Product: Weekly Highlights and Forecasts:Issued: 2011 Apr 19 1900 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 11 - 17 April 2011
Solar activity was at low to moderate levels. Low activity occurred during 11 - 14 April with C-class flares from Regions 1185 (N18, L=025, class/area Cso/100 on 05 April), 1190 (N13, L=338, class/area Eki/440 on 16 April), and 1193 (N17, L=266, class/area Eai/430 on 17 April). Activity increased to moderate levels on 15 April due to an M1/1f flare at 15/1712 UTC from Region 1190 associated with minor discrete radio emission. Region 1190 showed gradual spot growth during 12 - 15 April and displayed a beta-gamma magnetic configuration, then began to gradually decay on 16 April. Region 1193, which also contained a beta-gamma magnetic configuration, showed gradual spot growth during 13 - 17 April. An Earth-directed coronal mass ejection was observed early on 15 April, associated with a filament disappearance from the northeast quadrant late on 14 April. Estimated plane-of-sky velocity was for the CME was 390 km/s, based on an analysis of SOHO/LASCO coronagraph images. Activity decreased to low levels during 16 - 17 April with C-class flares from Regions 1185, 1190, and 1193.
No proton events were observed at geosynchronous orbit.
The greater than 2 MeV electron flux at geosynchronous orbit was at normal to moderate levels during 11 - 13 April. Fluxes increased to moderate to high levels during 14 - 16 April, then decreased to normal to moderate levels during 16 - 17 April.
Geomagnetic activity was at quiet to active levels on 11 April. Activity increased to quiet to minor storm levels on 12 April with major storm periods observed at high latitudes. Activity decreased to quiet to active levels on 13 April with minor to major storm periods observed at high latitudes. Activity decreased to quiet to
unsettled levels on 14 April. A further decrease to quiet levels at all latitudes occurred during 15 - 17 April. ACE solar wind observations indicated the activity during 11 - 13 April was associated with a coronal hole high-speed stream (CH HSS). he HSS source was an equatorward extension of the southern polar CH. The CH HSS commenced on 11 April following a negative- to positive-polarity solar sector boundary crossing. Velocities increased during 11 - 12 April, eventually reaching a peak of 674 km/s at 12/1940, then gradually decreased during the rest of the period. Interplanetary magnetic field (IMF) changes associated with the onset of the CH HSS
included increased Bt (peak 17 nT at 11/2001 UTC) as well as increased Bz variability with intermittent periods of southward Bz (maximum deflection -9 nT at 12/0525 UTC). The CH HSS began to gradually subside on 13 April.
Forecast of Solar and Geomagnetic Activity 20 April - 16 May 2011
Solar activity is expected to be low with C-class flares likely during the period. There will be a chance for moderate activity (isolated M-class flares) during the second half of the period due to the return of previously active regions.
No proton events are expected at geosynchronous orbit.
The greater than 2 MeV electron flux at geosynchronous orbit is expected to be at normal to moderate levels during most of the period. However, high flux levels are expected during 22 - 23 April, 30 April - 03 May, and 11 - 13 May.
Geomagnetic field activity is expected to be to be at quiet to unsettled levels during 20 - 22 April due to weak coronal hole effects on 20 - 21 April and weak coronal mass ejection effects on 22 April (associated with the Earth-directed CME observed on 15 April). Activity is expected to decrease to quiet levels during 23 -
27 April. Field activity is expected to increase to quiet to active levels during 28 April - 01 May due to recurrent coronal hole effects. Activity is expected to decrease to quiet levels during 02 - 07 May. Activity is expected to increase to quiet to active levels during 08 - 11 May due to recurrent coronal hole effects. Quiet conditions are expected during 12 - 16 May.
Product: 27-day Space Weather Outlook Table 27DO.txt
:Issued: 2011 Apr 19 1900 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 2011-04-19
#
# UTC Radio Flux Planetary Largest
# Date 10.7 cm A Index Kp Index
2011 Apr 20 110 10 3
2011 Apr 21 110 10 3
2011 Apr 22 115 10 3
2011 Apr 23 115 5 2
2011 Apr 24 115 5 2
2011 Apr 25 110 5 2
2011 Apr 26 110 5 2
2011 Apr 27 110 5 2
2011 Apr 28 110 7 3
2011 Apr 29 110 15 4
2011 Apr 30 115 12 3
2011 May 01 115 8 3
2011 May 02 115 5 2
2011 May 03 115 5 2
2011 May 04 110 5 2
2011 May 05 110 5 2
2011 May 06 105 5 2
2011 May 07 105 5 2
2011 May 08 105 8 3
2011 May 09 110 15 4
2011 May 10 115 15 4
2011 May 11 120 7 3
2011 May 12 120 5 2
2011 May 13 120 5 2
2011 May 14 115 5 2
2011 May 15 110 5 2
2011 May 16 115 5 2
(NOAA)
