Joint USAF/NOAA Report of Solar and Geophysical Activity 20 May 2012

:Product: Report of Solar-Geophysical Activity
:Issued: 2012 May 20 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 141 Issued at 2200Z on 20 May 2012
IA. Analysis of Solar Active Regions and Activity from 19/2100Z
to 20/2100Z: Solar activity was at very low levels. New Region 1487
(N19W05) emerged on the disk as a simple bi-polar group. Region 1483
(S25W43) developed additional trailer spots and is now classified as
a D-type group. All other regions were quiet and stable. No
Earth-directed CMEs were observed during the period.
IB. Solar Activity Forecast: Solar activity is expected to be at
predominately low levels for the next three days (21 – 23 May). A
slight chance for M-class activity exists all three days.
IIA. Geophysical Activity Summary 19/2100Z to 20/2100Z:
The geomagnetic field was at quiet to active levels with an isolated
minor storm interval during the 20/0300 – 0600Z period. At about
20/0136Z, the ACE satellite observed an interplanetary (IP) shock
passage with a corresponding weak sudden impulse observed at the
Boulder magnetometer (15 nT) at 20/0215Z. Prior to the IP shock,
solar wind velocities were generally in the 400 km/s range, the Bz
component of the interplanetary magnetic field (IMF) varied between
+/- 3 nT and the total field (Bt) was at 5 nT. Following the shock,
wind speeds increased to about 475 km/s, Bz varied between +/- 8 nT
and Bt increased to about 8 nT. The shock likely indicated the
arrival of the 17 May CME.
IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to be at predominately quiet levels for day one (21 May).
By days two and three (22 – 23 May), quiet to unsettled levels with
a slight chance for isolated active periods are expected due to
coronal hole high speed stream effects coupled with the arrival of
the 18 May CME.
III. Event Probabilities 21 May-23 May
Class M 15/15/15
Class X 05/05/05
Proton 01/01/01
PCAF green
IV. Penticton 10.7 cm Flux
Observed 20 May 131
Predicted 21 May-23 May 130/130/135
90 Day Mean 20 May 116
V. Geomagnetic A Indices
Observed Afr/Ap 19 May 005/005
Estimated Afr/Ap 20 May 010/012
Predicted Afr/Ap 21 May-23 May 007/006-010/010-007/010
VI. Geomagnetic Activity Probabilities 21 May-23 May
A. Middle Latitudes
Active 10/20/20
Minor storm 01/10/10
Major-severe storm 01/01/01
B. High Latitudes
Active 10/25/25
Minor storm 01/15/15
Major-severe storm 01/01/01