A good source for 8-14 day anomaly forecasts is the NAEFS -North American Ensemble Forecast System, co-run by NOAA and the Canadian weather service. Since its an anomaly forecast its good for tends above/below climatology. More detailed enemble mean fields are available from the site but precise day 8+ forecasts are usually not very reliable. Y'all may know this already and if so sorry for the unnecessary post. Cheers.