Space Weather Forecast Headline: Slight chance of isolated Moderate-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 up to five sunspot regions on the visible disc. The largest region on the disc is now transiting the northwest quadrant. This has slowly decreased in overall size, losing some of the peripheral spots and simplifying to a unipolar configuration. A bipolar region has rotated to the northwest limb. Another bipolar region, also in the northwest, has shown some weakening of the lead/trailer spots, with some minor spot emergence in its intermediate portion. Two additional relatively small regions have now rotated from the eastern limb, although these are difficult to fully assess due to the viewing angle. 

No Earth-directed Coronal Mass Ejections (CMEs) were observed in the past 24hrs.

Solar Wind / Geomagnetic Activity: Solar wind speeds, as observed by ACE and DSCOVR at L1, increased as coronal hole fast winds strengthened into the overnight UTC period, before easing slightly. Speeds were initially Elevated, 550km/s, rising to Strong and peaking 700-800km/s, before easing slightly to 650km/s. The Interplanetary Magnetic Field was Moderate, trending to Weak after midnight UTC. The north-south component followed a similar trend and was variable, often favouring negative (southward). Geomagnetic activity was at Active to G2/Moderate storm levels (Kp 4-6). 

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.

Ongoing fast solar winds are expected for Day 1 (16 May), then slowly declining Days 2 and 3 (17 and 18 May). Winds may reach Background to Slightly Elevated levels by Day 4 (19 May). Geomagnetic activity is expected to be Unsettled to Active (Kp 3-4), with a chance of further isolated G1/Minor storm intervals (Kp 5) on Day 1 (16 May). During Day 2 (17 May) activity will likely slowly decrease to mainly Quiet to Unsettled levels (Kp 2–3), with a chance of Active to G1/Minor storm intervals. (Kp 4-5). Through Days 3 and 4 (18 and 19 May), activity is expected to gradually reduce further.

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