Joint USAF/NOAA Report of Solar and Geophysical Activity 20 May 2005

 Prepared jointly by the U.S. Dept. of Commerce, NOAA,
Space Environment Center and the U.S. Air Force.
Updated 2005 May 20 2210 UTC

Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 140 Issued at 2200Z on 20 May 2005

IA. Analysis of Solar Active Regions and Activity from 19/2100Z
to 20/2100Z: Solar activity was at very low levels. Region 759
(N12W88) is transiting the solar west limb and quiescent throughout
the period. Region 765 (N09E51) was responsible for several low
level B-class flares today. Magnetically, this region remains
simply structured. No new regions were numbered today.

IB. Solar Activity Forecast: Solar activity is expected to be at
very low levels with a slight chance for an isolated C-class flare.

IIA. Geophysical Activity Summary 19/2100Z to 20/2100Z:
The geomagnetic field ranged from quiet to major storming levels
today. The most likely source for the major storming conditions was
the full halo CME seen early on 17 May. The greater than 2 MeV
electron flux at geosynchronous orbit reached high levels.

IIB. Geophysical Activity Forecast: The geomagnetic field should be
at quiet to unsettled levels throughout the period.

III. Event Probabilities 21 May-23 May

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

IV. Penticton 10.7 cm Flux

• Observed 20 May 084
• Predicted 21 May-23 May 080/085/090
• 90 Day Mean 20 May 091

V. Geomagnetic A Indices

• Observed Afr/Ap 19 May 007/011
• Estimated Afr/Ap 20 May 020/025
• Predicted Afr/Ap 21 May-23 May 006/010-006/008-004/008

VI. Geomagnetic Activity Probabilities 21 May-23 May

A. Middle Latitudes

• Active 15/15/15
• Minor storm 05/05/01
• Major-severe storm 01/01/01

B. High Latitudes

• Active 20/15/15
• Minor storm 05/05/05
• Major-severe storm 01/01/01