VORTEX is a Progressive Web App — no App Store required. To install it on your iPhone home screen:
1. Open vortexintel.app in Safari
2. Tap the Share button (box with arrow)
3. Tap "Add to Home Screen"
Once installed, VORTEX runs full screen like a native app.
1. Open vortexintel.app in Chrome
2. Tap the three-dot menu
3. Tap "Add to Home Screen" or "Install App"
On some Android versions, Chrome will automatically show an install banner at the bottom of the screen — tap it to install without going through the menu.
Go to Settings → Home Location and tap the map or search for your address. Your home location is used for all background alerting — this is the most important setup step.
| Feature | Free | Pro |
|---|---|---|
| Interactive map with heatmap layers (Temp, Wind, Humidity, CAPE, Dewpoint) | ✓ | ✓ |
| Storm Risk Score (0–100) | ✓ | ✓ |
| Live NEXRAD radar | ✓ | ✓ |
| Global precipitation (NASA GPM IMERG) | ✓ | ✓ |
| Satellite IR cloud-tops (GOES-East) | ✓ | ✓ |
| NWS watch & warning polygons | ✓ | ✓ |
| Past Tornadoes (30+ yrs SPC archive) | ✓ | ✓ |
| Past Warnings (NWS polygon archive) | ✓ | ✓ |
| Storm Briefings & City Tornado History pages | ✓ | ✓ |
| Weather detail panel for any map point | ✓ | ✓ |
| Phone call alerts (tornado + flash flood + proximity) | — | ✓ |
| Push notifications (all NWS types + risk score + pressure drop) | — | ✓ |
| Background alerting 24/7 | — | ✓ |
| Multi-location monitoring (home + 3 alert-enabled cities) | — | ✓ |
| Wildfire (NIFC) & earthquake (USGS) map overlays | — | ✓ |
| Prewarmed weather cache | — | ✓ |
| Alert history (30 days) | — | ✓ |
| Philips Hue smart light integration | — | ✓ Beta |
Triggered when the National Weather Service issues a Tornado Warning that includes your home location or a pinned city you've enabled alerts for.
You'll receive at most one call per active warning — if the same warning is extended or updated, you won't be called again for it.
Triggered by a Flash Flood Warning issued for your location. Disabled by default — enable it in Settings under Call Alerts.
Triggered when a tornado warning's storm is within your configured proximity radius (default 5 miles) and moving toward you.
Unlike the warning call — which is based on your county — the proximity check scans all active tornado warnings within range regardless of county lines. A tornado in the next county 3 miles away and heading your direction will trigger this call.
Two conditions must both pass before the call fires:
1. Distance — the storm (using NWS GPS coordinates when available, warning polygon edge as fallback) is within your proximity radius.
2. Direction — the storm's heading is within 90° of the bearing toward you. Storms moving away or parallel are suppressed.
All VORTEX alert calls come from (479) 552-5858.
Save this number in your contacts as VORTEX Alert so you recognize it immediately — and so Emergency Bypass works correctly (see below).
VORTEX places one call and reads the alert message twice within that call — so if you pick up partway through, you hear the full message. For the most reliable alerting, set up Emergency Bypass on the VORTEX contact directly.
iPhone — Emergency Bypass (Recommended)
Emergency Bypass allows a specific contact to ring and vibrate even when Do Not Disturb or Silent mode is on:
1. Save the VORTEX alert number as a contact (e.g. VORTEX Alert)
2. Open the contact → tap Edit
3. Tap Ringtone → enable Emergency Bypass
4. Tap Vibration → enable Emergency Bypass there too
With both enabled, the call will ring and vibrate regardless of Do Not Disturb, Silent mode, or Focus settings.
iPhone — Lock Your Ring Volume (Optional)
iOS allows apps and buttons to change your ringer volume independently of your media volume. To prevent your ring volume from being turned down accidentally:
Go to Settings → Sounds & Haptics → disable "Change with Buttons". This locks your ringer volume at its current level — note that this affects all incoming calls, not just VORTEX.
