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Weekly Highlights of Solar and Geomagnetic Activity, 25 - 31 July 2011
:Product: Weekly Highlights and Forecasts
:Issued: 2011 Aug 02 2058 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 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 predominantly 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 predominantly 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. |
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