####018005281#### FXUS63 KIWX 121941 CCA AFDIWX Area Forecast Discussion National Weather Service Northern Indiana 241 PM EST Fri Dec 12 2025 .KEY MESSAGES... - Lake effect snow showers tonight, primarily for Berrien County. Accumulations of less than one inch. - Light snow Saturday afternoon (accumulations 1 to 3 inches), transitioning to lake effect snow showers Saturday night into Sunday (additional 2-4"). - Wind chills of -15 or colder Saturday night and Sunday night. && .DISCUSSION... Issued at 228 PM EST Fri Dec 12 2025 Primary topics of interest this afternoon are 1) incoming clipper system Saturday afternoon and night (snow duration ~6 hours), followed by lake effect snow, and 2) below-zero wind chills Saturday night and Sunday night. A compact but strengthening upper-level disturbance races across the northern Rockies this afternoon, arriving on our doorstep Saturday afternoon just as an upper-level low drops due south from Ontario. This results in a strengthening area of frontogenesis across central Indiana. Forecast soundings depict a shallow dry layer saturating quickly amid this highly-forced environment and a deepening Dendritic Growth Zone through time (approaching 500mb after 21z/4PM EST). Given the continental polar source region of this air mass, snow ratios will be high (+/-15:1) resulting in efficient accumulation despite the brief residence time. Snow amounts of 2" to 3" are expected south of US 24 while most of the forecast area will see 1-2" from this clipper. The exception will be south-central Michigan which will generally miss both the clipper and subsequent lake effect. Wind from the northwest near 10 mph Saturday will result in some blowing and drifting. Wind gusts near 20mph will be confined to those downwind of lake Michigan. Synoptic ("system") snow ends before midnight. An advisory was considered for my far southern Indiana Counties, but seeing such low-end advisory amounts amid an above-average snow season so far made me less enthused for headlines. The incoming shift may update as needed, especially if the storm track shifts north. In the wake of this clipper, lake effect snow develops Saturday evening and persists through Sunday. This is preceded by a brief period of lake effect snow tonight, primarily for Berrien County and those along the toll road. Equilibrium levels are shallow (< 5k FT) with an elevated and poorly saturated DGZ. Thus, amounts by daybreak Saturday will be less than 1". Given this < 1" accumulation for tonight, opted to delay any headline issuance for the time being. For lake effect snow Saturday afternoon through Sunday, accumulation will favor Berrien, Cass (MI) La Porte, and St. Joseph (IN) Counties. Lake effect parameters will be most favorable Saturday night / early Sunday morning. Outside of the lake effect snow, temperatures will plummet Saturday night as skies clear and Canadian high pressure becomes established over the Ohio Valley. Those near White and Cass (IN) Counties will see lows below zero while the remainder of the forecast area will see single-digit lows. Being at the mercy of decreasing clouds, this decreases forecast confidence for the issuance of any Cold Weather Advisories at this time. Sunday night, with lake effect clouds decreasing, all areas are expected to be on either side of 0. Wind chills of -15 to -20 may warrant a Cold Weather Advisory. Thawing out Tuesday through Thursday as upper-level ridging moves in. Highs will creep into the 40s Wednesday and Thursday. Low pressure moves through the Upper Midwest late in the week bringing renewed chances for rain and snow. && .AVIATION /18Z TAFS THROUGH 18Z SATURDAY/... Issued at 1244 PM EST Fri Dec 12 2025 Patchy MVFR stratus continues across northern Indiana to begin this period with greatest coverage roughly from Knox IN to Fort Wayne IN. Conditions have temporarily improved to VFR at South Bend, but subtle southwest flow/low level theta-e northward moisture transport into early this evening in advance of a western Great Lakes upper level short wave should allow patchy MVFR cigs to affect KSBN later this afternoon into this evening. Slight veering of low level winds in response to this short wave passage (better fetch for lake enhancement) and some increase in inversion heights could promote some snow showers at KSBN. Greater confidence in snow is still with system snow for Saturday. This system will be highly sheared in nature and will feed off tight 700-500 mb baroclinicity/fgen. The heaviest snow is expected to remain south of the terminals but a period of snow is expected at both terminals with at least MVFR/IFR vsby restrictions. Best chance of vsbys <1SM during the Saturday afternoon period is at KFWA given proximity of the elevated frontal zone. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...None. OH...None. MI...None. MARINE...Small Craft Advisory from 10 PM this evening to 10 PM EST Sunday for LMZ043-046. && $$ DISCUSSION...Brown AVIATION...Marsili ####018007302#### FXUS63 KAPX 121944 AFDAPX Area Forecast Discussion National Weather Service Gaylord MI 244 PM EST Fri Dec 12 2025 .KEY MESSAGES... - Widespread light to moderate snow this evening and tonight with heavy lake enhanced snow over parts of NW lower, eastern upper, and near the tip of the mitt - Long duration lake effect snow and cold temperatures this weekend will lead to hazardous travel conditions for areas of northern lower and eastern upper. Wind chill values will struggle to reach above 0F Saturday - Chances for snow continue Monday as another system passes over northern MI - Temperatures begin to warm Tuesday with precipitation chances continuing next week && .SHORT TERM /THROUGH SATURDAY/... Issued at 210 PM EST Fri Dec 12 2025 Currently, surface observations place a stronger cold front near the MN/WI border. Surface gradients have been increasing this afternoon, leading to strengthening