A moderately strong solar flare measuring M1.9 erupted from geoeffective Active Region 4436 at 16:12 UTC on May 16, 2026. A coronal mass ejection (CME) was produced, but analysis remains incomplete pending coronagraph imagery.
A Type IV radio emission was registered at 16:05 UTC, suggesting a strong coronal mass ejection (CME) was produced.
Additionally, a 10 cm Radio Burst (TenFlare) with peak flux of 170 sfu was detected from 16:06 to 16:10 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.
Radio frequencies were forecast to be most degraded over parts of North America, the Caribbean Sea, and the North Atlantic Ocean at the time of the flare event.
The location of Region 4436 (beta) favors Earth-directed CMEs. However, coronagraph data are still not available to determine Earth-directed potential.
There are currently three numbered regions on the Earth side of the sun — 4435 (beta), 4436 (beta), and 4438 (beta). Regions 4436 and 4438 will soon begin their farside transit, but old regions 4423, 4424, and 4430 will return over the next two days.
A new active region is rapidly growing on the far side of the Sun and is expected to begin rotating onto the Earth-facing disk around May 22-24. If the region persists, it should become better positioned for Earth-directed eruptions during the final week of May, with central meridian passage roughly around May 29-31.
The solar wind parameters in 24 hours to 12:30 UTC today reflected increased influence from a negative polarity coronal hole high speed stream (CH HSS). Total interplanetary magnetic field strength unsteadily increased from around 3 nT to reach as high as 17 nT. The Bz component briefly reached as far south as -14 nT while Phi was in a predominantly negative orientation.
Wind speeds steadily increased to a peak of ~800 km/s between 23:00 UTC on May 15 and 03:30 UTC on May 16, followed by a gradual decline to a speed near 650 km/s by the end of the reporting period.
Solar wind parameters are expected to continue to be enhanced through May 18 due to the persistent influence of the negative polarity CH HSS.
The geomagnetic field reached G2 – Moderate geomagnetic storm levels during the same period due to the influence of a co-rotating interaction region (CIR) ahead of a negative polarity CH HSS.
G1 – Minor conditions are expected to continue through May 16 due to the ongoing effects of a negative polarity CH HSS. Active to G1 – Minor storm levels are likely to continue on May 17, decreasing to unsettled to active conditions by May 18 as lingering CH HSS influences diminish.
References:
1 Forecast Discussion – NOAA/SWPC – 12:30 UTC on May 16, 2026
Featured image: M1.9 solar flare on May 16, 2026. Credit: NASA/SDO AIA 304, The Watchers