Weekly Propagation Summary – 2015 May 04 16:10 UTC
Here is this week’s space weather and geophysical report, issued 2015 May 04 0612 UTC.
Highlights of Solar and Geomagnetic Activity
27 April – 03 May 2015
Solar activity was at very low to low levels during the period. Very
low levels were observed on 27 April and on 02 May. Solar activity
was in decline during the beginning of the period as Region 2331
(S10, L=021, class/area Dai/240 on 26 Apr) rotated around the SW
limb on 29 April. Only isolated low level C-class flaring was
observed for the majority of the period until new Region 2335 (S15,
L=192, class/area Dai/220 on 02 May) rotated around the SE limb on
30 April. This region slowly developed in both area and magnetic
class during its first few days on the visible disk and culminated
in seven C-class flares; the largest of which was a C2 flare at
01/0257 UTC. Other activity of note included an 18 degree filament
eruption, centered near S46E09, observed lifting off the visible
disk between 02/1500-1830 UTC. Associated with this eruption was a
partial-halo coronal mass ejection (CME) first observed in
SOHO/LASCO C2 imagery at 02/2036 UTC with an approximate speed of
473 km/s. Although the majority of the ejecta appeared to be
southward of the ecliptic plane, WSA/ENLIL modelling of the event
showed a potential impact after midday on 06 May.
No proton events were observed at geosynchronous orbit.
The greater than 2 MeV electron flux at geosynchronous orbit was at
normal to moderate levels. Moderate levels were observed on 27-29
April and again on 02-03 May.
Geomagnetic field activity was mostly quiet through late in the
period. At approximately 30/0515 UTC, total field showed an increase
from 6 nT to 11 nT with a weak increase in solar wind speed from
approximately 280 km/s to 350 km/s. Further increases in speed to
around 450 km/s occurred on 01 May as a weak, positive polarity
coronal hole high speed stream (CH HSS) became geoeffective. CH HSS
influence continued through the end of the period. The geomagnetic
field responded with quiet to unsettled conditions on 02-03 May.
Forecast of Solar and Geomagnetic Activity
04 May – 30 May 2015
Solar activity is expected to be at very low to low levels with a
chance for M-class (R1-R2, Minor-Moderate) flare activity from 04-21
May and again from 28-30 May with the return of old Regions 2322
(N11, L=116) and 2325 (N05, L=050).
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
possible from 07-08, 13-21, and 29-30 May due to CH HSS activity.
Geomagnetic field activity is expected to be at quiet to unsettled
levels from 05-07 May with active periods likely on 06-07 May due to
a combination of CH HSS effects and the arrival of the 02 May CME by
mid to late on 06 May. Unsettled to active conditions with likely
minor storm periods (G1-Minor) are expected from 12-15 and 17-20 May
due to a recurrent CH HSS. A weak CH HSS is expected to become
geoeffective from 27-30 May causing quiet to unsettled conditions.
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