Today's Weather Maps


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16 December 2023 – Climate Reanalyzer recently stopped processing daily outputs from the NCEP Climate Forecast System (CFS) after migrating to the newer ECMWF Reanalysis version 5 (ERA5). ERA5 is a latest-generation global reanalysis with improved physics, higher resolution, and longer record period (1940-present) compared to earlier reanalysis products. ERA5's production schedule typically has a 6-day latency, which means the most recent output grids lag the current date by about a week. Therefore, Today's Weather Maps will no longer display a table of global and regional anomalies for the previous day. However, daily temperature and anomaly estimates from ERA5 for these same areas are available via interactive chart on the Daily Surface Air Temperature page.
Historical sea surface temperature estimates from NOAA OISST
are available on the Daily Sea Surface Temperature page.

Page Overview & Data Sources

  • This page shows the current day's average weather for temperature, precipitation, wind, and other variables forecasted by the NOAA/NCEP Global Forecast System (GFS). GFS is a numerical modeling framework that uses a 13 km Finite-Volume Cubed-Sphere dynamical core (FV3) to produce 16-day forecasts four times each day. The weather maps here show 1-day average conditions calculated from eight 3-hourly GFS forecast timesclices beginning 0000 UTC. Sea ice concentration is an analysis field produced daily by the NCEP Environmental Monitoring Center. Sea surface temperature is from a NOAA gridded data product described below. All weather and sea ice data are downloaded from the NOAA Operational Model Archive and Data Distribution System (NOMADS). Visualizations are made using NCAR Command Language.

  • 2m Temperature refers to air temperature at 2 meters above the surface. 2m Temperature Anomaly refers to the departure of the current day's forecast temperature from a long-term mean for the same day of the year. The anomalies here are calculated from a 1979–2000 climatology from the NCEP Climate Forecast System Reanalysis (CFSR). This 22-year baseline, which is used instead a 30-year 1991–2020 climate normal, represents the early part of the CFSR record prior to significant warming observed across the Arctic since the early 2000s. Users are encouraged to learn more about reanalysis — approach, strengths, limitations, and product comparisons — from the NCAR Climate Data Guide. Additional information about reanalysis can be found at Advancing Reanalysis.

  • Sea Surface Temperature (SST) and SST Anomaly maps are generated from NOAA Optimum Interpolation SST (OISST). OISST is a 0.25°x0.25° gridded dataset that estimates temperatures based on a blend of satellite, ship, and buoy observations. OISST also includes SST anomaly (based on a 1971–2000 NOAA climatology) and sea ice concentration variables. A sea ice mask is applied to the SST and anomaly maps for gridcells where ice concentration is >= 50%. Learn more about the OISST, including strengths and limitations, from the NCAR Climate Data Guide.

  • Other variable definitions:
    • Precipitable Water (PWtr) – Total amount of water vapor in a column of air that could be precipitated.
    • Mean Sea Level Pressure (MSLP) – Atmospheric pressure as it would be observed at sea level.
    • Geopotential Height (GPH) – Estimated physical height of a pressure surface in the atmosphere, typically reported in decameters (dam) (1 dam = 10 meters).
    • Standardized Anomaly – Climate anomaly divided by the climatological standard deviation. Standardized (also called normalized) anomalies are useful for comparing the magnitude of an event without the effects of signal dispersion (such as the difference in seasonal ranges). The units are standard deviations (σ) from the mean of a normal distribution. Values within 1σ account for about 68% of observations; about 95% for 2σ; and about 99.7% for 3σ. The latter can be used as a general threshold for identifying extreme events.

  • Looking for long-term climate trends? Climate Reanalyzer has pages for plotting time series and maps from reanalysis and gridded data products. Or check out this page with U.S. temperature and precipitation data since 1895. Also refer to NOAA's Climate at a Glance for global temperature change since 1850.

Last updated 11 December 2023