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Space Weather Forecasting

Strategy: Begin at any one of the Steps below and try to predict what will happen at a future step. For example, start at Step1 and try to predict what will happen at Step 2 or Step 4. Start at Step 2 and predict what will happen at Step 3.

Step 1: Is there any solar activity present? The basic rule of thumb is that, if there are no sunspots, or if the sunspots are very small, it is unlikely that the conditions are present for solar storms that could trigger bad space weather here at Earth. Visit the National Solar Observatory or the Big Bear Solar Observatory links to get the latest image of the sun, and check for sunspots. Also visit the NOAA archive of solar data which summarizes the last 30 days of flares, sunspots and sunspot area. Here is a suggested scale from archived Mees Observatory images:

Class 0: No spots that you can easily see

Class 1: A few spots but not very large

Class 2: A medium-sized spot, or large group

Class 3: One or more very large spots

Step 2: Has a Coronal Mass Ejection Been launched towards Earth? A summary of the latest CME events is presented at NOAA . You can also visit the SOHO satellite image archive of CME events. Here is an example of a NOAA report that summarizes current solar activity:

"SPACE WEATHER ADVISORY BULLETIN #05- 11
2005 September 14 at 11:30 a.m. MDT (2005 September 14 1730 UTC): NOAA sunspot Region 808 continues to produce major solar flare activity as it rotates to the center of the visible surface of the Sun. On September 13, this sunspot region produced three solar flares that resulted in strong radio blackouts. A large Earth-directed coronal mass ejection (CME) erupted during one of these flares, and is expected to create a significant geomagnetic disturbance late today or early on September 15. Because of the current position of this region on the Sun, further flare activity has greater potential to impact Earth. Major flare activity over the next few days may result in significant geomagnetic and radiation storms. The threat of significant solar activity from Region 808 will diminish as it rotates to the far side of the Sun on September 21-22.."


CME images will show two kinds. Most CMEs look very dramatic because they come out from the sides of the sun, but these are directed away from Earth and do not affect us. CMEs directed towards Earth are called Halo CMEs because they look like an expanding cloud surrounding the entire disk of the sun. These are the ones you want to look for. Because we can see them on the far side of the sun, only about half of the Halo CMEs are on our side of the sun and directed wowards Earth. The second image below also shows that Halo CMEs produce showers of high-energy particles that cause 'snow' in the images taken by the SOHO satellite. See the two pictures below:

CME directed away from Earth

Halo CME and particle event 'snow'


Step 3: Has a disturbance been registered by the ACE satellite? If the sun has been active, and if NOAA reports that a CME is headed our way, yo ucan get a 1-hour notice of whether it is about to arrive by looking at data from the ACE satellite. The most important data is the strength and direction of the 'Bz' component of the solar wind magnetic field shown in the top plot in red. If this is large and negative, ( like -10 ,-50 ,-35 )the solar storm will produce a major effects here at Earth. If it is positive, (like +10, + 15, +25) the effects will be very minor or perhaps even absent. The data from ace looks like this:

ACE data. Bz at top in red


Step 4: Is there a magnetic storm in progress? The two best ways to check this are by looking at the Kp and Dst indices. The Kp index is available at NOAA and looks like the bar graph below. Every 3 hours, an estimate is made on a 9-point scale of how disturbed Earth's magnetic field is. '9' is extremely disturbed, while '1' to '4' is calm conditions. Anything above '7' means that a magnetic storm is in progress. A second line plot shows the Dst index and is provided at Kyoto Observatory. When yo usee a sharp downward change in this index, that means a severe magnetic storm is occurring. Normally, a large Kp value will show up in the Dst plot as a large downward change by up to 400 nT.

Kp graph with a Storm on October 22, 2001

Dst plot with a storm on October 28, 2003


Step 5: Have any aurora been sighted? The best way to check this is to actually live in Alaska where you can look at the sky and see an aurora! You can check the NOAA auroral activity images created by satellites. The first image shows typical daily activity which you can rate as 'Mild to Weak' that corresponds to Kp values of about '4'. The second image shows an active day that corrresponds to Kp values above 8.

NOAA Auroral Activity. Mild-Weak Kp=4

October 2003 Severe Storm. Kp=9

Additional Resources:

IMAGE Tracking a solar storm. A PDF file that introduces more advanced approaches to solar storm tracking, developed by the IMAGE satellite program. See also their illustrated guide with more details.

NASA Student Observation Network. Developed by NASA educators, this is a comprehensive introduction to solar storm tracking in which students may network across the world to make and log their own forecasts using an extensive collection of satellite and ground-based data from online sources, as well as student-built instruments.