Joint USAF/NOAA Report of Solar and Geophysical Activity 28 Sep 2003

SDF Number 271 Issued at 2200Z on 28 Sep 2003

IA. Analysis of Solar Active Regions and Activity from 27/2100Z
to 28/2100Z: Solar activity has been low. Region 464 has grown in
complexity, and produced several long-duration C-class flares,
including a C2.3 at 28/1428 UTC and a C6.8/Sf at 28/1558 UTC. An
11-degree filament at N56E01 erupted sometime between 27/2318 and
28/1359 UTC.

IB. Solar Activity Forecast: Solar activity is expected to be low
to moderate. Region 464 has become more complex and may produce C-
and M-class flares.

IIA. Geophysical Activity Summary 27/2100Z to 28/2100Z:
The geomagnetic field has been quiet to unsettled. Solar wind speeds
continue to decrease to below 400 km/s as a coronal hole leaves
geoeffective position. 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 quiet to unsettled throughout the period.

III. Event Probabilities 29 Sep-01 Oct

• Class M 50/50/50
• Class X 15/15/15
• Proton 05/05/05
• PCAF green

IV. Penticton 10.7 cm Flux

• Observed 28 Sep 137
• Predicted 29 Sep-01 Oct 125/125/125
• 90 Day Mean 28 Sep 119

V. Geomagnetic A Indices

• Observed Afr/Ap 27 Sep 013/009
• Estimated Afr/Ap 28 Sep 008/010
• Predicted Afr/Ap 29 Sep-01 Oct 012/015-012/015-012/015

VI. Geomagnetic Activity Probabilities 29 Sep-01 Oct

A. Middle Latitudes

• Active 30/30/30
• Minor storm 15/10/10
• Major-severe storm 05/05/05

B. High Latitudes

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