Geoeffective AR 1936 (S16W36, Eac/beta-gamma-delta) produced an M6.4 solar flare on Tuesday, December 31, 2013. The event started at 21:45 and peaked at 21:58 UTC. It is possible that Earth-directed CME was associated, a glancing blow to our planet is possible later this week.
January 1, 2014 - 13:30 UTC: No Earth-directed coronal mass ejection (CME) was detected from the flare, forecasters are still awaiting additional satellite imagery to evaluate the potential impacts.
Slightly elevated wind speeds should persist as the Earth continues to be influenced by a weak, negative-polarity CH HSS. Glancing blow CME effects are still possible on day one (Jan 1) from the Dec 29 CME. A second, stronger increase in wind speed is expected on Jan 02 as a positive-polarity CH HSS becomes geoeffective. Wind speeds in excess of 600 km/s are possible with this CH HSS, based upon past STEREO-B observations. Wind speed is expected to remain elevated on Jan 3 as the CH HSS persists. (SWPC)
M6.4 solar flare zoomed in - SDO / AIA 304.
Space Weather Message Code: SUMXM5
Serial Number: 109
Issue Time: 2013 Dec 31 2331 UTC
SUMMARY: X-ray Event exceeded M5
Begin Time: 2013 Dec 31 2145 UTC
Maximum Time: 2013 Dec 31 2158 UTC
End Time: 2013 Dec 31 2220 UTC
X-ray Class: M6.4
Optical Class: 2n
NOAA Scale: R2 - Moderate
Potential Impacts: Area of impact centered primarily on sub-solar point on the sunlit side of Earth.
Radio - Limited blackout of HF (high frequency) radio communication for tens of minutes.
Space Weather Message Code: SUM10R
Serial Number: 601
Issue Time: 2013 Dec 31 2224 UTC
SUMMARY: 10cm Radio Burst
Begin Time: 2013 Dec 31 2149 UTC
Maximum Time: 2013 Dec 31 2151 UTC
End Time: 2013 Dec 31 2155 UTC
Duration: 6 minutes
Peak Flux: 160 sfu
Latest Penticton Noon Flux: 145 sfu
Description: A 10cm radio burst indicates that the electromagnetic burst associated with a solar flare at the 10cm wavelength was double or greater than the initial 10cm radio background. This can be indicative of significant radio noise in association with a solar flare. This noise is generally short-lived but can cause interference for sensitive receivers including radar, GPS, and satellite communications.
A long-duration C8 flare occurred on the morning of December 31 from a region just beyond the southeast limb. It was associated with an eastward, non-Earth-directed coronal mass ejection (CME).
SDO / AIA 1600 on December 31, 2013 at 22:02 UTC.
SWPC forecast (00:30 UTC, December 31, 2013):
"A minor increase in wind speed is possible on January 01 due to a weak, negative-polarity coronal hole high-speed stream (CH HSS) and possible glancing blow from the December 29 CME.
A second, stronger increase in wind speed is expected on January 02 as a positive-polarity CH HSS becomes geoeffective.
Wind speeds in excess of 600 km/s are possible with this CH HSS, based upon past STEREO-B observations. Wind speed is expected to remain elevated on January 03 as the CH HSS persists."
Sunspots - December 31, 2013 at 23:27 UTC.
1931 S14W0* 290 130 2 HAX 1 A
1934 S16W83 272 80 11 EAC 5 BGD
1936 S16W36 225 280 14 EAC 36 BGD
1937 S12W09 198 10 4 BXO 3 B
1938 S09E09 179 30 2 HAX 3 A
1940 S12W44 233 20 4 DRO 4 B
1941 S13W22 211 30 4 DRO 3 B
1942 N10E62 127 20 1 HRX 1 A
1943 S11E67 122 20 1 CRO 1 B
"In last 24 hours new Region 1940 (S12W44, Dro/beta) emerged just northwest of Region 1936 and appeared to be in a gradual growth phase. It produced two C-class flares including a C4/Sf at 31/1859 UTC. Region 1934 (S16W83, Eac/beta-gamma-delta) was relatively stable and non-productive as it approached the west limb. Three other new spot groups were also numbered: 1941 (S13W22, Dro/beta), 1942 (N10E62, Hrx/alpha), and 1943 (S11E67, Cro/beta), none of which were impressive in morphological or magnetic aspects."
"Geomagnetic field activity is expected to increase from quiet to unsettled levels on Jan 01 due to a weak negative-polarity coronal hole high-speed stream (CH HSS) and a possible glancing blow from the Dec 29 CME. A further increase to quiet to minor storm levels (G1 - Minor) is expected on Jan 02 due to a combination of persistent CME effects and the onset of a positive-polarity CH HSS. Field activity is expected to decrease to quiet to unsettled levels on Jan 03 as CH HSS effects gradually subside." (SWPC)
NOAA SWPC forecasters estimate 40% chance for M-class, and 10% chance for X-class solar flare in the days ahead.
Featured image courtesy of NASA / SDO AIA 304.