Wednesday, September 14, 2011

Weekly Propagation Forecast Bulletins



Product: Weekly Highlights and Forecasts
:Issued: 2011 Sep 13 1952 UTC
# Prepared by the US Dept. of Commerce, NOAA, Space Weather Prediction Center
# Product description and SWPC web contact www.swpc.noaa.gov/weekly.html
#
# Weekly Highlights and Forecasts
#
Highlights of Solar and Geomagnetic Activity 05 - 11 September 2011

During the period, solar activity ranged from low to high levels due to a total of 7 M-class and 2 X-class events. The sharp increase in activity from the previous period originated from two regions; Region 1286 (N20, L=304, class/area Dso/080 on 03 September) and Region 1283 (N14, L=226, class/area Dai/230 on 07 September).

The period began at moderate levels due to two M1 x-ray events observed originating from Region 1286 at 05/0428 UTC and 05/0758 UTC respectively.

Solar activity increased to high levels on 06 September. Region 1283 produced an M5/1b flare at 06/0150 UTC and an X2/2b at 06/2220 UTC. The M5 flare had associated Types II and IV radio sweeps and an Earth-directed full-halo CME. The CME had an estimated speed of approximately 450 km/s, based upon STEREO-A COR2 data, with the bulk of the ejecta directed north of the ecliptic plane. The X2 flare was associated with Types II and IV radio sweeps, a 740 sfu Tenflare and an Earth-directed halo CME. The CME had an estimated speed of around 800 km/s, based on STEREO-A COR2 images, with the bulk of mass directed north of the ecliptic plane. 07 September saw high levels again as Region 1283 produced more major activity. Another major event was observed near the end of the 7th when Region 1283 produced an X1/3b at 07/2238 UTC with associated weak Types II and IV radio sweeps, a 1300 sfu Tenflare, and a non-Earth-directed CME. High activity levels persisted on 08 September when Region 1283 produced an M6/1n at 08/1546 UTC associated with a weak Type IV radio sweep.

Solar activity decayed to moderate levels on 09 September when Region 1283 produced two M-class flares. The first was an M2/1n at 09/0609 UTC with an associated Type II radio sweep (estimated velocity 717 km/sec) and a non-geoeffective CME. The second was an M1/1f at 09/1249 UTC. On 10 September, a significant filament eruption centered near N10W48 occurred around 10/0300 UTC. Associated with this eruption was a partial-halo CME (plane-of-sky speed of 620 km/s). As it neared the west limb, Region 1283 produced an M1/Sn at 10/0740 UTC with an associated limb-event CME. On 11 September, solar activity further decreased to low levels. A long duration C6/Sf flare was observed at 11/0851 UTC from Region 1283 as it rotated around the west limb.

There were no proton events observed at geosynchronous orbit. However, two separate enhancements, both in the 10 MeV and 100 MeV energy levels, were observed in the wake of the M5 event early on 06 September and the X2 event late on the 6th. The first enhancement saw a peak of 2.4 pfu at 06/1410 UTC at 10 MeVs and 0.15 pfu at 06/0850 UTC at 100 MeVs. The second enhancement saw a peak of 8.8 pfu at 07/0715 UTC at 10 MeVs and 0.4 pfu at 07/0410 UTC at 100 MeVs. Protons at all energy levels declined to background levels by 08/1800 UTC.

The greater than 2 MeV electron flux at geosynchronous orbit was at moderate levels on 05 - 06 September, reached high levels on 07 - 09 September and declined to normal levels on the 10th. Moderate levels were observed again on 11 September.

