Joint USAF/NOAA Report of Solar and Geophysical Activity 11 Dec 2007

Product: Report of Solar-Geophysical Activity
Issued: 2007 Dec 11 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 345 Issued at 2200Z on 11 Dec 2007

IA. Analysis of Solar Active Regions and Activity from 10/2100Z to 11/2100Z: Solar activity was very low. Today’s activity consisted of a few, low level B-class flares. Region 978 (S07E01) is the only sunspot region on the disk and is a 240 millionths Eai beta-gamma group. The group has been relatively stable during the past 24 hours. There appears to be a new region rotating around east limb near N28.

IB. Solar Activity Forecast: Solar activity is expected to be very low to low. There is a fair chance for an isolated C-class event sometime during the next three days (12-14 December).

IIA. Geophysical Activity Summary 10/2100Z to 11/2100Z: The geomagnetic field was mostly unsettled although there was an active period from 10/2100Z-11/0000Z. Solar wind observations from ACE show the onset of a co-rotating interaction region late yesterday, followed by the onset of a high speed stream around 11/0000Z. Peak solar wind speeds were around 650 km/s. Nonetheless the solar wind magnetic field has been relatively weak since 11/0130Z. The solar wind speed is currently declining slowly with values around 550 km/s at forecast issue time.

IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be predominantly unsettled with a chance for an isolated active period for 12 December. Conditions should be predominantly quiet for 13-14 December.

III. Event Probabilities 12 Dec-14 Dec

• Class M 10/10/10
• Class X 01/01/01
• Proton 01/01/01
• PCAF Green

IV. Penticton 10.7 cm Flux

• Observed 11 Dec 093
• Predicted 12 Dec-14 Dec 095/095/095
• 90 Day Mean 11 Dec 070

V. Geomagnetic A Indices

• Observed Afr/Ap 10 Dec 005/008
• Estimated Afr/Ap 11 Dec 012/012
• Predicted Afr/Ap 12 Dec-14 Dec 010/010-005/005-005/005

VI. Geomagnetic Activity Probabilities 12 Dec-14 Dec

A. Middle Latitudes

• Active 30/15/15
• Minor storm 15/05/05
• Major-severe storm 01/01/01

B. High Latitudes

• Active 30/15/15
• Minor storm 15/05/05
• Major-severe storm 10/01/01