Each alert card is color-coded by severity:

🔴 Red — Extreme (Tornado Warnings, Extreme Wind, etc.)
🟠 Orange — Severe (Severe Thunderstorm Warnings, etc.)
🟡 Yellow — Moderate (Flash Flood Warnings, etc.)
🔵 Blue — Minor / Watch / Advisory

Colors are assigned per event type to be consistent across all alerts.

Tags are automatically applied to alerts based on their content and NWS structured data:

🌀 Tornado Emergency — Life-threatening tornado emergency declared
💧 Flash Flood Emergency — Life-threatening flash flooding in progress
🔁 PDS — Particularly Dangerous Situation
☠ Life Threatening — Alert contains explicit life-threatening language
📡 Radar Confirmed — Radar-confirmed tornado or severe event
🌊 Damage Threat: Catastrophic — NWS has assigned the highest damage threat level
💥 Damage Threat: Destructive — NWS has assigned a destructive damage threat level
⚡ Damage Threat: Considerable — NWS has assigned a considerable damage threat level

Damage threat tags are pulled directly from the NWS structured alert data, so they reflect exactly what NWS forecasters have designated — not just keyword matching.

Tags help you instantly identify the most critical alerts in a long list.

User Tag Overrides — During active severe weather, you can manually adjust the tags on any alert to match your own assessment. Click an alert card to open its detail panel, where override options become available. This lets you flag or unflag alerts based on what you're seeing — your overrides are saved locally and don't affect other users.

Click any alert card in the sidebar, or click an alert polygon on the map, to open the Alert Details panel.

The panel has two tabs — DETAILS and IMPACTS:

DETAILS tab
• A color accent bar at the top matches the alert type color
• The issuing NWS office is shown above the event name
• The event name is displayed in the alert's color, with severity, urgency, and certainty chips below it (severity is color-coded: Extreme = red, Severe = orange, Moderate = yellow, Minor = green)
• Any active tags (PDS, damage threat, etc.) appear directly in the header
• A timing grid shows issued, expires, and last updated times, plus a live countdown showing time remaining until expiration
• The full headline, description, and instructions are shown below, with instructions highlighted in blue

IMPACTS tab
• Population & Households — Estimated population and household count across all affected counties (Census 2020)
• Vulnerable / At-Risk — Counts and percentages for elderly residents 65+, young children under 5, and mobile/manufactured homes (ACS 2022)
• Infrastructure — Grid showing counts of hospitals, nursing homes, urgent care, pharmacies, schools, colleges, child care centers, power plants, water systems, airports, and dams within the alert area
• Historical Flood Risk — Number of past FEMA-declared flood disasters in the affected counties, rated LOW / MODERATE / HIGH
• Storm Reports — Any active Local Storm Reports that fall inside the alert polygon, color-coded by type

Use the ⊕ Zoom button to pan the map to the alert, or ✕ Close to dismiss the panel.

Use the Sort dropdown at the top of the sidebar. Options include:

• Severity ↓ — Most dangerous first (default)
• Expires ↑ — Soonest to expire first
• Newest first — Most recently issued
• Alphabetical — By event type name

Toggle any layer on or off using the buttons in the map toolbar. Active layers are highlighted. Layers persist across sessions using your browser's local storage.

SPC ▾ and ERO ▾ are dropdown buttons — clicking them opens a small menu where you can independently toggle individual days (Day 1, Day 2, Day 3 for SPC; Day 1–5 for ERO) and Mesoscale Discussions. The button glows when any day inside is active.

Storm Reports are Local Storm Reports (LSRs) from Iowa State University IEM, showing confirmed severe weather events from the last 24 hours. Enable the STORM REPORTS toggle to show them on the map; reports load instantly without a page refresh.

Each report marker is age-coded visually — older reports fade in opacity and shrink in size, making it easy to see where active weather is versus where it has already passed.

