official data
G2 watch day so far: forecast said moderate storm — observed K stayed quiet-to-unsettled
NOAA SWPC’s Sep 9 products still carried a G1–G2 geomagnetic storm outlook from coronal-hole wind plus anticipated CME debris — while the planetary K series through morning UTC and the live NOAA G scale at midday stamp have not shown a G2 period yet.
Key facts
- Forecast
- 3-Day / Discussion issued 0030 UTC Sep 9 — G1–G2 likely 09 Sep (CH HSS + CME 05–06 Sep)
- Expected peak
- Greatest expected 3-hr Kp 5.67 (G2); Sep 9 rows include 00–03 UT Kp 5.00 (G1) and 03–06 UT Kp 5.67 (G2)
- Past-24h at issue
- Greatest observed 3-hr Kp = 5 (G1)
- Observed K Sep 9
- 00 UT 2.67 · 03 UT 1.33 · 06 UT 2.33 · 09 UT 2.67 — quiet-to-unsettled; no G1+ in those periods
- NOAA Scales
- ~12:13 UTC stamp — current G0 / none; forecast day still G2; prior day G1
- Prior alert
- ALTK05 Serial 2049 — Kp=5 / G1 threshold Sep 08 1744 UTC
- Flares / electrons
- C-class (discussion max C3.4); electron flux high / ALTEF3 continuation
- Live
- Kp / G-scale → live SWPC HUD — do not freeze this note
Note
Primary: NOAA/NWS SWPC 3-Day Forecast and Forecast Discussion issued 2026 Sep 09 0030 UTC, NOAA Scales JSON stamp 2026-09-09 12:13 UTC, planetary K-index product through the 09 UT synoptic period, and ALTK05 supporting alert.
What it is not: ECDO proof; a micronova or pole-shift claim; inventing live Kp; an X-flare note (window max C-class); a re-ship of the midnight WATA30 announcement without the observed-status update; an S1 proton storm.
Why it matters
Watch-day status vs midnight WATA30 announcement alone. Forecast vs meter is why gauges stay on the HUD. Geomagnetic storm scales are not ECDO, polar motion, or core–mantle proof.
Sources
- NOAA/NWS SWPC 3-Day Forecast + Forecast Discussion
- SWPC Forecast Discussion
- NOAA Scales JSON
- Planetary K-index
- Alerts JSON (ALTK05)
- SWPC home
Official data. Live values go to the HUD / source product.