Joint USAF/NOAA Report of Solar and Geophysical Activity 21 Dec 2007

Product: Report of Solar-Geophysical Activity
Issued: 2007 Dec 21 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 355 Issued at 2200Z on 21 Dec 2007

IA. Analysis of Solar Active Regions and Activity from 20/2100Z to 21/2100Z: 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 20/2100Z to 21/2100Z: The geomagnetic field was quiet to unsettled. Solar wind observations at ACE gradually decreased in velocity from a high of 745 km/s at 20/2128Z to 600 km/s at forecast issue time. The greater than 2 MeV electron flux at geosynchronous orbit reached high levels today.

IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be quiet to unsettled for the next three days (22-24 December). Isolated active conditions are possible at high latitudes for days 1 and 2 (22-23 December).

III. Event Probabilities 22 Dec-24 Dec

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

IV. Penticton 10.7 cm Flux

• Observed 21 Dec 071
• Predicted 22 Dec-24 Dec 070/069/069
• 90 Day Mean 21 Dec 071

V. Geomagnetic A Indices

• Observed Afr/Ap 20 Dec 010/012
• Estimated Afr/Ap 21 Dec 008/012
• Predicted Afr/Ap 22 Dec-24 Dec 008/010-006/008-005/005

VI. Geomagnetic Activity Probabilities 22 Dec-24 Dec

A. Middle Latitudes

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

B. High Latitudes

• Active 30/20/15
• Minor storm 10/05/05
• Major-severe storm 05/01/01