Solar Events (Space Weather) – Warning Alert Notifications

Coronal Mass Ejection[5]

The technological infrastructure, including the power grid and satellites used for communication and navigation, is vulnerable to space weather effects caused by the Sun’s variability. Awareness of the issue is on the rise both nationally and globally.

The NASA Goddard Space Weather Research Center provides space weather forecast, analysis and notifications mainly for NASA’s robotic missions, but is also available to the public.[1]

Likewise, the NOAA / NWS Space Weather Prediction Center (SWPC) is the nation’s official source of space weather alerts, watches and warnings.  SWPC provides real-time monitoring and forecasting of solar and geophysical events which impact satellites, power grids, communications, navigation, and many other technological systems. Receive NOAA Space Weather alerts, warnings, watches, forecasts, and summaries via email within moments of issue.[2]

Severity of Space Weather Alert Messages

There are 4 types of Space Weather Alert Messages issued by NOAA/Space Weather Prediction Center in the order of severity:[3]

Watch messages are issued for long-lead-time geomagnetic activity predictions.

Warning messages are issued when some condition is expected. The messages contain a warning period and other information of interest.

Alert messages are issued when an event threshold is crossed and contain information that is available at the time of issue.

Summary messages are issued after the event ends, and contain additional information available at the time of issue.


Categories of Space Weather Alert Messages

Space Weather Alert Messages are issued for the following categories with alerting criteria and descriptions:[4]

A solar X-ray flux arises from two factors. First, there is flux coming from sunspot regions and other features - the background flux - and this varies slowly from day-to-day. Second, solar flares produce large amounts of X-ray flux, but this is concentrated to the duration of the flare which is usually from minutes to several hours.

X-ray Flux ALERT: Issued in near-real-time, when flare x-ray flux exceeds the M5 (NOAA Scale R2 Moderate) level. Includes time of occurrence.

X-ray Event SUMMARY: Issued for all flares exceeding M5, after decrease to half-peak flux level. Includes event begin, maximum, and end times, optical class, location, the peak flux level (M5, X1, X10, or X20) and the appropriate NOAA Space Weather Scale (R2-R5).

Solar radio bursts begin with a solar flare that injects high-energy electrons into the solar upper atmosphere. Radio waves are produced which then propagate to the Earth and cover a broad frequency range. The radio waves act as noise over these frequencies including those used by GPS and other navigational systems which can degrade a signal.

Radio Burst ALERTS are issued based on the confirmed onset of Type II and IV radio sweep observations.

A Radio Burst SUMMARY will be issued for 10 cm Radio Bursts, upon receipt of a final observation report.

Geomagnetic Sudden Impulses (SIs) are sudden increases in the solar wind pressure as shock waves that hit the Earth and effect the geomagnetic field. These events are normally associated with events such as solar flares or Coronal Mass Ejections (CMEs).

A Geomagnetic Sudden Impulse WARNING is issued based primarily on solar wind data available from the ACE satellite. These warnings are generally for short lead-time (10-60 minutes), high confidence indication of an expected Geomagnetic Sudden Impulse, and possible onset of subsequent geomagnetic storming.

A Geomagnetic Sudden Impulse SUMMARY is issued upon its observation, and will generally be based on data from the primary Boulder USGS magnetometer, but may be based on a specified alternate magnetometer station if Boulder data is not available

K indexes reflect the geomagnetic conditions (solar particle effects on the earth's magnetic field). The K-index scale has a range from 0 to 9 (with 0 being inactive and 9 representing an extreme severe storm condition) and is directly related to the maximum amount of fluctuation (relative to a quiet day) in the geomagnetic field over a three-hour interval. Lower numbers mean a quieter ionosphere. The propagation of radio signals in the medium frequency band (MF: 300kHz-3MHz), the high frequency band (HF: 3MHz-30MHz) and even the very high frequency band (VHF: 30MHz-300MHz) are largely influenced by the condition and emissions of our sun. Trends in the K indexes are important to watch. When K rises you can expect HF propagation conditions to worsen, particularly towards the polar regions. On VHF bands a high K index would mean the possibility of an Aurora opening.

K-index Watches are long-lead-time predictions of the expected trend in geomagnetic activity (NOAA Planetary values). The highest expected K-index for a calendar day determines the Watch level and is reported in terms of the NOAA G scale. Each issued Watch supersedes all previous Watches.

K-index WARNINGS are issued by SWPC under two conditions: Warning of expected ONSET of geomagnetic activity, and/or, warning of expected PERSISTENCE of geomagnetic activity.

Electron Flux ALERTS for Electron Events are therefore issued once per "satellite day" based on data from SWPC's primary GOES satellite, when electron fluxes have exceeded the event threshold (1000 pfu).

During a large solar flare event, the Earth is showered with highly energetic solar particles (primarily protons) released from the flare site. When these protons arrive at Earth and enter the atmosphere over the polar regions, much enhanced ionization is produced at altitudes below 100 km. Ionization at these low altitudes is particularly effective in absorbing HF radio signals and can render HF communications impossible throughout the polar regions. This effect is called Radio Blackouts.

Proton Event products are issued for several thresholds. The 10 MeV products match the NOAA Solar Radiation Storm (S-scale) thresholds, based upon values observed on the primary GOES satellite.

Proton Event WARNINGS are issued by SWPC under two conditions: Warning of expected ONSET of a Proton Event, and/or, warning of expected PERSISTENCE of a Proton Event.



  1. NASA Goddard Space Weather Research Center Notifications –
    Space Weather Prediction Center –
  2. NOAA Space Weather Prediction Center’s Product Subscription Service –
  3. NOAA Space Weather Prediction Center –
  4. NOAA Space Weather Prediction Center –
  5. Image Source: [Accessed August 17, 2013]