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FXXX12 KWNP 190031

:Product: Forecast Discussion
:Issued: 2014 Apr 19 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 reached high (R2) levels. Region 2036 (S16W41,
Dhc/beta-gamma) produced an M7 flare at 18/1303 UTC, which was the
largest flare of the period. It was accompanied by a Tenflare (1000
sfu), a Castelli-U signature, as well as 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 began to show signs of decay but remains significant and
magnetically complex.

Region 2034 (N04W39, Ekc/beta) grew during the period and so did Region
2035 (S15W18, Ekc/beta-gamma-delta).  Region 2035 also became more
complex, developing a delta configuration.  A new spot group is being
monitored near S17E71 and will be numbered if it persists and flux
emergence was noted north of Region 2038 (S13E23, Dac/Beta).  The
remaining spot groups were either stable or decaying.

Solar activity is likely to be moderate (R1-Minor) for the next three
days (19-21 Apr) with the number of complex regions present.

Energetic Particle

.24 hr Summary...
The greater than 2 MeV electron flux at geosynchronous orbit was at
normal levels for the period. The greater than 10 MeV proton flux at
geosynchronous orbit began to rise following the M7 flare
described above, crossing the 10 pfu threshold (S1-Minor radiation
storm) at 18/1525 UTC and reaching a maximum of 42 pfu at 18/2355 UTC.
The 100 MeV proton flux was also enhanced but remained below the 1 pfu
alert threshold.

The greater than 2 MeV electron flux at geosynchronous orbit is expected
to be at normal levels for the next three days (19-21 Apr). The
greater than 10 MeV proton flux at geosynchronous orbit expected to
remain above the 10 pfu threshold (S1-Minor) into day 1 (19 Apr). S1
events remain likely on day 2 (20 Apr) with a continued chance on day 3
(21 Apr), particularly with the passage of the approaching CMEs.

Solar Wind

.24 hr Summary...
Solar wind speed began near 400 km/s and increased to 537 km/s by
18/1851 UTC. Phi was generally positive through the day. Bt rose past 10
nT by 18/2000 UTC and Bz was as low as -8 nT at 18/0243 UTC but mostly
neutral or positive throughout the period. These observations were
consistent with the presence of a small positive coronal hole high speed

Increased Bt and possible southward Bz are expected on day 1 (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 2 (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 day 2 (20 Apr), prolonging
the disturbed conditions through day 3 (21 Apr).


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

WSA-Enlil model output and manual prognosis suggest the back-to-back
arrivals of the CMEs from the 16th and 18th on day 2 (20 Apr) of the
forecast. Consequently, the geomagnetic field is expected to be quiet to
unsettled on day 1 (19 Apr) with the passage of two weak CMEs from 15
and 16 Apr embedded in the ambient solar wind. Early on day 2 (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 3 (21 Apr) before diminishing to active or unsettled levels. is the U.S. government's official web portal to all federal, state and local government web resources and services.