A geomagnetic sudden impulse, indicating the arrival of the March 23 CME, was observed at the Hartland magnetometer (23 nT) at 20:09 UTC on March 25.
The geomagnetic field is expected to be at unsettled to active levels (below G1-Minor) early on March 26 as CME effects continue. A return to mostly quiet conditions is expected on March 27 and 28 as CME effects wane.
Geomagnetic K-index of 4 threshold was reached at 01:42 UTC on March 26:
Space Weather Message Code: ALTK04
Serial Number: 1699
Issue Time: 2014 Mar 26 0149 UTC
ALERT: Geomagnetic K-index of 4
Threshold Reached: 2014 Mar 26 0142 UTC
Synoptic Period: 0000-0300 UTC
Active Warning: Yes
NOAA Space Weather Scale descriptions can be found at www.swpc.noaa.gov/NOAAscales
Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.
The impact, although weak, sparked nice aurora show. The following image was taken by Yann Hollander at Porjus, Swedish Lapland:
We had to wait 3 hours after the impact of the CME and finally at 00:00 the sky exploded above Porjus in Swedish Lapland. Best I have seen since 15 January due to clouds at crucial moments.
Image credit: Yann Hollander at Porjus, Swedish Lapland (via SpaceWeather)
Solar wind conditions are expected to continue under the influence of the CME today before returning to nominal conditions on March 27 - 28.
NOAA SWPC forecasters estimate 35% chance of M-class, and 1% chance of X-class solar flares in next three days.
Featured image: Yann Hollander at Porjus, Swedish Lapland (via SpaceWeather)