Report of Solar-Geophysical Activity

Issued: 2012 Jul 16 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 198 Issued at 2200Z on 16 Jul 2012

IA.  Analysis of Solar Active Regions and Activity from  15/2100Z
to 16/2100Z:  Solar activity was low. Region 1520 (S16W58) produced
today's largest event, a C7/Sf with maximum at 16/2003Z. Additional
low level C-class events were observed during the period with
regions 1520, 1519 (S17W81), 1521 (S22W71), and 1522 (N11W76) all
contributing. All of the spotted regions on the disk were generally
unchanged or slowly declining. There were some preliminary
observations indicating a new region (yet to be numbered) rotating
onto the disk in the southern hemisphere. No Earth-directed CME's
were observed during the past 24 hours. (NOTE: today's F10.7 flux is
based on the morning 1800Z reading because the 2000Z observation was
flare enhanced).
IB.  Solar Activity Forecast:  Solar activity is expected to be low,
but with a continued chance for an isolated M-class event. Region
1520 is the most likely source. A decline in activity and background
levels is expected on the third day as Regions 1519, 1520, and 1521
cross west limb.
IIA.  Geophysical Activity Summary 15/2100Z to 16/2100Z:
The geomagnetic field ranged from unsettled to major storm levels
(estimated Kp between 3 and 6). The period began with a continuation
of storm level activity in response to the 12 July CME. Activity
gradually subsided with mostly active conditions (estimated Kp of 4)
from 0600-1500Z and unsettled levels for the remainder of the
period. There were some lingering major storm intervals at high
latitudes in the 0600-1800Z timeframe. Solar wind observations from
ACE showed a continuation of the CME passage: initial values of the
Z-component of the interplanetary magnetic field were around -15 nT
and slowly weakened through the day, finally turning northwards at
1424Z. A second, much weaker phase of southward Bz began at 1755Z
with maximum value around -4.5 nT. Solar wind velocity declined
also, with initial values around 510 km/s and end-of-day values
around 440 km/s.
IIB.  Geophysical Activity Forecast:  Geomagnetic activity is
expected to be unsettled with a chance for active periods during the
next 24 hours (17 July). In addition, there is a chance for isolated
minor to major storm periods at high latitudes during the earlier
part of 17 July. Solar wind driving of the magnetosphere is expected
to continue to decrease in intensity throughout the day and
predominantly quiet levels are expected for the second and third
days (18-19 July).
III.  Event Probabilities 17 Jul-19 Jul
Class M    40/40/30
Class X    05/05/05
Proton     05/05/05
PCAF       green
IV.  Penticton 10.7 cm Flux
Observed           16 Jul 138
Predicted   17 Jul-19 Jul  135/120/105
90 Day Mean        16 Jul 129
V.  Geomagnetic A Indices
Observed Afr/Ap 15 Jul  039/086
Estimated Afr/Ap 16 Jul  021/032
Predicted Afr/Ap 17 Jul-19 Jul  007/012-006/005-007/005
VI.  Geomagnetic Activity Probabilities 17 Jul-19 Jul
A.  Middle Latitudes
Active                10/05/05
Minor storm           01/01/01
Major-severe storm    01/01/01
B.  High Latitudes
Active                15/15/15
Minor storm           20/10/10
Major-severe storm    10/05/05