Android — Allow Calls Through Do Not Disturb
Android doesn't have Emergency Bypass, but you can allow specific contacts to ring through DND:
1. Save the VORTEX alert number as a contact (e.g. VORTEX Alert)
2. Star/favorite the contact by tapping the ★ icon
3. Go to Settings → Sound → Do Not Disturb → Allow exceptions
4. Enable Calls from starred contacts (or select the VORTEX Alert contact directly if your Android version supports it)
On Samsung devices the path is: Settings → Notifications → Do Not Disturb → Allow exceptions → Calls → set to Favourite contacts or All contacts.
Sent when the National Weather Service issues any of the following for your location:
🌪 Tornado Warning · 👁 Tornado Watch
⛈ Severe Thunderstorm Warning
🌊 Flash Flood Warning · 💧 Flood Warning
❄️ Winter Storm / Blizzard / Ice Storm Warning
💨 High Wind / Extreme Wind Warning
Pushes are deduplicated — the same active alert won't push more than once.
Sent when your atmospheric Risk Score exceeds your configured threshold, even when no NWS warning is active. This is your early signal that dangerous conditions are developing at your specific location — before an official warning is issued.
Push only — no call. Your threshold can be set between 65–100 in Settings.
How often you'll be alerted: VORTEX fires once when the Risk Score crosses your threshold, then stays quiet — even if conditions stay dangerous all night. You'll get a fresh alert when:
Each alert is designed to map to a real change in conditions rather than a repeating timer, so you're notified when something genuinely shifts instead of on a fixed schedule.
Sent when barometric pressure drops rapidly at your location — a real-time signal that a severe storm is actively approaching. Triggers when pressure falls ≥ 2 mb in a 30-minute window. 30-minute cooldown.
Phone calls and push notifications are powerful tools, but no single alert system is 100% reliable — calls can be missed, phones can be silenced, and cell networks can be congested during major events.
For best protection, pair VORTEX with additional alerting layers:
📻 NOAA Weather Radio — broadcasts official NWS warnings 24/7, independent of cell service.
🔊 Outdoor Warning Sirens — know where yours are and what they mean in your area.
🏠 Pre-planned Shelter — know where you're going before a warning is issued. Seconds matter.
👥 Multiple Devices — make sure others in your household have alerts enabled too.
The goal isn't to rely on any one system — it's to make sure at least one alert always gets through.
VORTEX delivers push notifications via ntfy.sh — a free, open-source notification service. You control your own private channel. No account required.
Download the ntfy app from the App Store (iPhone) or Google Play (Android). Search for ntfy.
In the ntfy app, tap + Subscribe to topic and enter a unique name — something only you would know, like vortex-yourname-8472. This becomes your private channel.
In VORTEX, go to Settings → Integrations → ntfy Channel URL and enter:
That's it. VORTEX will send all push alerts to that channel from now on.
On iPhone, go to Settings → ntfy → Notifications and make sure notifications are allowed. For critical alerts to break through Do Not Disturb, enable Critical Alerts if prompted.
Some Android manufacturers (Samsung, Xiaomi, OnePlus, etc.) aggressively restrict background processes, which can prevent push notifications from delivering reliably. To prevent this:
Go to Settings → Battery → Battery Optimization (or App Battery Usage) → find the ntfy app → set to Unrestricted or Don't optimize.
The Risk Score (0–100) is VORTEX's composite index of how dangerous current atmospheric conditions are at your location. It's calculated from the latest available forecast model data and recalculates every 30 seconds in-app and every minute in the background alert engine.
