187 FXUS63 KGRB 162040 AFDGRB Area Forecast Discussion National Weather Service Green Bay WI 240 PM CST Sat Jan 16 2021 Forecast discussion for routine afternoon forecast issuance .SHORT TERM...Tonight and Sunday Issued at 239 PM CST Sat Jan 16 2021 Main forecast concern to be on light lake effect snow showers across north-central WI. The 19Z MSAS surface analysis indicated an area of low pressure well to our east over extreme southeast Ontario. A weak trough extended westward from the low pressure through Upper MI to the northeast corner of MN. The radar mosaic showed one band of mainly lake effect running along the western shores of Lake MI with a mix of light rain and snow. Surface obs showed scattered lake effect snow showers moving into north-central WI from Lake Superior. Temperatures remained well above normal by mid-January standards. Cyclonic flow and the west to east orientated surface trough to remain across the region tonight, thus at least some flurries will be possible from time to time. Lake effect snow showers/flurries from Superior to continue over north-central WI, although any accumulations would be very minor (one-half inch or less) due to the air mass aloft just not very cold (8H temperatures around -10C over western Lake Superior). Models continue to show a shortwave trough will dive from the northern Plains toward the mid-MS Valley by daybreak. This track would keep any light snow accumulations to our west, thus do not anticipate any snow from this feature. Otherwise, look for cloudy skies with min temperatures in the upper teens to around 20 degrees north-central WI, middle to upper 20s east-central WI. Persistent northwest winds will keep the chance for lake effect snow showers over north-central WI through Sunday. The air mass aloft remains only modestly cold with 8H temperatures holding at around -10C, thus little additional accumulation is anticipated. The rest of northeast WI to remain stuck in the clouds as time sections show plenty of low-level moisture remaining in place over the area. Cannot rule out some stray flurries at times, but for the most part Sunday should be mainly dry. Max temperatures to be in the middle to upper 20s north-central, lower 30s east-central WI. .LONG TERM...Sunday Night Through Saturday Issued at 239 PM CST Sat Jan 16 2021 A split flow pattern is forecast to continue through most of next week, with the most energy and moisture to stay to our south, and a few short wave troughs with little moisture passing to our north. Northwest upper flow and falling heights should result in temperatures close to normal through midweek, and then a bit colder than normal by the end of the week. Lake effect snow showers are likely at times in far northcentral Wisconsin but moisture and instability look insufficient for any significant accumulation. The ECMWF and GFS do have a significant upper trough in the southern stream lifting north towards the Northern Ohio Valley. It could bring several inches of snow if it occurs. && .AVIATION...for 18Z TAF Issuance Issued at 1138 AM CST Sat Jan 16 2021 Scattered flurries or sprinkles continued across eastern WI this afternoon as cyclonic flow persists. Otherwise, the RHI TAF site may see scattered lake effect snow showers at times. In general, most locations in northeast WI will see MVFR cigs, although areas from Y50-EZS will see VFR conditions due to downsloping. Not much change expected for tonight, other than the flurries/ sprinkles in the east will come to an end. Plenty of clouds remain over the region with MVFR cigs the prevalent condition. Still cannot rule out a few snow showers or flurries at RHI. A weak mid-level trough of low pressure to pass to our west and south late tonight into Sunday. It appears that this feature will be too far away to bring any precipitation to northeast Wisconsin. The rest of Sunday looks cloudy with more MVFR cigs and the persistent chance of lake effect snow showers in the vicinity of RHI. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM.....Kallas LONG TERM......RDM AVIATION.......Kallas