[Propagation+Space Weather] Today's Space Weather Forecast Discussion on 2016 Jul 20 1230 UTC

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Here is the current forecast discussion on space weather and geophysical activity, issued 2016 Jul 20 1230 UTC.

Solar Activity

24 hr Summary: Solar activity continued at low levels, as several C-class flares took place. Region 2567 (N05W31, Dki/beta-gamma) grew as the region gained penumbral coverage in lead, negative polarity spot and developed opposite, positive polarity umbra along the periphery of the lead penumbra. This made for increased magnetic shear within the region, with an already strengthened magnetic field gradient. The region was the source of three C-class flares, the largest was a C4/Sf at 20/0317 UTC. Region 2565 (N04W43, Cko/beta) changed little over the period. It retained its leading positive polarity spots and maintained a moderate magnetic gradient, with minor shear. The region produced a C2/Sf at 20/0335 UTC. Region 2569 (N15E05, Hrx/alpha) decayed further and was inactive.

No new Earth-directed CMEs were detected in available coronagraph imagery.

Forecast: Solar activity is likely to continue at low levels, with a chance for M-class flares (R1-R2/Minor-Moderate), over the next three days (20-22 Jul), due primarily to the elevated flare probabilities of Regions 2565 and 2567.

Energetic Particles

24 hr Summary: The greater than 2 MeV electron flux was at high levels with a peak flux of 7,070 pfu observed at 19/1440 UTC. The electron flux decreased to moderate and normal levels after 19/2350 UTC due to CME effects. The greater than 10 MeV proton flux continued at background levels.

Forecast: The greater than 2 MeV electron flux is expected to continue at normal levels for the remainder of day one (20 Jul). Electron flux is expected to be at normal to moderate levels on day two (21 Jul) due to electron redistribution from CH HSS influence, with a likely increase to moderate to high levels by day three (22 Jul). The greater than 10 MeV proton flux is expected to continue at background levels for the forecast period (20-22 Jul).

Solar Wind

24 hr Summary: Solar wind parameters, as measured by the ACE spacecraft, indicated the arrival of an interplanetary shock at 19/2305 UTC with an approximate speed of 450 km/s. Total IMF strength ranged from 2 to 5 nT until the the shock arrival when it initially reached 17 nT. Total field strength continued to increase with the transient passage and reached a maximum of 31 nT at 20/0052 UTC. The Bz component reached a maximum southward deviation of -12 nT upon shock arrival. The Bz component became variable afterwards and briefly reached a maximum southward value of -28 nT at 20/0022 UTC. Solar wind speed continued to increase with the transient passage, possibly indicative of the anticipated negative polarity CH HSS onset, and reached speeds of near 600 km/s by about 20/0700 UTC. The phi angle was primarily in a positive sector through the first half of the period, until about 20/0011 UTC, when it deflected into a negative (towards the Sun) sector.

Forecast: Solar wind parameters are expected to remain enhanced through the remainder of day one (20 Jul) due to the continued, but diminishing transient influence; and CH HSS effects. Enhanced, but diminishing conditions, are expected on days two and three (21-22 Jul) due to continued CH HSS influence.

Geospace

24 hr Summary: The geomagnetic field was quiet until a sudden storm commencement (SSC) escalated the planetary geomagnetic response to G1 (Minor) storm levels near the end of the 19 Jul 2100-2400 UTC synoptic period. The SSC occurred at 19/2355 UTC and the Boulder magnetometer measured a 64 nT deviation. G1 storming continued to 20/0600 UTC, before decreasing to unsettled to active levels of response.

Forecast: The geomagnetic field is expected to continue to react at unsettled to active levels, with an early isolated period of G1 (Minor) storming, during the remainder of day one (20 Jul) due to continued, but diminishing transient effects combined with CH HSS influences. Quiet to active levels, with a slight chance for G1 (minor) storm conditions are possible on day two (21 Jul) due to continued CH HSS effects. Quiet to unsettled conditions, with an isolated active period, are expected early on day three (22 Jul) as CH HSS effects persist.

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