WxChallenge Meteograms

Forecast guidance for the WxChallenge

Purpose. Model guidance for the WxChallenge forecast variables (06–06 UTC maximum and minimum 2-m temperature, maximum sustained 10-m wind, liquid precipitation) at any US ASOS station, defaulting to the current competition city. Three sections: (1) the model grid around the station, with the four grid points that surround it, at 850, 500 and 250 hPa; (2) surface time series with METAR observations and MOS; (3) time–height sections. GFS, HRRR, RRFS and NAM come from the Iowa Environmental Mesonet BUFKIT archive (full model levels); ECMWF IFS and AIFS from Open-Meteo (13 pressure levels). The layout follows Yoland Gao’s meteogram site.

Station (ICAO)

Model

Run (UTC)

Time-series window

1. Model grid around the station

Gridded field

Variable

Level

Contours

Forecast hour

(a) synoptic and smaller scales (±3.5° longitude, ±2.5° latitude)

(b) large-scale set-up (±22° longitude, ±15° latitude)

Table 1. Values at the four grid points surrounding the station and the bilinear interpolation to the station.

Grid point	Lat (°N)	Lon (°E)	Distance (km)	Value

2. Surface time series

Table 2. WxChallenge-day summary (06–06 UTC): model values from the hourly series, MOS from the same cycle where available, observations to date from METARs.

Forecast day	Max T (°F)	Min T (°F)	Max wind (kt)	Precip (in)	MOS max/min	Obs so far max/min/wind/precip

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.

MOS (GFS MAV; NAM MET at 00/12 UTC): IEM api/1/mos.json; red diamonds mark the MOS daily maximum/minimum (N/X). Observations: IEM ASOS/METAR archive (routine and special reports). The stochastic-wind ensemble of the original site is server-side and is not reproduced.

Grid panel: fields from the 6-hourly GFS / AIFS / IFS 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.