622 FXUS63 KUNR 251135 AFDUNR Area Forecast Discussion For Western SD and Northeastern WY National Weather Service Rapid City SD 435 AM MST Fri Jan 25 2019 .DISCUSSION...(Today Through Thursday) Issued at 300 AM MST Fri Jan 25 2019 Current surface map shows warm front pushing into central South Dakota with temperatures in the 20s for much of the forecast area. Some light snow across the Black Hills. Area will be in northwest flow through the middle of next week with deep upper low over Hudson Bay and ridging along the pacific coast. Upper low eventually drops into the Great Lakes region early next week. Shortwave drops across the area today, with spotty light precipitation precipitation today/tonight. Steep low level lapse rate and moist northwest flow favorable for upslope enhanced snow for the northern Black Hills. Through Saturday afternoon, looking at 3-7 inch snowfall amounts for the Bear Lodge Mountains and northern Black Hills with localized 10-12 inch accumulations for higher terrain from Four Corners to Cheyenne Crossing. With the longer duration for the snow accumulations, have issued a Winter Weather Advisory. Light precipitation will gradually end Saturday night for much of the area. Forecast soundings favorable for liquid precipitation Saturday night. With frozen ground, some icing is possible so will maintain mention of some light freezing rain. Strong Alberta clipper takes aim at the northern plains Sunday/Sunday night. Surface low dives from southern Saskatchewan Sunday afternoon into eastern South Dakota late Sunday evening. Warm day across the area Sunday, with highs into the 40s If there is enough sunshine, could even see low 50s in the Rapid City area. As arctic front crosses the area in the wake of low, strong winds will develop across western South Dakota. Isallobaric forcing with 5-10mb/3hr pressure rises and 50-60kt winds down to 1000ft agl favorable for high winds in K2WX-KRAP corridor. Will issue High Wind Watch. Some uncertainty as to extent of blowing snow with the strong winds. Current snow depth in watch area generally less than two inches...with deeper snow cover northeast of the watch area. Warmer temperatures today and Sunday will have some impact on remaining snow cover. 1040mb high drops into the Dakotas/Minnesota Tuesday and Wednesday. 00Z ECMWF is trending warmer for mid- week while GFS continues with very cold temperatures. Currently 10-15C difference in 850mb temperatures between ECMWF/GFS. Reinforcing shot of arctic air arrives for the end of the week. && .AVIATION...(For the 12Z TAFS Through 12Z Saturday Morning) Issued At 425 AM MST Fri Jan 25 2019 (For the 06Z TAFS Through 06Z Friday Night) Issued At 1020 PM MST Thu Jan 24 2019 MVFR to local IFR conditions expected over the area with intermittent snow showers. Later this afternoon, more widespread MVFR/IFR conditions will develop across most of the area as another weather disturbance brings -SN through the Northern Plains. IFR conditions with light snow expected across the Black Hills through the period. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...Winter Weather Advisory until 5 PM MST Saturday for SDZ024. High Wind Watch from Sunday evening through Monday morning for SDZ001-012-013-026-031-072-073. WY...Winter Weather Advisory until 5 PM MST Saturday for WYZ057. && $$ DISCUSSION...7 AVIATION...15