Thursday, February 24, 2011

Weekly Propagation Forecast Bulletins


Product: Weekly Highlights and Forecasts
:Issued: 2011 Feb 22 2026 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





Highlights of Solar and Geomagnetic Activity
14 - 20 February 2011

Solar activity ranged from low to high levels. The period began with moderate activity levels due to an M2.2/1F flare from Region 1158 (S21, L=33, class/area Ekc/620 on 16 February). Associated with this flare was a Type II Sweep with an estimated shock velocity of 1479 km/s and a 150 sfu Tenflare. A slow-moving, faint, full-halo CME was observed in LASCO C2 imagery, first seen at 14/1812Z, and was associated with the M2.2 event. Activity increased to high levels on 15 February as Region 1158 produced an impulsive X2.2 at 15/0156Z. Associated with this event were multi-spectral radio emissions spanning 25 MHz to 15.4 GHz including Type II (556 km/s) and Type IV Sweeps, a 250,000 sfu Burst measured at 410 MHz and a 1300 sfu Tenflare. In addition, a fast-moving, full-halo CME was observed, first seen in LASCO C2 imagery at 15/0236Z with an estimated plane-of-sky speed of 747 km/s. The X2.2 was the largest x-ray event since December 2006. By 16 February, solar activity decayed to moderate levels. Region 1158 produced an M1.6/1F at 16/1425Z with associated Type II (1386 km/s) and Type IV Sweeps and a 330 sfu Tenflare. Earlier on the 16th, Region 1158 produced an M1.0 at 16/0139Z. Region 1161 (N11, L=331, class/area Ekc/260 on 20 February) produced an M1.1 at 16/0744Z. This region emerged on the disk on 14 February and grew rapidly through the period. By 17 February, activity further decayed to low levels. A C1.1 x-ray event was observed from Region 1158 at 17/2135 with an associated Type II Sweep (1695 km/s). Activity increased to high levels on 18 February due to an impulsive M6.6 x-ray event at 18/1011Z observed from Region 1158. New Region 1162 (N18, L=336 class/area Dai/260 on 18 February) emerged rapidly on the disk and produced three M-class x-ray events, the largest an M1.3 at 18/2104Z. 19 and 20 February saw a return to low solar activity levels.

A greater than 10 MeV proton enhancement was observed at geosynchronous orbit. Proton flux began a slow rise at about 15/0700Z, peaked at 15/1115Z (2.5 pfu) and decayed to background levels by about 16/1500Z

The greater than 2 MeV electron flux at geosynchronous orbit was at high levels on 14 and 20 February and at normal levels 15 - 19 February.

Geomagnetic field activity ranged from quiet to minor storm levels during the period. Activity was quiet until 14/1800Z when activity increased to unsettled to active levels. Solar wind data indicated a shock arrival at the ACE spacecraft at 14/1456Z. A 12nT sudden impulse, measured at the Boulder magnetometer, was observed at 14/1600Z. Following the shock, solar wind velocities increased from about 300 km/s to near 410 km/s while the total magnetic field (Bt)increased to near 20 nT. The source of this transient was likely an east limb event from late on 11 February. Quiet to active levels persisted through 15/1500Z. Thereafter, and through the end of 17 February, the field was quiet. Early on 18 February, activity increased to unsettled to active levels, with isolated high latitude minor storm periods. A shock passage at the ACE spacecraft was observed at 18/0049Z and shortly after at 18/0136Z, a 33 nT sudden impulse was recorded at the Boulder magnetomter. After the shock passage, solar wind speeds rapidly increased from about 325 km/s to near 500 km/s and reached a maximum velocity of 706 km/s at 18/1203Z. Coincident with the shock, the Bz component of the interplanetary magnetic field dipped south between -8 to -15 nT, and remained so for a period of about 12 hours. This activity was due to the effects of the CMEs observed from solar activity during the 13 - 15 February timeframe. By 18/2100Z, geomagnetic activity decayed to mostly quiet to unsettled levels, and remained so through the balance of the summary period.

Forecast of Solar and Geomagnetic Activity
23 February - 21 March 2011

Solar activity is expected to be at low to moderate levels through 25 February when Regions 1161 and 1162 rotate around the west limb. Very low to low levels will persist until 04 March. Low to moderate levels, with a slight chance for high levels, are expected from 05 - 21 March when old Regions 1158 (S21, L=31), 1162 (N18, L=335) and 1161 (N11, L=331) are due to rotate onto the disk on 05, 09 and 10 March respectively.

No proton events are expected at geosynchronous orbit.

The greater than 2 MeV electron flux at geosynchronous orbit is expected to be normal to moderate levels from 23 February - 04 March. High levels are expected from 05 - 13 March. A return to normal to moderate levels are expected from 14 - 18 March followed by high levels from 19 - 21 March.

Geomagnetic field activity is expected to be at quiet to unsettled levels from 23 - 24 February due to a recurrent coronal hole high speed stream (CH HSS). Quiet levels are expected from 25 - 26 February. An increase in activity to quiet to unsettled levels are expected from 27 February - 02 March due to another recurrent CH HSS. Quiet levels will persist from 03 - 06 March. Quiet to unsettled levels will return from 07 - 10 March due to a recurrent CH HSS. A brief period of quiet levels are expected from 11 - 13 March. Another recurrent CH HSS will raise activity levels to quiet to unsettled from 14 - 15 March followed by a period of quiet conditions from 16 - 21 March.

Product: 27-day Space Weather Outlook Table 27DO.txt
:Issued: 2011 Feb 15 1953 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 2011-02-15
#
# UTC Radio Flux Planetary Largest
# Date 10.7 cm A Index Kp Index
2011 Feb 16 100 8 3
2011 Feb 17 100 18 4
2011 Feb 18 100 25 5
2011 Feb 19 98 10 3
2011 Feb 20 98 5 2
2011 Feb 21 95 5 2
2011 Feb 22 90 5 2
2011 Feb 23 84 5 2
2011 Feb 24 80 5 2
2011 Feb 25 80 5 2
2011 Feb 26 80 5 2
2011 Feb 27 80 5 2
2011 Feb 28 80 5 2
2011 Mar 01 80 8 3
2011 Mar 02 80 10 3
2011 Mar 03 82 10 3
2011 Mar 04 82 8 3
2011 Mar 05 84 5 2
2011 Mar 06 84 5 2
2011 Mar 07 88 5 2
2011 Mar 08 88 5 2
2011 Mar 09 88 5 2
2011 Mar 10 90 5 2
2011 Mar 11 90 5 2
2011 Mar 12 95 5 2
2011 Mar 13 95 5 2
2011 Mar 14 95 5 2
(NOAA)

** Solar Flare's for our newer VHF DXers **

What is now happening on the sun, the earth and to radio propagation is likely new to our colleagues licensed in the past five years. This is for them .... Solar Flare Theory Click here: http://hesperia.gsfc.nasa.gov/sftheory/index.htm
(Source: W0WOI via VHF Reflector!)
Dont forget to report your AURORA QSOs to MMMonVHF:
http://www.mmmonvhf.de/au.php if an AURORA occurs next weeks...
(VHS Newsletter 2011-2-24)