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FXXX12 KWNP 281231

:Product: Forecast Discussion
:Issued: 2016 Apr 28 1230 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 reached low levels. Region 2535 (N07E22, Cro/beta)
remained mostly inactive for the first half of the period. At
approximately 28/0126 UTC, this region produced a B8 flare that appeared
to have an associated CME, first observed in SOHO/LASCO coronagraph
imagery at 28/0216 UTC, departing the northeast limb. Analysis indicated
that the Earth may see a weak glancing blow from this CME with an
expected arrival early on 1 May. Region 2535 then produced three C1
flares at 28/0342, 0602, 0852 UTC, respectively. An additional CME was
observed in coronagraph imagery at approximately 28/0636 UTC, believed
to be associated with the C1 flare that occurred at 0602 UTC. Analysis
is underway to determine if this CME has an Earth-directed component as

Region 2536 (N16E34, Dao/beta) exhibited slight growth in its trailer
spots, but dissipation in its intermediate spots, and remained mostly
inactive during the period. Region 2537 (S07W56, Dao/beta) continued to
experience overall growth and separation between its leader and trailer
spots. This region remained mostly inactive during the period, only
producing optical subflares. The remaining regions were inactive and
stable or in decay.

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

Energetic Particle

.24 hr Summary...
The greater than 2 MeV electron flux continued at normal to moderate
levels and the greater than 10 MeV proton flux remained at background

The greater than 2 MeV electron flux is expected to continue at normal
to moderate levels on days one and two (28-29 Apr) and decrease to
normal levels on day three (30 Apr) due to electron redistribution from
expected CIR and CH HSS effects. The greater than 10 MeV proton flux is
expected to continue at background levels.

Solar Wind

.24 hr Summary...
The solar wind environment was indicative of a slightly enhanced state
in the wake of waning positive polarity CH HSS influence. Solar wind
speed was variable and measured primarily between 400-500 km/s. The IMF
strength ranged predominantly from 4 to 6 nT, while the Bz component was
variable between +/- 4 nT. The phi angle was in a mostly positive
configuration, with a few isolated deviations into a negative sector.

Solar wind parameters are expected to continue at slightly elevated
levels early on day one (28 Apr) due to waning influences of the
positive polarity CH HSS. A return to more ambient background levels is
expected by midday on day one as the CH HSS rotates out of geoeffective
position. Conditions are expected to become enhanced later on day two
(29 Apr) due to an expected solar sector boundary crossing (SSBC) and
preliminary CIR effects. Day three (30 Apr) is likely to see a further
enhancement due to the anticipated CIR passage, followed by solar wind
speed increases due to connection with a negative polarity CH HSS.


.24 hr Summary...
The geomagnetic field was mostly quiet with an isolated unsettled
period, likely in response to prolonged southward Bz orientation.

The geomagnetic field is expected to be mostly quiet with an isolated
unsettled period possible on day one (28 Apr) as CH HSS influences taper
off. Day two (29 Apr) is expected to see geomagnetic responses start
quiet, but elevate to unsettled to active levels later in the day as the
solar wind environment is enhanced in response to the expected CIR. Day
three (30 Apr) is likely to experience responses to minor storm
(G1-Minor) levels due to the anticipated CIR and CH HSS effects. is the U.S. government's official web portal to all federal, state and local government web resources and services.