069 FXUS63 KFSD 192057 AFDFSD AREA FORECAST DISCUSSION National Weather Service Sioux Falls SD 257 PM CST Sat Nov 19 2022 .SHORT TERM...(This Evening through Sunday Night) Issued at 256 PM CST Sat Nov 19 2022 Key Messages: 1. Breezy northwesterly winds will decrease throughout the evening before shifting to southerly. 2. Warmer and more seasonal conditions return by Sunday and continue into the work week. 3. Drier conditions should continue through at least the midweek just in time for holiday travel. For the rest of today, expect partly cloudy conditions to continue through this evening as the surface high pressure continues to build across the region. As we head into the evening, the breezy northwesterly winds are expected to gradually dissipate as light southerly winds move in on the backside of the ridge. Conditions should continue to clear overnight which will promote some radiational cooling across most of the area with lows expected to be largely in the teens to upper single digits. Unfortunately this means another morning of wind chills in the single digits especially for areas east of I-29. On the bright side, the chilly start on Sunday will give way to more seasonal conditions as mostly clear skies and westerly winds will help boost temperatures to the 10th percentile mean of climatology. In other words, this means temperatures should get closer to our seasonal averages with highs peaking in the upper 30s to 40s as the warmer side of an eastward moving ridge passes overhead. Unfortunately. the ridge won't hang around very long as a weak and dry cold front is expected to pass through Sunday afternoon bringing some weak CAA and more westerly winds to the region. The resulting high temperatures will drop a few degrees temporarily bringing Monday's highs back into the 30s. Otherwise, seasonal conditions will continue through the start of the work week. .LONG TERM...(Monday through Saturday) Issued at 256 PM CST Sat Nov 19 2022 The work week kicks off with mainly westerly flow aloft. Looking towards the surface, high pressure will be moving through the Northern Plains, resulting in light and variable winds throughout the day. Forecast soundings show the top of the mixed layer reaching around 925 mb. Temperatures at the top of the mixed layer look to reside in the 0 to -4 degree Celsius range. Mixing this to the surface will again result in warmer highs in the 30s across the forecast area with the warmest temperatures residing along the Missouri River. As the surface high pushes off to the east, southerly flow sets up in its wake. Lows look to fall into the teens to low 20s come Tuesday morning. Southerly flow continues into Tuesday as the wave slides through. Warm air advection (WAA) ahead of the wave will raise 925 mb temperatures to 0 to +4 degrees Celsius. This will continue the warming trend as highs warm into the 40s across the area. A welcomed return to seasonable temperatures! Light winds out of the south will be turning to out of the northwest throughout the day as a weak front pushes through the region, making for a more typical Fall day. WAA returns to the area on Wednesday as another wave traverses the Northern Plains. Ensembles depict 850 mb temperatures on the order of 5-7 degrees above average with respect to climatology. With such warm temperatures aloft, highs in the mid to upper 40s are probable. Medium range guidance is in agreement in this wave dragging a cold front through the forecast area. However, there remain timing differences regarding how quickly the front moves through the forecast area. Due to the timing differences, have left the NBM for Wednesday. Aside from timing issues, the front looks to deliver a shot of cold air advection (CAA) along with breezy winds in its wake. Thanksgiving day looks to be a breezy day as winds at the top of the mixed layer remain strong in the wake from the previously mentioned cold front. Stronger winds are supported by the Euro Extreme Forecast Index (EFI) as it shows about 50% of its members suggesting above average winds for the holiday. Medium range guidance continues to struggle with the evolution of the wave as the GFS and Canadian show an open wave while the Euro develops a closed low. Despite the differences in the wave, ensembles are in good agreement in a near 0% chance for receiving a tenth of an inch or more of precipitation. For now, have continued with a dry forecast. With the new post frontal airmass in place, highs should cool to seasonable. Ensembles support this as they depict highs within a few degrees of climatology. The week looks to end with upper ridging across the western CONUS. With the forecast area downstream of this ridge, upper level subsidence along with northwesterly flow look to keep the region dry. && .AVIATION...(For the 18Z TAFS through 18Z Sunday Afternoon) Issued at 1156 AM CST Sat Nov 19 2022 Mostly VFR/MVFR conditions are expected to continue with occasional IFR ceilings due to lingering snow showers. Visible satellite imagery now shows a cumulus field has developed with some embedded snow showers west of tri-state boarder. The light flurries/snow showers are expected to stay slightly west of KFSD, but should move through KSUX over the next hour or so. As a result, a tempo group with light snow has been included in the TAF through 20z. Conditions are expected to largely clear as we head into the evening hours. Otherwise, northwesterly flow will give to more southerly to southwesterly flow to end the TAF period. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. IA...None. NE...None. && $$ SHORT TERM...Gumbs LONG TERM...Meyers AVIATION...Gumbs