:Product: Report of Solar-Geophysical Activity
:Issued: 2012 Jul 17 2200 UTC
# Prepared jointly by the U.S. Dept. of Commerce, NOAA,
# Space Weather Prediction Center and the U.S. Air Force.
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 199 Issued at 2200Z on 17 Jul 2012
IA. Analysis of Solar Active Regions and Activity from 16/2100Z
to 17/2100Z: Solar activity was moderate. Today's activity was
dominated by a very long-duration M1 flare that occurred between
1203-1904Z with maximum at 1715Z. The source region appeared to
primarily be Region 1520 (S17W75), although it appears that Region
1521 (S19W85) was involved in the early phase and may have been the
initial trigger for the overall event. An associated, bright CME was
observed off the southwest limb beginning at 1400Z; the leading edge
plane-of-sky speed was estimated to be about 960 km/s in the LASCO
C3 field of view. The proximity of Regions 1519 (S17 just past west
limb), 1520, and 1521 to the west limb hindered analysis of the spot
groups. New Region 1524 (S18E52) was assigned and is a simple C-type
sunspot group. An additional new spot group appeared to be emerging
just south of Region 1524.
IB. Solar Activity Forecast: Solar activity is expected to be
moderate for the next 24 hours with 1520 and 1521 as the most likely
source regions. Activity and background levels are expected to
decrease significantly by the second and third days as these regions
rotate beyond west limb.
IIA. Geophysical Activity Summary 16/2100Z to 17/2100Z:
The geomagnetic field ranged from active to quiet levels with some
isolated minor and major storm intervals at high latitudes.
Unsettled to active levels prevailed duing the earlier part of the
period and quiet to unsettled levels dominated from 17/0900Z through
the end of the day. Solar wind observations from the ACE spacecraft
showed continued influence of the 12 July CME from the beginning of
the period through about 17/0600Z. The z-component of the
interplanetary magnetic field was initially negative and reached a
peak negative value of about -9 nT during this latter phase of the
CME passage. Nominal solar wind conditions prevailed from 17/0600Z
through the end of the day. A greater than 10 MeV proton event began
at 17/1715Z in response to today's long-duration M1 and associated
CME event. The peak value observed so far was 87 PFU at 17/2030Z.
The greater than 2 MeV electron flux at geosynchronous orbit reached
high levels during the period.
IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to be quiet for the next three days. Model results for
today's CME from the west limb indicate an interplanetary
disturbance that is too far west to produce geomagnetic activity.
The greater than 10 MeV proton event is expected to continue through
part of the first day (18 July).
III. Event Probabilities 18 Jul-20 Jul
Class M 55/40/25
Class X 10/10/05
IV. Penticton 10.7 cm Flux
Observed 17 Jul 128
Predicted 18 Jul-20 Jul 115/105/095
90 Day Mean 17 Jul 129
V. Geomagnetic A Indices
Observed Afr/Ap 16 Jul 027/040
Estimated Afr/Ap 17 Jul 015/020
Predicted Afr/Ap 18 Jul-20 Jul 006/005-007/005-006/005
VI. Geomagnetic Activity Probabilities 18 Jul-20 Jul
A. Middle Latitudes
Minor storm 01/01/01
Major-severe storm 01/01/01
B. High Latitudes
Minor storm 10/10/10
Major-severe storm 05/05/05