Space Weather Forecast Headline: Reducing chance of isolated M-class solar flares. G1/Minor storm intervals Likely Day 1 (16 May).

Analysis of Space Weather Activity over past 24 hours

Solar Activity: Solar Activity was Low over the past 24hrs, with occasional Common-class flares observed, peaking at C9.5 at 15/1614 UTC from a sunspot region in the northwest. There are currently three sunspot regions on the visible disc, all bipolar. The largest region in the north central disc appears to be simplifying, with another region just rotating off the western limb. The other sunspot region appears stable and simple.

No Earth-directed Coronal Mass Ejections (CMEs) were observed in the past 24hrs. A CME originating from a sunspot region in the north centre disk was observed early on 15 May, though after analysis is expected to miss above earth.

Solar Wind / Geomagnetic Activity: Solar wind speeds, as observed by ACE and DSCOVR at L1, were generally at background levels until the arrival of coronal hole fast winds from CH53/-. They started around 380-400 km/s and then steadily rose through the day, reaching Strong around 15/1430 UTC. They peaked at 810 km/s at 15/2311 UTC. The  Interplanetary Magnetic Field, Bt, started weak, rising to Moderate after 15/0300 UTC. It then had a brief period were it increased to Above Average between about 15/1500-1700 UTC. The north-south component (Bz)  was weak and generally positive (northward) at first, becoming generally Moderate and negative (southward) from around 15/0930 UTC.  Geomagnetic activity started Quiet to Unsettled (Kp 1-3), but also had a G1/Minor storm interval. 

Energetic Particles / Solar Radiation: GOES18 high energy (>10 MeV) proton flux was at Background.

Four-Day Space Weather Forecast Summary

Solar Activity: Solar activity is forecast to continue generally Low, but with a slight chance of Moderate-class flares.

Solar Wind / Geomagnetic Activity: There no Earth-directed CMEs in the forecast. Solar wind speeds are expected to be influenced by a coronal hole for much of the period. Speeds have already reached strong (650-700 km/s), with similar expected for Day 1 (16 May), slowly declining after this, possibly reaching background to slightly elevated levels by Day 4 (19 May).

Geomagnetic activity is expected to be Unsettled to Active (Kp 3-4) with likely G1/Minor storm intervals (Kp 5) and a slight chance of G2/Moderate storms (Kp 6) on Day 1 (16 May). During Day 2 (17 May) activity will likely decrease to mainly Quiet to Unsettled (Kp 1-3), reducing further on Days 3 & 4 (18&19 May).

Energetic Particles / Solar Radiation: GOES18 high energy (>10 MeV) proton flux is expected to remain at Background levels, with no solar radiation storms expected.