M2.7 solar flare erupts from Region 4392, Earth-directed CME produced
A moderately strong solar flare measuring M2.7 erupted from Active Region 4392 at 12:15 UTC on March 16, 2026. The event lasted 24 minutes.
M2.7 solar flare on March 16, 2026. Credit: NASA SDO/AIA 131, The Watchers
A Type II Radio Emission with an estimated velocity of 1 227 km/s was associated with the flare, indicating a coronal mass ejection (CME) was produced. A Type IV radio emission was detected at 12:12 UTC, suggesting a strong CME was produced.
Additionally, a 10cm Radio Burst lasting 8 minutes and with a peak flux of 380 sfu was registered from 12:09 to 12:17 UTC. 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.
“There are indications of a possible associated CME,” SWPC forecasters said. “We are currently waiting for coronagraph imagery to be available in order to determine if a CME indeed erupted from the Sun and, if so, to analyze and model it to determine a potential Earth-directed component.”
Radio frequencies were forecast to be most degraded over the Atlantic Ocean, Africa, and southern Europe at the time of the event.
Solar activity was at low levels in 24 hours to 12:30 UTC today. Region 4395 (beta) produced a C1.1 flare at 15:09 UTC on March 15 — the strongest of the period. Minor growth was observed in the region as well as in Region 4392 (gamma) — the source of today’s M2.7.
The remaining active regions on the visible disk were either stable or in gradual decay.
The >2 MeV electron flux reached high levels, peaking at 1 430 pfu at 19:00 UTC on March 15, while the >10 MeV proton flux remained at background levels. The electron flux is expected to remain at high levels through March 18, while the proton flux is expected to stay at background levels over the same period.
Solar wind conditions over the past 24 hours reflected the continued influence of a positive polarity coronal hole high-speed stream (CH HSS).
The total magnetic field measured 5–6 nT, while the Bz component fluctuated between ±5 nT. Solar wind speeds gradually decreased from peaks of about 675 km/s to around 500 km/s by the end of the period, with the phi angle predominantly oriented in a positive solar sector.
Solar wind parameters are expected to remain elevated but gradually decline through March 18.
Geomagnetic field activity reached unsettled levels during the past 24 hours. Geomagnetic conditions are expected to be primarily quiet to unsettled from March 16–18, with isolated active periods possible on March 16.
Solar activity is expected to be at low levels, with a slight chance for M-class flares through March 18.
Update
20:57 UTC, March 16
Coronagraph imagery suggests a part of the CME is Earth-directed, with arrival expected on March 19. As a result, a G2-Moderate geomagnetic storm watch is now in effect.
Under G2 geomagnetic storm conditions, impacts are expected mainly poleward of 55° geomagnetic latitude. Possible effects include power grid fluctuations and voltage alarms in high-latitude systems, minor satellite orientation irregularities, and increased drag on low-Earth orbit satellites. HF radio propagation may weaken at higher latitudes.
Aurora could become visible farther south, potentially extending from New York and Wisconsin to Washington state.
References:
1 Forecast Discussion – NOAA/SWPC – Issued at 12:30 UTC on March 16, 2026
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