Joint USAF/NOAA Report of Solar and Geophysical Activity 19 Apr 2009

Product: Report of Solar-Geophysical Activity
Issued: 2009 Apr 19 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 109 Issued at 2200Z on 19 Apr 2009

IA. Analysis of Solar Active Regions and Activity from 18/2100Z
to 19/2100Z: 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 18/2100Z to 19/2100Z:
The geomagnetic field was quiet. Observations from the ACE
spacecraft show solar wind speeds gradually decayed through the
period from about 540 km/s to near 450 km/s as the coronal hole high
speed stream waned.

IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to be mostly quiet for 20 April. Quiet to unsettled levels
are expected for 21 – 22 April due to a recurrent enhancement in
solar wind velocities.

III. Event Probabilities 20 Apr-22 Apr
Class M 01/01/01
Class X 01/01/01
Proton 01/01/01
PCAF green

IV. Penticton 10.7 cm Flux
Observed 19 Apr 070
Predicted 20 Apr-22 Apr 070/070/070
90 Day Mean 19 Apr 070

V. Geomagnetic A Indices
Observed Afr/Ap 18 Apr 008/008
Estimated Afr/Ap 19 Apr 005/005
Predicted Afr/Ap 20 Apr-22 Apr 005/005-008/008-007/007

VI. Geomagnetic Activity Probabilities 20 Apr-22 Apr
A. Middle Latitudes
Active 05/15/10
Minor storm 01/05/05
Major-severe storm 01/01/01
B. High Latitudes
Active 05/15/10
Minor storm 01/05/05
Major-severe storm 01/01/01