Weekly Highlights of Solar and Geomagnetic Activity, 14 - 20 May 2012

[SWPC.We...@noaa.gov]

:Product: Weekly Highlights and Forecasts
:Issued: 2012 May 21 1636 UTC
# Prepared by the US Dept. of Commerce, NOAA, Space Weather Prediction Center
# Product description and SWPC contact on the Web
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# Weekly Highlights and Forecasts
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Highlights of Solar and Geomagnetic Activity
14 - 20 May 2012

Solar activity ranged from very low to moderate levels. Region 1476
(N09, L=180, class/area Fkc/1050 on 09 May) continued to be the
major contributor of x-ray flare activity throughout the week. It
produced 13 C-class flares and an M-flare. Region 1476 began the
week as an Fko type group with a beta-gamma configuration. As it
rotated off the west limb on 17 May, the region produced an M5/1f
flare at 17/0147 UTC. This event was accompanied by a 22 minute 10cm
Radio Burst (600 sfu) at 17/0142 UTC, Type II (645 km/s) and Type IV
radio sweeps, and a partial halo CME. The CME was first observed by
the SOHO/LASCO C3 spacecraft beginning at 17/0206 UTC with an
estimated plane-of-sky speed of approximately 1200 km/s. The
majority of the ejecta was directed off the west limb. Region 1476
continued to produce C-class flares as it rotated off the visible
disk on 18 May. A filament eruption produced a CME that was observed
in STEREO A COR 2 imagery (plane-of-sky speed approximately 482
km/s) beginning at 18/0709 UTC on 18 May. The ejecta was slightly
north of the ecliptic plane, however a glancing blow is possible
from that event.

A greater than 10 MeV and greater than 100 MeV proton event at
geosynchronous orbit was observed associated with the 17 May M5
flare. The greater than 10 MeV proton event began at 17/0210 UTC and
reached a peak flux of 255 pfu at 17/0430 UTC, ended at 18/1620UTC.
The greater than 10 MeV proton event crossed the 100 pfu threshold
(S2) at 17/0245 UTC and fell below 100 pfu at 17/0945 UTC. The
greater than 100 MeV proton event began at 17/0200 UTC and reached a
maximum of 20 pfu at 17/0230 UTC, ended at 17/1725 UTC.

The greater than 2 MeV electron flux at geosynchronous orbit was at
moderate to high levels from 14 through 16 May. Moderate levels were
observed from 17 through 20 May.

Geomagnetic field activity ranged from quiet to active levels. Quiet
levels were observed on 15, 17, and 19 May. Quiet to unsettled
levels were observed on 14 and 18 May. Quiet to unsettled levels
with isolated active periods were observed on 16 and 20 May. On 16
May, an extended period of the southward Bz component of the
interplanetary magnetic field caused an isolated active level during
the 16/2100 - 2400 UTC period. At approximately 20/0136 UTC, the ACE
satellite ovserved an interplanetary shock passage with a
corresponding weak sudden impulse observed in the Boulder
magnetometer (15 nT) at 20/0215 UTC. The shock passage was likely
associated with the 17 May CME. The geomagnetic field responded with
an isolated active period during the 20/0300 - 0600 UTC period.



Forecast of Solar and Geomagnetic Activity
21 May - 16 June 2012

Solar activity is expected to be at very low to low levels with a
slight chance for M-class flares through 31 May and again from 14
June through the end of the forecast period. Low to moderate levels
are expected from 31 May through 13 June due to the return of old
Region 1476.

A chance for a greater than 10 MeV proton event at geosynchronous
orbit exists from 31 May through 13 June due to the return of old
Region 1476.



The greater than 2 MeV electron flux at geosynchronous orbit is
expected to be at normal levels on 21 - 23 May, 30 May - 05 June,
and again on 13 - 16 June. High levels are expected on 24 - 29 May
and again on 06 - 12 June. High levels are in response to recurrent
coronal hole high speed wind streams.

Geomagnetic field activity is expected to be quiet to active on 22 -
23 May as the arrival of the 18 May CME as well as a coronal hole
high speed stream become geoeffective. Quiet to active conditions
are also expected on 06 - 09 June as another recurrent coronal hole
high speed stream moves into geoeffective position. Mostly quiet to
unsettled conditons are expected for the remainder of the forecast
period.