The RASP weather API.
RASP - Regional Atmospheric Soaring Prediction - is the standard set of post-processed fields pilots use to plan flights. Convek is the first RASP API: the same fields you'd scrape off a regional RASP website, served as JSON over HTTP, updated four times daily.
What RASP actually is
RASP was coined by Dr. John W. (Jack) Glendening in the early 2000s as a convention for post-processing mesoscale model output into fields that matter to soaring pilots - thermal strength, boundary layer depth, cloudbase, trigger temperature, convergence, and upper-level winds.
Over the last two decades, volunteer-run regional RASP websites have sprung up worldwide. They render the fields as static maps and soundings. They're excellent - and if you just want to look at a map before a flight, they work great.
But there has never been a RASP API. If you want to pull wstar into an app, or feed a day rating into your instrument, or build a map overlay for your club - you've had to scrape images or ask someone nicely for a CSV dump. Convek fixes that.
What a RASP API gets you
Same fields, different interface - and a very different set of things you can build.
Queryable, not just visible
Traditional RASP is a set of static PNG images on a regional website. Convek returns the same fields as structured JSON you can parse, filter, and join to your own data.
Any lat/lon, any hour
Ask for a specific point and time - you don't have to pick a map tile and eyeball the pixel. /v1/site returns the values at your coordinate.
Full-day and grid endpoints
/v1/forecast returns every hour for a day at a point. /v1/grid returns a slice you can render as your own heatmap. Corridor sampling follows a route.
Stable schema
Field names, units, and response shapes are documented and versioned. Build against it once, don't scrape screenshots.
Core RASP fields - available via API
The fields every RASP site publishes, now queryable by coordinate and hour.
wstar_msThermal updraft velocity - the core RASP field for thermal strength.
hglider_agl_mGlider-capped thermalling ceiling - PBL top with moisture and glider performance caps.
cloudbase_agl_ftConvective cloudbase height above ground - LCL-based with microphysics correction.
thermal_trigger_temp_cSurface temperature required for positively buoyant thermals to start firing.
surface_wind + upper levels10 m wind plus 925, 850, 800, 700 hPa - the levels soaring pilots actually fly.
day_ratingComposite 0-5 label: poor, marginal, fair, good, excellent. The field pilots check first.
Plus convergence, sounding profiles, surface heat flux, Bowen ratio, Cu/OD potential, and more - see the full field list.
Who a RASP API is for
Pilots
Pull today's RASP into your pre-flight checklist, your club's dashboard, or your own planning spreadsheet.
Developers
Add soaring forecasts to an app without scraping, image parsing, or a paid desktop export. Free tier to prototype.
Instrument makers
Ship RASP fields to variometers, flight computers, and tablet apps over a stable HTTP contract.
A RASP call looks like this
Request
curl "https://api.convek.dev/v1/site \ ?region=gb&resolution=4km&lat=51.94&lon=-2.08" \ -H "Authorization: Bearer cvk_live_abc123"
Response (RASP fields)
{
"rasp_model": "gb/4km",
"valid_time": "14:00",
"site": {
"wstar_ms": 2.1,
"hglider_agl_m": 1340,
"cloudbase_agl_ft": 4800,
"thermal_trigger_temp_c": 17.5,
"day_rating": "good",
"convergence_ms": 0.3
}
}How Convek produces RASP fields
Convek runs its own WRF (Weather Research and Forecasting) simulations at 4 km over the UK, four times a day, initialised from NOAA GFS. A post-processor derives the RASP-style fields from the raw WRF output and serves them through the API.
The full pipeline - model version, physics schemes, cycles, known limitations - is documented on the WRF model page. Coverage regions and resolution tiers are on the coverage page.
Try the RASP API.
Free tier - 25 queries/day. Any UK coordinate, any hour of the forecast.