National Weather Service Text Product Display

Routine Space Environment Product (Daily)
Issued by NWS
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13
000
FXXX12 KWNP 190030
DAYDIS

:Product: Forecast Discussion
:Issued: 2013 May 19 0030 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
C6/Sf flare at 18/0345 UTC from Region 1748 (N12E11, Dao/beta-delta).
Some weakening was observed in the delta of the leader spots in Region
1748 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 (N06W54, Dao/beta) appears to have lost its gamma
magnetic configuration.  Slight growth was observed in the intermediate
area of Region 1750 (S09W54, Dao/beta).  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 was at normal to moderate levels.
The greater than 10 MeV proton flux at geosynchronous orbit was in
decline through the period.  The greater than 10 MeV protons were above
the 10 pfu (S1-Minor) threshold early in the period and crossed below
threshold levels at 18/1445 UTC.  Values remained enhanced near the 10
pfu threshold for the rest of the period.

.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 370 km/s to 476 km/s.  At
about 18/0023 UTC, a shock passage was detected at the ACE spacecraft.
Solar wind speeds sharply increased from about to 380 km/s to near 450
km/s. Coincident with the increase in wind speed were jumps in
interplanetary magnetic field (IMF) Bt from 8 to 13 nT, IMF Bz from -6
to -11 Bz and gradual increases in density and temperature.  This
discontinuity in ACE measurements was most likely the result of the 15
May CME passage.  Solar wind speeds slowly decreased through the period
to around 430 km/s while total field measurements were variable between
4 nT and 10 nT with the Bz component variable between +8 nT and -6 nT by
18/0402 UTC.

.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 minor storm levels.  Field
activity increased to minor storm levels through from 18/0000-0600 UTC
due to the arrival of the 15 May CME.  A 31 nT sudden impulse was
detected at the Boulder magnetometer at 18/0112 UTC.  Activity decreased
to unsettled to active levels from 18/0600-1200 UTC.  Quiet to unsettled
levels persisted from 18/1200 UTC through the remainder of the period.

.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).
National Weather Service Weather Forecast Office
