[Propagation+Space Weather] Today's Space Weather Forecast Discussion on 2015 Jul 10 1230 UTC

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Here is the current forecast discussion on space weather and geophysical activity, issued 2015 Jul 10 1230 UTC.

Solar Activity

24 hr Summary: Solar activity was at very low levels. Region 2381 (N15W18, Fko/beta) continued in slow decay as penumbral area decreased. Solar synoptic analysis indicated the region spread further in longitudinal extent and the magnetic shear in the center of spot group decreased. However, some magnetic mixing resurfaced as weak pores, in the trailer portion, indicative that some instability still exists. To this extent, there were some plage enhancements and occasional surging from the region.

A new area of spots emerged and was assigned as NOAA Region 2385 (N07W47, Dri/beta). The region evolved from a simple set of unipolar spots into an increasingly complex group and produced a few optical sub-flares late in the period.

Region 2373 (N16W87, Hsx/alpha) remained unchanged as it rotated to the limb, but produced a B9/Sf flare at 09/1828 UTC. This flare had an associated bright surge of ejecta as observed in SDO/AIA 304 imagery and was a possible source of a coronal mass ejection (CME) noted off the WNW limb first seen in SOHO/LASCO C2 coronagraph imagery at 09/1900 UTC. All indications are the CME is off the Sun-Earth line. The remaining regions were little changed, stable, or in slow decay.

A linked series of fragmented filaments erupted from along the southern-most solar sector boundary as noted in GONG/H-alpha and SDO/AIA 304/193 imagery. The center of the nearly 49 degree long, broken set of filaments was at approximately S43W16 as reported by USAF solar observatories. The filaments became unstable and active at about 09/1300-1400 UTC and erupted about 09/2100-2300 UTC. The eruption continued through about 10/0300-0400 UTC. Analysis of SDO imagery indicates much of the ejecta was unable to escape the Sun and ultimately reabsorbed. A CME was noted in LASCO coronagraph imagery and initial indications are that the CME may be south of the Earths orbital plane, although additional analysis is on-going to confirm.

Forecast: Solar activity is likely to be at low levels with a slight chance for M-class (R1-R2/Minor-Moderate) flares over the next three days (10-12 Jul), primarily due to higher flare potential of Region 2381 and new Region 2385.

Energetic Particle

24 hr Summary: The greater than 2 MeV electron flux was at mostly moderate levels, but did briefly reach high levels, with a peak flux of 1350 pfu at 10/1200 UTC. The greater than 10 MeV proton flux remained at background levels through the period.

Forecast: The greater than 2 MeV electron flux is expected to be at moderate to high levels throughout the period (10-12 Jul). The greater than 10 MeV proton flux is expected to remain at background levels (Below S1-Minor).

Solar Wind

24 hr Summary: Solar wind parameters at ACE were representative of ambient background conditions. Solar wind velocities steadily decreased from between 350-375 km/s down to an average of about 340 km/s by periods end. Interplanetary magnetic field (IMF) total field strength ranged from 2-6 nT. The Bz component varied between north and south orientations and had a maximum negative deflection of -4 nT. The phi angle continued in a primarily negative (towards the Sun) sector.

Forecast: An ambient solar wind environment is forecast to continue through the first half of day one (10 Jul) until a recurrent positive polarity coronal hole high speed stream (CH HSS), preceded by a co-rotating interaction region (CIR), is expected later in the day. Based on recurrence, CH HSS influences are expected to drive solar wind speed increases to near 600 km/s. Some enhancement in the IMF is also likely due to the CIR and CH HSS. Peak impact of the CH HSS is forecast for day two (11 Jul), with waning effects lasting into day three (12 Jul).

Geospace

24 hr Summary: Geomagnetic activity was quiet as the ambient solar wind and IMF caused little response in the Earths geomagnetic field.

Forecast: The geomagnetic field is expected to be at quiet levels through the first half of day one (10 Jul) until CIR and CH HSS influences are likely to produce periods of active conditions late in the day. The geomagnetic field is expected to become further disturbed on day two (11 Jul), with G1 (minor) storming levels likely. Waning CH HSS effects are expected to persist into day three (12 Jul), with active levels possible.

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