The NW7US Beacon

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 period.

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