Click any marker to see a popup with the report details:

🌩 Hail — size shown in inches (e.g. 1.75″), marked estimated or measured
💨 Wind — speed shown in mph (e.g. 70 mph)
🌪 Tornado — rated by EF scale (e.g. EF2)
🌀 Funnel Cloud — funnel observed but not confirmed touchdown
🌊 Waterspout — tornado over water
💧 Flash Flood — confirmed flash flooding event

Each popup shows the source of the report (e.g. trained spotter, emergency manager, law enforcement). Enable SPOTTERS ONLY (appears next to Storm Reports when active) to filter to reports from trained spotters and SKYWARN only.

For Day 1 and Day 2, SPC publishes separate probability forecasts for each hazard type. These show the probability that a severe weather event will occur within 25 miles of any given point. Day 1 and Day 2 probabilities are shown as separate map toggles — you can enable or disable each day independently under the SPC ▾ dropdown.

• Tornado % — Probability of any tornado
• Wind % — Probability of damaging wind gusts ≥58 mph
• Hail % — Probability of hail ≥1 inch in diameter

Significant areas are shown as hatched overlays on the probability layer using Conditional Intensity Groups (CIG):

• CIG 1 — Higher-end significant severe weather
  Tornado: max intensity EF2 · Wind: 65+ kt (75+ mph) gusts · Hail: ≥2" (tennis ball)
• CIG 2 — More intense significant weather
  Tornado: EF3 · Wind: 73+ kt gusts / MCS or derecho · Hail: ≥3.5" (softball)
• CIG 3 — Extreme significant weather potential
  Tornado: EF4+ violent · Wind: high-end derecho potential · Hail: extreme hail

Each CIG level uses a distinct hatch pattern on the map — forward diagonal for CIG 1, backward diagonal for CIG 2, and crosshatch for CIG 3. Clicking inside a hatched area shows the CIG level and description in the popup.

SPC draws separate polygons for each hazard type (tornado, wind, hail). These are overlaid on top of each other and appear as one polygon visually because they share the same risk category color.

However, the wind polygon might cover a slightly different area than the hail polygon. So clicking at one spot inside the "Marginal" area might show both wind and hail, while another spot shows only hail — both are accurate to what SPC forecasters drew.

• Day 1 — Valid today (through 12Z tomorrow). Most detailed, includes individual hazard probabilities.
• Day 2 — Valid tomorrow. Also includes hazard probabilities.
• Day 3 — Valid the day after tomorrow. Categorical risk only — individual probabilities are not available at this range.

Mesoscale Discussions are short-fuse SPC products issued in the hours before a Watch is expected, highlighting an area of concern for rapidly developing severe weather or heavy rainfall.

When one or more MDs are active, an orange 🔶 MD IN EFFECT (n) badge appears in the top toolbar showing the count. Clicking it takes you to the SWCC page for more detail.

On the map, active MD areas are drawn as dashed orange outlines. Enable them independently using the MDs item inside the SPC ▾ dropdown — they have their own toggle and do not require Day 1 to be active.

Clicking an MD polygon (or selecting it from the overlap picker) opens a popup showing:

• MD number and subject (e.g. "Concerning supercell thunderstorms")
• Watch issuance confidence percentage, color-coded by likelihood
• Issued and expires times with a live countdown
• Areas affected and the full discussion text fetched directly from SPC

The MD popup is draggable — click and drag the header bar to reposition it anywhere on screen. It stays open until you click ✕.

MDs are not warnings — they signal that conditions are becoming favorable for severe weather and a Watch may be issued soon.

ERO categories correspond to the probability that rainfall will exceed flash flood guidance at any point within the outlined area:

• Marginal — At least 5% chance. Localized flash flooding possible, mainly in poor drainage areas, burn scars, or steep terrain.
• Slight — At least 15% chance. Isolated flash flooding possible with nuisance flooding likely in low-lying areas.
• Moderate — At least 40% chance. Scattered flash flooding and river flooding expected.
• High — At least 70% chance. Life-threatening flooding likely with widespread flash and river flooding.

