Report of Solar-Geophysical Activity

Issued: 2005 Dec 28 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 362 Issued at 2200Z on 28 Dec 2005 IA. Analysis of Solar Active Regions and Activity from 27/2100Z to 28/2100Z: Solar activity was at very low levels today. Region 843 produced the largest flare of the period, a B9 x-ray flare which occurred at 28/1125Z. No new regions were numbered today.

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

IIA. Geophysical Activity Summary 27/2100Z to 28/2100Z:

The geomagnetic field ranged from unsettled to minor storm levels. A recurrent trans-equatorial high speed coronal hole stream was responsible for the elevated conditions. 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 at predominantly unsettled to active levels with isolated minor storm periods possible through 29 December. A return to quiet to unsettled levels is expected on 30 and 31 December as the coronal hole moves out of geoeffective position.

III. Event Probabilities 29 Dec-31 Dec

Class M 01/01/01

Class X 01/01/01

Proton 01/01/01

PCAF green

IV. Penticton 10.7 cm Flux

Observed 28 Dec 089

Predicted 29 Dec-31 Dec 090/090/090

90 Day Mean 28 Dec 084

V. Geomagnetic A Indices

Observed Afr/Ap 27 Dec 010/018

Estimated Afr/Ap 28 Dec 015/020

Predicted Afr/Ap 29 Dec-31 Dec 012/020-008/015-005/010 VI. Geomagnetic Activity Probabilities 29 Dec-31 Dec A. Middle Latitudes

Active 25/20/15

Minor storm 10/05/01

Major-severe storm 05/01/01

B. High Latitudes

Active 40/35/25

Minor storm 25/15/10

Major-severe storm 10/05/05