Weekly Highlights of Solar and Geomagnetic Activity, 25 - 31 July 2011

Weekly Highlights of Solar and Geomagnetic Activity, 25 - 31 July 2011

Post by SWPC.Webmas.. » Thu, 04 Aug 2011 02:30:07

:Product: Weekly Highlights and Forecasts
:Issued: 2011 Aug 02 2058 UTC
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Highlights of Solar and Geomagnetic Activity
25 - 31 July 2011

Solar activity ranged from very low to high levels during the
period. The period began with very low activity during 25 July, with
B-class flares pre***ly from Region 1260 (N19, L=358,
class/area Ehi/330 on 30 July). Activity increased to low levels on
26 July with two C-class flares from Region 1260. Activity increased
to moderate levels on 27 July due to an M1/1n flare at 27/1607 UTC,
as well as frequent to occasional low-level C-class flares, from
Region 1260. Activity decreased to low levels during 28 - 29 July
with 13 C-class flares on each of those days. The largest during
this period was a C6/1f at 29/1640 UTC from Region 1261 (N16, L=330,
class/area Eki/350 on 31 July). Activity increased to high levels on
30 July due to an impulsive M9 flare from Region 1261 at 20/0209
UTC. A 180 sfu Tenflare was associated with this flare. Low levels
returned on 31 July with several C-class events, the largest of
which was a C3/Sn at 31/0254 UTC from Region 1261.

No proton events were observed at geosynchronous orbit.

The greater than 2 MeV electron flux at geosynchronous orbit was at
normal to high levels during 25 - 26 July. Flux increased to
moderate to high levels during 27 - 29 July. Flux decreased to
normal to moderate levels on 30 - 31 July.

Geomagnetic field activity ranged from quiet to minor storm levels
during the period. Activity began the period at quiet to unsettled
levels, with isolated active to minor storm levels at high latitudes
on 25 July, due to a coronal hole high-speed stream (CH HSS).
Activity decreased to mostly quiet to unsettled levels on 26 July.
Activity decreased to mostly quiet levels during 27 - 29 July.
Activity increased to quiet to active levels with an isolated minor
storm period at high latitudes during 30 July. Mostly unsettled
conditions were observed on 31 July.

Forecast of Solar and Geomagnetic Activity
03 August - 29 August 2011

Solar activity is expected to be at low to moderate levels during 03
- 08 August, with a chance for M-class flares greater than M5 from
Region 1261. Activity is expected to decrease to very low to low
levels during the rest of the period as Region 1261 departs. A
chance for M-class activity increases on 20 August when Region 1261
rotates back around the east limb.

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 on 03 - 04 August. Normal
to moderate levels are expected during 05 - 07 August. Moderate to
high levels are expected during 08 - 13 August due to effects from a
recurrent CH HSS. Normal to moderate levels are expected on 14 - 15
August followed by moderate to high levels from 16 - 25 August due
to a second CH HSS. Normal to moderate levels are expected for the
remainder of the period.

Geomagnetic field activity is expected to be pre***ly quiet
during 03 - 04 August. A CME observed at approximately 02/0706 UTC
on LASCO C3 imagery is expected to arrive late on 04 August and
increase activity to unsettled to active levels with a chance for
minor storm conditions through the first few periods of 06 August.
Major storm periods are possible at high latitudes during this time.
Quiet to unsettled conditions are expected for the rest of 06 August
through 11 August due to effects from a recurrent CH HSS. Activity
is expected to decrease to mostly quiet levels from 12 - 13 August
as the CH HSS effects subside. Activity is expected to increase to
quiet to unsettled levels from 14 - 22 August, with a chance for
active levels on 15 - 17 August due to another recurrent CH HSS.
Conditions are expected to decrease to quiet levels until the
arrival of a third CH HSS anticipated to become geoeffective on 26
August. Quiet to unsettled conditions with a chance for isolated
active periods are expected to prevail for the remainder of the
forecast period.