Joint USAF/NOAA Report of Solar and Geophysical Activity 21 April 2011

:Product: Report of Solar-Geophysical Activity
:Issued: 2011 Apr 21 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 111 Issued at 2200Z on 21 Apr 2011
IA. Analysis of Solar Active Regions and Activity from 20/2100Z
to 21/2100Z: Solar Activity has been at low levels for the past 24
hours. Region 1195 (S17E43) has been the most active region
producing multiple C-class events, the largest being a C8/Sf at
21/0948Z. Region 1193 (N16W32) remains magnetically complex, but has
yet to produce any notable activity. Region 1197 (S16E57) was
numbered early in the period and has remained stable and quiet.
IB. Solar Activity Forecast: Solar activity is expected to be at
low levels with a slight chance for M-class activity for the next
three days (22-24 April).
IIA. Geophysical Activity Summary 20/2100Z to 21/2100Z:
The geomagnetic field has been at quiet levels for the past 24 hours.
The effects of the latest coronal hole high-speed stream continue to
wane. Solar wind speeds, as measured by the ACE spacecraft, have
decreased from 500 – 440 km/s.
IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to be at mostly quiet levels for the next three days (22-24
April).
III. Event Probabilities 22 Apr-24 Apr
Class M 20/20/20
Class X 01/01/01
Proton 01/01/01
PCAF green
IV. Penticton 10.7 cm Flux
Observed 21 Apr 113
Predicted 22 Apr-24 Apr 115/115/115
90 Day Mean 21 Apr 105
V. Geomagnetic A Indices
Observed Afr/Ap 20 Apr 011/016
Estimated Afr/Ap 21 Apr 005/005
Predicted Afr/Ap 22 Apr-24 Apr 008/008-005/005-005/005
VI. Geomagnetic Activity Probabilities 22 Apr-24 Apr
A. Middle Latitudes
Active 15/05/05
Minor storm 01/01/01
Major-severe storm 01/01/01
B. High Latitudes
Active 20/05/05
Minor storm 05/01/01
Major-severe storm 01/01/01