Joint USAF/NOAA Report of Solar and Geophysical Activity 26 May 2003

SDF Number 146 Issued at 2200Z on 26 May 2003

IA. Analysis of Solar Active Regions and Activity from 25/2100Z
to 26/2100Z: Solar activity was at moderate levels. Region 365
(S06W06) produce two M-class events with the largest one an M1.9/1f
at 0550Z. This region also produced a long duration C7 flare at
1744Z. LASCO C2 imagery indicates narrow CME’s associated with the
two M-class events but neither one has an Earth directed component.
Region 365 continues to grow in area coverage but the rate of growth
has slowed since yesterday.

IB. Solar Activity Forecast: Solar activity is expected to be at
low to moderate levels. Region 365 is expected to produce C-class
flares and has the potential for isolated M-class events.

IIA. Geophysical Activity Summary 25/2100Z to 26/2100Z:
The geomagnetic field was at quiet to active levels. Residual
effects from a high speed stream produced active conditions.

IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to be at unsettled to minor storm levels. A coronal hole
high speed stream is expected to produce minor storming on day one
and day two of the period. By day three, conditions are expected to
at quiet to unsettled.

III. Event Probabilities 27 May-29 May

• Class M 20/15/15
• Class X 01/01/01
• Proton 01/01/01
• PCAF green

IV. Penticton 10.7 cm Flux

• Observed 26 May 125
• Predicted 27 May-29 May 125/125/120
• 90 Day Mean 26 May 125

V. Geomagnetic A Indices

• Observed Afr/Ap 25 May 014/022
• Estimated Afr/Ap 26 May 018/018
• Predicted Afr/Ap 27 May-29 May 025/030-020/025-012/015

VI. Geomagnetic Activity Probabilities 27 May-29 May

A. Middle Latitudes

• Active 45/40/35
• Minor storm 25/20/15
• Major-severe storm 15/10/05

B. High Latitudes

• Active 50/45/35
• Minor storm 25/25/15
• Major-severe storm 15/10/05