:Product: 1217RSGA.txt
:Issued: 2007 Dec 17 2203 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