Joint USAF/NOAA Report of Solar and Geophysical Activity 21 Apr 2009

Product: Report of Solar-Geophysical Activity
Issued: 2009 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 2009

IA. Analysis of Solar Active Regions and Activity from 20/2100Z
to 21/2100Z: Solar activity was very low. No flares were observed.
New Region 1015 (N22 W65) was numbered during the period. The
region formed on the disk and is a simple Axx alpha spot group.

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

IIA. Geophysical Activity Summary 20/2100Z to 21/2100Z:
The geomagnetic field was mostly quiet. Observations from the ACE
spacecraft indicated a gradual decay in wind speeds, from near 450
km/s to 390 km/s, through about 21/1100Z. Since that time, and
through the remainder of the period, wind velocities increased to
about 460 km/s.

IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to be at quiet to unsettled levels for 22 April due to a
recurrent enhancement in solar wind velocities. On 23 – 24 April,
mostly quiet conditions are expected.

III. Event Probabilities 22 Apr-24 Apr
Class M 01/01/01
Class X 01/01/01
Proton 01/01/01
PCAF green

IV. Penticton 10.7 cm Flux
Observed 21 Apr 071
Predicted 22 Apr-24 Apr 070/070/070
90 Day Mean 21 Apr 070

V. Geomagnetic A Indices
Observed Afr/Ap 20 Apr 003/004
Estimated Afr/Ap 21 Apr 006/007
Predicted Afr/Ap 22 Apr-24 Apr 007/007-005/005-005/005

VI. Geomagnetic Activity Probabilities 22 Apr-24 Apr
A. Middle Latitudes
Active 10/05/05
Minor storm 05/01/01
Major-severe storm 01/01/01
B. High Latitudes
Active 10/05/05
Minor storm 05/01/01
Major-severe storm 01/01/01