This interface is for viewing weather forecasts from NOAA/NCEP numerical models. To change maps, select Forecast Type (this refers to global or U.S. regional models), Map Area, and Variable from the pulldown menus at the top of this page. Choices for Map Area and Variable change depending on which Forecast Type is selected. Use the Image Slider or playback controls to animate the maps. If viewing from a low bandwidth network connection, then keep the switch Load Fewer Images set to Yes. This changes the output interval to reduce the total number of image downloads (for example, GFS output interval changes from 3-hourly to 6-hourly, reducing the number of transferred files from 64 to 32). Users with fast network connections should change Load Fewer Images to No. The weather models accessible here are shown below with forecast period, default output interval, and approximate image update schedule.
Global Forecast System (GFS)
7-day fcst [00Z & 12Z init] / 3-hourly / refresh @ 0700 & 1700 UTC
North American Mesoscale (NAM)
2-day fcst [00Z & 12Z init] / 1-hourly / refresh @ 0600 & 1800 UTC
High Resolution Rapid Refresh (HRRR)
18-hour fcst / 1-hourly / refresh hourly 0900-2400 UTC
Climate Reanalyzer obtains all original model output from the NOAA Operational Model Archive and Distribution System. Forecast maps on this page are generated using NCAR Command Language (NCL).
The variable Temperature 2m Anomaly is available for the GFS model. Temperature anomaly (at 2 meters above the surface) refers to the departure of the current forecasted temperature from a climate baseline. Climate Reanalyzer uses a 1979-2000 climate baseline derived from the reanalysis of the NCEP Climate Forecast System (CFSR/CFSV2). This baseline is chosen over the more typical 1981-2010 climate normal for the simple reason that it better approximates historical climatology, as shown here in relation to a 1880-2014 global land-ocean temperature index from NASA GISS.
GFS temperature anomaly maps for the World, Arctic, and Antarctic display at the right of the image a list of area-weighted average anomaly values for the World, Northern Hemisphere (Eq-90°N), Southern Hemisphere (Eq-90°S), Arctic (65°N-90°N), Antarctic (65°S-90°S), and Tropics (25°S-25°N).
It is important to note that GFS has a systematic model bias in which diurnal extremes are greater than in CFSR/CFSV2 over some parts of the globe. Correction terms are therefore be applied to each region of interest in order to bring GFS into better accord with CFSR/CFSV2. These terms are calculated from the mean monthly temperature differences between GFS and CFSV2 for the period June 2015 to May 2016 (see here). A comparison of uncorrected and corrected GFS vs. CFSR/CFSV2 temperature anomaly maps is shown here. The resultant bias-corrected GFS-CFSR temperature anomalies will differ somewhat from those calculated entirely within the CFSV2-CFSR framework, but in all this method affords reasonable temperature anomaly estimates for the GFS forecast period. The most reliable temperature anomaly estimates, CFSV2-CFSR, can be found in the Daily Reanalysis Maps image archive. The daily reanalysis archive is updated once or twice per month.
See this NCEP/NWS discussion for additional information on model bias.