Data health

Storm Mode / Tracked area

Illinois

Wall mode

0 warnings total · 0 tornado warnings · 1 alert including watches and advisories

Current alert feed · checked

Warnings in area

1 of 1 alerts
  1. Frost AdvisoryMcLean; Logan; De Witt; Piatt; Champaign; Vermilion; Sangamon; Christian; Macon; Moultrie; Douglas; Coles; Edgar; Shelby; Cumberland; Clark; Effingham; Jasper; Crawford; Clay; Richland; LawrenceNWS Lincoln IL · until advisory · radar-alerts checked

Watched places

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Layers

Map

  • Frost Advisory 1

NWS’s polygons as issued, or the zones a zone-issued alert names; SPC’s watches by their counties. Checked . Data: NOAA/NWS, NOAA/SPC.

Agency warning geometry · no observed imagery displayed
North ↑

Interactive imagery loads separately. Missing radar does not remove warnings or imply clear weather.

Alert outlines: NOAA/NWS; cell points/observed segments: IEM/NEXRAD. A warning polygon is not a tornado footprint.

Lightning activity — GOES GLM

Total lightning, including in-cloud activity. Not ground-strike locations or a safe-to-go-outside signal.

Cached lightning observations have not loaded. An empty map is not zero lightning.

Cached lightning source details and text readings

Snow analysis — NOHRSC

Source-rendered snow depth and snow water equivalent for the lower 48. History changes this snow picture only; warnings and radar keep their own clocks.

Stored snow depth · footprint valid 2026-10-18 06:00:00 UTC, picture retrieved 2026-10-18 12:23:04.796 UTC.

No NOHRSC picture displayed on the interactive map.

  • 0 - 0.39 in
  • 0.39 - 2.0 in
  • 2.0 - 3.9 in
  • 3.9 - 9.8 in
  • 9.8 - 20 in
  • 20 - 39 in
  • 39 - 59 in
  • 59 - 98 in
  • 98 - 197 in
  • 197 - 295 in
  • 295 - 394 in
  • 394 - 787 in
NOHRSC snow analysis for the lower 48; see the adjacent source legend and time qualification
NOAA/NWS/NOHRSC’s original picture and legend. No station or address value is inferred.

NOHRSC footprint times are metadata; pixel analysis time is not independently verified. Snow-depth pixels have previously differed from the footprint time. This is modeled/assimilated snow analysis, not a measurement at a place. Unshaded and no-data areas do not establish zero snow.

Snow pictures, retained history and source provenance

Change time or forecast product

Replay uses retained source bytes. Recording begins with activation; missing history is not clear weather.

Live sources keep independent clocks.

Replay coverage and interpretation

Rolling target: 24 hours; cells: six hours. Radar: NOAA MRMS national overview, 8-minute tolerance. Satellite: original GOES GeoColor day/night picture, hourly sampling, 75-minute tolerance. No interpolation or latest-image fallback. Warning and source checks retain their own clocks. “Recorded by” is collector acquisition evidence, not exact browser publication history.

Current GLM density, velocity and specialist layers are hidden during replay. Snow uses retained footprint metadata with unverified pixel time. Forecast uses one pinned issuance/run and exact valid time.

No observed replay frame displayed.

Open the complete replay reader (works without scripting or WebGL)
Radar-derived cells (0) · current

Collector checked ; feed generated . Zero cells does not establish coverage or clear weather. Observations from different radars are not merged.

    Station and river observations (42)

    Surface source current; observed water-level source current. Each reading keeps its own time. Map markers show at most 500 stations and 500 gauges; the complete source directory is paginated.

    Circle: surface station; square: water-level gauge. Filled: current reading and source; hollow: stale, unconfirmed or missing observation. Marker color is not a hazard category. Enable “Stations and gauges” in Layers to inspect them on the map.

    Showing 42 of 42 listed sources. All surface stations and retained trends · All supported gauges and forecasts

    Inspector

    Choose a warning, cell or place

    Select a row or map feature for its official details. Overlapping features offer a choice; all peer warnings remain in the list.

    Recent source changes

    Recording coverage and limits
    • warnings: retained from 2026-10-17T13:30:25.525Z through 2026-10-18T13:30:07.777Z
    • outlooks: retained from 2026-10-17T13:30:25.525Z through 2026-10-18T13:30:08.160Z
    • hydro: retained from 2026-10-17T13:30:25.525Z through 2026-10-18T13:25:06.863Z
    • analysis: retained from 2026-10-17T13:30:25.525Z through 2026-10-18T13:30:07.253Z
    • winter: retained from 2026-10-17T13:30:25.525Z through 2026-10-18T13:23:04.425Z

    Source-message history is not recorded imagery replay. Recorded radar/satellite imagery is not available in this view.

