Report of Solar-Geophysical Activity
Issued: 2007 Dec 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 351 Issued at 2200Z on 17 Dec 2007

IA. Analysis of Solar Active Regions and Activity from 16/2100Z
to 17/2100Z: Solar activity was low. Region 978 (S10W78) produced
today's only C-class event, a C2 at 0716Z. The region appears to be
decaying as it approaches west limb.
IB. Solar Activity Forecast: Solar activity is expected to be very
low, although there continues to be a chance for an isolated C-class
event.
IIA. Geophysical Activity Summary 16/2100Z to 17/2100Z:
The geomagnetic field ranged from quiet to minor storm levels. The
field was initially quiet but became disturbed after a sudden
impulse was observed at 0300Z. The sudden impulse was preceded by a
weak shock in the solar wind observed at ACE at 0204Z. The shock was
followed by an increase in velocity and magnetic field at ACE
consistent with a corotating interaction region which was then
followed by a high speed stream. Active to minor storm conditions
prevailed from 0600-1200Z, followed by mostly active conditions. As
of forecast issue time the solar wind velocity remains elevated with
values around 550-600 km/s.
IIB. Geophysical Activity Forecast: Geomagnetic activity is
expected to be unsettled to active for the next three days (18-20
December), due to continued influence of the high speed stream.
III. Event Probabilities 18 Dec-20 Dec
Class M 01/01/01
Class X 01/01/01
Proton 01/01/01
PCAF Green
IV. Penticton 10.7 cm Flux
Observed 17 Dec 080
Predicted 18 Dec-20 Dec 075/070/070
90 Day Mean 17 Dec 071
V. Geomagnetic A Indices
Observed Afr/Ap 16 Dec 001/002
Estimated Afr/Ap 17 Dec 022/025
Predicted Afr/Ap 18 Dec-20 Dec 015/015-015/015-015/015
VI. Geomagnetic Activity Probabilities 18 Dec-20 Dec
A. Middle Latitudes
Active 50/50/50
Minor storm 20/20/20
Major-severe storm 05/05/05
B. High Latitudes
Active 50/50/50
Minor storm 25/25/25
Major-severe storm 10/10/10
 

NOAA Space Weather Scale descriptions can be found at www.sec.noaa.gov/NOAAscales