Joint USAF/NOAA Report of Solar and Geophysical Activity 20 Dec 2007

Product: Report of Solar-Geophysical Activity
Issued: 2007 Dec 20 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 354 Issued at 2200Z on 20 Dec 2007

IA. Analysis of Solar Active Regions and Activity from 19/2100Z to 20/2100Z: Solar activity was very low. The visible disk remains spotless.

IB. Solar Activity Forecast: Solar activity is expected to be very low.

IIA. Geophysical Activity Summary 19/2100Z to 20/2100Z: The geomagnetic field ranged from quiet to active levels due to a coronal hole high speed stream. The solar wind velocity observed at ACE reached a maximum of around 745 km/s at 20/1733Z. As of forecast issue time, the solar wind remains elevated with values around 670-700 km/s. The greater than 2 MeV electron flux remained at high levels today.

IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be predominantly quiet to unsettled for the next three days (21-23 December). Active conditions are possible on 21 December, with isolated minor storm period possible at high latitudes, due to the continued influence of the high speed stream.

III. Event Probabilities 21 Dec-23 Dec

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

IV. Penticton 10.7 cm Flux

• Observed 20 Dec 073
• Predicted 21 Dec-23 Dec 072/071/070
• 90 Day Mean 20 Dec 071

• V. Geomagnetic A Indices
• Observed Afr/Ap 19 Dec 007/008
• Estimated Afr/Ap 20 Dec 010/015
• Predicted Afr/Ap 21 Dec-23 Dec 010/015-008/010-005/008

VI. Geomagnetic Activity Probabilities 21 Dec-23 Dec

A. Middle Latitudes

• Active 30/25/15
• Minor storm 10/05/01
• Major-severe storm 01/01/01

B. High Latitudes

• Active 35/30/20
• Minor storm 15/10/05
• Major-severe storm 05/05/05