    Checks every minute; each layer keeps its own time.

    Analysis and model context

    Current cached context, independently dated. Regional reference: IL; a reference within a wider monitoring area does not replace the complete warning geography. This section remains separate from the historical replay cursor and official cyclone forecast. Use Forecast to pin a retained model package.

    Storm ingredients: SPC’s hourly analysis

    SPC mesoanalysis map, Significant tornado parameter (effective layer), lower 48, analysis for 13Z. Its key and units are in SPC’s picture; what it shows is described beside it.
    Analysis SPC mesoanalysis for . The lower 48. Data: NOAA/SPC.

    Tornado index: Significant tornado parameter (effective layer) (no units)

    An index SPC combines from instability, cloud-base height, shear and low-level spin. Above 1 the environment has looked like those of strong tornadoes. It is not a tornado forecast and says nothing where storms do not form.

    The technical reading

    Effective-layer STP, with CIN: (MLCAPE / 1500 J/kg) × ((2000 − MLLCL) / 1000 m) × (effective SRH / 150 m²/s²) × (effective bulk shear / 20 m/s) × ((200 + MLCIN) / 150 J/kg), with SPC’s limits, dimensionless. Most significant tornadoes have occurred with values above 1 in an environment with supercells.

    An ingredient, not a forecast: SPC’s analysis of the hour, from observations and a short-range model’s first guess. No one value is a warning or an outcome; storms need several ingredients together, and something to start them.

    SPC mesoanalysis checked · Data: NOAA/SPC

    Spotlight: Winter Storm Severity Index

    1 of 15

    Winter Storm Severity Index

    WPC: “WSSI does not depict official warnings and should always be used in context with official NWS forecasts and warnings.”

    • Winter Weather Area
    • Minor Impacts
    • Moderate Impacts
    • Major Impacts
    • Extreme Impacts

    Highest in this area, by day and by cause

    Day 1
    nothing drawn
    Day 2
    nothing drawn
    Day 3
    nothing drawn
    Snow amount, Days 1–3
    nothing drawn
    Snow load, Days 1–3
    nothing drawn
    Ice, Days 1–3
    nothing drawn
    Blowing snow, Days 1–3
    nothing drawn

    Each day and cause on the Winter tab, with its own issue time

    WPC’s WSSI, overall impact, Days 1–3, valid to , issued . WPC issues each day and cause on its own clock. Not a warning, and not a chance. Data: NOAA/NWS/WPC.

    Chance of Moderate impacts or worse, Day 1

    WPC: “WSSI does not depict official warnings and should always be used in context with official NWS forecasts and warnings.”

    • 5–10%
    • 10–20%
    • 20–30%
    • 30–40%
    • 40–50%
    • 50–60%
    • 60–70%
    • 70–80%
    • 80–90%
    • 90–95%
    • 95% or more

    Each level and day on the Winter tab

    WPC’s WSSI-P: no chance drawn for Day 1. Data: NOAA/NWS/WPC.

    Chance of at least 4 inches of snow, Day 1

    WPC gives no chance of 4 inches of snow or more in this area over the next three days, so Day 1’s 4 inches is shown.

    • Slight: at least 10%
    • Moderate: at least 40%
    • High: at least 70%

    Every day and amount on the Winter tab

    WPC’s Probabilistic Winter Precipitation Forecast, to , issued . Outlines, as WPC draws them. Data: NOAA/NWS/WPC.

    Winter watches, warnings and advisories

    • Frost Advisory 1 until · NWS Lincoln IL

    NWS’s winter and cold alerts in force in the area, by event as issued, each counted once, with the offices that issued them and the latest end. Data: NOAA/NWS.

    Snow on the ground

    NOHRSC snow depth and snow water equivalent use the source’s original pictures and legends, with qualified footprint times. Open the cached source page for availability and retained history. This wall has no snow picture to rotate; missing imagery does not mean no snow.

    NOHRSC snow analysis and retained pictures

    Data: NOAA/NWS/NOHRSC. Snow analysis, not a measurement at a place.

    WPC’s heavy snow and icing discussion

    The whole discussion

    Issued , for to . WPC’s words, as written. Data: NOAA/NWS/WPC.

    SPC Day 1 outlook

    • General Thunderstorms Risk

    SPC’s Day 1 categorical outlook, valid to , issued . SPC’s categories, as drawn. Data: NOAA/SPC.

    Watches

    No tornado or severe thunderstorm watch in force in this area.

