Official Space Weather Advisory issued by NOAA Space Weather Prediction Center Boulder, Colorado, USA SPACE WEATHER ADVISORY OUTLOOK #15-16 2015 April 19 at 7:00 p.m. MDT (2015 April 20 0100 UTC) **** SPACE WEATHER OUTLOOK **** Summary For April 13-19 Geomagnetic storms reaching G1 (minor) were observed on 15-16 April while G2 (moderate) storms were observed on 16 April. These storms were the result of a negative polarity coronal hole high speed stream (CH HSS). Outlook For April 20-26 Geomagnetic storms reaching G1 (minor) are likely on 21-22 April with a slight chance for G2 (moderate) on 21 April due to a combination of CH HSS effects coupled with a coronal mass ejection (CME) impact midday on 21 April. Data used to provide space weather services are contributed by NOAA, USAF, NASA, NSF, USGS, the International Space Environment Services and other observatories, universities, and institutions. More information is available at SWPC's Web site http://swpc.noaa.gov Thank you for using the Product Subscription Service. If you would like to remove a product subscription or update the personal information in your account, go to the Product Subscription Site. Please do not use the from address for correspondence, as it is not monitored. For comments or help, please contact SWPC Help.