- 4.8.0WRF-ARW version
- 3 kmFinest nest
- 72 hForecast length
- 00Z & 12ZGFS cycles, twice daily
An operational WRF-ARW configuration run in house each day and co-located with the Lekwena radar and the NWU station network for verification. Model documentation is maintained by the WRF user community.
Official warnings
Issued by the South African Weather Service.
Synoptic overview
Surface analysis with the two upper-air levels that drive it, stepped three-hourly from T+12 h to T+72 h — on the model's own 9 km domain, and on the wider GFS fields that force it.
-
9 km domain
WRF Synoptic Overview
Mean sea-level pressure, 10 m wind, dew point and 6-hourly precipitation, over 500 hPa geopotential height and vorticity and the 850 hPa wind and relative humidity.
Open the overview ↗ -
GFS 0.25 deg · 10W-65E, 48S-15N
GFS Large-Scale Overview
The same surface and upper-air layout as the WRF overview, rendered from the raw NCEP GFS boundary-forcing data across the wider region the model sits inside.
Open the overview ↗
Impact dashboards
Model output scored per location against storm, heat, frost, fire and agricultural decision thresholds.
-
9 km domain
National Impact Dashboard
Eighteen towns - the 9 km sounding sites - scored for convection, rainfall, wind, heat stress (Heat Index and WBGT), livestock heat load (THI), frost, fire danger, spray windows and irrigation scheduling.
Open dashboard ↗ -
3 km domain
NWU Campus Dashboard
Convection-permitting guidance for the Potchefstroom, Mahikeng and Vanderbijlpark (Vaal) campuses, scored against the same hazards as the national dashboard.
Open dashboard ↗
Agri forecast
Developed under the Maize Trust Early Warning for Farmers project. Start with the town dashboard, or open a regional map for a single decision.
| Regional map | What it shows |
|---|---|
| Rain per day | Gauge-day rainfall against the 25 mm planting-rain threshold. |
| Spray conditions | Hourly Delta-T, wind and rain against spraying limits. |
| Field access | Topsoil moisture against field capacity, for trafficability. |
| Irrigation need | Mid-season maize water use (FAO-56) less effective rain. |
| Leaf-wetness hours | Hours of likely leaf wetness, against rust and leaf-blight thresholds. |
| Soil temperature for planting | 0-10 cm at 08:00 SAST, against germination and emergence bases. |
| Night minimum | Lowest overnight temperature, against frost thresholds. |
| Day maximum | Highest daytime temperature, against crop heat-stress thresholds. |
Interactive maps
Zoomable maps over a street basemap, with a frame slider through the run. Pick a field and a resolution: the 3 km nest resolves convection explicitly and is the better guide to thunderstorm timing, placement and mode over the Highveld.
-
Experimental · 9 km only
Severe Convective Environment (SCEP)
How supportive the atmosphere is for a storm that forms to turn severe, on a 0-100 scale, from instability aloft, shear, low-level moisture and freezing level. Not historically trained, not a calibrated probability, not a warning.
Vertical profiles for 34 locations are on the soundings page.
Model domains
| Domain | Resolution | Grid | Extent | Coverage |
|---|---|---|---|---|
| d02 Outer domain |
9 km | 214 x 200 | 14.7-36.1E, 20.5-36.9S | South Africa, Lesotho and Eswatini Forced directly from GFS at the lateral boundary; cumulus parameterised |
| d03 Convection-permitting nest |
3 km | 246 x 156 | 21.9-29.4E, 23.6-27.9S | North West and Gauteng Cumulus scheme off - convection resolved explicitly |
The two domains are two-way nested. The 9 km domain takes its lateral boundary conditions directly from GFS; both are published.
Configuration
| Dynamical core | WRF-ARW v4.8.0, non-hydrostatic |
|---|---|
| Map projection | Lambert Conformal (true latitudes -23.7 and -34.0) |
| Microphysics | Thompson (mp_physics = 6) |
| Cumulus | Kain-Fritsch on d02, off on d03 |
| Longwave radiation | RRTMG (ra_lw_physics = 3) |
| Shortwave radiation | RRTMG (ra_sw_physics = 3) |
| Planetary boundary layer | YSU (bl_pbl_physics = 1) |
| Surface layer | Revised MM5 Monin-Obukhov (sf_sfclay_physics = 1) |
| Land surface | Unified Noah LSM (sf_surface_physics = 2), 4 soil layers |
| Initial and boundary conditions | NCEP GFS 0.25 deg, 3-hourly |
| Forecast length | 72 h |
| Cycles | Twice daily, from the 00Z and 12Z GFS cycles |
Practical limits
Static image versions, without the interactive basemap: gridded and agri fields, SCEP and the SAWS warnings list.