Sea Surface Temperature
Sea Surface T Anomaly
Precipitation & Clouds
Mean Sea Level Pressure
Sea Ice & Snow
* 2/23/2016 — See note below on new GFS model bias correction for daily temperature anomaly calculations
The weather maps shown here are generated from the NCEP Global Forecast System (GFS) model. GFS is the primary operational model framework underlying U.S. NOAA/NWS weather forecasting. The model is run four times daily on a global T1534 gaussian grid (~13 km) to produce 16-day forecasts. Here, we use 0.25°x0.25° (~30 km) output grids available from NOMADS, and calculate daily averages from eight 3-hourly timeslices starting at 0000 UTC.
* 2/23/2016 — NEW GFS MODEL BIAS CORRECTION FACTORS calculated from winter (DJF) GFS-CFSR estimates: 0.7 (World), 0.75 (Northern Hemisphere), 0.5 (Southern Hemisphere), 1.1 (Arctic), 1.0 (Antarctic) and 0.5 (Tropics). GFS model bias appears to vary with the seasons due to snow/ice and albedo processes, and therefore season-specific correction terms will be applied from now on. As stated below, refer to the CFSR/CFSV2 Daily Reanalysis Maps interface for the most reliable daily temperature anomalies. CFSR/CFSV2 daily reanalysis maps are current as of 2/22/2016, and updated manually every couple weeks.
Note that bias-corrected GFS-CFSR temperature anomalies will differ slightly from those calculated from CFSV2-CFSR (see these comparisons for June 30, 2015). CFSV2-CFSR is apples-to-apples; therefore, difference maps within the Daily Reanalysis Maps image archive should be considered reliable, and take precedent over the GFS-CFSR anomaly maps shown here as part of the current 7-day forecast.
See this NCEP/NWS discussion for additional information on model bias.