Joint USAF/NOAA Report of Solar and Geophysical Activity 20 Apr 2009

Product: Report of Solar-Geophysical Activity
Issued: 2009 Apr 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 110 Issued at 2200Z on 20 Apr 2009

IA. Analysis of Solar Active Regions and Activity from 19/2100Z
to 20/2100Z: Solar activity was very low. No flares were observed.
The visible disk remains spotless.

IB. Solar Activity Forecast: Solar activity is expected to be very
low.

IIA. Geophysical Activity Summary 19/2100Z to 20/2100Z:
The geomagnetic field was quiet. Observations from the ACE
spacecraft indicated steady solar wind speeds throughout the period
averaging about 450 km/s.

IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to be at quiet to unsettled levels for 21 – 22 April due to
a recurrent enhancement in solar wind velocities. By 23 April,
mostly quiet conditions are expected.

III. Event Probabilities 21 Apr-23 Apr
Class M 01/01/01
Class X 01/01/01
Proton 01/01/01
PCAF green

IV. Penticton 10.7 cm Flux
Observed 20 Apr 070
Predicted 21 Apr-23 Apr 070/070/070
90 Day Mean 20 Apr 070

V. Geomagnetic A Indices
Observed Afr/Ap 19 Apr 004/004
Estimated Afr/Ap 20 Apr 005/005
Predicted Afr/Ap 21 Apr-23 Apr 007/008-007/007-005/005

VI. Geomagnetic Activity Probabilities 21 Apr-23 Apr
A. Middle Latitudes
Active 10/10/05
Minor storm 05/05/01
Major-severe storm 01/01/01
B. High Latitudes
Active 15/10/05
Minor storm 05/05/01
Major-severe storm 01/01/01