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FXXX12 KWNP 211231

:Product: Forecast Discussion
:Issued: 2014 Dec 21 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 was at moderate levels due to an M1/1n flare at 21/0732
UTC from Region 2242 (S18W50, Ekc/beta-gamma-delta).  Region 2242
contributed to the majority of the C-class flaring as well.  Both
Regions 2241 (S10W27, Ehc/beta-gamma-delta) and 2242 exhibited penumbral
decay within its intermediate and trailing areas.  Moderate growth and
consolidation was observed in Region 2244 (S04E32, Dao/beta-delta).  New
Region 2245 (N08E66, Cao/beta) was numbered during the period.  No
Earth-directed coronal mass ejections (CMEs) were observed.

Solar activity is expected to be at moderate (R1-R2/Minor-Moderate)
levels with a chance for further X-class flaring (R3-Strong or greater)
for the next three days (21-23 Dec) as Regions 2241 and 2242 remain
large and magnetically complex.

Energetic Particle

.24 hr Summary...
The greater than 2 MeV electron flux at geosynchronous orbit was at
normal to moderate levels. The greater than 10 MeV proton flux was
slightly enhanced near 0.9 pfu, however it remained well below the 10
pfu (S1-Minor) threshold.

The greater than 2 MeV electron flux is expected to be at normal to
moderate levels for the forecast period (21-23 Dec). There is a chance
for a greater than 10 MeV proton event (S1-Minor) due to the potential
for significant flare activity from Regions 2241 or 2242.

Solar Wind

.24 hr Summary...
Solar wind parameters indicated the possible arrival of a glancing blow
from the 17 Dec CME.  A small discontinuity in total field measurements
occurred at 21/0235 UTC.  Total field increased slightly from 6 nT to 8
nT while the Bz component deflected south after 21/0037 UTC and remained
southward reaching -8 nT for almost 5 hours.  No significant increase in
solar wind speeds was observed, however.  Phi angle was mostly positive
(away).  Lower energy particle measurements (as seen in the ACE/EPAM
plot) continue to increase indicating the approach of the 18 Dec CME.
However, the current levels support a later arrival of the CME.

Solar wind parameters are expected to become enhanced later in the UTC
day on day one (21 Dec) to early on day two (22 Dec) with the arrival of
the CME from 18 Dec.  Solar wind speeds reaching 600 km/s is likely with
the event.  Enhanced solar wind conditions is expected to decrease on
day three (23 Dec) as CME effects diminish.


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

The geomagnetic field is expected to continue at mostly unsettled levels
until the arrival of the 18 Dec CME by late on day one to early on day
two (21-22 Dec).  Geomagnetic storming reaching minor to major storm
levels (G1-G2/Minor-Moderate) is expected with the arrival of the CME.
Unsettled to active levels are expected to persist through the rest of
day two.  Quiet to unsettled levels are expected on day three (23 Dec)
as CME effects wane. is the U.S. government's official web portal to all federal, state and local government web resources and services.