000 FXUS63 KDLH 122112 AFDDLH Area Forecast Discussion National Weather Service Duluth MN 312 PM CST Thu Dec 12 2019 .SHORT TERM...(This evening through Friday night) Issued at 311 PM CST Thu Dec 12 2019 One round of accumulating snow moves out, and another moves in for Friday and Friday night, with the next system mainly impacting our northern areas, with some heavy lake effect snow possible along the North Shore. There will be some chances of lake effect snow along the western arm of Lake Superior this evening and overnight tonight. The last of the accumulating snow over northwest Wisconsin will continue to wind down this afternoon. However, lingering low-level moisture and east to northeast flow will support some continued chances of lake effect snow, mainly near the Twin Ports and up along the North Shore, and over the Bayfield Peninsula. Some of the guidance is supporting some additional snowfall of between 1 to 2 inches in these areas through the overnight hours tonight. Overnight lows should fall into the single digits above zero. Attention then turns to yet another system that will bring light accumulating snowfall to much of the Northland. This next system looks to move in around mid-day Friday, and continue through Friday night. The large-scale forcing with this Friday system looks weaker compared to the system that just went through today, but there will be enough 850-700 mb layer Q-vector convergence to support some accumulating snow. There is a bigger concern for heavy lake effect snow along the North Shore, with the worst conditions expected Friday afternoon and evening. East to southeasterly on-shore flow off Lake Superior, with 850 mb temperatures in the 10 to 13 degree C below zero range, which should be sufficiently cold to support some lake effect snow bands. The orographic lift should also enhance snowfall amounts as well, with the most likely area to be impacted between Silver Bay and Lutsen. These areas could see between 5 to 9 inches of new snowfall, with some locally higher amounts possible as the high- resolution guidance is hinting at some heavier lake effect banding. I would not be surprised if some isolated areas saw nearly a foot of snow from this persistent lake effect. Due to this heavy lake effect snow potential, decided to issue a Winter Storm Watch for Lake and Cook counties in the Minnesota Arrowhead region. .LONG TERM...(Saturday through Thursday) Issued at 311 PM CST Thu Dec 12 2019 An inverted trough will extend through the Upper Peninsula into northeast Minnesota Saturday morning and it will weaken through the day Saturday as colder air moves in behind a cold front. Light snow will continue Saturday morning with additional snowfall limited to a dusting to an inch over eastern Minnesota and inland from Lake Superior in northern Wisconsin. However, higher amounts will be likely along the South Shore as the colder air moves over Lake Superior and low level winds turn northerly. Lake effect snow will continue to be possible Saturday afternoon into Sunday morning along the South Shore with new snowfall Saturday into Saturday night of several inches. There may be a 6-10 hour period where the snow is heavy over the snowbelt of Ashland and Iron Counties Saturday afternoon and night and higher snowfall amounts may occur. For now, we will not issue a Winter Storm Watch but one may be needed if confidence in higher snowfall totals increases. Lake effect snow will diminish or end on Sunday as low level winds back to more westerly and deeper moisture decreases further. An area of high pressure will move through the region Sunday and Sunday night providing mostly dry conditions. A shortwave and reinforcing shot of colder air will arrive Monday into Monday night. We kept the forecast dry for now but there may be some light snow or flurries that occur Monday night with the arrival of very cold air. The GFS has been consistent over the past several runs bringing in colder air Monday night into Tuesday and is still colder than the ECMWF. The GFS has 850MB temperatures dropping to -22 to -27C by 12Z Tuesday. High pressure will again move in later Tuesday into Tuesday night. Saturday will be the warmest day of the period with highs in the teens to lower twenties then they will be in the single digits to around 10-13 degrees through Wednesday. Another clipper will bring light snow chances back into the region next Wednesday into Thursday. && .AVIATION...(For the 18Z TAFS through 18Z Friday afternoon) Issued at 1135 AM CST Thu Dec 12 2019 A clipper system will continue to move through the region today, departing this evening. Another area low pressure will be on its heels moving in on Friday. The snow will continue to diminish from west to east today, lingering longer close to Lake Superior due to lake processes. Portions of northern Minnesota will see VFR conditions for a time today before MVFR ceilings develop again tonight. VFR ceilings will also develop for a time over northern Wisconsin late this afternoon and evening, away from Lake Superior, before redeveloping late tonight into Friday morning. More snow will move in on Friday, spreading in from west to east through the day. && .MARINE... Issued at 311 PM CST Thu Dec 12 2019 East to northeast winds will continue tonight and waves will build along a portion of the North Shore into the Twin Ports to the Bayfield Peninsula to 3 to 6 feet and we will issue a Small Craft Advisory. The waves will diminish through the day Friday but take the longest to decrease along the North Shore. The wind will veer slightly on Friday to east to southeast to 15 knots or less and waves by late afternoon are expected to be 4 feet or less. Most areas will see winds decrease further Friday night as another low pressure system moves through the region. However, easterly winds around 15 knots will be possible along the North Shore, north and east of Taconite Harbor. The wind will back on Saturday to north and be from 10 to 20 knots. Waves will build, especially along the South Shore, possibly leading to hazardous conditions for small craft. && .PRELIMINARY POINT TEMPS/POPS... DLH 10 23 14 18 / 40 90 80 50 INL 1 20 7 13 / 10 80 80 40 BRD 4 18 8 13 / 10 80 40 10 HYR 5 23 17 23 / 0 90 90 50 ASX 10 27 20 24 / 20 80 90 70 && .DLH WATCHES/WARNINGS/ADVISORIES... WI...None. MN...Winter Storm Watch from Friday morning through late Friday night for MNZ012-020-021. LS...Small Craft Advisory until 10 AM CST Friday for LSZ144>147. Small Craft Advisory until 4 PM CST Friday for LSZ142-143. && $$ SHORT TERM...JTS LONG TERM...Melde AVIATION...Melde MARINE...Melde