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FXXX12 KWNP 010031

:Product: Forecast Discussion
:Issued: 2015 Sep 01 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 low levels. The largest flare of the period was a
C2 flare at 31/0522 UTC from the vicinity of departed Region 2403
(S15,L=193). Region 2406 (N03E09, Cro/beta) and Region 2407 (N15W62,
Cro/beta) underwent some growth earlier in the period, but stabilized or
began some decay as the period progressed. Region 2405 (S21W03,
Axx/alpha) underwent decay, but managed to produce a small B4Sf at
31/1438 UTC. Despite the flare, the region was predominantly inactive as
it dissipated slowly. Region 2408 (S12W77, Axx/alpha) was numbered but
remained inactive as it rotated towards the limb.

A prominence from beyond the NW limb first became visible in SDO/AIA-304
imagery at about 31/0930 UTC as it lifted and erupted outwards. Between
31/1000-1200 UTC, a 9 degree long filament centered at approximately
N41W27 was observed in SDO imagery erupting northward, although most of
that material appeared to have been reabsorbed. SOHO/LASCO C2
coronagraph imagery confirmed a coronal mass ejection (CME) associated
with the eruptive prominence from beyond the NW limb. A CME was also
observed from the West limb in association with the C2 flare from
departed Region 2403. Neither CME was on a Sun-Earth line and no
Earth-directed CMEs were observed in available coronagraph imagery
during the period.

Solar activity is expected to be low on day one (01 Sep). Solar activity
is expected to decrease further to very low levels on days two and three
(02-03 Sep) with a slight chance for C-class flares.

Energetic Particle

.24 hr Summary...
The greater than 2 MeV electron flux was at moderate to high levels with
a peak flux of 2912 pfu at 31/1940 UTC. The greater than 10 MeV proton
flux was at background levels.

The greater than 2 MeV electron flux is expected to continue at moderate
to high levels on day one (01 Sep). A decrease to normal to moderate
levels is expected on day two (02 Sep) and continue into day three
(03 Sep) as a coronal hole high speed stream (CH HSS) becomes

Solar Wind

.24 hr Summary...
Solar wind parameters as measured by the ACE spacecraft, indicated a
return to nearly ambient conditions as solar wind velocities continued a
slow downward trend from around 410-425 km/s to around 375-385 km/s by
periods end. The total interplanetary magnetic field (IMF) strength
ranged from 2-7 nT and the Bz component was variable with a maximum
southward deflection of -4 nT. The phi angle remained negative (towards
the Sun).

A solar sector boundary crossing (SSBC) is expected later on day one (01
Sep) just ahead of a co-rotating interaction region (CIR) preceding 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 become
geoeffective. The increased solar wind speeds are expected to continue
into day two and much of day three (02-03 Sep).


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

The geomagnetic field is expected to be primarily quiet to unsettled
early on day one (01 Sep) before becoming agitated to active to minor
(G1-Minor) storming levels as the CIR disturbs the Earths
magnetosphere and the positive polarity CH HSS becomes geoeffective.
Minor (G1-Minor) storming is expected to continue into day two (02 Sep)
before decreasing down to unsettled to active conditions later in the
day. Unsettled to active conditions are expected on day three (03 Sep)
as the CH HSS continues to impact the Earths magnetosphere. is the U.S. government's official web portal to all federal, state and local government web resources and services.