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FXXX12 KWNP 180030

:Product: Forecast Discussion
:Issued: 2014 Apr 18 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 was at low levels. No new significant or notable solar
activity occurred during the period. Solar X-ray backgrounds were near
C1, and only a few modest C-level flares occurred. Analysis of the
aforementioned CME indicates a potential arrival at Earth on 19 April at
approximately 1800 UTC, following the expected arrival of two faint CMEs
from 15/16 April. Both were difficult to fully analyze due to limited
imagery, but both are believed to be moving on a partial Sun-Earth line
at near the ambient background solar wind speed. Regions 2034 (N05W26,
Dhc/beta), 2035 (S14W04, Fsc/beta-gamma), 2036 (S15W28, Dhc/beta-gamma),
and 2037 (S09W27, Dai/beta-gamma) all remained moderately complex,
maintaining beta-gamma magnetic configurations, however, all
were largely inactive this period. The remaining spot groups were either
stable or exhibited slight decay.

Solar activity is likely to be moderate (R1-Minor) for the next three
days (18 - 20 Apr) due to retained solar region complexity.

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 was at background levels.

The greater than 2 MeV electron flux at geosynchronous orbit is expected
to be at normal levels for the next three days (18 - 20 Apr). The
greater than 10 MeV proton flux at geosynchronous orbit is likely to
be at background levels (Below S1-Minor), though a slight chance of
protons has been added to the forecast during the period due to the
complexity of regions moving towards the West limb.

Solar Wind

.24 hr Summary...
Solar wind parameters, measured at the ACE spacecraft, indicated a solar
wind speed increase from approximately 350 km/s to 400 km/s over the
period. Both IMF Bt and Bz remained variable through the end of the
period, with Bt as high as 10 nT, while the Phi angle settled into a
mostly positive (away) orientation.

Solar wind enhancements, including modest speed and Bt increases, are
expected on day one (18 Apr) due to recurrent activity. The impact of
two faint/slow CMEs believed to be on the Sun-Earth line are expected on
day two (19 Apr). Not much of solar wind speed increase is expected,
though a magnetic interaction in the form of increased Bt and possible
southward Bz is possible. Late on day two, the arrival of a third CME is
expected to begin with a modest increase in speed and density at onset,
as well as a magnetic response.


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

The geomagnetic field is expected to be quiet to unsettled periods for
day one (18 Apr) and the first half of day two (19 Apr) in response to
possible recurrent enhancements in solar wind parameters as well as two
weak CMEs embedded in the ambient solar wind velocity. The field should
increase to active levels late on day two, and as high as minor storm
(NOAA Scale G1 - minor) on day three, with the arrival of a third CME,
modeled in Enlil, late on day two. is the U.S. government's official web portal to all federal, state and local government web resources and services.