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04200030forecast_discussion.txt
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:Product: 04200030forecast_discussion.txt
:Issued: 2014 Apr 20 0030 UTC
# Prepared by the U.S. Dept. of Commerce, NOAA, Space Weather Prediction Center
#
Solar Activity
.24 hr Summary...
Solar activity was low, with only low-level C-class flares observed
during the period. New Region 2044 (S20E52, 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 C2/Sf event at
19/1231 UTC. Region 2032 (N12W83, Hsx/alpha) produced the largest flare
of the period, a C4 at 19/1932 UTC as it approached the west limb.
Region 2034 (N05W46, Ekc/beta-gamma) remained the largest group on the
disk although there was some consolidation in its leader spots. It
developed a weak beta-gamma magnetic configuration. The other
significant regions with beta-gamma magnetic configurations, Regions
2035 (S16W31, Ekc/beta-gamma) and 2036 (S17W54, Dkc/beta-gamma) also saw
a reduction in areal extent. Region 2038 (S11E15, Dsi/beta) had rapid
spot development to the north and west of the region.
The remaining spotted regions indicated little change during the period.
No Earth-directed CMEs were detected but latent coronagraph imagery is
still being received.
.Forecast...
Solar activity is expected to be low with another moderate (R1-Minor)
event likely through day 1 (20 Apr). Low levels of activity are
expected to persist through Days 2-3 with a chance for moderate
(R1-Minor) event as Regions 2034, 2035 and 2036 continue to decay.
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
on 18 Apr, the greater than 10 MeV proton flux at geosynchronous
orbit passed the 10 pfu (S1-Minor radiation storm) threshold yesterday
at 18/1525 UTC. Flux reached maximum of 58 pfu at 19/0105 UTC UTC and
remained above 10 pfu at the time of this report while flux measured by
ACE/SIS is approaching the 100 pfu mark.
.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 (20-22 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 (20 Apr),
with an enhancement from the expected CME arrivals that day. S1 events
remain likely on day two (21 Apr) with a continued chance on day three
(22 Apr).
Solar Wind
.24 hr Summary...
Solar wind speed at the ACE spacecraft began the period in the upper 400
to lower 500 km/s range. Bz fluctuated between -6 nT and +9 nT during
the period while Bt ranged between 5-10 nT. A small shock was observed
at 19/1754 UTC suggesting the possible arrival of one of the weak CMEs
expected today. Wind speed subsequently increased from around 460 km/s
to 560 km/s. Phi was generally positive and low energy particle flux
continued to rise throughout the period.
.Forecast...
Early on day one(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 (22
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 one (20 Apr) of the
forecast. In light of the already disturbed condition of the
geomagnetic field and further analysis of the approaching CMEs, the
forecast was nudged upward. Early on 20 Apr, the arrival of a 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 is expected to drive the geomagnetic field to major (G2)
storm levels with localized episodes of severe storm conditions possible
at high latitudes. Minor (G1) storm conditions are expected to persist
into the early hours of day two (21 Apr) before diminishing to active or
unsettled levels. Unsettled conditions will linger into day three (22
Apr).