Forecaster summary - Issued 2025-06-16T00:23:56

The greater than 2MeV electron flux observed at GEO by GOES19 has been at mostly moderate levels. With the arrival of the HSS from CH57/+, a large southern hemisphere coronal hole, wind speeds may become elevated to strong, which could cause an increase in electron flux below GEO. As the HSS wanes through Day 1 (16 Jun), an increase in high energy electron flux is then possible, with an increasing potential for the electron flux to reach high levels from Day 2 (17 Jun). A possible resurgence of the HSS later Day 2 into Day 3 (17-18 Jun) may see electron flux suppressed again below GEO, before responding again on Day 4 (19 Jun).

Electron fluence may rise close to the Active threshold on Day 1 (16 Jun). This risk persists into Days 2 & 3 (17-18 Jun), however any resurgence in the HSS may see the suppression of the electron belts again, and subsequent decrease in electron fluence, as suggested by MOSWOC REFM, with a further rise possible on Day 4 (19 Jun) as this resurgence ease. Overall, the electron forecast is low confidence with uncertainties in the geomagnetic forecast.