:Product: Weekly Highlights and Forecasts
:Issued: 2011 Aug 09 2323 UTC
# Prepared by the US Dept. of Commerce, NOAA, Space Weather Prediction Center
# Product description and SWPC contact on the Web
# http://www.swpc.noaa.gov/weekly.html
#
# Weekly Highlights and Forecasts
#
Highlights of Solar and Geomagnetic Activity
01 - 07 August 2011

Solar activity ranged from very low to high levels during the
period. The period began with low activity on 31 July - 01 August,
with C-class flares predominantly from Regions 1261 (N15, L=332,
class/area Dai/380 on 04 August) and Region 1263 (N17, L=301,
class/area Ekc/720 on 04 August). Activity increased to moderate
levels on 02 August due to a long-duration M1/1n at 02/0619Z from
Region 1261, with associated Type IV, Type II (estimated speed of
1067 km/s), and Tenflare (220 sfu) radio emissions. LASCO C3 imagery
indicated a full halo coronal mass ejection with this flare.
Activity increased to high levels on 03 August with three M-class
flares. The largest of these was an M6/2b at 03/1348Z from Region
1261, with associated Type IV, Type II (estimated speed of 812
km/s). A CME was subsequently observed in STEREO-A Cor2 imagery at
03/1409Z. Solar activity remained at high levels on 04 August due to
an M9/2b from Region 1261 at 04/0357Z, with associated Type IV, Type
II (estimated speed of 750 km/s), and Tenflare (720 sfu). A CME was
also associated with the M9 flare with an approximate speed of 2100
km/s in STEREO-A COR-2 imagery. Activity decreased to low levels on
05 - 07 August, with C-class flares predominantly from Regions 1261,
1263, and 1267 (S17, L=243, class/area Bxo/010 on 05 August). A long
duration C1 flare was observed at 06/1807Z. Two CMEs were observed
by SOHO/LASCO C2 at 06/1036Z and 06/1736Z, but the majority of the
ejecta was directed to the west and not geoeffective. Late on 06
August, a recurrent positive polarity CH moved into a potentially
geoeffective position.

No proton events were observed at geosynchronous orbit during 31
July - 03 August. The 100 MeV proton flux at geosynchronous orbit
exceeded 1 pfu beginning at 04/0510Z, reaching maximum at 04/0740Z,
and ending at 04/1110Z. The maximum 100 MeV proton flux was 1.8 pfu.
The 10 MeV proton flux at geosynchronous orbit exceeded 10 MeV
beginning at 04/0635Z, reaching maximum of 96 pfu at 05/2150Z, and
ending at 06/0515Z. The 10 MeV proton flux remained enhanced, but
below threshold and trailing towards quiet background on 07 August.

The greater than 2 MeV electron flux at geosynchronous orbit was at
normal levels on 31 July. Fluxes increased from normal to moderate
levels during 01 - 02 August. Flux values returned to moderate
levels on 03 and 04 August. Normal to moderate levels were observed
on 05 - 07 August.

Geomagnetic activity was quiet to unsettled, with isolated active
levels on 31 July due to a coronal hole high-speed stream (CH HSS).
Quiet to unsettled levels were observed on 01 August as the CH HSS
subsided. Activity remained quiet on 02 - 03 August. Predominantly
quiet levels were observed on 04 August, before the first of three
CME shocks was observed transiting ACE at 04/2105Z, followed by a 20
nT sudden impulse observed by Earth based magnetometers at 04/2155Z.
A magnetopause crossing was also observed by the GOES 13 and 15
satellites. Quiet to unsettled levels were observed between 04/2100
- 05/1800Z. Two additional shock passages were seen by ACE at
05/1722Z and 05/1834Z, accompanied by a noticeable increase in solar
wind density, velocity and magnetic field, which included Bz
fluctuation to -20 nT. Activity increased to minor to severe storms
during 05/2100 - 06/0600Z due to effects from the CME shock
arrivals. Early on 06 August, activity steadily declined from active
to quiet levels, before the polarity transitioned to a mostly
positive Phi angle and recurrent CH HSS effects began. This
triggered an isolated minor storm at high latitudes between
06/1200-1500Z. Otherwise, geomagnetic activity remained mostly quiet
for the remainder of 06 August and throughout 07 August.

Forecast of Solar and Geomagnetic Activity
10 August - 05 September 2011

Solar activity is likely to be at Moderate (R1 - Minor) during 10
August, with a chance for M-class flares from Region 1263. Activity
is expected to decrease to very low to low levels during 11 - 17
August with the absence of mature spot groups on the disk. Activity
is expected to increase to very low to low levels, with a chance for
M-class flares from 18 August - 03 September from old regions; 1260
(N19, L=001), 1261 (N15, L=332), and 1263 (N17, L=301). Activity is
expected to decrease to very low to low levels 04 - 05 September.
However, there is a chance that new, rapidly emerging flux regions
could increase activity to moderate or greater levels at any time
during the outlook period.

The greater than 10 MeV Proton flux levels at geosynchronous orbit
are likely to remain above threshold (S1 - Minor) on 10 August, as
an event that is currently in progress carries over early into the
period. No proton events are expected at geosychronous after 10
August though the end of the period.

The greater than 2 MeV electron flux at geosynchronous orbit is
expected to be at moderate to high levels on 10 and 11 August.
Normal to moderate levels are expected 12 - 15 August. Moderate to
high levels are expected again 16 - 31 August. Normal to moderate
levels are expected 01 - 03 September.

The geomagnetic field is expected to be at quiet to unsettled
levels, with a chance for active levels 10 - 11 August, due to a CH
HSS. Activity is expected to decrease to predominantly quiet levels
during 12 - 15 August. Activity is expected to increase to quiet to
unsettled levels, with a chance for active levels 16 - 18 August and
again 21 - 22 August due to two recurrent CH High Speed Streams.
Activity is expected to decrease to quiet to unsettled levels on 23
August CH HSS effects subside. Quiet levels are expected 23 - 25
August, before increasing to quiet to unsettled levels, with a
chance for active levels at high latitudes 26 - 28 August due to
another CH HSS. Mostly quiet conditions are again forecast to return
from 29 August until 03 September, before another CH HSS ends out
the period (04 - 05 September) with unsettled and active conditions.