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FXXX12 KWNP 230031

:Product: Forecast Discussion
:Issued: 2017 Mar 23 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 remained very low. Region 2643 (N08E56, Hsx/alpha)
changed little and was inactive. A small, faint filament over the NE
quadrant of the Sun disappeared between approximately 22/1700-1800 UTC,
as observed in GONG/H-alpha imagery. Analysis of SDO/AIA-304 imagery
indicated the filament was eruptive in nature. A CME was first observed
in SOHO/LASCO-C2 imagery at 22/2000 UTC that appears to be related to
this event. We await further coronagraph imagery before further
additional analysis can be conducted to determine if there is any
possible Earth-directed component to this CME.

Solar activity is expected to remain very low, with a slight chance for
C-class flares all three days (23-25 Mar) mainly due to Region 2643.
Another active region was observed in STEREO-A/EUV imagery that is
anticipated to rotate onto the Earth-side visible disk on day two and
will likely contribute to the slight chance of C-class flare potential.

Energetic Particle

.24 hr Summary...
The greater than 2 MeV electron flux was at normal to high levels with a
maximum flux reading of 3,545 pfu observed at 22/2020 UTC. The greater
than 10 MeV proton flux remained at background values.

The greater than 2 MeV electron flux is expected to continue at high
levels all three days (23-25 Mar), with a chance for very high levels by
day three (25 Mar) due to CH HSS effects. 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 continued CH HSS influences.
The total IMF strength began the period at 12 to 13 nT, before it
weakened after 22/0323 UTC and finished the period at about 5 to 6 nT.
The Bz component was variable with a few periods of prolonged southward
direction, but no long-duration pronounced negative deviations. Solar
wind speed remained elevated and ranged from primarily 650-750 km/s most
of the period. The phi angle was predominantly in a positive (away from
Sun) sector.

Solar wind speed is anticipated to remain elevated on day one (23 Mar)
due to continuing CH HSS influences, but may begin a slow decline as the
CH HSS begins to rotate away from a more favorable Earth-connected
position. Solar wind speed is likely to continue waning on day two (24
Mar) as the CH HSS rotates further towards the W limb and away from a
geoeffective position. There is a chance for an enhancement in the IMF
on day two, due to possible arrival of the weak transient detected on 19
Mar. Solar wind speed is likely to approach more ambient-background like
speeds by day three (25 Mar); however, the IMF may become disturbed due
to an approaching solar sector boundary crossing (SSBC) into a negative


.24 hr Summary...
The geomagnetic field was at mostly active levels due to CH HSS effects.

The geomagnetic field is expected to respond with an isolated period of
minor (G1-Minor) storming early on day one (23 Mar); otherwise unsettled
to active levels of response are expected due to continuing CH HSS
effects. Weakening solar wind conditions on day two (24 Mar) are
expected to elicit mostly quiet to unsettled levels of response, with an
isolated period of active conditions likely in reaction to the still
elevated, but waning solar wind speeds and possible enhancement of the
IMF. Quiet to unsettled conditions are expected on day three (25 Mar) as
CH HSS effects wane further. is the U.S. government's official web portal to all federal, state and local government web resources and services.