Joint USAF/NOAA Report of Solar and Geophysical Activity 18 Dec 2007

Product: Report of Solar-Geophysical Activity
Issued: 2007 Dec 18 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 352 Issued at 2200Z on 18 Dec 2007

IA. Analysis of Solar Active Regions and Activity from 17/2100Z to 18/2100Z: Solar activity was at low levels. Region 978 (S08W91) has produced several C-class events, the largest being a C2 at 18/1320Z.

IB. Solar Activity Forecast: Solar activity is expected to be at very low to low levels. Activity levels should decrease with the rotation of Region 978 beyond the west limb.

IIA. Geophysical Activity Summary 17/2100Z to 18/2100Z: The geomagnetic field was at predominately unsettled to active levels. This elevated activity is due to a coronal hole high speed stream that has rotated into a geoeffective position. Measurements at the ACE spacecraft indicated a steady increase in solar wind speed. At the time of forecast issue the wind speed was approximately 700 km/s.

IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be at mostly unsettled to active levels for 19 to 21 December due to the continued influence of the high speed stream.

III. Event Probabilities 19 Dec-21 Dec

• Class M 05/01/01
• Class X 01/01/01
• Proton 01/01/01
• PCAF Green

IV. Penticton 10.7 cm Flux

• Observed 18 Dec 077
• Predicted 19 Dec-21 Dec 070/070/070
• 90 Day Mean 18 Dec 071

V. Geomagnetic A Indices

• Observed Afr/Ap 17 Dec 012/017
• Estimated Afr/Ap 18 Dec 015/020
• Predicted Afr/Ap 19 Dec-21 Dec 015/015-015/015-012/012

VI. Geomagnetic Activity Probabilities 19 Dec-21 Dec

A. Middle Latitudes

• Active 50/50/40
• Minor storm 20/20/15
• Major-severe storm 05/05/05

B. High Latitudes

• Active 50/50/40
• Minor storm 25/25/20
• Major-severe storm 10/10/05