Joint USAF/NOAA Report of Solar and Geophysical Activity 17 April 2011

:Product: Report of Solar-Geophysical Activity
: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