    SPC’s watches, by number, matched by the counties they list. Data: NOAA/SPC.

    Mesoscale discussions

    No mesoscale discussion reaches this area.

    SPC’s mesoscale discussions whose outline reaches the area. Data: NOAA/SPC.

    Storm ingredients

    SPC’s hourly mesoanalysis, observed soundings and model guidance for the area, on the Analysis tab with its own clocks.

    Open the Analysis tab

    Drawn by the Analysis tab’s own renderer. Data: NOAA/SPC, NOAA/NCEP.

    Flash-flood risk, Day 1

    • Marginal

    WPC’s excessive rainfall outlook, to , issued : a chance of flash flooding, in four categories. Data: NOAA/WPC.

    River gauges in flood

    No river, coastal or lake gauge in this area is in flood, observed or forecast.

    NWS’s gauges at flood stage or above in the area, worst first, each with its forecast hydrograph on Rain & rivers. Data: NOAA/NWPS.

    Rain expected and rain that fell

    WPC’s rain forecast and MRMS’s radar estimate of the rain that fell, on the Briefing’s map for the area.

    Open Rain & rivers

    Data: NOAA/WPC, NOAA/NSSL MRMS.

    The tropics

    NHC’s and JTWC’s storms, their official graphics and the watches and warnings for them. Storm Mode’s own tropical panels arrive with its tropical events.

    Open the Tropics page

    Data: NOAA/NHC, JTWC.

    Radar, winter preset

    The Radar page’s winter preset over the area: HRDPS forecast snow with NWS’s warnings on top, loaded by your browser. A forecast, labelled as one there.

    Open the radar

    Live tiles; the radar keeps no last-good copy.

    What changed, last 60 minutes

    1. Frost Advisory no longer in force: Montgomery; Bond; Fayette; Clinton; Marion; Washington; Randolph; Madison; St. Clair; Monroe; Franklin; Jefferson; Crawford; Washington; St. Francois; Ste. Genevieve; Iron; Madison; Reynolds
    2. Frost Advisory no longer in force: Carroll; Warren; Tippecanoe; Fountain; Vermillion; Parke; Putnam; Marion; Vigo; Clay; Owen; Morgan; Johnson; Sullivan; Greene; Monroe; Brown; Bartholomew; Knox; Daviess; Martin; Lawrence; Jackson; Jennings
    3. Frost Advisory no longer in force: Jefferson; Wayne; Edwards; Wabash; Perry; Franklin; Hamilton; White; Jackson; Williamson; Saline; Gallatin; Union; Johnson; Pope; Hardin; Alexander; Pulaski; Massac; Gibson; Pike; Posey; Vanderburgh; Warrick; Spencer; Fulton; Hickman; Carlisle; Ballard; McCracken; Graves; Livingston; Marshall; Calloway; Crittenden; Lyon; Trigg; Caldwell; Union; Webster; Hopkins; Christian; Henderson; Daviess; McLean; Muhlenberg; Todd; Perry; Bollinger; Cape Girardeau; Wayne; Carter; Ripley; Butler; Stoddard; Scott; Mississippi; New Madrid
    4. Frost Advisory no longer in force: Kankakee; Livingston; Iroquois; Ford; Eastern Will; Lake; Porter; Newton; Jasper; Benton

    The products’ own words and times, and what is no longer in force since the last read. Never written by AI.

    Monitoring area, legacy alert summary and selection rules
    Area
    Illinois (NWS states: IL)
    Hazards
    Every kind of warning, watch and advisory this site carries
    Window
    In force now, with the next days of SPC’s and WPC’s products
    Made by
    This address: anyone can make one, and nothing is stored. Change the area or hazards

    An area you chose, not a storm’s footprint: everything here is in force in this area, never “from this storm”.

    In force in this area 1

    1. Frost Advisory1until 14:00Z
    Every alert in this area, most urgent first
    1. Frost AdvisoryMcLean; Logan; De Witt; Piatt; Champaign; Vermilion; Sangamon; Christian; Macon; Moultrie; Douglas; Coles; Edgar; Shelby; Cumberland; Clark; Effingham; Jasper; Crawford; Clay; Richland; Lawrenceuntil · NWS Lincoln IL

    Most urgent first, by the Briefing’s ranking. Checked .

    Sources

    Choose another storm or areaChange monitoring areaSource status

    Not an official warning service. Warnings and watches are the National Weather Service’s, outlooks and reports the Storm Prediction Center’s and the Weather Prediction Center’s (Data: NOAA/NWS, NOAA/SPC, NOAA/WPC). When a warning is issued for you, act on it, and use weather.gov or a NOAA Weather Radio for where you are.