Joint USAF/NOAA Report of Solar and Geophysical Activity 21 Apr 2004

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

Updated 2004 Apr 21 2210 UTC

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 112 Issued at 2200Z on 21 Apr 2004

IA. Analysis of Solar Active Regions and Activity from 20/2100Z
to 21/2100Z: Solar activity has been low. Region 596 (S07E19)
produced the only C-class events in the past 24 hours. The daily
consensus for this region has it as a magnetic beta-gamma
configuration, however, earlier in the period a small delta
configuration developed. A new region was numbered today as Region
598 (S05W30).

IB. Solar Activity Forecast: Solar activity is expected to be low.
Region 596 is expected to continue producing C-class flares with a
chance for an isolated M-class event.

IIA. Geophysical Activity Summary 20/2100Z to 21/2100Z:
The geomagnetic field has been at quiet to unsettled levels.

IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to be predominately quiet to unsettled.

III. Event Probabilities 22 Apr-24 Apr

• Class M 25/25/25
• Class X 05/05/05
• Proton 01/01/01
• PCAF green

IV. Penticton 10.7 cm Flux

• Observed 21 Apr 113
• Predicted 22 Apr-24 Apr 115/120/120
• 90 Day Mean 21 Apr 107

V. Geomagnetic A Indices

• Observed Afr/Ap 20 Apr 004/004
• Estimated Afr/Ap 21 Apr 006/006
• Predicted Afr/Ap 22 Apr-24 Apr 005/008-010/010-010/012

VI. Geomagnetic Activity Probabilities 22 Apr-24 Apr

A. Middle Latitudes

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

B. High Latitudes

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