Joint USAF/NOAA Report of Solar and Geophysical Activity 18 Apr 2008

Product: Report of Solar-Geophysical Activity
Issued: 2008 Apr 18 2200 UTC
Prepared jointly by the U.S. Dept. of Commerce, NOAA,
Space Weather Prediction Center and the U.S. Air Force.

Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 109 Issued at 2200Z on 18 Apr 2008

IA. Analysis of Solar Active Regions and Activity from 17/2100Z to 18/2100Z: Solar activity was very low.

IB. Solar Activity Forecast: Solar activity is expected to remain very low.

IIA. Geophysical Activity Summary 17/2100Z to 18/2100Z: The geomagnetic field was quiet to unsettled.

IIB. Geophysical Activity Forecast: The geomagnetic field is expected to remain mostly quiet for days 1 and 2 (19-20 April) becming mostly unsettled by day 3 (21 April) as a recurrent coronal hole begins to rotate into a geoeffective position.

III. Event Probabilities 19 Apr-21 Apr

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

IV. Penticton 10.7 cm Flux

• Observed 18 Apr 070
• Predicted 19 Apr-21 Apr 070/075/075
• 90 Day Mean 18 Apr 071

V. Geomagnetic A Indices

• Observed Afr/Ap 17 Apr 007/008
• Estimated Afr/Ap 18 Apr 007/007
• Predicted Afr/Ap 19 Apr-21 Apr 005/005-005/005-008/015

VI. Geomagnetic Activity Probabilities 19 Apr-21 Apr

A. Middle Latitudes

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

B. High Latitudes

• Active 10/10/40
• Minor storm 05/05/10
• Major-severe storm 01/01/05