Routine Space Environment Product (Daily)
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000
FXXX12 KWNP 210030
DAYDIS

:Product: Forecast Discussion
:Issued: 2015 Apr 21 0030 UTC
# Prepared by the US Dept. of Commerce, NOAA, Space Weather Prediction Center
# Product description and SWPC contact on the Web
# http://www.swpc.noaa.gov/wwire.html
#
#             Forecast Discussion
#
Solar Activity

.24 hr Summary...
Solar activity was low. An unnumbered region behind the northeast limb
produced a few low level C-class flares. New region 2330 (N15E32,
Dso/beta) was numbered today. All eight numbered regions on the visible
disk were unremarkable and inactive. No Earth-directed CMEs were
observed this period.

.Forecast...
Solar activity is likely to be low with a slight chance for M-class
(R1-Minor) flares over the next three days (21-23 Apr).

Energetic Particle

.24 hr Summary...
The greater than 2 MeV electron flux was at normal to high levels this
period.  The greater than 10 MeV proton flux was at background levels
throughout the period.

.Forecast...
The greater than 2 MeV electron flux is expected to be at moderate to
high levels over the next three days (21-23 Apr) in response to the
anticipated onset of a positive polarity coronal hole high speed stream
(CH HSS).  The greater than 10 MeV proton flux is expected to persist at
background levels over the next three days (21-23 Apr).

Solar Wind

.24 hr Summary...
Solar wind parameters began the period with an ambient solar wind
regime. Solar wind velocities were steady near 375 km/s, before a solar
sector boundary crossing (SSBC) from a negative orientation to a
positive phi position at around 20/1200 UTC. Velocities then increased
to near 460 km/s by the end of the period. IMF total field values were
steady between 4-6 nT before the SSBC, when Bt increased to near 12nT.
Bz reached a maximum southward component of -5 nT late in the period.

.Forecast...
Solar wind parameters are expected to become enhanced late on day one
(21 Apr) due to the anticipated arrival of the 18 Apr CME as well as the
influence of a positive polarity coronal hole high speed stream (CH
HSS). Elevated solar wind velocities and magnetic tendencies are
forecast to persist through day two (22 Apr). Solar wind parameters are
expected to begin decreasing midday on day three (23 Apr) as CH HSS and
CME effects begin to wane.

Geospace

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

.Forecast...
The geomagnetic field is expected to be at quiet to unsettled levels for
the first half of day one (21 Apr). The anticipated arrival of the 18
Apr CME midday on day one is expected to trigger periods of G1 (Minor)
geomagnetic storm conditions in conjunction with a positive polarity CH
HSS moves into geoeffective position. Day two (22 Apr) is forecast to
persist with G1 conditions. Unsettled to active conditions are expected
to return after 0900 UTC on day three (23 Apr) as CH HSS and CME effects
subside.


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