Scientists around the world will be watching closely as three eruptions from the Sun reach the Earth over Thursday and Friday.
These "coronal mass ejections" will slam into the Earth's magnetic shield.
The waves of charged solar particles are the result of three solar flares directed at Earth in recent days, including the most powerful since 2006.
The biggest flares can disrupt technology, including power grids, communications systems and satellites.
The northern lights (Aurora Borealis) may also be visible further south than is normally the case - including from northern parts of the UK.
"Our current view is that the effect of the solar flare is likely to reach Earth later today (Thursday GMT), possibly tomorrow morning," said Alan Thomson, head of geomagnetism at the British Geological Survey (BGS).
He told BBC News: "In the scientific community, there's a feeling that it's not as intense as we first thought it might be. But it's possible still that it could be a large enough event for us to see the northern lights in the UK."
However, weather forecasts suggested cloudy conditions could mar views of any aurorae.
The US National Oceanographic and Atmospheric Administration (Noaa) said that three coronal mass ejections (CMEs) were en route as the result of solar flares on the 13, 14 and 15 February (GMT).
"The last of the three seems to be the fastest and may catch both of the forerunners about mid-to-late day tomorrow, February 17," read a statement from Noaa's Space Weather Prediction Center.
Aurorae The northern lights could be seen further south than is normal
The flare recorded at 0156 GMT on 15 February was the strongest such event in four years, according to the US space agency (Nasa), which has been monitoring activity on the Sun. The event was classified as a so-called X-flare, the most intense type.
The source of all three events, sunspot 1158, has expanded rapidly in recent days.
Solar flares are caused by the sudden release of magnetic energy stored in the Sun's atmosphere.
Their effects can interfere with modern technology on Earth, such as electrical power grids, communications systems and satellites - including satellite navigation (or sat-nav) signals.
Although scientists are expecting most geomagnetic activity to occur on Thursday, Chinese state media has already reported some disruption to shortwave radio communications in the south of the country.
In 1972, a geomagnetic storm provoked by a solar flare knocked out long-distance telephone communication across the US state of Illinois. And in 1989, another storm plunged six million people into darkness across the Canadian province of Quebec.
Dr Thomson said it was possible infrastructure could be affected this time, but stressed: "The X-flare that was observed the other day was lower in magnitude than similar flares that have been associated with technological damage such as the loss of the Quebec power grid... and even the large magnetic storm in 2003, which caused some damage to satellites in orbit."
Scientists will have around half an hour's notice that the wave of charged particles is about to hit the Earth's magnetic shield.
This is taken from the point at which a Nasa satellite called Ace (the Advanced Composition Explorer) registers the solar radiation on its instruments: "We're sitting waiting for that event to happen," said Dr Thomson.
Researchers say the Sun has been awakening after a period of several years of low activity.
They fear a huge solar flare is due to erupt in 2013 - causing blackouts and global chaos.
The once-in-a-century disaster could see power grids crash, communication systems collapse, planes grounded, food supplies hit and the internet shut down.
Everything from home freezers to car sat navs would be affected.
The disaster could mirror the Great Solar Flare of 1859.
That wreaked horrendous damage across Europe and America - burning out telegraph wires across both continents.
The threat of another disaster - which could mirror scenes in Hollywood blockbuster 2012 - is so great that Defence Secretary Liam Fox called an emergency conference in London yesterday.
Dr Fox told experts that incalcul-able damage would be caused if an explosion similar to the one in 1859 occurred in modern times. He called on scientists to build a strategy against the impending disaster.
The talks, organised by the Electric Infrastructure Security Council, heard that the Sun will reach a critical stage of its cycle in 2013.
A surge of magnetic energy in its atmosphere is likely to trigger radiation storms which cause massive power surges.
Such a phenomenon occurs only once about every 100 years.
The last big flare, in 1859, smothered two thirds of the Earth's skies in a blood-red aurora. Such scenes could occur again, causing cloud storms in major modern cities such as London, Paris and New York.
In 1989, a more common smaller solar flare took out power stations in Quebec, Canada.
