Long duration M6.5 solar flare erupts from Region 2371, 4th Earth-directed CME produced


Active Region 2371, the source of two Earth-directed Coronal Mass Ejections (CMEs) over the past couple of days, produced an M6.5 solar flare (R2-Moderate) at 18:23 UTC on June 22, 2015. The event started at 17:39 and ended at 18:51 UTC. 

Region 2371 is one of the largest in current solar cycle, it is very active, capable of producing more strong to major eruptions on the Sun and is in geoeffective position. CMEs produced by this region over the coming days will most likely be Earth-directed.

Associated with M6.5 event was a Castelli-U spectral burst including a 1000 sfu Tenflare and a Type II radio sweep (1480 km/s estimated shock velocity) indicating a CME was produced.

A full halo CME was produced, estimated time of arrival is June 24 at 23:00 UTC. 

Further analysis and subsequent models runs will be performed to better ascertain the intensity, timing, and duration of additional geomagnetic storm response from this latest CME. A G1 (Minor) Watch has been issued for June 24 and 25 as a preliminary response, SWPC said at 00:30 UTC on June 23.


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Space Weather Message Code: SUMXM5
Serial Number: 138
Issue Time: 2015 Jun 22 1854 UTC

SUMMARY: X-ray Event exceeded M5
Begin Time: 2015 Jun 22 1739 UTC
Maximum Time: 2015 Jun 22 1823 UTC
End Time: 2015 Jun 22 1851 UTC
X-ray Class: M6.5
Location: N13W14
NOAA Scale: R2 – Moderate

NOAA Space Weather Scale descriptions can be found at

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: ALTTP2
Serial Number: 1017
Issue Time: 2015 Jun 22 1833 UTC

ALERT: Type II Radio Emission
Begin Time: 2015 Jun 22 1805 UTC
Estimated Velocity: 1480 km/s

NOAA Space Weather Scale descriptions can be found at

Description: Type II emissions occur in association with eruptions on the sun and typically indicate a coronal mass ejection is associated with a flare event.


Space Weather Message Code: SUM10R
Serial Number: 666
Issue Time: 2015 Jun 22 1850 UTC

SUMMARY: 10cm Radio Burst
Begin Time: 2015 Jun 22 1820 UTC
Maximum Time: 2015 Jun 22 1825 UTC
End Time: 2015 Jun 22 1830 UTC
Duration: 10 minutes
Peak Flux: 1100 sfu
Latest Penticton Noon Flux: 130 sfu

NOAA Space Weather Scale descriptions can be found at

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.


Meanwhile, all three CMEs (from June 18, 19 and 21) have finally arrived at our planet causing geomagnetic storms reaching G4-Severe levels on June 22 and 23.

WSA-Enlil CME model run at 15:23 UTC on June 21, 2015. Annotation: TW.

Space Weather Message Code: ALTK08
Serial Number: 21
Issue Time: 2015 Jun 22 1858 UTC

ALERT: Geomagnetic K-index of 8
Threshold Reached: 2015 Jun 22 1852 UTC
Synoptic Period: 1800-2100 UTC

Active Warning: Yes
NOAA Scale: G4 – Severe

NOAA Space Weather Scale descriptions can be found at

Potential Impacts: Area of impact primarily poleward of 45 degrees Geomagnetic Latitude.
Induced Currents – Possible widespread voltage control problems and some protective systems may mistakenly trip out key assets from the power grid. Induced pipeline currents intensify.
Spacecraft – Systems may experience surface charging; increased drag on low earth orbit satellites, and tracking and orientation problems may occur.
Navigation – Satellite navigation (GPS) degraded or inoperable for hours.
Radio – HF (high frequency) radio propagation sporadic or blacked out.
Aurora – Aurora may be seen as low as Alabama and northern California.


Proton levels are still on the rise. Our planet is currently experiencing S3-Strong Solar Radiation Storm.

According to NOAA, there are about 10 such events per each solar cycle (11 years).

Space Weather Message Code: ALTPX3
Serial Number: 28
Issue Time: 2015 Jun 22 1912 UTC

ALERT: Proton Event 10MeV Integral Flux exceeded 1000pfu
Begin Time: 2015 Jun 22 1900 UTC
NOAA Scale: S3 – Strong

NOAA Space Weather Scale descriptions can be found at

Potential Impacts: Radiation – Passengers and crew in high latitude, high altitude flights may experience increasing radiation exposures. Astronauts on EVA (extra-vehicular activity) are exposed to elevated radiation levels.
Spacecraft – Single-event upsets to satellite operations, noise in imaging systems, and slight reduction of efficiency in solar panels are likely.
Radio – Degraded or episodically blacked-out polar HF (high frequency) radio propagation.


Featured image: M6.5 solar flare on June 22, 2015. Credit: NASA SDO/AIA.

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