[ips-sf] IPS Summary Forecast for 21 September - issued 0004UT/21-Sep-2015

[rwc]

Solar activity was moderate for 20 September with an M1.5 flare from
region 2420 towards the north-east limb and a long duration M2.1 flare
from region 2415 in the south-west. A type II radio sweep and CME were
observed in association with this flare and a glancing blow from the
CME is possible late on 22 September. A solar filament centred around
S15E05 was observed to disappear between 06-07UT. There was a weak CME
observed in LASCO C2 difference imagery around this time although it
was slightly more west directed than expected. There is a reasonable
chance of M-class flare for 21 September. A moderate shock was
observed in the solar wind at 0526UT in association with the earlier
than anticipated CME arrival. Solar wind speeds reached approximately
600 km/s and are presently above 500 km/s. Solar wind speeds are
expected to decline slowly before the arrival of the CME later on 22
September. The IPS magnetometer data observed a weak impulse of 20nT
at 0604UT in association with the CME impact. Active to minor storm
periods were observed over the Australian region following the CME
impact with major to severe storms at high latitudes. Mostly unsettled
to active periods are expected for 21 September with activity possibly
increasing later in the UT day of 22 September with the arrival of
another CME. Degraded HF conditions are expected to continue over the
next few days due to low levels of ionising solar radiation and
renewed increased geomagnetic activity. SWFs are possible. Solar
energetic proton fluxes have increased in association with the M2.1
flare, however they are presently below event threshold values.

Space Weather Services              email: asfc at ips.gov.au
Bureau of Meteorology
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Haymarket NSW 1240  AUSTRALIA       FTP: ftp://ftp.ips.gov.au 
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