:Product: 20030525RSGA.txt :Issued: 2003 May 25 2200 UTC # Prepared jointly by the U.S. Dept. of Commerce, NOAA, # Space Environment Center and the U.S. Air Force. # Joint USAF/NOAA Report of Solar and Geophysical Activity SDF Number 145 Issued at 2200Z on 25 May 2003 IA. Analysis of Solar Active Regions and Activity from 24/2100Z to 25/2100Z: Solar activity was at low levels. Region 368 (S33E37) produced the largest event of the period, a C3.0/Sf flare that occurred at 25/1754Z. This region exhibits a simple Hax alpha magnetic structure. Region 365 (S08E08) has shown rapid growth throughout the period in penumbral coverage and magnetic complexity. Late in the period this region produced its first reported flare, a B5.2 x-ray flare occurring at 25/2036Z. No new regions were numbered today. IB. Solar Activity Forecast: Solar activity is expected to be at low levels. Region 365 has become capable of producing C-class flares, if growth continues at this rate an isolated M-class flare may be a possibility over the next 24-48 hours. IIA. Geophysical Activity Summary 24/2100Z to 25/2100Z: The geomagnetic field was at quiet to minor storm levels. An oscillating Bz component of the interplanetary magnetic field allowed for two consecutive periods of minor storm conditions at both the middle and high latitudes during local nighttime hours. Elevated conditions are due to a high speed stream coronal hole. The greater than 2 MeV electron fluxes at geosynchronous orbit reached high levels today. IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be at predominantly active levels through the forecast period. Minor storm conditions are possible especially at local nighttime hours. Isolated major storm intervals are possible on day two of the period. The elevated activity is expected in anticipation of yet another recurrent high speed stream coronal hole. III. Event Probabilities 26 May-28 May Class M 15/15/15 Class X 01/01/01 Proton 01/01/01 PCAF Green IV. Penticton 10.7 cm Flux Observed 25 May 121 Predicted 26 May-28 May 125/125/120 90 Day Mean 25 May 125 V. Geomagnetic A Indices Observed Afr/Ap 24 May 014/022 Estimated Afr/Ap 25 May 020/020 Predicted Afr/Ap 26 May-28 May 020/025-025/030-020/025 VI. Geomagnetic Activity Probabilities 26 May-28 May A. Middle Latitudes Active 40/45/40 Minor storm 20/25/20 Major-severe storm 10/15/10 B. High Latitudes Active 45/50/45 Minor storm 25/25/25 Major-severe storm 10/15/10