Joint USAF/NOAA Report of Solar and Geophysical Activity 21 Oct 2003

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

Updated 2003 Oct 21 2200 UTC

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 294 Issued at 2200Z on 21 Oct 2003

IA. Analysis of Solar Active Regions and Activity from 20/2100Z
to 21/2100Z: Solar activity has been moderate. There has been a
steady series of C-class flares and a single M1.0 at 21/0827 UTC.
Region 484 (N05E26) continues to grow, but at a lesser rate than
yesterday. The region is now 1650 millionths with at least a 50%
increase in magnetic intensity. A region just beyond the East limb,
generated a strong CME at approximately 21/0300 UTC, but does not
appear to be Earth-directed.

IB. Solar Activity Forecast: Solar activity is expected to remain
moderate. Region 484, and the new Region approaching the East limb,
are a combined threat to continue to generate C-class activity, with
an occasional M-class flare. There is a slight chance for an
isolated X-class event, and an even lesser chance for a
proton-producing flare. By day three, Region 484 will near central
meridian, and become a slightly higher threat for producing a flare
event which could generate protons at near-Earth.

IIA. Geophysical Activity Summary 20/2100Z to 21/2100Z:
The geomagnetic field has been at active to minor storm levels. A
favorably positioned coronal hole is supporting a high-speed solar
wind stream, which is in turn supporting elevated magnetic activity
at Earth. 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 minor storm levels for the next three
days. The coronal hole will proceed out of geoeffective range
around the second day, but a faint shock associated with a CME which
occurred on the 19th should lightly impact Earth, once again
elevating magnetic activity on day three.

III. Event Probabilities 22 Oct-24 Oct

• Class M 70/70/70
• Class X 15/15/15
• Proton 10/10/15
• PCAF green

IV. Penticton 10.7 cm Flux

• Observed 21 Oct 152
• Predicted 22 Oct-24 Oct 150/155/160
• 90 Day Mean 21 Oct 114

V. Geomagnetic A Indices

• Observed Afr/Ap 20 Oct 020/030
• Estimated Afr/Ap 21 Oct 028/030
• Predicted Afr/Ap 22 Oct-24 Oct 020/025-020/020-025/020

VI. Geomagnetic Activity Probabilities 22 Oct-24 Oct

A. Middle Latitudes

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

B. High Latitudes

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