KBIS issues Area Forecast Discussion (AFD) valid 2019-11-29T03:00:00Z 497 FXUS63 KBIS 290300 AFDBIS Area Forecast Discussion National Weather Service Bismarck ND 900 PM CST Thu Nov 28 2019 .UPDATE... Issued at 857 PM CST Thu Nov 28 2019 Reports from social media indicate widespread freezing drizzle generally along and west of US Highway 83. Freezing drizzle is also now being observed here at the office and have expanded the Winter Weather Advisory to include Burleigh and Emmons counties with this update. An eastward expansion is possible, however, low level omega is not as great across the James River Valley to be as condusive to freezing drizzle. UPDATE Issued at 712 PM CST Thu Nov 28 2019 Quick update to expand the Winter Weather Advisory for freezing drizzle to Highway 83. Will continue to monitor trends for a further eastward expansion. UPDATE Issued at 631 PM CST Thu Nov 28 2019 NDDOT webcams and the road conditions map continue to highlight widespread freezing drizzle across western North Dakota this evening. So far, precipitation across central North Dakota has been either all snow, or very minimal freezing drizzle. The KBIS 00Z sounding shows an ever so slight amount of dry air between 880-750mb. Once this saturates up, perhaps the freezing drizzle threat may become greater. However, timing this is somewhat uncertain. UPDATE Issued at 416 PM CST Thu Nov 28 2019 Several NDDOT webcams across western North Dakota show glazes of ice on the lenses from freezing drizzle. With the overall low level thermodynamic, moisture and lift profiles not expected to change much tonight and Friday before the snow arrives, issued a Winter Weather Advisory for the freezing drizzle threat. This may have to be expanded into central North Dakota. && .SHORT TERM...(This evening through Friday) Issued at 245 PM CST Thu Nov 28 2019 Will upgrade the watch to a winter storm warning beginning Friday night with near blizzard wording for all but the far north where we will issue a winter weather advisory. We still anticipate a period of light freezing drizzle tonight and Friday, with accumulations amounting to a light glaze. For this we will continue to message this through social media posts and and special weather statements, but at this time do not think a winter weather advisory will be needed. The gusty winds west today will diminish this evening. Lows tonight teens north and 20s south. Highs Friday mid 20s north and lower 30s south. .LONG TERM...(Friday night through Thursday) Issued at 245 PM CST Thu Nov 28 2019 Winer storm warning for all of central and southern North Dakota Friday night through Sunday morning. Winter weather advisory for the far north Friday night through Sunday morning. Global models have been consistent bringing a high impact winter weather event through North Dakota Friday night through Sunday morning. Concerning moisture, the precipitable water is well above normal for this time of the year, and the water vapor transport will continually add to the precipitation potential. Initial conditions favor some light freezing drizzle tonight and Friday with low level vertical motion saturating the low layers and dry air aloft causing a lack of ice crystals growth. While this will be a threat, we feel the ice accretions will be fairly light, creating a light glaze of ice on roads and bridges tonight Friday. The snow will rapidly develop Friday night becoming heavy by Saturday morning. The snow will spread north reaching northern north Dakota about 6 to 12 hours later. This is a powerful storm. Even the 10 percentile for snow amounts, (90 percent chance of higher amounts) show 4 to 6 inches of snow across central and southern North Dakota. The 50th percentile has 10 to 12 inches, and the 90th 12 to 15 inches. We feel comfortable with a 9 to 15 inch snow total across central and southern North Dakota and 2 5 inches far north to by Sunday morning. As the storm wraps up, east to northeast winds up to 45 mph with cause near blizzard conditions central and south. Roads could become blocked, damage to tree branches could cause power outages. After this storm, a quiet weather period will be seen through the extended with a slow moderating temperature trend. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 857 PM CST Thu Nov 28 2019 Concerns for aviation include widespread MVFR to IFR conditions in stratus. Areas of light freezing drizzle and fog are also expected through Friday. Strong southeast winds with gusts of 25 to 30 kts will continue this evening across southwest North Dakota. Then a significant winter storm will impact the Northern Plains from Montana and Wyoming through the Dakotas and Minnesota. Widespread very low IFR in snow and blowing snow are in the outlook beginning Friday night through Sunday morning. && .BIS WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until 6 PM CST /5 PM MST/ Friday for NDZ001>003-009>011-017>021-031>035-040>046. Winter Storm Warning from 6 PM CST /5 PM MST/ Friday to noon CST /11 AM MST/ Sunday for NDZ010>013-017>023-025-031>037-040>048- 050-051. Winter Weather Advisory from midnight Friday night to noon CST Sunday for NDZ001>005-009. && $$ UPDATE...PA SHORT TERM...WAA LONG TERM...WAA AVIATION...PA