Environment · Instrument dossier
Severe Weather
Active watches, warnings and advisories issued by the US National Weather Service, with the source's own severity, urgency and affected areas. Escalating alert volumes can indicate a major weather system affecting people, transport and power infrastructure.
Current reading
406 active weather alerts at the latest collection. Not enough data yet for a historical comparison.
Reading time:
United States and territories only. This is not a global weather monitor.
- Collector availability
- Live
- Collection freshness
- Last successful collection .
Historical comparison
Severe Weather at each collection · breaks = gaps (not interpolated) · expected range appears once 5 earlier days exist at each hour
Interpretation
Not enough data yet. The available history cannot establish whether this reading is typical or unusual.
What movement could mean
- A large storm system
- Heat, flood or winter weather events
Descriptive only. No predictive validity for non-weather events has been tested. Source-reported severity, statistical deviation and real-world risk are different questions. This reading does not independently support a hypothesis about intent or cause.
Evidence and limitations
- Cadence and latency
- Collection is scheduled every 30 minutes. Collection cadence is not source latency; no measured end-to-end latency is provided here. Source publication and revisions can delay what is visible.
Known false-positive patterns
- Routine seasonal advisories
- Many small zones covered by one weather system
Coverage and blind spots
- US coverage only.
- Alert counts have strong seasonal and time-of-day patterns.
- Source severity is not the same as a statistical anomaly or a risk judgment.
Technical detail
- Measurement definition
- Each observation is one NWS alert. At every collection the observatory also records how many alerts are active, building a history from which a baseline can later be estimated.
- Raw metric
- active_alerts
- Method
- Alerts are upserted by their NWS identifier. Severity is copied exactly as NWS classifies it (Extreme, Severe, Moderate, Minor, Unknown). Map points are polygon centroids, marked as approximate; alerts without geometry are not mapped.
- Stored observations
- 807
Normal versus unusual
A baseline cannot yet be established. The observatory needs more history before it can say what "normal" looks like for this signal, so no anomaly score is shown.
4 historical samples so far · Snapshot count vs. historical snapshots
Source severity
The label the publishing agency assigns (e.g. NWS 'Severe'). Shown verbatim.
Statistical anomaly
How far today's value sits from this signal's own history. Says nothing about consequences.
Real-world risk
A judgment the observatory does not make. Consult official sources for safety decisions.
Observations in range
- Beach Hazards Statement issued November 1 at 10:29AM PST until November 2 at 6:00PM PST by NWS Los Angeles/Oxnard CANWSSevere WeatherUnited Statessource severity: Moderate
- Flash Flood Warning issued November 1 at 11:27AM MST until November 1 at 2:30PM MST by NWS Tucson AZNWSSevere WeatherUS · AZsource severity: Severe
- Small Craft Advisory issued November 1 at 1:25PM EST until November 2 at 3:00AM EST by NWS Wilmington NCNWSSevere WeatherUS · NC, SC, NMsource severity: Minor
- Special Marine Warning issued November 1 at 1:24PM EST until November 1 at 3:30PM EST by NWS Tallahassee FLNWSSevere WeatherUS · NM, FLsource severity: Severe
- Special Weather Statement issued November 1 at 1:23PM EST by NWS Tallahassee FLNWSSevere WeatherUnited Statessource severity: Moderate
- Marine Weather Statement issued November 1 at 2:23PM AST by NWS San Juan PRNWSSevere WeatherUS · NMsource severity: Minor
- Flood Watch issued November 1 at 11:22AM MST until November 1 at 10:00PM MST by NWS El Paso Tx/Santa Teresa NMNWSSevere WeatherUnited Statessource severity: Severe
- Small Craft Advisory issued November 1 at 1:20PM EST until November 2 at 7:00AM EST by NWS Jacksonville FLNWSSevere WeatherUS · FL, NMsource severity: Minor
- Small Craft Advisory issued November 1 at 1:20PM EST until November 3 at 11:00PM EST by NWS Jacksonville FLNWSSevere WeatherUS · FL, NMsource severity: Minor
- Small Craft Advisory issued November 1 at 1:20PM EST until November 4 at 4:00AM EST by NWS Jacksonville FLNWSSevere WeatherUS · GA, FL, NMsource severity: Minor
