Tag Archives: auroraCast

Mid March G1 Storm Watch Posted

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Northern Lights Now – Less than a week after the last active period for aurora a new storm watch has been posted by SWPC indicating the potential for G1 storming conditions. The current watch, posted for March 22nd, is due to the anticipated high speed solar wind from a center disk coronal hole.

The current coronal hole is a little further south than the one that brought aurora activity earlier this week and is much closer to center disk. It is smaller than the previous coronal hole, so NLN is forecasting a shorter duration period of activity. Here’s an image of the coronal hole from the SDO satellite.

Southern Hemisphere coronal hole extends northward across the Solar Equator
Southern Hemisphere coronal hole extends northward across the Solar Equator

The initial increase in winds should arrive midday on March 22nd with the KP levels rising soon afterward. Wind velocity should increase from today’s baseline of around 350 km/s to above 500km/s. The best monitor solar wind speed is by keeping an eye on the NLN Solar Wind Dynamics page. The page automatically refreshes with the latest data from DSCOVR every minute.

The timing of the expected activity is shown here on the NLN aurora clock. The period of orange (G1 storming) is expected late in the UTC day.

NLN Aurora Clock shows expected G1 storming late in the UTC day March 22, 2018
NLN Aurora Clock shows expected G1 storming late in the UTC day March 22, 2018

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Coronal Hole Prompts G2 Storm Watch for Dec 4 and 5

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Northern Lights Now – SWPC has issued a G2 geomagnetic storm watch for December 4th and 5th. Aurora activity is expected to increase as the high solar wind speeds associated with a coronal hole arrive at Earth. G2 storming means KP values above 5.67 – or strong enough to see aurora in upper mid-latitudes. The storm is arriving just after a full moon, so observation will be a little harder than normal.

The Northern Hemisphere coronal hole responsible for this activity was pointed towards Earth on December 1 and spans a relatively wide longitude. The wider than average longitude means the period of high speed winds is expected to be longer. Data from STEREO and previous rotations of this coronal hole indicate that wind speeds could be over 550 km/s for 24-36 hours and could peak above 650 km/s.

Coronal hole pointed towards Earth on Dec 1
Coronal hole pointed towards Earth on Dec 1

SWPC is currently predicting the heaviest activity at the beginning of the storm late on Dec 4 UTC (afternoon/evening for the US East coast). Typically the most aurora in a coronal hole induced storm happens at the beginning of the storm as the CIR impacts earth, then towards the end as the winds have been pushing on Earth’s magnetosphere for an extended time. This shows in the forecast as another period of G1 storming late on Dec 5. It is likely this watch will be extended into Dec 6 as a G1 watch. Here are the rough timings for the expected activity.

Predicted Aurora activity on Dec 4 and Dec 5
Predicted Aurora activity on Dec 4 and Dec 5

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G1-G2-G1 Storm Watch for Oct 24 through October 26

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Northern Lights Now – High speed wind from the coronal hole mentioned in the previous NLN post is expected to arrive sometime on October 24 and should induce G1 and G2 storm conditions through the 26th. SWPC has issued storm watches for all three days with G1 watches on the 24th and 26th and a G2 storm watch on October 25. This means KP levels could reach 5.67 or more.

SWPC notifications timeline shows three days of storm watches posted
SWPC notifications timeline shows three days of storm watches posted

Models are predicting an extended period of elevated solar winds reaching as high as 650km/s for all three days. The initial winds will arrive with a CIR (co-rotating interaction Region) where densities are higher and the magnetic fields are more complex. This means you can monitor the progress of the arriving wind stream – it will show up as proton densities as measured at L1 by DSCOVR will rise. Once Earth is in the body of the high speed solar wind stream, density decreases and winds increase.

Current forecasts show geomagnetic activity reaching G1 levels (KP=4.67 and above) the second half of Oct 24, then reaching G2 (KP=5.67 and above) on the first part of Oct 25. Activity should slowly decline over the following 36 hours, but there may be spike of activity if the magnetic fields line up just right.

NLN AuroraCast shows three days of G1 and G2 activity from October 24-26
NLN AuroraCast shows three days of G1 and G2 activity from October 24-26

As an update to the features in that previous post, the filament did lift off, but was subsequently reabsorbed, so it did not generate a CME. The active regions rotating into view on the East limb seem to have lost their magnetic complexity. Space Weather forecasters are not expecting they will be active flare producers in the next several days.

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