Space Weather
Space Weather
Space weather describes changing environmental conditions in near-Earth space. Magnetic fields, radiation, particles and matter, which have been ejected from the Sun, can interact with the Earth’s upper atmosphere and surrounding magnetic field to produce a variety of effects.
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Aurora forecasts
Northern Hemisphere
The auroral oval may be slightly enhanced at times through this period, but with aurora mostly confined to higher latitudes. There is just a slight chance of visible aurora reaching northern Scotland and similar latitudes, mainly overnight 27/28 April and again on 30 April, and perhaps later on 1 May.
Southern Hemisphere
The auroral oval may be slightly enhanced at times through this period, but with aurora mostly confined to higher latitudes. The greatest chance of visible aurora is overnight on 27/28 April and again on 30 April, and perhaps later on 1 May.
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Forecast overview
Space Weather Forecast Headline: Chance of Moderate-class flares and slight chance of Strong flares.
Analysis of Space Weather Activity over past 24 hours
Solar Activity: Activity is currently Moderate, with two lower Moderate class flares from the largest and most magnetically complex region, currently located in the southwest quadrant of the visible disc. Aside from this region the other regions are relatively small, simple and stable or in slight decay. Seven of these lie in the western solar hemisphere, with one toward the northeast limb.
A Coronal Mass Ejection (CME) was observed starting around 26/1830 UTC, which emerged from the southeast of the disc. The resulting CME is mostly passing behind and below Earth's orbit, but there is just a slight chance of a glancing blow early on day 3 (30 Apr).
Solar Wind / Geomagnetic Activity: Solar winds have shown the onset of a coronal hole fast wind, perhaps combined with some weak CME influence. Wind speeds started at background levels but rose to become elevated approaching midday UTC, from around 330 km/s to near 500 km/s. Thereafter, wind speeds reduced erratically, 400-450km/s. The Interplanetary Magnetic Field has been mostly Moderate, but with some brief Strong peaks between 27/0400-0630 UTC. However, in recent hours it has become weak The north-south component showed alternating periods of moderately north/south orientation. Geomagnetic activity was Quiet to Unsettled (Kp 1 to 3).
Energetic Particles / Solar Radiation: Solar radiation was at background levels.
Four-Day Space Weather Forecast Summary
Solar Activity: There is a chance of Moderate-class flares and a slight chance of Strong flares, this mainly from the largest and most magnetically complex group, which is currently in the southwest quadrant.
Solar Wind / Geomagnetic Activity: A CME which originated late on 26 Apr from an area of plage and a filament eruption in the southeast of the disc, could give a glancing blow early on day 3 (30 Apr).
Recent coronal hole fast wind influence from has weakened during the second half of the 27 Apr. However, further weak coronal hole influences from two further small coronal holes in the southwest are possible in the next few days, although these lie progressively further to the south. Later on day 4 (1 May) a more likely connection comes from the narrow trans-equatorial coronal hole, which could become geoffective. This is a recurrent feature which gave Unsettled geomagnetic conditions on the last rotation.
Geomagnetic activity is expected to be Quiet to Unsettled for much of the period, but with a slight chance of Active to G1/Minor Storm intervals, mainly on days 1, 3 and 4 due to coronal hole or possible glancing CME influences.
Energetic Particles / Solar Radiation: Solar radiation is likely to remain at background levels, but with a decreasing slight chance of reaching the S1/Minor Radiation Storm threshold, as the sunspot cluster which was in the southwest rotates well away from the limb.
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Solar imagery
SDO AIA-193
This channel highlights the outer atmosphere of the Sun - called the corona - as well as hot flare plasma. Hot active regions, solar flares, and coronal mass ejections will appear bright here. The dark areas - called coronal holes - are places where very little radiation is emitted, yet are the main source of solar wind particles.
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SDO AIA-304
This channel is especially good at showing areas where cooler dense plumes of plasma (filaments and prominences) are located above the visible surface of the Sun. Many of these features either can't be seen or appear as dark lines in the other channels. The bright areas show places where the plasma has a high density.
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