- Rip Current Statement issued November 1 at 1:20PM EST until November 3 at 7:00PM EST by NWS Miami FLNWSSevere WeatherUnited Statessource severity: Moderate
- Coastal Flood Advisory issued November 1 at 1:20PM EST until November 2 at 7:00PM EST by NWS Miami FLNWSSevere WeatherUnited Statessource severity: Minor
- High Surf Advisory issued November 1 at 1:20PM EST until November 2 at 7:00AM EST by NWS Miami FLNWSSevere WeatherUnited Statessource severity: Minor
- Coastal Flood Advisory issued November 1 at 1:20PM EST until November 2 at 7:00PM EST by NWS Miami FLNWSSevere WeatherUnited Statessource severity: Minor
- Rip Current Statement issued November 1 at 1:20PM EST until November 3 at 7:00PM EST by NWS Miami FLNWSSevere WeatherUnited Statessource severity: Moderate
- Small Craft Advisory issued November 1 at 1:19PM EST until November 3 at 10:00AM EST by NWS Miami FLNWSSevere WeatherUS · FL, NMsource severity: Minor
- Rip Current Statement issued November 1 at 1:13PM EST until November 3 at 11:00PM EST by NWS Jacksonville FLNWSSevere WeatherUnited Statessource severity: Moderate
- Coastal Flood Advisory issued November 1 at 1:13PM EST until November 2 at 7:00PM EST by NWS Jacksonville FLNWSSevere WeatherUnited Statessource severity: Minor
- High Surf Advisory issued November 1 at 1:13PM EST until November 2 at 7:00PM EST by NWS Jacksonville FLNWSSevere WeatherUnited Statessource severity: Minor
- Rip Current Statement issued November 1 at 1:13PM EST until November 3 at 11:00PM EST by NWS Jacksonville FLNWSSevere WeatherUnited Statessource severity: Moderate
- Rip Current Statement issued November 1 at 1:13PM EST until November 3 at 11:00PM EST by NWS Jacksonville FLNWSSevere WeatherUnited Statessource severity: Moderate
- Coastal Flood Advisory issued November 1 at 1:13PM EST until November 2 at 7:00PM EST by NWS Jacksonville FLNWSSevere WeatherUnited Statessource severity: Minor
- Small Craft Advisory issued November 1 at 1:12PM EST until November 4 at 7:00AM EST by NWS Charleston SCNWSSevere WeatherUS · SC, GA, NMsource severity: Minor
- Small Craft Advisory issued November 1 at 1:12PM EST until November 1 at 7:00PM EST by NWS Charleston SCNWSSevere WeatherUnited Statessource severity: Minor
- Small Craft Advisory issued November 1 at 1:12PM EST until November 5 at 7:00AM EST by NWS Charleston SCNWSSevere WeatherUS · GA, NMsource severity: Minor
- Small Craft Advisory issued November 1 at 1:12PM EST until November 4 at 7:00AM EST by NWS Charleston SCNWSSevere WeatherUS · SC, NMsource severity: Minor
- Small Craft Advisory issued November 1 at 1:12PM EST until November 4 at 7:00AM EST by NWS Charleston SCNWSSevere WeatherUS · GAsource severity: Minor
- Flood Warning issued November 1 at 11:11AM MST until November 1 at 1:00PM MST by NWS Phoenix AZNWSSevere WeatherUS · AZsource severity: Severe
- Flood Warning issued November 1 at 11:09AM MST until November 1 at 2:45PM MST by NWS Flagstaff AZNWSSevere WeatherUS · AZsource severity: Severe
- Flood Advisory issued November 1 at 10:05AM PST until November 1 at 11:00AM PST by NWS Las Vegas NVNWSSevere WeatherUS · AZsource severity: Minor
- Flood Warning issued November 1 at 11:04AM MST until November 3 at 5:00AM MST by NWS Albuquerque NMNWSSevere WeatherUS · NMsource severity: Severe
- Flood Warning issued November 1 at 11:04AM MST until November 1 at 5:00PM MST by NWS Phoenix AZNWSSevere WeatherUS · AZsource severity: Severe
- Flood Warning issued November 1 at 11:03AM MST until November 3 at 4:00AM MST by NWS Albuquerque NMNWSSevere WeatherUS · NMsource severity: Severe
- Flood Warning issued November 1 at 11:02AM MST until November 3 at 2:00AM MST by NWS Albuquerque NMNWSSevere WeatherUS · NMsource severity: Severe
- Flash Flood Warning issued November 1 at 11:02AM MST until November 1 at 2:15PM MST by NWS Flagstaff AZNWSSevere WeatherUS · AZsource severity: Severe
- Special Marine Warning issued November 1 at 1:02PM EST until November 1 at 1:45PM EST by NWS Miami FLNWSSevere WeatherUnited Statessource severity: Severe
- Small Craft Advisory issued November 1 at 1:01PM EST until November 1 at 10:00PM EST by NWS Caribou MENWSSevere WeatherUS · ME, NMsource severity: Minor
- Small Craft Advisory issued November 1 at 12:01PM CST until November 4 at 3:00PM CST by NWS Milwaukee/Sullivan WINWSSevere WeatherUS · WI, ILsource severity: Minor
- Beach Hazards Statement issued November 1 at 10:01AM PST until November 2 at 6:00PM PST by NWS San Diego CANWSSevere WeatherUnited Statessource severity: Moderate