In the movie 2012, starring John Cusack, a solar flare causes global temperatures to soar. The planet is then battered by tsunamis and earthquakes, threatening mankind.
Yesterday's conference also heard that a hostile power could cause a similar effect by exploding a nuclear weapon in space.
Dr Fox added: "While we all benefit from scientific advances, so we also create vulnerabilities that can be exploited by our enemies.
"However advanced we become, the chain of our security is only as strong as its weakest link."
Last night the electric security council discussed a plan of action.
And former US government defence adviser Dr Avi Schnurr warned: "A geomagnetic storm could shatter nations all over the earth. We cannot wait for disaster to spur us to action."
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The scale measuring their strength has three general categories – Class C, Class M and Class X – with Class X flares being the most powerful.
The GOES X-ray Flux plot contains 5 minute averages of solar X-ray output in the 1-8 Angstrom (0.1-0.8 nm) and 0.5-4.0 Angstrom (0.05-0.4 nm) passbands. Data from the SWPC Primay GOES X-ray satellite is shown. As of Feb 2008, no Secondary GOES X-ray satellite data is available. Some data dropouts will occur during satellite eclipses.
The GOES Hp plot contains the 1-minute averaged parallel component of the magnetic field in nanoTeslas (nT), as measured at GOES-13 (W75) and GOES-11 (W135). The Hp component is perpendicular to the satellite orbit plane and Hp is essentially parallel to Earth's rotation axis. If these data drop to near zero, or less, when the satellite is on the dayside it may be due to a compression of Earth's magnetopause to within geosynchronous orbit, exposing satellites to negative and/or highly variable magnetic fields. On the nightside, a near zero, or less, value of the field indicates strong currents that are often associated with substorms and an intensification of currents in the Earth's geomagnetic tail.
SWPC Real-time Monitor Displays
Global D-Region Absorption Prediction
Conditions in the D-Region of the Ionosphere have a dramatic effect on High Frequency (HF) communications and Low Frequency (LF) navigation systems like Loran. The global D-Region Absorption Product depicts the D-region at high latitudes where it is driven by particles as well as low latitudes, where photons cause the prompt changes. This product merges all latitudes using appropriate displays, and is useful to customers such as commercial aviation and maritime users.
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The most powerful flare of the last 500 years was the first flare to be observed, on September 1, 1859, and was reported by British astronomer Richard Carrington. The event is named the Solar storm of 1859, or the “Carrington event”. The flare was visible to a naked-eye, and produced stunning auroras down to tropical latitudes such as Cuba or Hawaii, and set telegraph systems on fire. The flare left a trace in Greenland ice in the form of nitrates and beryllium-10, which allow its strength to be measured today (New Scientist, 2005).
In modern times, the largest solar flare measured with instruments occurred on November 4, 2003 (initially measured at X28 and later upgraded to X45). Other large solar flares also occurred on April 2, 2001 (X20), October 28, 2003 (X17) and September 7, 2005 (X17). In 1989, during former solar cycle 22 two large flares occurred in March, 6 (X15) and August, 16 (X20) causing disruptions in electric grids and computer systems.
A complete list is available at http://www.spaceweat.../topflares.html
If the estimated velocity does stay constant, then the bulk of the storm will be absorbed by the Atlantic Ocean in the Northern Hemisphere and the majority of the South American continent in the Southern Hemisphere. This increase in water temperature should cause evaporation leading to heavy precipitation in Western Europe and North Africa over the latter part of the week. South America may see record temperatures for this time of year as well.
If the storm slows down, then the bulk of the energy may be absorbed by the east coast of North America and by the Andes in South America. In both cases it may cause high elevation water trapped as snow to melt and cause flooding downstream a few days later.
Continued flares from sunspot 1158 may extend heating
Though smaller flares, the series of 4 flares following the ‘big one’ may extend the heating affect to most of the North American continent, as well as a portion of the Pacific Ocean. The affects may be more global in nature. We expect heavy precipitation around the globe. Stay tuned for more updates.