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FXXX12 KWNP 020030

:Product: Forecast Discussion
:Issued: 2015 Sep 02 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 at very low levels this period with only a few
optical subflares observed. Region 2407 (N16W75, Cso/beta) grew slightly
in area and with the exception of an optical Sf at 01/0716 UTC, the
region was primarily stable and remained a simple bipolar configuration.
NOAA SWPC Region 2409 (N05E54, Dro/beta) was assigned this period as
spots emerged early in the period and grew steadily into a bipolar
group. The region produced several optical subflares, but was otherwise
inactive. Overall magnetic field intensity increased sightly with no
perceptible gain in shear, however, the regions N-S alignment could
stress magnetic field lines should the region continue to develop. The
remaining active regions changed little or underwent some decay.

A prominence was noted lifting outward from behind the SE limb as seen
in SDO/AIA-304 imagery beginning after 01/0200 UTC. The prominence
eventually erupted and an associated coronal mass ejection (CME) was
observed in SOHO/LASCO-C2 imagery. Analysis indicated no Earth-directed
component to this CME. A set of CMEs was also observed from the N limb
of the Sun after 01/0400 UTC. Coronal dimming was evident from the far N
hemisphere of the Sun in association with these CMEs, as observed in
SDO/AIA-193 imagery. Analysis indicated all of these CMEs are off the
Sun-Earth line. No Earth-directed CMEs were observed in available
coronagraph imagery during the period.

Solar activity is expected to remain very low with a slight chance for
C-class flares all three days (02-04 Sep) primarily due to the
development of Region 2409.

Energetic Particle

.24 hr Summary...
The greater than 2 MeV electron flux was at moderate to high levels with
a maximum flux of 3144 pfu at 01/1730 UTC. The greater than 10 MeV
proton flux was at background levels.

The greater than 2 MeV electron flux is expected to remain at primarily
high levels into day one (02 Sep) and decrease down to normal to
moderate levels later on day one and on into days two and three (03-04
Sep) after a coronal hole high speed stream (CH HSS) becomes
geoeffective. The greater than 10 MeV proton flux is expected to
continue at background levels all three days.

Solar Wind

.24 hr Summary...
The solar wind and interplanetary magnetic field (IMF) parameters were
indicative of a return to ambient conditions. Solar wind velocities were
primarily between 350-375 km/s and the IMF total field strength was
fairly steady between 4-6 nT. The Bz component was variable, but was
predominantly in a northward orientation with a maximum southward
deflection of -4 nT. The phi angle was primarily positive (away from the

A solar sector boundary crossing (SSBC) is expected early on day one (02
Sep), to be followed by a co-rotating interaction region (CIR) ahead of
a positive polarity CH HSS. The SSBC and CIR are likely to disturb the
IMF and solar wind velocities are expected to increase as the CH HSS
becomes geoeffective. The higher solar wind speeds are expected to
continue into days two and three (03-04 Sep).


.24 hr Summary...
The geomagnetic field remained quiet.

The geomagnetic field is expected to reach minor (G1-Minor) storm
conditions early on day one (02 Sep) as the Earths geomagnetic field
responds to expected disturbances due to the CIR and CH HSS. Unsettled
to active conditions are expected on day two (03 Sep) due to geomagnetic
field responses to CH HSS influences. Unsettled periods are expected on
day three (04 Sep) due to continued CH HSS effects. is the U.S. government's official web portal to all federal, state and local government web resources and services.