The score is conditioned on the SPC Day 1 tornado outlook: inside a 2% contour it's capped at 65, 5% at 80, 10% at 95, and 15%+ is uncapped. Outside a contour, that tier's influence extends up to 25 miles beyond its edge and fades smoothly with distance — the same 25-mile radius SPC itself uses to define "probability within 25 miles of a point" — instead of snapping to full strength the instant you cross a line on the map. Beyond 25 miles of every contour, scores above 30 are compressed into the 30–50 band instead of hard-capped, so quiet days still show visible differences. The SPC TORNADO badge beside the gauge reads the tier percentage when you're inside a contour, NEAR <tier> - <distance> MI when a tier's decaying influence is what's driving the number, or NONE when nothing is within 25 miles. If SPC data is unavailable or stale, the uncapped environmental score is shown (badge reads N/A) — an SPC outage never suppresses the score or your alerts.
| Factor | Max pts | What it measures |
|---|---|---|
| CAPE | 35 | Atmospheric instability — energy available for storm development |
| Storm Helicity | 30 | Rotational potential in the lowest 3 km — computed from model wind profiles (pressure-level winds and Bunkers storm motion), not estimated |
| Wind Shear | 15 | Change in wind speed/direction with altitude |
| Lifted Index | 10 | How easily air parcels rise — negative values indicate instability |
| Dewpoint | 6 | Moisture available to fuel storms |
| Humidity | 4 | Surface moisture |
The score is capped by the tornado-probability tier in the live SPC Day 1 outlook at your location, and that cap fades in gradually rather than switching on the instant you cross a contour line. Within a contour the numbers below apply at full strength; for up to 25 miles outside a contour, the cap's pull weakens smoothly with distance until it fully releases into the no-contour compression. This mirrors how SPC itself defines a tornado-probability percentage — the chance of a tornado within 25 miles of a point — so a location just outside the 5% line is treated as meaningfully different from one 20 miles outside it, not identically "uncapped."
| SPC Day 1 tornado outlook (inside the contour) | Score ceiling |
|---|---|
| None — no tornado contour within 25 mi | Compressed into 30–50 |
| 2% | 65 |
| 5% | 80 |
| 10% | 95 |
| 15%+ | Uncapped |
With no tornado contour within 25 miles, scores up to 30 pass through unchanged and anything above 30 is compressed into the 30–50 band (a raw 100 reads 50) rather than hard-capped — so differences between quiet days stay visible. The SPC TORNADO badge next to the gauge reads the tier percentage when you're inside a contour, NEAR <tier> - <distance> MI when a nearby contour's fading influence is what's driving the number, or NONE when every contour is more than 25 miles away.
When conditioning changes the displayed number, the risk pill shows both figures and says why: ADJUSTED means distance-based blending outside an outlook area is pulling the score toward the no-contour compression; CAPPED means you're inside a tier's contour and its ceiling is what set the number. ENV is the raw environmental score before either applies — it only appears alongside ADJUSTED or CAPPED, since otherwise the displayed score already is the environmental score.
| Data | Source | Source Updates | In-App | Background Alert Engine |
|---|---|---|---|---|
| NWS warnings & watches | api.weather.gov | As-issued (real-time) | 1 min | 1 min |
| Weather (CAPE, wind, etc.) | Open-Meteo | Hourly | 10 min | Hourly |
| Risk Score | Calculated | Hourly (inputs from Open-Meteo) | 30 sec | 1 min |
| Radar (US) | NEXRAD / Iowa State | ~5–10 min | 2 min | — |
| Global precipitation (IMERG) | NASA GIBS (GPM Late Run) | Every 30 min, ~3.5h source latency | 1–2 min | — |
| Satellite IR (cloud tops) | NASA GIBS (GOES-East Band 13) | Every 10 min, ~15–20 min source latency | 1–2 min | — |
| Earthquakes | USGS | ~1–5 min after detection | 5 min | — |
| Wildfires | NIFC via ArcGIS | 12–24 hrs (perimeters) | 5 min | — |
Live Radar (US): NEXRAD ground-based weather radar showing real-time precipitation intensity across the continental US, Alaska, Hawaii, and Puerto Rico. Best for current rain/snow/hail in storm cells. Updates every 5–10 min.
Global Precip (IMERG): NASA's satellite-derived global precipitation product. Unlike ground radar, IMERG works anywhere on Earth between 50°N and 50°S — over oceans, remote areas, and countries without dense radar networks. It's not as sharp or as current as NEXRAD (~3.5 hour latency), but it's the best available source for global precipitation and is useful for tracking storms moving in from the ocean or for international travel.
