[Propagation+Space Weather] Today's Space Weather Forecast Discussion on 2017 Dec 17 1230 UTC

[nw7us@sunspotwatch.com]

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Here is the current forecast discussion on space weather and geophysical activity, issued 2017 Dec 17 1230 UTC.

Solar Activity

24 hr Summary: Solar activity was very low. The solar disk remained spotless. The 15 Dec filament eruption mentioned in previous discussion products was determined to contain a potentially geoeffective component. WSA-Enlil model analysis suggests a southeasterly trajectory with a radial velocity of approximately 245 km/s. Based on this transit speed any potential impacts to the Earths magnetosphere should occur late on day three (19 Dec), in conjunction with the forecasted positive polarity CH HSS. There were no additional Earth-directed CMEs observed in available satellite imagery during the reporting period.

Forecast: Solar activity is expected to continue at very low levels over the next three days (17-19 Dec).

Energetic Particles

24 hr Summary: The greater than 2 MeV electron flux was at normal to moderate levels with a peak flux of 247 pfu observed at 16/2215 UTC. The greater than 10 MeV proton flux was at background levels.

Forecast: The greater than 2 MeV electron flux is expected to be at normal to moderate levels on day one (17 Dec). An increase to moderate to high levels is likely on days two and three (18-19 Dec) in response to elevated wind speeds from a recurrent CH HSS. The greater than 10 MeV proton flux is expected to continue at background levels throughout the forecast period.

Solar Wind

24 hr Summary: Solar wind parameters indicated background conditions through about 16/2100 UTC. Solar wind speeds ranged between 320-350 km/s. Total magnetic field strength was below 2 nT while the Bz component ranged from +2 nT to -3 nT.

After 16/2100 UTC, a CIR signature became evident. Bt increased sharply to 10 nT and further increased during the period to a maximum of 14 nT at 17/0800 UTC. The Bz component indicated increased variability between +11 nT to -9 nT. Wind speeds increased initially to about 375 km/s, hit a first maximum of near 500 km/s at about 17/0815 UTC and finished the period with speeds approaching 550 km/s. Phi angle was oriented in a mostly positive solar sector throughout the period.

Forecast: The solar wind environment is expected to continue at elevated levels for the remainder of day one (17 Dec) due to CIR/CH HSS effects. By day two (18 Dec) through day three (19 Dec), wind parameters are expected to be further enhanced due to CH HSS influence. Wind speeds are anticipated to exceed 600 km/s with this feature. An additional enhancement is possible late on day 19 Dec due to glancing blow impacts from the aforementioned CME from 15 Dec.

Geospace

24 hr Summary: The geomagnetic field was at quiet to minor storm levels (G1-Minor) due to a CIR arrival in advance of an anticipated recurrent, positive polarity CH HSS.

Forecast: The geomagnetic field is expected to be at mostly unsettled to isolated G1 (minor) levels through the remainder of day one (17 Dec) due to CIR/CH HSS effects. By day two (18 Dec) through day three (19 Dec), unsettled to G1 (Minor) conditions are expected to persist due to CH HSS influence coupled with potential glancing blow effects from the 15 Dec CME.

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