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FXXX12 KWNP 280031

:Product: Forecast Discussion
:Issued: 2016 Sep 28 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. Region 2597 (S14W52, Dao/beta)
simplified slightly into a bipolar magnetic configuration; although a
small area of minor shear was present near the leader spots. The region
produced a C1/Sf at 27/0748 UTC. An area of coronal dimming occurred
over the southern hemisphere after 26/2200 UTC as observed in SDO/AIA
imagery, and continued on into early this period. The dimming appeared
to be associated with a CME from the SW limb first observed in
SOHO/LASCO C2 imagery at 27/0024 UTC. Forecaster analysis and WSA/Enlil
modeling determined the CME to be off the Sun-Earth line.

Other activity included a disappearing solar filament (DSF) centered
near S26W49 that occurred from 27/2256 UTC to 27/2354 UTC, as observed
in SDO/AIA 304 and GONG H-Alpha imagery. More forecaster analysis will
occur to determine if there is a CME associated with this eruption as
LASCO coronagraph imagery becomes available.

Solar activity is expected to be at very low levels with a chance for
C-class flares over the next three days (28-30 Sep).

Energetic Particle

.24 hr Summary...
The greater than 2 MeV electron flux reached high levels, with a max
flux of 6,692 pfu at 27/1715 UTC. The greater than 10 MeV proton flux
remained at background values.

Due to CH HSS effects, the greater than 2 MeV electron flux is expected
to be at moderate to high levels, with a chance for very high levels the
next two days (28-29 Sep). Day three (30 Sep) is expected to reach high
to very high levels. The greater than 10 MeV proton flux is expected to
continue at background levels all three days.

Solar Wind

.24 hr Summary...
Solar wind parameters were indicative of the likely onset of an expected
positive polarity CH HSS. Solar wind speed gradually increased
throughout the period and reached speeds near 700 km/ by periods end.
The total IMF strength was enhanced and ranged primarily between 7 to 10
nT. The Bz component oscillated between north and south orientations,
but had several prolonged periods of southward direction. Density was
slightly enhanced and the phi angle was predominantly positive.

Solar wind speed is expected to increase further as the CH HSS rotates
into a more favorable position by day one (28 Sep). Elevated solar wind
speeds are expected to continue throughout days two and three (29-30
Sep) as the CH HSS remains geoeffective.


.24 hr Summary...
The overall planetary geomagnetic response reached active to moderate
storm levels (G1-G2/Minor-Moderate) due to CH HSS influences.

The geomagnetic field is likely to respond with G1 (Minor) and a few
periods of G2 (Moderate) storm levels all three days (28-30 Sep) due to
CH HSS effects. There is a chance for an isolated period of G3 (Strong)
storming on day two (29 Sep) as the solar wind speed reaches peak
levels; and slight chances for isolated periods of G3 storming on days
one and three (28 and 30 Sep). is the U.S. government's official web portal to all federal, state and local government web resources and services.