139 FXUS63 KGRB 031124 AFDGRB Area Forecast Discussion National Weather Service Green Bay WI 524 AM CST Sun Nov 3 2019 Updated aviation portion for 12Z TAF issuance .SHORT TERM...Today...Tonight...and Monday Issued at 257 AM CST Sun Nov 3 2019 The main concerns in the short-term will be the rain/snow potential tonight into Monday along with continued below normal temperatures. Some slippery travel may develop for the Monday morning commute, mainly northwest of the Fox Valley. Satellite imagery shows widespread cloud cover lingering across much of the area, with some clearing occurring in west wind favored downslope locations. Radar was showing very little activity around the area with the exception of some lake effect snow across both Lower and Upper Michigan. Temperatures were being kept a bit warmer with the continued cloud cover with most locations ranging form the mid 20s to the mid 30s. Today...The next small chance of precipitation will arrive this afternoon along and ahead of a weak vort max associated with southwest to northeast moving 700-850mb FGEN band/weak warm front. It looks like temperatures above 900mb would support snow; however, low-level temperatures are expected to warm into the upper 30s to low 40s, especially with the day starting warmer due to overnight clouds. This would indicate a better chance of seeing mainly rain where it does precipitate, especially during the afternoon hours. Overall, not expecting much in the way of QPF with the system today, in fact, most models are painting out very little in the way of QPF as forcing and deep-layer moisture is not overly impressive. Tonight into Monday: A surface low is expected to shift from central MN early this evening to eastern Upper Michigan by 12Z Monday. This will allow the surface warm front to lift northward into much of northeast WI this evening. The warm front is expected to quickly be followed by a cold front, which should pass through the area between 06Z and 12Z Monday. At the same time, a vort max is progged to slide from South Dakota through central WI. The forcing associated with these features will provide enough lift to produce widespread precipitation. The more concentrated area of precipitation will likely remain across central portions of WI, where the better vort max is noted. Models are painting out around 0.10 to 0.25 inches of QPF across the area, lightest across north-central into far northeast WI, with the heaviest totals central into east-central WI. Thermal profiles show warmer low- levels across central into east- central WI tonight, which would lead to mainly rain with a few snowflakes possibly mixing in at times. Farther north, across north- central WI and far northeast WI, thermal profiles support mainly snow. This would end up giving an inch or so of accumulation up that way, while much of central and east-central WI sees little to no snow accumulation. The minor accumulation may make for some slippery travel northwest of the Fox Valley Monday morning. The aforementioned surface low will shift farther eastward into southern Ontario by Monday afternoon. This will keep cyclonic flow in place across much of the area along with some lingering wrap- around moisture. At the same time, much of WI will be under the 500mb trough axis. This will keep a lingering chance of rain/snow showers through much of the day. Surface to 850mb winds are expected to be out of the northwest Monday afternoon, which may lead to some lake effect snow chances developing across northern Vilas County. Only minor additional accumulations are expected. Temperatures are expected to be in the in the mid 30s central/east- central to mid 20s north-central and far northeast. High temperatures are forecast to be in the upper 30s to low 40s for Monday. .LONG TERM...Monday Night Through Saturday Issued at 257 AM CST Sun Nov 3 2019 The 500mb ridge off the west coast of North America will expand eastward across the western half of North America later in the week. Meanwhile, a downstream trough at 500mb will remain across the central and eastern United States. Below normal temperatures are expected through the period along with periodic chances for rain and snow. For Monday night, weak high pressure will build into the region. There is still a small chance of light snow across the north. A few lingering lake effect snow showers are possible across the far north Tuesday morning. High pressure moves across the area Tuesday afternoon, and then east of the state Tuesday night. Meanwhile, a potent system will move towards the area Tuesday night and then across the western Great Lakes region on Wednesday. Models indicating strong 850mb warm advection, while a strong 300mb jet streak (145 knots) will pass north of the state late Tuesday night and Wednesday morning. The forecast area will be in the favored right entrance region of the jet to enhance the lift. At this time, it appears that several inches of snow are possible. There is still some uncertainty in the track of the storm, amount of warm air working into the region ahead of the system, and associated precipitation amounts that could impact snowfall totals. Will continue to mention this system in the Hazardous Weather Outlook (HWO). Per the ECMWF, most of the snow should exit the area later Wednesday morning with high pressure building into the region Wednesday afternoon and Wednesday night. Behind the system, a 1040+ mb Canadian high pressure system will drop south into the northern plains on Thursday. It now appear that the first widespread day with high temperatures below freezing are expected with highs in the 20s to around 30. The chances of lake effect snow showers will linger across the far north Thursday night into Friday morning. Otherwise, mainly dry and cold conditions expected Friday and Saturday. High temperatures on most days will run 5 to 15 degrees below normal. && .AVIATION...for 12Z TAF Issuance Issued at 524 AM CST Sun Nov 3 2019 A brief ridge of high pressure will continue to shift off to the east of the area this morning. Stubborn low stratus has lingered at all of the TAF sites and will likely do so throughout this TAF issuance. High end VFR conditions have been noted at RHI, while most of the rest of there area has seen ceilings around 3.5kft. There may be a few breaks in the clouds this morning; however, this will be short-live as the next batch of mid to high clouds are already approaching from MN and the Dakotas. A low pressure system and frontal boundaries will pass through the area tonight, allowing for a rain/snow mixture at each of the TAF sites. The best chance of seeing mainly snow will be at AUW, CWA and RHI. Both ceilings and visibilities are expected to be reduced even lower tonight, with some IFR conditions expected. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM.....Cooley LONG TERM......Eckberg AVIATION.......Cooley