Report of Solar-Geophysical Activity

Issued: 2005 Dec 27 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 361 Issued at 2200Z on 27 Dec 2005 IA. Analysis of Solar Active Regions and Activity from 26/2100Z to 27/2100Z: Solar activity was at very low levels. Most spotted regions showed some decay during the period with no significant solar activity reported. No new regions were numbered today.

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

IIA. Geophysical Activity Summary 26/2100Z to 27/2100Z:

The geomagnetic field ranged from quiet to minor storm levels. A recurrent high speed trans-equatorial coronal hole stream became geoeffective late in the period. The solar wind speed increased from near 300 km/sec in the early part of the period to greater than 600 km/sec at the time of this writing.

IIB. Geophysical Activity Forecast: The geomagnetic field is expected to range from quiet to active levels with isolated minor storming periods possible, due to coronal hole effects. A return to quiet to unsettled levels is expected on 30 December as the high speed stream wanes.

III. Event Probabilities 28 Dec-30 Dec

Class M 05/05/05

Class X 01/01/01

Proton 01/01/01

PCAF green

IV. Penticton 10.7 cm Flux

Observed 27 Dec 092

Predicted 28 Dec-30 Dec 090/090/090

90 Day Mean 27 Dec 084

V. Geomagnetic A Indices

Observed Afr/Ap 26 Dec 006/006

Estimated Afr/Ap 27 Dec 010/010

Predicted Afr/Ap 28 Dec-30 Dec 015/020-012/020-008/015 VI. Geomagnetic Activity Probabilities 28 Dec-30 Dec A. Middle Latitudes

Active 35/25/20

Minor storm 15/10/05

Major-severe storm 10/05/01

B. High Latitudes

Active 45/45/35

Minor storm 25/25/15

Major-severe storm 15/15/10