Routine Space Environment Product (Daily)
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FXXX12 KWNP 180031

:Product: Forecast Discussion
:Issued: 2017 Aug 18 0030 UTC
# Prepared by the US Dept. of Commerce, NOAA, Space Weather Prediction Center
# Product description and SWPC contact on the Web
#             Forecast Discussion
Solar Activity

.24 hr Summary...
Solar activity was very low. Region 2671 (N11E34, Fkc/beta-gamma) grew
further in E to W extent, but its penumbral areal coverage decreased
and its magnetic gradient loosened further. While it retained mixed
polarities, magnetic shear weakened and the region produced only B-class
and optical subflares. No Earth-directed CMEs were observed in available
coronagraph imagery.

Solar activity is expected to remain very low with a slight chance of
M-class flares (R1-R2; Minor-Moderate radio blackouts) on days one and
two (18-19 Aug); and a decreasing chance of C-class flares all three
days (18-20 Aug). This expectation is based primarily on the latest
dissipation and decreased activity trends of Region 2671.

Energetic Particle

.24 hr Summary...
The greater than 2 MeV electron flux was at normal to moderate levels
due to electron redistribution associated with CIR arrival and CH HSS
onset. The greater than 10 MeV proton flux continued at background

The greater than 2 MeV electron flux is expected to be at normal to
moderate levels on day one (18 Aug) and increase to moderate to high
levels on days two and three (19-20 Aug) due to continuing CH HSS
influences. The greater than 10 MeV proton flux is expected to remain at
background levels all three days.

Solar Wind

.24 hr Summary...
Solar wind parameters were indicative of CIR arrival and CH HSS onset.
Total IMF strength ranged from 6 to 13 nT before it decreased after
17/1600 UTC to end the period at about 6 to 7 nT. The Bz component
underwent wide variations after about 17/0600 UTC, with a few pronounced
and prolonged periods of southward direction until about 17/1730 UTC
when the variations became more weak. Solar wind speed was steady at
near 410 km/s until 17/0330 UTC, when speed began to increase and
reached 525-575 km/s as the period progressed. The phi angle was
primarily positive (away from Sun).

The solar wind environment is expected to continue under the influence
of an extension of the north polar CH HSS all three days (18-20 Aug);
with elevated solar wind speeds throughout the forecast period.


.24 hr Summary...
The geomagnetic field was quiet to unsettled until after the 17/0600 UTC
synoptic period, when minor storming (G1-Minor) occurred in response to
CIR and CH HSS onset influences. The overall planetary geomagnetic
response decreased to unsettled to active levels after 17/1500 UTC.

The geomagnetic field is expected to be unsettled to active with
isolated periods of G1 (Minor) storming likely on day one (18 Aug) as CH
HSS influences continue. The overall geomagnetic response is expected to
decrease to mainly unsettled to active conditions, with a chance for G1
storming, on days two and three (19-20 Aug) due to continuing CH HSS
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