The WPC Hazards Outlook (Days 3–7) covers areas with elevated risk of:

🌧️ Heavy Rain — Flash flooding and river flooding possible
💧 Flooding — River and/or flash flooding hazard
❄️ Snow — Significant snowfall, travel impacts
🧊 Ice — Ice accumulation, dangerous travel
🥶 Extreme Cold — Dangerously cold conditions, hypothermia risk
🌡️ Extreme Heat — Dangerous heat, heat illness risk elevated
🔥 Fire Weather — Critical fire conditions, rapid wildfire spread possible
🌵 Drought — Ongoing or developing drought conditions

• ERO — Refreshes every 5 minutes on the dashboard (WPC updates it a few times per day)
• WPC Hazards — Refreshes every 10 minutes (the outlook itself updates infrequently, typically once or twice per day)

Enable the 🔥 Active Fires toggle to display VIIRS satellite fire detections from the past 24 hours via NASA FIRMS (Fire Information for Resource Management System).

Fire dots are color and size coded by Fire Radiative Power (FRP), a measure of fire intensity in megawatts:

🔴 Large (FRP > 500 MW) — intense, rapidly spreading fire
🟠 Medium (FRP 50–500 MW) — active, moderate-intensity fire
🟡 Small (FRP < 50 MW) — low-intensity detection

Clicking a dot shows the FRP, confidence level (Nominal or High), whether it was a day or night detection, and the acquisition time. Only Nominal and High confidence detections are shown — low confidence detections (sensor noise, cloud edges) are filtered out.

Enable NHC Tracks to display active tropical cyclone tracks from the NOAA National Hurricane Center. Each active storm shows its current position, category, and forecast track.

During quiet periods (outside of hurricane season or when no storms are active), the layer will show nothing — this is expected behavior.

Plays an audio alert chime whenever a new NWS alert is received. Useful when monitoring the dashboard in the background. Toggle ON/OFF — defaults to OFF.

Reads new alerts aloud using your browser's text-to-speech engine — for Severe and above only (Severe Thunderstorm Warnings, Tornado Warnings, etc.).

Use the voice selector dropdown to pick from your system's available voices, and the Test Voice button to preview it before enabling.

When a new alert arrives, the map automatically pans and zooms to show it. Use Auto-Zoom Types to control which alerts trigger this:

• All New Alerts — Zooms for every new alert
• Severe+ Only — Only Severe and Extreme alerts
• Tornado / Extreme Only — Only the highest severity alerts
• Selected Types Only — Only the alert types you've checked in the filter list

Rotation automatically cycles through active alerts on the map, panning to each one in sequence. Useful for monitoring multiple active alerts at once.

Cycle Mode controls which alerts are included in the rotation:

• All Selected — Rotates through all visible alerts
• Severe+ Only — Only Severe and Extreme alerts
• Most Severe Only — Only the single highest-severity alert

Restricts the dashboard to show alerts only from specific states. Toggle State Filter ON, then use the search box to find and select the states you want to monitor.

Use All States to select everything or Clear to deselect all. When active, only alerts from your selected states appear in the sidebar and on the map.

Flash Speed — Controls how fast Tornado Warnings and active severe alerts flash/pulse on the map and in the sidebar. Choices: Slow, Medium, Fast.

Ticker Speed — Controls how fast the alert ticker scrolls across the top bar. Faster means quicker scrolling through long alert names.

When enabled, hovering a polygon on the map automatically scrolls the sidebar to show the matching alert card. Useful when there are many alerts and you want the sidebar to stay in sync with what you're hovering on the map.

• Disable Alaska Alerts — Hides all alerts from Alaska. Useful if you're only monitoring the contiguous US.

• Hide Debug Stats — Hides the small performance/debug stats shown in the status bar at the bottom of the page.

• Select All / Select None — Quickly enable or disable all alert type filters at once.

• Reset Defaults — Restores all settings to their original default values.

The lower section of the settings panel lists every NWS alert type. Check or uncheck types to control exactly which alerts appear in the sidebar and on the map.

Use the search box to quickly find a specific type (e.g. "Wind", "Flood", "Winter"). Your selections are saved and restored automatically.