WxChallenge Meteograms

Forecast guidance for the WxChallenge

Purpose. Model guidance and observations for the WxChallenge, a forecasting contest in which students predict, for one US airport, the maximum and minimum temperature, the maximum sustained wind and the precipitation over a 24-h “forecast day” that runs from 06 UTC to 06 UTC (in US Eastern time, 2 am to 2 am in summer and 1 am to 1 am in winter). The page works for any US airport weather station and opens on the current contest city. The layout follows Yoland Gao’s meteogram site.

How to use. Type a 4-letter station code (for example KBOS) and press Go, or press Competition city. The latest model run loads automatically. Table 2 summarises each forecast day; Fig. 2 shows the hour-by-hour forecast with observations; Fig. 1 shows the weather pattern around the station, and its slider steps through forecast (or, for satellite and radar, past) times; Fig. 3 shows the vertical structure above the station.

Abbreviations

GFS: NOAA Global Forecast System. HRRR and RRFS: NOAA 3-km models for the US (RRFS is replacing the NAM, the older NOAA regional model). GDPS: the Canadian (ECCC) global model. NBM: National Blend of Models, NOAA’s calibrated blend of many models; NBS and NBE are its short-range (3-hourly, to 72 h) and extended text guidance. IFS: the ECMWF (European Centre) global model. AIFS: ECMWF’s machine-learning global model. MOS: Model Output Statistics, a statistically corrected station forecast. METAR: the routine hourly airport weather report. ASOS: Automated Surface Observing System, the US airport stations. BUFKIT: model vertical profiles at a station. UTC: Coordinated Universal Time (Z).

Station (ICAO)

Model

Run (UTC)

Time-series window

1. Maps around the station: model grid and observed imagery

These maps have their own Source selector and always show the latest published run; the Model and Run selected above apply to Table 2 and Figs. 2 and 3.

Source

Variable

Level

Contours

Surface elevation

show elevation contours

Forecast hour

(a) close-up

(b) wider view

Table 1. Values at the four model grid points around the station (filled dots in panel a) and at the station itself. Scroll sideways for more columns.

Grid point	Latitude	Longitude	Distance (km)	Value

2. Surface time series

Table 2. Forecast-day summary (06–06 UTC). Model values come from the hourly series of the selected run; guidance values from the statistical guidance that matches the model automatically (GFS MOS for GFS runs, NAM MOS for NAM runs, NBM short range otherwise; all products are compared in Table 3) (maximum and minimum from its daily max/min, wind from its highest sustained wind at its 3- or 6-hourly times, with * where only part of the day is covered, precipitation from its 6- or 12-h amounts, where \u2020 marks NBE 12-h amounts that cover 00\u201300 UTC instead; GFS and NAM MOS give no amounts); observations to date from METARs. Note that MOS and NBM maxima and minima are for daytime (about 7 am–7 pm local standard time) and night-time (about 7 pm–8 am) periods, not the 06–06 UTC contest day: when temperatures fall after a front, the day’s highest value can occur near 06 UTC and exceed the guidance maximum. Bold: the day covered by the next 00 UTC deadline. Scroll sideways for more columns.

Forecast day	Max T (°F)	Min T (°F)	Max wind (kt)	Precip (in)	Guidance max (°F)	Guidance min (°F)	Guidance wind (kt)	Guidance precip (in)	Observed so far: max / min / wind / precip

Table 3. Statistical guidance for each forecast day, all products (the latest bulletin of each). Max/min are the products’ daytime and night-time values; wind is the highest sustained wind at their 3-, 6- or 12-hourly times (* part of the day only); precipitation sums their 6- or 12-h amounts († 00–00 UTC). Scroll sideways for more columns.

Forecast day	Product (issued)	Max (°F)	Min (°F)	Wind (kt)	Precip (in)

3. Time–height sections

Method notes and sources

BUFKIT models (GFS, HRRR, RRFS, NAM): Iowa Environmental Mesonet api/1/nws/bufkit.json. Surface series: T2MS, TD2M (°C→°F), UWND/VWND (m s⁻¹→kt), P01M/C01M (mm→in), CAPE, LIFT, KINX, PWAT (mm→in), precipitation type from the WXTR/WXTS/WXTZ/WXTP flags. Boundary-layer wind: maximum and pressure-weighted mean of the profile wind from the surface to the level where θ first exceeds the surface value by 0.4 K. Profiles are interpolated in ln p to a fixed 60-level grid (1000–100 hPa); levels below the model surface are masked.

Open-Meteo models (ECMWF IFS 0.25°, AIFS-single): hourly 2-m temperature and dew point, 10-m wind, precipitation, CAPE (IFS only) and 12 pressure levels (1000–100 hPa) of temperature, relative humidity, wind, geopotential height, vertical velocity (converted to ω = −w p g/(R_d T)) and cloud cover; θ and θ_e (Bolton 1980) are computed here. Specific runs come from the Open-Meteo single-runs API. Lifted and K indices are not available for these models.

Statistical guidance from the IEM MOS archive (api/1/mos.json): GFS MOS (MAV, 00/06/12/18 UTC), NAM MOS (MET, 00/12 UTC), and the National Blend of Models text bulletins NBS (short range, 3-hourly to 72 h, 00/06/12/18 UTC) and NBE (extended, 00/12 UTC). The page uses the bulletin issued at or before the selected model run. Red diamonds mark the daily maximum and minimum (MOS N/X, NBM TXN); NBM precipitation amounts (6-h Q06, 12-h Q12, hundredths of an inch) are summed over each 06–06 UTC day. NBM gridded forecasts (2.5 km; hourly output from the runs at 00, 03, …, 21 UTC that Open-Meteo archives; surface variables only, so no time–height sections) come from Open-Meteo. Observations: IEM ASOS/METAR archive (routine and special reports). The stochastic-wind ensemble of the original site is server-side and is not reproduced.

Observed imagery (past only; satellites provide no forecasts): GOES-East or GOES-West Advanced Baseline Imager (whichever views the station better; clean infrared band 13, red visible band 2, GeoColor and air-mass RGB) and the GPM IMERG Early Run 30-min precipitation rate, both served by NASA GIBS, whose time domains decide which frames the slider offers; and the NEXRAD base-reflectivity composite over the contiguous US from the Iowa Environmental Mesonet. Images are requested in latitude–longitude coordinates for exactly the map box, so they overlay the coastlines without resampling. Colour bars use the providers’ own colour tables.

Surface level: 2-m temperature and dew point (°F), 10-m wind (kt), mean-sea-level pressure (hPa) and precipitation accumulated over the 6 h ending at the valid time (in; GFS 6-h bucket, ECMWF difference of run totals).

Grid panel models: GFS (NOAA), AIFS and IFS (ECMWF) and GDPS (ECCC, the Canadian global model, 00/12 UTC runs; contains information licensed under the Data Server End-use Licence of Environment and Climate Change Canada) are global; HRRR (NOAA, 3 km, to 48 h) and NBM (2.5 km, surface fields only, to 72 h) cover the US and are interpolated from their Lambert-conformal grids to a 0.05° latitude–longitude grid, with HRRR winds rotated to true north.

Grid panel: fields from the 6-hourly GFS / AIFS / IFS / GDPS / HRRR / NBM dataset behind the Northern Hemisphere viewer (0.25° CONUS window, 0.5° elsewhere). The four surrounding 0.25° grid points are exact model grid nodes; for HRRR/RRFS the 3-km Lambert-conformal cell nodes around the station are drawn from the published grid definition (no field values). Competition city: from wxchallenge.com, refreshed weekly; fallback KBOS.