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000
FXXX12 KWNP 191230
DAYDIS

:Product: Forecast Discussion
:Issued: 2013 May 19 1230 UTC
# Prepared by the US Dept. of Commerce, NOAA, Space Weather Prediction Center
# Product description and SWPC contact on the Web
# http://www.swpc.noaa.gov/wwire.html
#
#             Forecast Discussion
#
Solar Activity

.24 hr Summary...
Solar activity was at low levels.  The largest flare of the period was a
C3/1f flare at 19/0915 UTC from Region 1750 (S09W60, Cao/beta).  Slight
growth was observed in the intermediate area of Region 1750.  Some
weakening was observed in the delta of the leader spots in Region 1748
(N12E07, Fao/beta-delta) along with slight decay in the trailing spots.
However, a strong east-west inversion line was still evident just north
of the trailer spots.  Region 1744 (N06W60, Dao/beta) appears to have
lost its gamma magnetic configuration.  The rest of the spotted regions
were either stable or decaying.  No Earth-directed coronal mass
ejections (CMEs) were observed during the period.

.Forecast...
Solar activity is likely to be moderate with a chance for X-class flares
for the forecast period (19-21 May).  Region 1748 continues to be the
most likely source for production of major flare activity.

Energetic Particle

.24 hr Summary...
The greater than 2 MeV electron flux at geosynchronous orbit was at
normal levels.  The greater than 10 MeV proton flux at geosynchronous
orbit was in decline through the period.  The S1-Minor event began at
15/1325 UTC, reached a maximum of 41 pfu at 17/1720 UTC and ended at
18/1445 UTC.  Flux values remain enhanced near 4 pfu.

.Forecast...
The greater than 2 MeV electron flux at geosynchronous orbit is expected
to continue at normal to moderate levels.  There is a chance for a
greater than 10 MeV proton enhancement above the 10 pfu (S1-Minor)
levels on day 1 (19 May) due to the shock arrival from the 17 May CME.
On days 2-3 (20-21 May), there is a continued chance for 10 MeV proton
events due to further potential flare activity from Region 1748.

Solar Wind

.24 hr Summary...
Solar wind speed ranged from approximately 362 km/s to 443 km/s.  The
interplanetary magnetic field (IMF) Bt ranged from 3 to 10 nT, IMF Bz
ranged from -6 to +8 Bz. The phi angle was generally in a negative
(towards) orientation for most of the period although there was a shift
from negative to positive and back to negative around 19/0045 UTC due to
a solar section boundary crossing.

.Forecast...
WSA/ENLIL model suggests a shock enhancement of solar wind speeds at the
ACE spacecraft around 19/1400 UTC.  Estimates of the speed of the shock
are in the 500 km/s range with a corresponding increase in density and
total interplanetary magnetic field values (Bt).  Solar wind conditions
are expected to be enhanced through day 2 (20 May) as CME effects wane.
Conditions are expected to return to nominal levels by day 3 (21 May).

Geospace

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

.Forecast...
By midday on day 1 (19 May), the 17 May CME is expected to impact the
geomagnetic field causing minor to major storm (G1-Minor to G2-Moderate)
levels.  By day 2 (20 May), conditions are expected to be at quiet to
active levels as CME effects wane.  A return to quiet to unsettled
levels is expected on day 3 (21 May).