Joint USAF/NOAA Report of Solar and Geophysical Activity 27 Sep 2003

SDF Number 270 Issued at 2200Z on 27 Sep 2003

IA. Analysis of Solar Active Regions and Activity from 26/2100Z
to 27/2100Z: Solar activity has been low. Region 464 has produced
several C-class flares, including a C1.3/Sf at 27/1143 UTC and a
C1.3/Sf at 1204 UTC. This Region is stable in size and magnetic
complexity. New Region 469 (S09W24) was numbered today.

IB. Solar Activity Forecast: Solar activity is expected to be low.
Region 464 has the potential to produce C-class and isolated M-class
flares.

IIA. Geophysical Activity Summary 26/2100Z to 27/2100Z:
The geomagnetic field was at quiet to minor storm conditions. Solar
wind speed from a coronal hole in geoeffective position continued to
decrease to below 500 km/s. 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 at quiet to unsettled conditions all three days.
Isolated minor storm conditions are possible day one due to the last
remaining effects of the coronal hole passing out of geoeffective
position.

III. Event Probabilities 28 Sep-30 Sep

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

IV. Penticton 10.7 cm Flux

• Observed 27 Sep 130
• Predicted 28 Sep-30 Sep 130/125/125
• 90 Day Mean 27 Sep 120

V. Geomagnetic A Indices

• Observed Afr/Ap 26 Sep 011/017
• Estimated Afr/Ap 27 Sep 012/015
• Predicted Afr/Ap 28 Sep-30 Sep 012/020-012/015-012/015

VI. Geomagnetic Activity Probabilities 28 Sep-30 Sep

A. Middle Latitudes

• Active 35/30/30
• Minor storm 04/04/04
• Major-severe storm 01/01/01

B. High Latitudes

• Active 30/35/35
• Minor storm 25/20/15
• Major-severe storm 20/15/10