS/GEM both bring a more developed upper trough through the Northern Plains Monday. The ECMWF on the other hand drops most of this energy into the Southwestern US. Both camps would suggest at least some snow chances early next week, but to varying degrees. && .AVIATION...(For the 06Z TAFS through 06Z Wednesday night) Issued at 1013 PM CST Tue Jan 15 2019 Back edge of the ongoing MVFR to locally IFR stratus continues to work southward and should makes its way through KHON and KFSD in the next couple of hours, later at KSUX. The approach of a weak disturbance will lead to increasing mid level clouds thru the afternoon Wednesday, perhaps lowering toward the lower end of VFR by the evening hours. Could see a few snow showers by the evening hours, although confidence in occurrence an any one single terminal is low. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. IA...None. NE...None. && $$ SHORT TERM...Dux LONG TERM...Dux AVIATION...Kalin