Joint USAF/NOAA Report of Solar and Geophysical Activity 24 Oct 2003

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

Updated 2003 Oct 24 2200 UTC

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 297 Issued at 2200Z on 24 Oct 2003

IA. Analysis of Solar Active Regions and Activity from 23/2100Z
to 24/2100Z: Solar activity has been high. Region 486 (S16E57)
produced several flares, including a M7.6/1n at 24/0254 UTC, with an
associated Type IV radio sweep. An associated CME was observed on
SOHO/LASCO imagery with an estimated velocity of 900 km/s, although
the CME did not appear to be earth-directed. Region 484 (N05W15)
produced an M1.3 at 24/1856 UTC. Region 484 appears to be decaying
slightly, while Region 486 is growing. Both regions continue to
exhibit large, complex beta-gamma-delta magnetic configurations.
The F10 value is flare enhanced and is estimated due to solar
activity at the time of the measurement.

IB. Solar Activity Forecast: Solar activity is expected to be high.
Regions 484 and 486 are expected to produce major flares.

IIA. Geophysical Activity Summary 23/2100Z to 24/2100Z:
The geomagnetic field has been at quiet to severe storm levels. An
interplanetary shock was observed at ACE at 24/1450 UTC, with a
subsequent sudden impulse observed at 1530 UTC. The sudden impulse
was followed by about two hours of severe geomagnetic storm
activity, and produced a magnetopause crossing at GOES 12. Solar
wind data show high density flow with strong magnetic fields (about
30 nT), although so far Bz has been strongly northwards. 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 active to severe storm conditions for day one, due
to persistence from the current transient-driven activity. Activity
should subside to unsettled to minor storm levels on days two and
three.

III. Event Probabilities 25 Oct-27 Oct

• Class M 90/90/90
• Class X 45/45/45
• Proton 15/20/25
• PCAF yellow

IV. Penticton 10.7 cm Flux

• Observed 24 Oct 191
• Predicted 25 Oct-27 Oct 190/195/200
• 90 Day Mean 24 Oct 117

V. Geomagnetic A Indices

• Observed Afr/Ap 23 Oct 005/007
• Estimated Afr/Ap 24 Oct 035/040
• Predicted Afr/Ap 25 Oct-27 Oct 035/040-030/040-020/030

VI. Geomagnetic Activity Probabilities 25 Oct-27 Oct

A. Middle Latitudes

• Active 30/40/40
• Minor storm 40/30/30
• Major-severe storm 30/20/15

B. High Latitudes

• Active 20/20/20
• Minor storm 40/40/40
• Major-severe storm 40/40/30