southwest winds over Lake MI and northern MI. Radar is hinting at some light snow showers forming just off the coast of Charlevoix and moving into Emmet Co. Tonight: An approaching system will continue to spread light to moderate snow over northern lower and eastern upper this evening. Stronger winds aloft and the tighter surface pressure gradient will continue to strengthen winds as they veer westerly. This "punch" of colder air will encompass northern MI by early Saturday morning. Times of moderate and heavy snowfall will be seen initially along the snowbelts, tip of the mitt, northern Lake MI coast, and areas of eastern upper late this evening and tonight. The stronger west to west-northwest winds and colder air during this time will result in powder like snow. This snow has slightly lower SLRs (still a dry snow), but is so fine that visibilities are greatly reduced when it blows around. Peak snowfall intensity is seen early Saturday for much of NW lower early Saturday as snow transitions to more of a lake effect footprint. Saturday: Snowfall will become more confined to the northern section of the NW lower snowbelt as winds remain west-northwest. A band of focused snow could form near Little Traverse Bay, resulting in the potential for Emmet and Cheboygan counties to see spots of heavy snow through much of Saturday. Intensity of snowfall over the southern part of NW lower will weaken, but snow should persist. Around 2 to 6" is expected over the advised areas of northern lower by late Saturday, with locally higher amounts up to +8". Over eastern upper, heavy snow will likely be confined to northern Chippewa (Whitefish Point and the SOO), with light to moderate times of snow meandering into other parts of Chippewa. Bands of heavier lake effect snow will begin early Saturday and linger for much of the day, resulting in accumulations of 4 to 8 inches with locally higher amounts of +10" near Whitefish point and near the SOO. Although the snow characteristic will be more of a powder, an ideal environment and some synoptic help will allow for times of snowfall rates of 1-2" per hour under the heavier bands. Gusty winds and cold temperatures will be present for most of northern MI Saturday, resulting in areas of blowing snow and wind chill values that struggle to rise above 0F the whole day. See the latest winter weather products for more details. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... Issued at 210 PM EST Fri Dec 12 2025 Late Saturday into Sunday, the upper closed low amplifies west to east and rotates southward over the area. This helps push the final slug of cold air southward. Winds over the CAN shield will turn north-northeast early Sunday. As they do, established lake aggregate troughing over NE Lk Superior will shift over the Whitefish Bay. With this, heavy snow could be pointed right at the SOO, leading to a 3-6 hour window of 1-2" per hour rates. There is still some uncertainty with the exact time this will occur - Saturday evening or more Saturday night; however the potential remains high for total snow accumulations (Sat & Sun) to reach +8" near the SOO. This will also be a night of very cold temperatures, especially for spots that can see clearer skies overnight (parts of NE lower). During the day Sunday, winds will veer north and weaken. Potential exists for some areas of LL convergence near Grand Traverse Bay, which could keep areas near, south and west of Grad Traverse Bay snowy most of Sunday. Another system quickly approaches the area Monday, returning southwest winds and snow chances to most of eastern upper and parts of northern lower. Some brief lake effect snow will be seen late Monday as the system passes. The focus of snow amounts for this system looks to be eastern upper at this time. Tuesday thru end of period: Temperatures begin to warm Tuesday with breezy southwest winds. Precipitation chances continue for eastern upper late Tuesday into Wednesday, likely in the form of snow up there. Temperatures will warm above freezing beginning mid week, with multiple rounds of precipitation next week as temperatures remain relatively mild. && .AVIATION /18Z TAFS THROUGH 18Z SATURDAY/... Issued at 1155 AM EST Fri Dec 12 2025 CIGs hovering right in the vicinity of 3,000ft this afternoon, resulting in a potpourri of VFR and MVFR at times. Clipper system infiltrates the region tonight, bringing a period of snow through the evening, which will lead to firmly MVFR TAFs for most sites... least affected will be APN. During bouts of heavier snow, certainly possible to see some IFR to LIFR VSBYs. Transition from steadier snow to lake effect snow set to occur through the night as the system departs. As such, SHSN will prevail at all sites except APN and CIU as we head into Saturday morning. Potential for periodically lower CIGs and VSBYs during snow shower passages, but in general, MVFR to prevail at all sites, with the exception being APN and CIU, which may squeak out VFR conditions Saturday morning. Current SW winds will trend gustier through this evening as winds veer W to WNW through the period. Some gusts of 25 to 30 knots possible later this evening through the remainder of the forecast period. && .APX WATCHES/WARNINGS/ADVISORIES... MI...Winter Weather Advisory until 7 PM EST Saturday for MIZ016-020- 025-031. Winter Weather Advisory from 7 PM this evening to 7 PM EST Saturday for MIZ017-021-022-026>028-032-099. Winter Storm Warning from 10 PM this evening to 10 PM EST Saturday for MIZ086-087. Winter Weather Advisory from 10 PM Saturday to 1 AM EST Sunday for MIZ086-087. MARINE...Small Craft Advisory from 7 PM this evening to 7 PM EST Saturday for LHZ345>349. Small Craft Advisory until 7 PM EST Saturday for LMZ323-341- 342-344>346. Small Craft Advisory from 10 PM this evening to 7 PM EST Saturday for LSZ321-322. && $$ SHORT TERM...ELD LONG TERM...ELD AVIATION...HAD