:Product: 0417RSGA.txt
:Issued: 2011 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 2011
IA.  Analysis of Solar Active Regions and Activity from  16/2100Z
to 17/2100Z:  Solar activity remained at low levels. Region 1185
(N14, L=032) produced four C-class flares as it rotated off of the
solar limb. Region 1193 (N16E19) continues to increase in areal
coverage and maintains its beta-gamma magnetic configuration. Region
1190 (N14W53) showed decreases in both spot number and areal
coverage, however, it retains its beta-gamma magnetic configuration.
IB.  Solar Activity Forecast:  Solar activity is expected to be at
low levels, with C-class flares expected for the next three days
(18-20). There remains a chance for M-class flares during the
period.
IIA.  Geophysical Activity Summary 16/2100Z to 17/2100Z:
The geomagnetic field was at quiet levels.
IIB.  Geophysical Activity Forecast:  The geomagnetic field is
expected to be at predominantly quiet levels on days one and two
(18-19 April). Activity is expected to increase to quiet to
unsettled levels on day three (20 April), with a chance for active
levels as well as a slight chance for minor storm levels at high
latitudes. The increase in activity is due to a coronal hole
high-speed stream.
III.  Event Probabilities 18 Apr-20 Apr
Class M    40/40/40
Class X    05/05/05
Proton     05/05/05
PCAF       Green
IV.  Penticton 10.7 cm Flux
Observed           17 Apr 114
Predicted   18 Apr-20 Apr  115/112/110
90 Day Mean        17 Apr 103
V.  Geomagnetic A Indices
Observed Afr/Ap 16 Apr  002/004
Estimated Afr/Ap 17 Apr  003/005
Predicted Afr/Ap 18 Apr-20 Apr  005/005-005/005-010/010
VI.  Geomagnetic Activity Probabilities 18 Apr-20 Apr
A.  Middle Latitudes
Active                05/05/35
Minor storm           01/01/10
Major-severe storm    01/01/05
B.  High Latitudes
Active                10/10/40
Minor storm           01/01/15
Major-severe storm    01/01/05