Joint USAF/NOAA Report of Solar and Geophysical Activity 17 April 2012

Prepared jointly by the U.S. Dept. of Commerce, NOAA,
Space Weather Prediction Center and the U.S. Air Force.
Updated 2012 Apr 17 2200 UTC

Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 108 Issued at 2200Z on 17 Apr 2012

IA. Analysis of Solar Active Regions and Activity from 16/2100Z
to 17/2100Z: Solar activity has been low for the past 24 hours. A
long duration C1 flare was observed from new Region 1461 (N13E66) at
17/0809Z. An associated CME became visible in LASCO C2 imagery at
17/0800Z but does not appear to be Earth-directed. A filament
eruption occurred at approximately 17/1330Z near N24W40. The
associated CME was first visible in LASCO C2 imagery at 17/1424Z but
is not expected to be geoeffective. New Region 1460 (N16E26) was
also numbered overnight and is considered a Dso-beta type spot
group. Region 1459 (S15E40) has shown a significant decrease in
areal coverage and is now a Dao-beta type spot group.

IB. Solar Activity Forecast: Solar activity is expected to be low
with a slight chance for an M-class flare for the next three days
(18-20 April).

IIA. Geophysical Activity Summary 16/2100Z to 17/2100Z:
The geomagnetic field was mostly quiet during the past 24 hours. The
greater than 2 MeV electron flux at geosynchronous orbit reached
high levels during the period.

IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to be mostly quiet on days one and two (18-19 April). Quiet
to unsettled conditions are expected with a chance for isolated
active periods on day three (20 April) due to a recurrent Solar
Sector Boundary Crossing (SSBC).

III. Event Probabilities 18 Apr-20 Apr
Class M 20/15/10
Class X 01/01/01
Proton 01/01/01
PCAF green

IV. Penticton 10.7 cm Flux
Observed 17 Apr 114
Predicted 18 Apr-20 Apr 115/115/110
90 Day Mean 17 Apr 112

V. Geomagnetic A Indices
Observed Afr/Ap 16 Apr 005/005
Estimated Afr/Ap 17 Apr 006/008
Predicted Afr/Ap 18 Apr-20 Apr 004/005-004/005-007/008

VI. Geomagnetic Activity Probabilities 18 Apr-20 Apr
A. Middle Latitudes
Active 10/10/25
Minor storm 01/01/10
Major-severe storm 01/01/01
B. High Latitudes
Active 15/15/15
Minor storm 15/15/30
Major-severe storm 10/10/30