7-day fog outlook · Grayslake / Lake County

7-day fog outlook — Grayslake / Lake County

run 2026-10-19T21:30-05:00 · home point 42.3434, -88.0412

Set-up score = the same factor blend the day-1 report uses, before calibration. It ranks mornings; it is not a probability. Day 1 is calibrated in the main report. ★ = best-ranked morning beyond tomorrow.

morning	set-up	band	type	light	T−Td min	wind	mid+high cloud	sunrise	models
Tue 20 Oct	0.70	decent set-up	deep fog bank	sun will reach the fog top	0.0 °C	2.2 kt	0 %	07:11 · 103.5°	5 (HRRR primary), spread 0.82
Wed 21 Oct	0.69	decent set-up	deep fog bank	sun will reach the fog top	0.0 °C	1.0 kt	0 %	07:12 · 103.9°	5 (HRRR primary), spread 0.86
Thu 22 Oct	0.65	decent set-up	shallow ground fog	sun will reach the fog top	0.9 °C	3.8 kt	0 %	07:13 · 104.4°	4 (ECMWF primary), spread 0.70
Fri 23 Oct ★	0.69	decent set-up	shallow ground fog	sun will reach the fog top	1.3 °C	3.2 kt	0 %	07:14 · 104.9°	4 (ECMWF primary), spread 0.84
Sat 24 Oct	0.49	marginal	shallow ground fog	overcast above the fog	1.5 °C	4.8 kt	74 %	07:15 · 105.4°	4 (ECMWF primary), spread 0.62
Sun 25 Oct	0.19	poor	shallow ground fog	overcast above the fog	4.6 °C	5.9 kt	100 %	07:17 · 105.9°	4 (ECMWF primary), spread 0.49
Mon 26 Oct	0.31	poor	shallow ground fog	overcast above the fog	2.6 °C	6.7 kt	100 %	07:18 · 106.3°	4 (ECMWF primary), spread 0.34

What a set-up score has meant (day-1 backtest, raw score before calibration, airport mornings)

strong set-up (≥ 0.75): fog on 25 % of 44 mornings
decent set-up (≥ 0.60): fog on 17 % of 82 mornings
marginal (≥ 0.45): fog on 12 % of 154 mornings
poor (≥ 0.00): fog on 8 % of 285 mornings

Ranking skill by lead (AUC from the lead backtest; 0.5 = none, 1 = perfect): 1 day ahead 0.746, 2 days ahead 0.726, 3 days ahead 0.738, 5 days ahead 0.627

Tue 20 Oct — set-up 0.70, decent set-up

Confidencesee the main report (calibrated, HRRR included)Typedeep fog bankLightsun will reach the fog topSunrise07:11 at 103.5° ESEHours saturated2Per modelgfs_hrrr 0.94, ecmwf_ifs025 0.626, gfs_global 0.119, icon_seamless 0.529, ncep_nbm_conus 0.83

Wed 21 Oct — set-up 0.69, decent set-up

ConfidenceHRRR reaches this morning; models usually agree on the airmass; backtest AUC at this lead 0.726 (measured at 2 days)Typedeep fog bankLightsun will reach the fog topSunrise07:12 at 103.9° ESEHours saturated4Per modelgfs_hrrr 0.984, ecmwf_ifs025 0.706, gfs_global 0.123, icon_seamless 0.499, ncep_nbm_conus 0.656

Thu 22 Oct — set-up 0.65, decent set-up

Confidenceset-up only: dewpoint, wind and sky from the global models; backtest AUC at this lead 0.738 (measured at 3 days)Typeshallow ground fogLightsun will reach the fog topSunrise07:13 at 104.4° ESEHours saturated2Per modelgfs_hrrr None, ecmwf_ifs025 0.814, gfs_global 0.126, icon_seamless 0.667, ncep_nbm_conus 0.828

Fri 23 Oct — set-up 0.69, decent set-up

Confidenceset-up only: dewpoint, wind and sky from the global models; backtest AUC at this lead 0.738 (measured at 3 days)Typeshallow ground fogLightsun will reach the fog topSunrise07:14 at 104.9° ESEHours saturated0Per modelgfs_hrrr None, ecmwf_ifs025 0.643, gfs_global 0.134, icon_seamless 0.971, ncep_nbm_conus 0.893

Sat 24 Oct — set-up 0.49, marginal

Confidencepattern only; expect the number to move; backtest AUC at this lead 0.627 (measured at 5 days)Typeshallow ground fogLightovercast above the fogSunrise07:15 at 105.4° ESEHours saturated0Per modelgfs_hrrr None, ecmwf_ifs025 0.509, gfs_global 0.084, icon_seamless 0.707, ncep_nbm_conus 0.589

Sun 25 Oct — set-up 0.19, poor

Confidencepattern only; expect the number to move; backtest AUC at this lead 0.627 (measured at 5 days)Typeshallow ground fogLightovercast above the fogSunrise07:17 at 105.9° ESEHours saturated0Per modelgfs_hrrr None, ecmwf_ifs025 0.098, gfs_global 0.056, icon_seamless 0.544, ncep_nbm_conus 0.131

Mon 26 Oct — set-up 0.31, poor

Confidencepattern only; expect the number to move; backtest AUC at this lead 0.627 (measured at 5 days)Typeshallow ground fogLightovercast above the fogSunrise07:18 at 106.3° ESEHours saturated0Per modelgfs_hrrr None, ecmwf_ifs025 0.298, gfs_global 0.074, icon_seamless 0.411, ncep_nbm_conus 0.401

Honesty notes

Days 2–7 use ECMWF, GFS, ICON and NBM (HRRR where its 48 h reach allows). The set-up score is the raw factor blend; it ranks mornings and is not a calibrated probability.
Skill falls with lead. Use days 5–7 only to spot a pattern; re-check nightly and treat the day-1 report as the decision.
No vertical profile, river gauge or NBM bulletin feeds the outlook; those are day-1 checks only.