:Product: 04191230forecast_discussion.txt
:Issued: 2014 Apr 19 1230 UTC
# Prepared by the U.S. Dept. of Commerce, NOAA, Space Weather Prediction Center
#
Solar Activity

.24 hr Summary...
Solar activity reached high (R2-Moderate) levels early in the period
with only low-level C-class activity observed since. Region 2036
(S17W48, Dkc/beta-gamma) produced an M7 flare at 18/1303 UTC; the
largest flare of the period. This event was accompanied by a Castelli-U
discrete radio signature to include a 1000 sfu Tenflare and Type II (851
km/s) and Type IV radio emissions.  An asymmetric halo CME was
subsequently observed in SOHO/LASCO C2 coronagraph imagery at 18/1325
UTC. Analysis suggested the ejecta was moving at approximately 1000 km/s
and Earth-directed. Region 2036 indicated some intermediate spot
development during the period.

Region 2034 (N05W46, Ekc/beta-gamma) remained the largest group on the
disk. The region showed some consolidation in its leader spots and
developed a weak beta-gamma magnetic configuration. The region produced
a C1/Sf flare at 19/0600 UTC. Region 2038 (S11E15, Dsi/beta) had rapid
spot development to the north and west of the region.

Two new regions were numbered over the past 24 hours. New Region 2044
(S20E58, Bxo/beta) developed on the disk and produced a C2 x-ray event
at 20/0324 UTC. New Region 2045 (S25E84, Hax/alpha) rotated onto the
disk and produced a C1 x-ray event at 19/0939 UTC.

The remaining spotted regions indicated little change during the period.
No additional Earth-directed CMEs were detected.

.Forecast...
Solar activity is likely to be moderate (R1-Minor) with a slight chance
for high (R3-Strong) or greater for the next three days (19-21 Apr) due
to the number of complex regions currently populating the disk.

Energetic Particle

.24 hr Summary...
The greater than 2 MeV electron flux at geosynchronous orbit was at
normal to moderate levels for the period. Following the M7 event
described above, the greater than 10 MeV proton flux at geosynchronous
orbit exceeded the 10 pfu threshold (S1-Minor radiation storm) at
18/1525 UTC. As of this report, a maximum of 58 pfu was reached at
19/0105 UTC UTC. The 100 MeV proton flux was enhanced to 0.66 pfu at
18/1420 UTC, but remained below the 1 pfu alert threshold.

.Forecast...
The greater than 2 MeV electron flux at geosynchronous orbit is expected
to be at normal to moderate levels for the next three days (19-21 Apr).
The greater than 10 MeV proton flux at geosynchronous orbit is expected
to remain above the 10 pfu threshold (S1-Minor) into day one (19 Apr).
S1 events remain likely on day two (20 Apr) with a continued chance on
day three (21 Apr), particularly with the passage of the approaching
CMEs.

Solar Wind

.24 hr Summary...
Solar wind speed began the period near 450 km/s and slowly increased to
average speeds of 500 to 525 km/s. Phi was generally in a positive
(away) orientation through the day. IMF Bt varied between 6 to 10 nT
while the Bz component was generally positive to +8 nT through about
18/2130 UTC. Thereafter, Bz rotated between +8 to -6 nT through the end
of the period. These observations were consistent with the presence of a
small positive coronal hole high speed stream. ACE low energy particles
observed a slow, steady increase through the period.

.Forecast...
Increased Bt and possible southward Bz are expected on day one (19 Apr)
with the anticipated arrival of the two faint/slow CMEs from 15/16 Apr,
believed to be on the Sun-Earth line. Early on day two (20 Apr), the
arrival of a CME from 16 Apr is expected to begin with a modest increase
in speed and density at onset, as well as a magnetic response. The CME
from 18 Apr is expected to arrive midday on 20 Apr, prolonging the
disturbed conditions through day three (21 Apr).

Geospace

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

.Forecast...
WSA-Enlil model output and manual prognosis suggest the back-to-back
arrivals of the CMEs from the 16th and 18th on day two (20 Apr) of the
forecast. Consequently, the geomagnetic field is expected to be quiet to
active on day one (19 Apr) with the passage of two weak CMEs from 15
and 16 Apr embedded in the ambient solar wind. Early on 20 Apr, the
arrival of another CME from 16 Apr is expected to bring active to
minor (G1) storm conditions before being reinforced by the midday
arrival of the CME from 18 Apr. The second impact will prolong minor
storm conditions and introduce a chance for major (G2) storm levels. 
Minor (G1) storm conditions are expected to persist into the early hours
of day three (21 Apr) before diminishing to active or unsettled levels.