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

Product: Report of Solar-Geophysical Activity
Issued: 2007 Oct 20 2200 UTC
Prepared jointly by the U.S. Dept. of Commerce, NOAA,
Space Environment Center and the U.S. Air Force.

Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 293 Issued at 2200Z on 20 Oct 2007

IA. Analysis of Solar Active Regions and Activity from 19/2100Z to 20/2100Z: Solar activity was very low. No flares were observed during the past 24 hours and the solar disk continues to be 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. Unsettled to active levels prevailed from the beginning of the period through 1200Z, after which conditions declined to quiet to unsettled levels through the end of the period. Real-time solar wind observations from ACE show the continued presence of a recurrent high speed solar wind stream; solar wind velocity varied between 600-680 km/s throughout the day. The greater than 2 MeV electron flux at geosynchronous altitude reached high levels during the past 24 hours.

IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be predominantly quiet to unsettled for the first day (21 October), although there is a chance for isolated active periods early in the day due to persistence from the high speed stream. Conditions are expected to be quiet for the second day (22 October) and quiet to unsettled for the third day (23 October).

III. Event Probabilities 21 Oct-23 Oct

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

IV. Penticton 10.7 cm Flux

• Observed 20 Oct 067
• Predicted 21 Oct-23 Oct 067/067/067
• 90 Day Mean 20 Oct 068

V. Geomagnetic A Indices

• Observed Afr/Ap 19 Oct 011/015
• Estimated Afr/Ap 20 Oct 015/015
• Predicted Afr/Ap 21 Oct-23 Oct 007/010-005/005-005/008

VI. Geomagnetic Activity Probabilities 21 Oct-23 Oct

A. Middle Latitudes

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

B. High Latitudes

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