Joint USAF/NOAA Report of Solar and Geophysical Activity 19 Aug 2006

Product: Report of Solar-Geophysical Activity
Issued: 2006 Aug 19 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 231 Issued at 2200Z on 19 Aug 2006

IA. Analysis of Solar Active Regions and Activity from 18/2100Z to 19/2100Z: Solar activity was low. Region 903, a plage region on the west limb, produced a C3.8 flare at 19/1124Z. Region 904 (S14W54) has shown little activity, producing only B-class flares.

IB. Solar Activity Forecast: Solar activity is expected to be very low to low, with a slight chance for an isolated M-class flare from Region 904.

IIA. Geophysical Activity Summary 18/2100Z to 19/2100Z: The geomagnetic field has been at quiet to major storm levels. At approximately 19/1100Z a small shock was observed at ACE. The total IMF strength increased to about 20 nT while the Bz component turned southward and reached -15 nT. The solar wind speed also increased from about 400 km/s to about 450 km/s. This resulted in two periods of major storm levels at high latitudes from 1200 – 1800Z. At time of issue Bz remained southward at approximately -10 nT and solar wind speed had decreased to about 400 km/s. Today’s shock arrival is likely due to the full halo CME observed on 16 August. IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be unsettled to active with a chance for isolated minor storm periods on 20 August due to an expected coronal hole high speed stream. Quiet to unsettled conditions are expected on 21 – 22 August.

III. Event Probabilities 20 Aug-22 Aug

• Class M 10/10/10
• Class X 01/01/01
• Proton 01/01/01
• PCAF green

IV. Penticton 10.7 cm Flux

• Observed 19 Aug 089
• Predicted 20 Aug-22 Aug 090/090/090
• 90 Day Mean 19 Aug 077

V. Geomagnetic A Indices

• Observed Afr/Ap 18 Aug 009/012
• Estimated Afr/Ap 19 Aug 020/035
• Predicted Afr/Ap 20 Aug-22 Aug 015/025-008/010-005/008

VI. Geomagnetic Activity Probabilities 20 Aug-22 Aug

A. Middle Latitudes

• Active 30/20/15
• Minor storm 15/10/05
• Major-severe storm 05/01/01

B. High Latitudes

• Active 35/25/20
• Minor storm 20/10/10
• Major-severe storm 10/01/01