Joint USAF/NOAA Report of Solar and Geophysical Activity 17 Apr 2009

Product: Report of Solar-Geophysical Activity
Issued: 2009 Apr 17 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 107 Issued at 2200Z on 17 Apr 2009

IA. Analysis of Solar Active Regions and Activity from 16/2100Z
to 17/2100Z: Solar activity was very low. No flares were observed
during the past 24 hours. The solar disk remains spotless.

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

IIA. Geophysical Activity Summary 16/2100Z to 17/2100Z:
The geomagnetic field was at quiet levels. Observations from the ACE
spacecraft show solar wind speed averaging around 420 km/s with Bz
fluctuations around +/- 4 nT.

IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to be predominately quiet for 18-19 April. Quiet to
unsettled levels are expected for 20 April due to a recurrent
enhancement in solar wind velocities.

III. Event Probabilities 18 Apr-20 Apr
Class M 01/01/01
Class X 01/01/01
Proton 01/01/01
PCAF Green

IV. Penticton 10.7 cm Flux
Observed 17 Apr 070
Predicted 18 Apr-20 Apr 070/070/070
90 Day Mean 17 Apr 070

V. Geomagnetic A Indices
Observed Afr/Ap 16 Apr 003/006
Estimated Afr/Ap 17 Apr 003/006
Predicted Afr/Ap 18 Apr-20 Apr 005/005-005/005-007/008

VI. Geomagnetic Activity Probabilities 18 Apr-20 Apr
A. Middle Latitudes
Active 05/05/10
Minor storm 01/01/05
Major-severe storm 01/01/01
B. High Latitudes
Active 10/10/15
Minor storm 01/01/05
Major-severe storm 01/01/01