[Propagation+Space Weather] Today's Space Weather Forecast Discussion on 2015 Aug 23 1230 UTC

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Here is the current forecast discussion on space weather and geophysical activity, issued 2015 Aug 23 1230 UTC.

Solar Activity

24 hr Summary: Solar activity was a moderate levels. Region 2403 (S15W01, Ekc/beta-gamma-delta) produced two M-class flares throughout the period. An M2/1n flare at 22/1323 UTC and an M3/1b at 22/2124 UTC. Region 2403 remained complex, continuing to develop new intermediate spots and consolidating spots in both the leader and trailer spots. Region 2404 (N13W10, Cri/beta) increased in overall size developing an intermediate spot with penumbra and spots near the trailer.

A coronal mass ejection (CME) was observed off of the East limb of the Sun in SOHO/LASCO C2 imagery around 23/0436 UTC. It was likely associated a low level C-class flare from a plage region near N10E30. The ejected appeared to be moving East of the Earth-Sun line. No other CMEs were observed in available coronagraph imagery.

Forecast: Solar activity is likely to continue at moderate levels (R1-R2, Minor-Moderate) with a chance for X-class flares (R3-Strong or greater) for the forecast period due to the flare potential of Region 2403.

Energetic Particle

24 hr Summary: The greater than 2 MeV electron flux reached high levels with a maximum of 1,690 pfu at 22/1600 UTC. The greater than 10 MeV proton flux was at background levels throughout the period.

Forecast: The greater than 2 MeV electron flux is likely to decrease to normal to moderate levels for the forecast period (23-25 Aug) with the arrival of a geoeffective positive polarity coronal hole high speed stream (CH HSS) as well as the arrival of a combination of the 21 and 22 Aug CMEs. A slight chance for a greater than 10 MeV proton event (S1-Minor) exists on day three (25 Aug) as Region 2403 transits into a better connected location.

Solar Wind

24 hr Summary: Solar wind parameters, measured at the ACE satellite, suggested enhancement by the onset of a co-rotating interaction region transitioning to a positive polarity coronal hole high speed stream. Total magnetic field trended up throughout the day reaching a peak of 15 nT in the later half of the period. Density followed a similar trend slowing increasing throughout the period reaching a peak flux around 23/0600 UTC. Wind velocity remained mostly low between 350 - 400 km/s until the later portion of the day. After 23/0700 UTC, wind velocity began to increase sharply, to between 500 - 550 km/s, as density decreased. This suggests the transition into the high speed stream from the co-rotating interaction region. A notable period of prolonged Bz southward was observed after 23/0522 UTC with values reaching as low as -11 nT. Phi remained predominantly positive (away) throughout the period.

Forecast: Solar wind parameters are expected to remain enhanced through day two (24 Aug) by the positive polarity coronal hole high speed stream. Early on day two, a further enhancement is expected with the arrival CMEs from 21 and 22 Aug. Activity is expected to persist into day three (25 Aug)

Geospace

24 hr Summary: The geomagnetic field began the period with quiet to unsettled conditions. After 23/0600 UTC, the geomagnetic field responded to a prolonged southward Bz component of the solar wind causing strong coupling with the interplanetary magnetic field during the onset of a coronal hole high speed stream. This resulted in G2 (Moderate) geomagnetic storm levels.

Forecast: The geomagnetic field is expected to be at active to major storm (G2-Moderate) levels on day one (23 Aug) as the coronal hole high speed stream sets in. Day two (24 Aug) is expected see continued influence of the high speed stream with further enhancements causing periods of G1 (Minor) storming in response to the arrival of CMEs from 21 and 22 Aug. Mostly unsettled to active conditions are expected to persist through day three (25 Aug)

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