The geomagnetic field ranged from quiet to severe storm levels. The period began with mostly quiet conditions from 05 September through midday on 09 September. Brief periods of active to minor storm conditions were observed at high latitudes on 06 September due to extended periods of southward Bz. Midday on 09 September, two sudden impulses (SI) were observed at 09/1243 UTC and 09/1250 UTC (16nT and 28nT respectively, as measured by the Boulder USGS magnetometer). At 09/1150 UTC, ACE data indicated an interplanetary shock arrival preceding the Boulder SIs. Bt reached up to 24nT, Bz dropped to -23nT, density spiked up to 35p/cc, wind speeds peaked at 602km/s, and temperature increased. As a result, geomagnetic activity levels increased to active to isolated high latitude severe storm levels. Activity was due to combined CME effects associated with 06 - 07 September major flare activity. The storm conditions persisted through 10 September. Late on 10 September, solar wind speed increased to around 620 km/s while the total IMF field (Bt) dropped to around 4nT indicating a likely transition into a negative polarity coronal hole high speed stream (CH HSS). Mostly quiet to unsettled levels were seen on 11 September with an isolated minor storm period at high latitudes.

Forecast of Solar and Geomagnetic Activity 14 September - 10 October 2011

Solar activity is expected to be at low to moderate levels through 10 October. A slight chance for an X-class event is possible on 18 September through 07 October as old Regions 1286 (N20, L=304) and 1283 (N14, L=226) rotate back on to the visible disk. Chances for major activity will further increase on 24 September through 01 October when both regions are on the visible disk. Activity is expected to decrease to low to moderate levels from 08 October through the remainder of the period.

No proton events are expected at geosynchronous orbit through 17 September and again from 08 - 10 October. There is a slight chance for a proton enhancement from 18 September through 07 October due to potential flare activity from Regions 1283 and 1286.

The greater than 2 MeV electron flux at geosynchronous orbit is expected to be at high levels from 14 - 17 September and normal to moderate levels 18 - 25 September. High levels are expected on 26 - 27 September due to effects from a geoeffective CH HSS. Normal to moderate levels are expected from 28 September - 01 October. High levels are expected again on 02 - 03 October due to another CH HSS. Normal to moderate levels are expected from 04 - 09 October followed by another period of high levels on 10 October due to a third CH HSS.

The geomagnetic field is expected to be mostly quiet through the period. Unsettled conditions are possible on 18 - 19 and 24 - 25 September due to recurrent CH HSS rotating into a geoeffective position. Unsettled conditions with isolated active periods possible are expected on 30 September as a positive polarity CH HSS becomes geoeffective. Unsettled conditions will continue into 01 October. Mostly quiet condtions are expected from 02 through 07 October until another recurrent CH HSS becomes geoeffective. Mostly unsettled conditions are then expected from 08 - 10 October with isolated active periods possible on 09 October.

Product: 27-day Space Weather Outlook Table 27DO.txt
:Issued: 2011 Sep 13 1952 UTC
# Prepared by the US Dept. of Commerce, NOAA, Space Weather Prediction Center
# Product description and SWPC web contact www.swpc.noaa.gov/wwire.html
#
# 27-day Space Weather Outlook Table
# Issued 2011-09-13
#
# UTC Radio Flux Planetary Largest
# Date 10.7 cm A Index Kp Index
2011 Sep 14 130 12 3
2011 Sep 15 125 8 3
2011 Sep 16 125 5 2
2011 Sep 17 125 5 2
2011 Sep 18 120 5 2
2011 Sep 19 115 7 2
2011 Sep 20 110 5 2
2011 Sep 21 110 5 2
2011 Sep 22 110 5 2
2011 Sep 23 110 5 2
2011 Sep 24 110 7 2
2011 Sep 25 115 7 2
2011 Sep 26 115 5 2
2011 Sep 27 115 5 2
2011 Sep 28 115 5 2
2011 Sep 29 115 5 2
2011 Sep 30 120 15 4
2011 Oct 01 120 8 3
2011 Oct 02 120 5 2
2011 Oct 03 120 5 2
2011 Oct 04 120 5 2
2011 Oct 05 120 5 2
2011 Oct 06 120 5 2
2011 Oct 07 120 5 2
2011 Oct 08 120 8 3
2011 Oct 09 120 15 4
2011 Oct 10 120 12 3
(NOAA)