:Product: 0418RSGA.txt :Issued: 2010 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 108 Issued at 2200Z on 18 Apr 2010 IA. Analysis of Solar Active Regions and Activity from 17/2100Z to 18/2100Z: Solar activity was very low. The visible disk remained spotless. A very long duration B1.3 X-ray event was observed at 18/0218Z. The possible source region of this event was from an area of surging on the east limb between N13 and N27 as observed in GOES-14 SXI imagery. IB. Solar Activity Forecast: Solar activity is expected to remain at very low levels. A slight chance for C-class activity exists as the new area of interest on the NE limb rotates onto the disk. IIA. Geophysical Activity Summary 17/2100Z to 18/2100Z: Geomagnetic field activity was quiet at all latitudes. IIB. Geophysical Activity Forecast: Geomagnetic field activity is expected to be quiet on days one and two (19 - 20 April). Activity is expected to increase to quiet to unsettled levels, with isolated active periods, on day three (21 April) as two coronal hole wind streams rotate into a geoeffective position. These coronal holes are currently located, one each, in the NE and SE quadrants of the disk and generally lie along a similar longitudinal line. 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 075 Predicted 19 Apr-21 Apr 078/079/080 90 Day Mean 18 Apr 082 V. Geomagnetic A Indices Observed Afr/Ap 17 Apr 001/002 Estimated Afr/Ap 18 Apr 002/005 Predicted Afr/Ap 19 Apr-21 Apr 005/005-005/005-008/010 VI. Geomagnetic Activity Probabilities 19 Apr-21 Apr A. Middle Latitudes Active 05/05/25 Minor storm 01/01/05 Major-severe storm 01/01/01 B. High Latitudes Active 10/10/35 Minor storm 01/01/15 Major-severe storm 01/01/01