Weekly Space Weather Highlights

Highlights of Solar and Geomagnetic Activity
20 - 26 March 2017

Solar activity was very low during through 24 March. However, by 25
March, a region began to develop in the NE quadrant and was numbered
as Region 2644 (N12, L=054, class/area, Dao/050 on 26 March). As
this region grew, it produced multiple B-class flares as well as a
C1/Sf at 27/0000 UTC. No Earth-directed coronal mass ejections were
observed during the period. 

No proton events were observed at geosynchronous orbit.

The greater than 2 MeV electron flux at geosynchronous orbit was at
normal to moderate levels on 20-21 March and reached high levels
from 22-26 March. The largest flux of the period was 19,100 pfu
observed at 23/1735 UTC. 

Geomagnetic field activity ranged from quiet to G1 (Minor) storm
conditions. The period began under nominal solar wind conditions
with solar wind speed near 310 km/s and total field near 4 nT. This
continued until a co-rotating interactive region (CIR) preceding a
positive polarity coronal hole high speed stream (CH HSS) became
geoeffective starting around 21/0027 UTC. Total field increased to a
maximum of 18 nT by 21/0722 UTC while the Bz component deflected
southward to -17 nT at 21/0607 UTC. Solar wind speed began to
increase beginning at 20/2349 UTC and reached a maximum of 755 km/s
22/1513 UTC. The geomagnetic field responded with quiet conditions
on 20 March, quiet to G1 (Minor) storming on 21 March, and unsettled
to G1 (Minor) storming on 22 March. By 23 March, a secondary
increase in total field and solar wind speed was observed. Total
field increased from 2 nT to 10 nT while the solar wind speed
increased from 550 km/s to near 730 km/s. From 24 March through the
end of the period, solar wind conditions gradually returned to
nominal levels. However, late on 26 March, an increase in density
and total field was observed around 2000 UTC followed by a solar
sector boundary crossing into the negative sector suggesting the
onset of a subsequent CIR preceding a negative polarity CH HSS. The
geomagnetic field was at quiet to active conditions on 23 March,
quiet to unsettled levels on 24 March, and quiet levels on 25-26

Forecast of Solar and Geomagnetic Activity
27 March - 22 April 2017

Solar activity is expected to be at very low levels with a chance
for isolated C-class flares from Region 2644 during its transit
across the visible disk from 27 March - 04 April. 

No proton events are expected at geosynchronous orbit.

The greater than 2 MeV electron flux at geosynchronous orbit is
expected to be at normal to moderate levels with high levels likely
from 29 March - 11 April and again from 18-22 April due to CH HSS

Geomagnetic field activity is expected to be at unsettled to active
levels from 27 March - 06 April and 17-19 April with G1 (Minor)
storm levels likely on 27-31 March and 17-18 April. G2 (Moderate)
storm levels are likely on 28-29 March. Heightened activity during
these periods is due to recurrent CH HSS effects. Quiet conditions
are expected for the remainder of the forecast period.