Satellite IR: Infrared imagery from the GOES-East geostationary satellite (Band 13, "Clean Infrared"). It shows the temperature of cloud tops — colder colors (purples, whites) mean very tall clouds, which usually means strong thunderstorms. Warmer colors (oranges, reds) mean low clouds or clear air. This is the view meteorologists use to spot storm development before radar can see inside it. Covers the Americas (GOES-East field of view). Updates every 10 min.
NWS Warnings: Active watches and warnings issued by the National Weather Service — tornado, severe thunderstorm, flash flood, winter storm, and more. Polygons on the map match the exact area the NWS warned. US only. During a tornado warning, the red or amber dot is the storm's current position and the trailing dots are our 15- and 30-minute projections — tap any of them for warning details and live projection accuracy.
Risk Score: VORTEX's proprietary 0–100 severe weather composite, calculated from CAPE, storm-relative helicity, wind shear, humidity, dewpoint, and lifted index. Updated every 30 seconds at your pinned locations, hourly across the broader map.
Heatmap layers (Temperature, Wind Vectors, Humidity, CAPE Index, Dewpoint): free overlays that color the map by the selected atmospheric variable. Useful for "why is the risk score high right now?" — toggle CAPE or Wind Vectors to see what's driving it. Heatmap layers currently require the legacy map (append ?oldmap=1 to the URL); native MapLibre support is on the roadmap.
Past Tornadoes: Reported tornado touchdowns from SPC's daily storm reports, covering April 2025 to present. Most reports stay preliminary: SPC's rating field is not upgraded after publication, so a dot shows an EF rating only when an NWS damage survey result appears in the report text — those are marked as survey-derived. Everything else is labelled Preliminary. Tap any dot for date, rating, and path details. Free.
Past Warnings: NWS tornado-warning polygon archive. Shows every warned area over the recent window with a dark halo so you can see how often your neighborhood has been under a warning. Free.
Earthquakes & Wildfires (Pro): Recent earthquake points from USGS (global, last 7 days, magnitude-scaled) and active wildfire perimeters from NIFC (US only). Hover or tap any point for details.
Alaska & Hawaii cards: The MapLibre base uses Web Mercator projection, so Alaska and Hawaii aren't inset into the CONUS view like on old-style maps. Instead, small clickable cards in the bottom-left corner of the map show the current active-alert count for each state — tap a card to fly the map to that region.
A daily plain-English write-up of what the atmosphere is doing — active threats, storm recaps, explainers, and historical deep-dives. Generated every afternoon from SPC outlooks and the last 24 hours of local storm reports, then validated against the source data before publishing.
Open Menu → Storm Briefings or visit vortexintel.app/blog. Free for everyone.
Browse every surveyed tornado within a 25-mile radius of 3,000+ US cities, going back to 1950. Each city page shows total count by decade, strongest event, most-active month, and a paginated list of individual events with EF rating, length, width, and fatalities.
Open Menu → Tornado History or visit vortexintel.app/tornadoes. State hubs (/tornadoes/arkansas, etc.) link out to city-level pages. Free for everyone.
| Alert type | Cooldown | Daily cap |
|---|---|---|
| Tornado / Flood warning call | Once per active warning | None |
| Proximity alert call | Once per active warning | None |
| Risk Score push | Edge-triggered (rearm on −5 dip, or 6h fallback) | None |
| Pressure drop push | 30 min | None |
| NWS warning pushes | Once per active event | None |
All alerts apply to your home location by default. You can also enable alerts for any pinned city by toggling the Alert switch on that city in Settings → My Cities.
The background engine checks all alert-enabled locations on every run — home location and any alert-enabled cities are all monitored simultaneously.
Pro accounts can have up to 3 alert-enabled cities in addition to the home location. You can pin up to 10 cities total on the map, but only 3 can have background alerting active at a time. Disable one to free up a slot.