Key messages
- Turning much cooler and windy for today with lake effect rain showers expected. The strongest wind gusts are expected downwind of Lake Michigan across Berrien and La Porte Counties where gusts to 45 mph are likely Friday afternoon and evening. A wind advisory has been hoisted as a result.
- Chances for frost are best on Saturday night, however some frost cannot be ruled out tonight.
- After below normal temperatures this weekend, temperatures will warm back above normal early next week. Additionally, dry weather looks to persist through much of next week.
Discussion
Issued at 257 AM EDT Fri Oct 16 2026
As a mid level trough digs across the Central US, an upper low gets shoved northeastward pushing a surface low into southeast Canada/Northeast US. At the same time, a 1040 mb surface high slides southeastward into the Central CONUS. The presence of this strong surface high often indicates the arrival of a cooler airmass and that is the case this time. Given our departure of above normal temperatures and the arrival of this cool airmass, we'll have some hazards to contend with today and this weekend. First, yesterday's cold front shifts eastward and the vigorous vort max associated with the mid level trough dives through Lk MI late this afternoon into this evening. Given the warm lake and the 850 mb temps dipping to around or below 0C, lake enhancement is expected to cause rain. A surface trough is expected to swing through the southeast area of Lk MI around 18z with ample low level moisture, low level wind convergence, and building lake enhanced instability. Given the movement of this trough and swiveling trajectories from northwest to north, the area with the best chance to see "higher" QPF is southern Berrien into LaPorte where 0.25 to 0.5" is forecast, tapering off the farther away from the lake you are. The heaviest of the rain appears to get into Berrien county midday (15 or 16z) and continues swiveling southward through the afternoon and into the evening. The other hazard is wind gusts, which look to get underway along lk MI- adjacent locations around 19 or 20z before pulling away around 3z. Given the surface trough, there could be some isentropic downglide enough to work an isolated 45 kt gust down to the surface. Otherwise, it appears that frequent gusts between 30 and 40 mph will be possible during that time as low level lapse rates become conducive. The strongest of the gusts are adjacent to the lake, tapering off the farther away you get. This is why the wind advisory was hoisted for Lk MI- adjacent locales.
The mention of the cold air also brings to mind the chance for frost. Especially with overnight lows dropping into the 30s from from tonight/Sat AM to Sunday night/Mon AM and potentially again Tue AM. The main issue with Friday night/Sat AM is the gradient which could keep winds strong enough to eliminate formation of frost. A lesser possibility is lake clouds hang on, but would probably lean towards subsidence on the eastern side of the lake clouds removing them. Clouds appear to already be dissipating on the NAM by around 6 to 9z for maybe all of our counties (lowest confidence on LaPorte to White county line). This would give areas along or about IN-15 north of US-24 on into MI the best chance to see frost tonight. Surface high pressure continues to poke into the area Saturday morning with the stronger gradient lurking to our north. So, cloud cover appears less of factor. It's often that as return flow begins to occur that we get our best frost chances as winds slacken, but the boundary layer is able to get back to what it was the previous night or potentially colder. So, Saturday night has the best chance for frost. There is also the possibility of a freeze primarily along and south of US-24 Sun AM with a couple hours of temps right around there then.
Surface high pressure then becomes stagnant across the eastern CONUS as blocking builds across the Atlantic. The NAO/AO both drop negative during this time. The upper jet also retreats back up into Canada. A slow moving trough moves into the western CONUS, but takes its time arriving into the area potentially continuing to provide dry weather into next weekend. Temperatures trend warmer with highs returning to the 70s during the next work week and lows warming slowly through the 40s.
Aviation /06Z Tafs Through 06Z Saturday/
Issued at 543 AM EDT Fri Oct 16 2026
Post-frontal cold advection will keep mainly MVFR cigs and gusty west-northwest winds going today. A digging upper level trough and associated secondary low level trough sink south through the area this afternoon bringing increasing chances for showers and vis restrictions, particularly at KSBN where there will be lake enhancement. This transitions to pure lake effect this evening at KSBN with additional shower chances and high MVFR cigs. Winds remain gusty and veer more northerly otherwise later this afternoon and evening.
Iwx Watches/Warnings/Advisories
IN...Wind Advisory from 1 PM this afternoon to 10 PM CDT this evening for INZ103-203. OH...None. MI...Wind Advisory from 2 PM this afternoon to 11 PM EDT this evening for MIZ177-277. MARINE...Small Craft Advisory until 11 AM EDT this morning for LMZ043- 046. Gale Warning from 11 AM this morning to 2 AM EDT Saturday for LMZ043-046.
DISCUSSION...Roller AVIATION...Steinwedel