The message below is from the NOAA Space Weather Prediction Center.  We are currently experiencing a G3 Geomagnetic Storm, which is rated as Strong.
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Expect wide-spread GPS outages and poor convergence of everything from WAAS to RTK, and it will affect GPS from all manufacturers.  Systems that do appear to show good signal may still be subject to large amounts of GPS drift.
Space Weather Message Code: WARK07 Serial Number: 37 Issue Time: 2012 Apr 24 0204 UTC
WARNING: Geomagnetic K-index of 7 or greater expected Valid From: 2012 Apr 24 0205 UTC Valid To: 2012 Apr 24 0600 UTC Warning Condition: Onset NOAA Scale: G3 or greater – Strong to Extreme Potential Impacts: Area of impact primarily poleward of 50 degrees Geomagnetic Latitude. Induced Currents – Power system voltage irregularities possible, false alarms may be triggered on some protection devices. Spacecraft – Systems may experience surface charging; increased drag on low Earth-orbit satellites and orientation problems may occur. Navigation – Intermittent satellite navigation (GPS) problems, including loss-of-lock and increased range error may occur. Radio – HF (high frequency) radio may be intermittent. Aurora – Aurora may be seen as low as Pennsylvania to Iowa to Oregon.