Joint USAF/NOAA Report of Solar and Geophysical Activity 29 May 2003

SDF Number 149 Issued at 2200Z on 29 May 2003

IA. Analysis of Solar Active Regions and Activity from 28/2100Z
to 29/2100Z: Solar activity was at high levels. Region 365 (S07W45)
once again produced a major flare early in the period. An X1.1/2b
event occurred at 29/0105Z that had an associated Tenflare, Type IV
and Type II (estimated shock velocity of 1170 km/s.) radio sweeps.
SOHO/LASCO imagery depicts a very symmetric full halo CME resulting
from the event. This region remains extremely complex
(a beta-gamma-delta structure) although the penumbral coverage has
shown little growth during the period. Region 368 (S32W15) also
managed to produce two notable flares today, an M2.7/1n event at
29/1937Z and an M1.5/1f event at 29/0217Z. This region did show some
magnetic growth during the period. No new regions were numbered today.

IB. Solar Activity Forecast: Solar activity is expected to be at
moderate to high levels. Region 365 continues to show the potential
to produce major flare activity.

IIA. Geophysical Activity Summary 28/2100Z to 29/2100Z:
The geomagnetic field was at unsettled to severe storm levels. A
recurrent coronal hole was responsible for the initial elevated
conditions. At approximately 29/1155Z the first of two transients
associated with the first two X-class flares from late on the 27th
and early on the 28th passed the NASA/ACE space craft. The second
occurred at approximately 29/1830Z and was responsible for the
severe storm conditions seen late in the period. The greater than
10 MeV proton fluxes at geosynchronous orbit achieved event levels
at 28/2335Z and reached a maximum of 121 pfu at 29/1530Z. 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 to major storm levels with
severe storm condition anticipated. Another transient passage is
expected between 30/0600 and 1200Z on day one of the period. The
greater than 10 MeV proton fluxes should remain above threshold
levels through day one of the interval.

III. Event Probabilities 30 May-01 Jun

• Class M 75/75/75
• Class X 25/25/25
• Proton 80/50/25
• PCAF in progress

IV. Penticton 10.7 cm Flux

• Observed 29 May 138
• Predicted 30 May-01 Jun 145/140/135
• 90 Day Mean 29 May 125

V. Geomagnetic A Indices

• Observed Afr/Ap 28 May 022/036
• Estimated Afr/Ap 29 May 050/060
• Predicted Afr/Ap 30 May-01 Jun 050/060-025/040-015/025

VI. Geomagnetic Activity Probabilities 30 May-01 Jun

A. Middle Latitudes

• Active 25/50/30
• Minor storm 35/25/15
• Major-severe storm 35/15/05

B. High Latitudes

• Active 20/30/35
• Minor storm 35/35/20
• Major-severe storm 40/30/15