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

SDF Number 144 Issued at 2200Z on 24 May 2003

IA. Analysis of Solar Active Regions and Activity from 23/2100Z
to 24/2100Z: Solar activity was at very low levels. The largest
event was a B7 flare at 1428Z on the southwest limb. The most
likely source is Region 357 (S16W99) from beyond the west limb. The
remaining regions on the visible disk are small and have simple
magnetic configurations.

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

IIA. Geophysical Activity Summary 23/2100Z to 24/2100Z:
The geomagnetic field was at quiet to minor storm levels. Elevated
solar wind speed resulted in an isolated period of minor storm
levels during local nighttime hours.

IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to be at quiet to active levels. Elevated solar wind
speeds are likely to result in isolated active conditions and
possibly isolated minor storm levels on day one of the period. By
day three, another coronal high speed stream is expected to be in a
favorable geo-effective position with active to minor storm levels
possible.

III. Event Probabilities 25 May-27 May

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

IV. Penticton 10.7 cm Flux

• Observed 24 May 117
• Predicted 25 May-27 May 120/120/125
• 90 Day Mean 24 May 124

V. Geomagnetic A Indices

• Observed Afr/Ap 23 May 018/021
• Estimated Afr/Ap 24 May 020/020
• Predicted Afr/Ap 25 May-27 May 012/015-015/020-020/025

VI. Geomagnetic Activity Probabilities 25 May-27 May

A. Middle Latitudes

• Active 25/30/40
• Minor storm 10/10/20
• Major-severe storm 05/05/10

B. High Latitudes

• Active 40/45/55
• Minor storm 15/20/30
• Major-severe storm 05/10/15