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

Product: Report of Solar-Geophysical Activity
Issued: 2007 Sep 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 263 Issued at 2200Z on 20 Sep 2007

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

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

IIA. Geophysical Activity Summary 19/2100Z to 20/2100Z: The geomagnetic field was initially quiet, but increased to unsettled to active levels beginning at 1300Z. The increased activity was most likely due to a solar sector boundary crossing. ACE data reflected the approaching high speed stream as solar wind speed and temperature began to increase in the latter portion of the day.

IIB. Geophysical Activity Forecast: The geomagetic field is expected to be quiet to unsettled, with a chance for active to minor-storm periods at high latitudes, as the recurrent coronal hole-high speed steam becomes increasingly geoeffective. These conditions are expected to last from 21 September through 23 September.

III. Event Probabilities 21 Sep-23 Sep

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

IV. Penticton 10.7 cm Flux

• Observed 20 Sep 067
• Predicted 21 Sep-23 Sep 070/070/070
• 90 Day Mean 20 Sep 069

V. Geomagnetic A Indices

• Observed Afr/Ap 19 Sep 002/004
• Estimated Afr/Ap 20 Sep 009/008
• Predicted Afr/Ap 21 Sep-23 Sep 010/010-015/015-015/015

VI. Geomagnetic Activity Probabilities 21 Sep-23 Sep

A. Middle Latitudes

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

B. High Latitudes

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