Subsiding geomagnetic storm (April 13,2011)

A geomagnetic storm that sparked auroras around the Arctic Circle and sent Northern Lights spilling over the Canadian border into the United States on April 12th is subsiding. At the height of the display, Shawn Malone took this picture from the shores of Lake Superior near Marquette, Michigan:

The recent spat of sunspots continue with regions 1191 and 1192 being numbered on Tuesday. There has been C-Class flare activity around 1191 and existing Sunspot 1190 located in the northern hemisphere. Yet another sunspot is rotating into view on the northeast limb just to the northeast of new sunspot 1191. There will be a small chance for an M-Class flare. (SolarHam)
NOAA forecasters estimate a 25% chance of more geomagnetic activity during the next 24 hours. (SpaceWeather)

CURRENT SOLAR DATA:

Solar wind
speed: 638.0 km/sec
density: 0.2 protons/cm³

Planetary K-index
Now: Kp= 3 quiet
24-hr max: Kp= 5 storm

Interplanetary Mag. Field
B_total: 5.3 nT
B_z: 2.1 nT south

Minor geomagnetic storming took place on Tuesday at high latitudes and this was caused by a Solar Wind which increased to over 600 km/s. A south tilting magnetic field (Bz) helped trigger this storm. (SolarHam)

Joint USAF/NOAA Report of Solar and Geophysical Activity:
The geomagnetic field was at quiet to minor storm levels. Two periods of K=5 were observed at high latitudes during the period. The increase was in response to a coronal hole high-speed stream. Solar wind speeds measured at the ACE Spacecraft increased from approximately 550 km/s to approximately 650 km/s during the past 24 hours.

The geomagnetic field is expected to be at mostly quiet levels for the next three days (13 – 15 April) as the coronal hole high-speed stream effects decrease.