Weekly Propagation Summary – 2015 May 18 16:10 UTC
Here is this week’s space weather and geophysical report, issued 2015 May 18 0402 UTC.
Highlights of Solar and Geomagnetic Activity
11 – 17 May 2015
Solar activity was low from 11-15 May. The largest event of the
period was a C9/1n at 13/1838 UTC associated with a filament
eruption near Region 2345 (N16, L=113, class/area Axx/020 on 13
May). Region 2339 (N13, L=129, class/area Fkc/900 on 08 May) was the
most active region on the disk and produced 19 C-class events during
the period. There were several filament eruptions observed during
the period however, none of them turned out to be geoeffective.
Solar activity decreased to very low levels for 16-17 May.
The greater than 10 MeV proton flux at geosynchronous orbit was
enhanced on 12 May reaching a peak flux of 6 pfu at 12/0720 UTC but
never crossed alert threshold.
The greater than 2 MeV electron flux at geosynchronous orbit was at
normal to moderate levels on 11-13 May before reaching high levels
daily for the remainder of the period in response to effects from a
negative polarity coronal hole high speed stream (CH HSS).
Geomagnetic field activity was at unsettled to active levels on 11
May and mostly unsettled levels on 12 May due to extended periods of
negative Bz. On 13 May, geomagnetic field conditions increased to
active to major storm levels due to the onset of a recurrent
negative polarity CH HSS. Quiet to unsettled levels persisted on
14-15 May as effects from the HSS subsided. Quiet conditions
prevailed for the remainder of the period.
Forecast of Solar and Geomagnetic Activity
18 May – 13 June 2015
Solar activity is expected to be at very low levels with a chance
for C-class flares and a slight chance of M-class flares on 18 May
before decreasing further to only a chance for C-class flares once
Region 2339 rotates fully around the west limb on 19 May. The chance
for M-class activity increases on 25 May with the return of old
Region 2335 (S15, L=192) and remain elevated through the remainder
of the forecast period.
No proton events are expected at geosynchronous orbit.
The greater than 2 MeV electron flux at geosynchronous orbit is
expected to be at moderate to high levels from 18-28 May due to
residual effects from last weeks negative polarity CH HSS followed
by effects from an anticipated positive polarity HSS due to become
geoeffective on 18 May. Normal to moderate levels are expected to
prevail with the exception of 31 May-01 Jun, 04-06 Jun, and 10-12
Jun following various recurrent CH high speed streams.
Geomagnetic field activity is expected to be quiet to active on
18-19 May due to effects from a positive polarity CH HSS. Mostly
quiet conditions are expected from 20 May to 01 Jun. Quiet to
unsettled conditions with a chance for active periods are expected
on 02-03 Jun due to effects from a negative polarity HSS followed by
quiet conditions through 06 Jun. Unsettled conditions are expected
on 07 and 10 Jun as well as active to minor storm conditions on
08-09 Jun due to the anticipated return of the recurrent negative
polarity CH HSS that yielded major storm conditions this week.
Mostly quiet conditions are expected for the remainder of the
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