Joint USAF/NOAA Report of Solar and Geophysical Activity 24 Apr 2005

Prepared jointly by the U.S. Dept. of Commerce, NOAA,
Space Environment Center and the U.S. Air Force.

Updated 2005 Apr 24 2210 UTC

Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 114 Issued at 2200Z on 24 Apr 2005

IA. Analysis of Solar Active Regions and Activity from 23/2100Z
to 24/2100Z: Solar activity continues at very low levels. There are
currently no sunspots on the visible disk. Occasional B-class flares
were associated with activity in a new region rotating on the east
limb near S05. This region was the likely source of CME activity on
22 April.

IB. Solar Activity Forecast: Solar activity is expected to be very
low to low. The new region rotating on the southeast limb may
elevate activity levels.

IIA. Geophysical Activity Summary 23/2100Z to 24/2100Z:
The geomagnetic field was quiet to unsettled with isolated active
periods. A weak recurrent coronal hole high speed stream continues.
Solar wind speed is elevated to near 550 km/s, but the IMF Bz is
weak and predominantly northward.

IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to be quiet to unsettled with isolated active periods on 25
April. Expect mostly quiet conditions on 26 and 27 April as the
current high speed solar wind stream subsides.

III. Event Probabilities 25 Apr-27 Apr

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

IV. Penticton 10.7 cm Flux

• Observed 24 Apr 082
• Predicted 25 Apr-27 Apr 085/090/090
• 90 Day Mean 24 Apr 089

V. Geomagnetic A Indices

• Observed Afr/Ap 23 Apr 005/006
• Estimated Afr/Ap 24 Apr 010/015
• Predicted Afr/Ap 25 Apr-27 Apr 008/010-005/008-005/005

VI. Geomagnetic Activity Probabilities 25 Apr-27 Apr

A. Middle Latitudes

• Active 20/15/15
• Minor storm 05/05/05
• Major-severe storm 01/01/01

B. High Latitudes

• Active 25/20/20
• Minor storm 10/05/05
• Major-severe storm 01/01/01