Links to the GWTC-2 forecasts are available here.

The returned files will be a 59-day forecast (with the first day being the day in the file name), using CFSv2 forecast data from 12Z the previous day (i.e. a Tuesday forecast is made using the 12Z Monday CFS forecast model output data). The forecasts should be updated daily around 00z (or, 6-7pm Eastern Time the previous day). The first day of available forecasts is 30 January 2019. Again, please note that these are still experimental, so please use at your own risk!

The files are 259,921-by-61 (rows-by-columns) and CSV formatted; each is about 47 MB in size, with grid-point locations as rows and days as columns. The top row is an Excel-readable date number (1-Jan-1979 = 28856) and the first two columns are the latitudes and longitudes (0-360) in 0.5-degree increments. All other data in each file are the forecasted GWTC-2 weather types for the location and day. Please use the table at the bottom of the page to decode the weather types in the files.

The global GWTC-2 forecasts were derived using the same methodology as the original GWTC (described in Lee, 2014) with the modifications noted here. Additionally forecast data are interpolated in space and time to align the CFSv2 forecast datasets with the full-resolution historical CFSv2 datasets.

Current GWTC-2 forecast maps are shown below, along with daily Warm/Cool Index (WCI) and Global Extremes Index (GEI) forecasts. NOTE: the percentiles shown in these figures are relative to the most recent observed daily WCI and GEI values (as found here), current as of 1-2 months ago. Earth-AMPS (Earth's Air Mass Percentage Split) is an easier to interpret version of the WCI... it is simply the (latitude-adjusted) percentage of area covered by any of the three hot air masses minus that for the three cold air masses. Thus, positive Earth-AMPS indicate how much more (in percentage-points) of the Earth is under warmer-than-average air than is under cooler-than-average air, based upon the definition of GWTC2 air masses.

59-Day Forecast Loop (updated daily around 00z):

Today's GWTC-2 Forecast (updated daily around 00z):

Tomorrow's GWTC-2 Forecast (updated daily around 00z):

Day 3 GWTC-2 Forecast (updated daily around 00z):

0-15 Day WT Frequency Forecast (updated daily around 00z):

0-30 Day WT Frequency Forecast (updated daily around 00z):

0-60 Day WT Frequency Forecast (updated daily around 00z):

Use the table below to interpret GWTC-2 files


Weather Type
11 Humid Cool HC
12 Humid H
13 Humid Warm HW
21 Cool C
22 Seasonal S
23 Warm W
31 Dry Cool DC
32 Dry D
33 Dry Warm DW
72 Cold Front Passage CFP
73 Warm Front Passage WFP