Joint USAF/NOAA Report of Solar and Geophysical Activity 23 Sep 2004

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

Updated 2004 Sep 23 2210 UTC

Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 267 Issued at 2200Z on 23 Sep 2004

IA. Analysis of Solar Active Regions and Activity from 22/2100Z
to 23/2100Z: Solar activity was low. A C1.4 flare was observed off
the west limb at N06. This event occurred at 23/0800Z and is likely
associated with Region 672 (N04, L=351). Region 673 (S13W31) is in
a slow decay phase and has produced several B-class flares.

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

IIA. Geophysical Activity Summary 22/2100Z to 23/2100Z:
The geomagnetic field was quiet to unsettled with two active periods
from 23/0000Z to 23/0600Z. The active levels followed a period of
southward Bz. The greater than 2MeV electron flux reached high
levels today.

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

III. Event Probabilities 24 Sep-26 Sep

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

IV. Penticton 10.7 cm Flux

• Observed 23 Sep 090
• Predicted 24 Sep-26 Sep 090/090/090
• 90 Day Mean 23 Sep 111

V. Geomagnetic A Indices

• Observed Afr/Ap 22 Sep 012/016
• Estimated Afr/Ap 23 Sep 008/014
• Predicted Afr/Ap 24 Sep-26 Sep 005/010-005/008-005/008

VI. Geomagnetic Activity Probabilities 24 Sep-26 Sep

A. Middle Latitudes

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

B. High Latitudes

• Active 25/25/25
• Minor storm 15/15/15
• Major-severe storm 05/05/05