- Flash Flood Warning issued November 1 at 11:00AM MST until November 1 at 2:15PM MST by NWS Flagstaff AZNWSSevere WeatherUS · AZsource severity: Severe
- Rip Current Statement issued November 2 at 3:59AM ChST until November 2 at 4:00PM ChST by NWS Tiyan GUNWSSevere WeatherUnited Statessource severity: Moderate
- High Surf Advisory issued November 2 at 3:59AM ChST until November 2 at 4:00PM ChST by NWS Tiyan GUNWSSevere WeatherUnited Statessource severity: Minor
- Flood Watch issued November 1 at 12:58PM EST until November 2 at 3:00PM EST by NWS Tampa Bay Ruskin FLNWSSevere WeatherUnited Statessource severity: Severe
- Flash Flood Warning issued November 1 at 12:58PM EST until November 1 at 2:15PM EST by NWS Melbourne FLNWSSevere WeatherUS · FLsource severity: Severe
- Winter Storm Warning issued November 1 at 10:57AM MST until November 2 at 11:00AM MST by NWS Pueblo CONWSSevere WeatherUnited Statessource severity: Severe
- Marine Weather Statement issued November 1 at 12:56PM EST by NWS Key West FLNWSSevere WeatherUS · NMsource severity: Minor
- Flood Warning issued November 1 at 10:53AM MST until November 2 at 8:00AM MST by NWS Phoenix AZNWSSevere WeatherUS · AZsource severity: Severe
- Winter Storm Warning issued November 1 at 8:52AM AKST until November 1 at 3:00PM AKST by NWS Juneau AKNWSSevere WeatherUnited Statessource severity: Severe
- Flood Warning issued November 1 at 9:52AM PST until November 2 at 9:15AM PST by NWS Las Vegas NVNWSSevere WeatherUS · AZsource severity: Severe
- Flood Advisory issued November 1 at 12:52PM EST until November 1 at 2:45PM EST by NWS Miami FLNWSSevere WeatherUS · FLsource severity: Minor
- Flash Flood Warning issued November 1 at 10:52AM MST until November 1 at 1:45PM MST by NWS Tucson AZNWSSevere WeatherUS · AZsource severity: Severe
- Flood Warning issued November 1 at 10:50AM MST until November 2 at 7:00PM MST by NWS Grand Junction CONWSSevere WeatherUS · COsource severity: Severe
- Small Craft Advisory issued November 1 at 9:50AM PST until November 1 at 9:00PM PST by NWS Eureka CANWSSevere WeatherUS · CAsource severity: Minor
- Flood Watch issued November 1 at 12:49PM EST until November 2 at 3:00PM EST by NWS Miami FLNWSSevere WeatherUnited Statessource severity: Severe
- Flood Watch issued November 1 at 12:49PM EST until November 2 at 3:00PM EST by NWS Miami FLNWSSevere WeatherUnited Statessource severity: Severe
- Flash Flood Warning issued November 1 at 10:49AM MST until November 1 at 2:00PM MST by NWS Tucson AZNWSSevere WeatherUS · AZsource severity: Severe
- Flood Advisory issued November 1 at 12:43PM EST until November 1 at 2:15PM EST by NWS Melbourne FLNWSSevere WeatherUS · FLsource severity: Minor
- Flash Flood Warning issued November 1 at 10:43AM MST until November 1 at 1:45PM MST by NWS Tucson AZNWSSevere WeatherUS · AZsource severity: Severe
- Frost Advisory issued November 1 at 12:40PM EST until November 2 at 8:00AM EST by NWS Mount Holly NJNWSSevere WeatherUnited Statessource severity: Minor
- Winter Weather Advisory issued November 1 at 10:40AM MST until November 2 at 8:00PM MST by NWS Billings MTNWSSevere WeatherUnited Statessource severity: Moderate
Recent collection runs
- · running · 0 stored
- · success · 406 stored
- · success · 406 stored
- · success · 407 stored
- · success · 406 stored
- · success · 410 stored
- · success · 402 stored
- · success · 405 stored
- · failed · 0 stored · Interrupted before finishing (no result recorded)
- · success · 404 stored
- · success · 402 stored
- · success · 398 stored
How this works
We read every active alert from the US National Weather Service every 30 minutes. Severity (Extreme, Severe, Moderate, Minor) is copied exactly as NWS states it; we never re-grade it.
The number we watch is how many alerts are active at each collection. "Normal" is the count at the same hour of the day on earlier days (at least 5 such hours), because storms and warnings follow a daily cycle.
Limits: US only. Busy storm seasons push counts up for weeks, which this comparison does not yet adjust for. Map dots are the middle of each alert's area, not a storm's position.
FAQ
- Is an "Extreme" alert an anomaly?
- Not by itself. Severity is NWS's judgement of one alert. Our anomaly reading is about the number of alerts compared with normal — a separate question.
- Why only the US?
- NWS publishes a clean, free, machine-readable feed. Other countries' services vary and aren't connected yet.