Conditions are favorable for a hazardous weather event to develop in the watch area, but one has not yet occurred. A watch is issued hours in advance — sometimes a day or more — to give people time to prepare.

Think of a watch as: "Be ready. This could happen."

Examples: Tornado Watch, Severe Thunderstorm Watch, Flash Flood Watch. Watches typically cover large areas — often multiple counties.

A hazardous weather event is imminent, occurring, or has been detected. Warnings require immediate action — take shelter, move to higher ground, or get off the water now.

Think of a warning as: "Take action now. This is happening."

Examples: Tornado Warning, Severe Thunderstorm Warning, Flash Flood Warning. Warnings target smaller, more specific areas than watches.

Conditions will cause significant inconvenience and may be hazardous if caution is not exercised, but the threat does not rise to warning level.

Think of an advisory as: "Be aware and take extra care."

Examples: Heat Advisory, Wind Advisory, Winter Weather Advisory, Frost Advisory.

The National Weather Service uses Impact-Based Warnings (IBW) to communicate not just that a storm is occurring, but how severe and what type of damage to expect. StormPulse reads these tags directly from NWS alert data and highlights them in the alert display.

Like tornado warnings, NWS severe thunderstorm warnings use an Impact-Based Warning system with four tiers. In StormPulse, these are color-coded from yellow through dark pink so you can immediately gauge severity.

The Storm Prediction Center (SPC) is a division of NOAA/NWS based in Norman, Oklahoma. They issue daily forecasts for severe thunderstorm and tornado risk across the contiguous United States — called Convective Outlooks — for Days 1 through 8.

StormPulse queries the SPC's data for Days 1–3 and displays the risk level and hazard probabilities in each 7-day forecast card.

For Days 1 and 2, StormPulse also shows the SPC's probabilistic forecasts for three specific hazards. These represent the probability of that hazard occurring within 25 miles of any given point in the outlook area.

Tornado probability: Chance of a tornado within 25 miles of you.
Hail probability: Chance of hail ≥1" (quarter size) within 25 miles.
Wind probability: Chance of wind gusts ≥58 mph within 25 miles.

A 10% tornado probability sounds low — but it means on days with similar setups, a tornado occurs within 25 miles of that point 1 in 10 times. That is meaningful risk worth monitoring.

The Enhanced Fujita Scale rates tornado intensity based on damage to structures and vegetation after the tornado has passed. It ranges from EF0 (weakest) to EF5 (strongest). The "EF" replaced the older "F" Fujita scale in 2007 with improved damage indicators.

EF ratings are assigned by NWS damage survey teams after a tornado event and are not known in real time during an active warning.

Dew point is the temperature at which air becomes fully saturated with moisture — when dew point equals the air temperature, you get fog, dew, or precipitation. Higher dew point = more moisture in the air = more humid it feels.

Unlike relative humidity (which changes with temperature), dew point is a direct, stable measure of how much water vapor is actually in the air. A dew point of 70°F feels oppressive whether the air temperature is 80° or 100°.

If you've always been a little confused about what rain chances actually mean, you're not alone — it's one of the most commonly misunderstood concepts in weather. Most of us have grown up hearing different explanations, and honestly, even the official definition isn't the most intuitive thing in the world.

Here's the simple version: rain probability is the likelihood that rain will fall at your specific location during a given time period. It's not about how much of your area will see rain, how long it will last, or how hard it will rain. A 70% chance of rain and it stays sunny at your house all day? The forecast wasn't wrong — rain just happened somewhere else in the region, not at your exact spot.

Think of it this way:

The 24-hour rain chances chart in Your Backyard Forecast shows hourly probabilities as color-coded bars:

■ Yellow (70%+) — Rain likely
■ Bright blue (40–69%) — Rain expected
■ Faint blue (5–39%) — Rain possible

The 7-day forecast cards show the daily maximum precipitation probability — the highest hourly probability across the entire day.

Feels-like temperature (also called apparent temperature) is a calculated value that combines air temperature with other factors to estimate how hot or cold it actually feels to a person outdoors. It accounts for two effects:

Heat index (warm weather): When temperature and humidity are both high, your body's ability to cool itself through sweating is reduced. The combination makes it feel hotter than the actual temperature. A heat index above 103°F is dangerous with prolonged exposure.

Wind chill (cold weather): Moving air strips heat away from exposed skin faster than still air. Cold temperatures combined with wind can feel significantly colder than the thermometer reading.

Local Storm Reports (LSRs) are official reports issued by NWS forecast offices documenting confirmed severe weather events. They are submitted by trained storm spotters, emergency managers, law enforcement, and the public — then verified and issued by NWS meteorologists.

StormPulse automatically displays LSRs within 75 miles of your location from the past 24 hours when any of the following have been reported nearby:

🌪 Tornado · 🌀 Funnel Cloud · 🌩 Wall Cloud · 🧊 Hail · 💨 Thunderstorm Wind Damage · 💨 Thunderstorm Wind Gust · 🌊 Flash Flood · 🌊 Flood · 🌬 Non-Thunderstorm Wind

Each storm report shows the event type, magnitude (e.g. hail size in inches, wind speed in mph), the reporting location, and the time of the event. Reports are sourced directly from NOAA's NWS LSR MapServer and refresh every 30 minutes.

LSRs represent confirmed events that have already occurred — they are historical records, not active warnings. An active Tornado Warning or Severe Thunderstorm Warning in the alert banner should always take priority.