WRF-EXTREME is the result of years of deep, hands-on modification of core WRF components. Pioneering modifications span every major physics layer — boundary-layer parameterizations with built-in cold air drainage, a breakthrough sigma-coordinate correction that eliminates spurious warming in valleys, full 7-species microphysics-radiation coupling, terrain-aware snow initialization, and completely rewritten 2-metre diagnostics.
Every change targets a known, specific failure mode of the standard WRF — and together they deliver a step-change in forecast accuracy for mountainous and coastal regions.
A breakthrough budget-based module that diagnoses and corrects the spurious warming caused by sigma-coordinate terrain-following levels over stable nocturnal boundary layers in valleys and basins — a long-standing, fundamental WRF weakness.
! Terrain modulation grad_term = MIN(terrain_grad_mag(i,j) & / grad_ref, 1.0) basin_term = 0.0 IF (terrain_tpi(i,j) .GT. 0.0) THEN basin_term = MIN(terrain_tpi(i,j) & / tpi_ref, 1.5) ENDIF terrain_factor = MAX(grad_term, & basin_term) ! Stability ramp stab_factor = MIN((br(i,j)-ri_crit) & / (ri_strong-ri_crit), 1.0) ! Apply compensating correction correction = -alpha * excess & * terrain_factor * stab_factor * safety rthbten(i,k,j) = rthbten(i,k,j) & + correction
Pioneering katabatic drainage parameterization embedded directly into both YSU PBL scheme. Models nocturnal cold air pooling in valleys that standard WRF completely ignores — gated by inversion strength, wind speed, surface temperature, and TPI-derived basin geometry.
Extended WSM7 microphysics to compute effective radii for all 7 hydrometeor species — rain, graupel, and hail now feed directly into the Goddard radiation scheme alongside cloud water, ice, and snow. Cloud optical depth floor and pressure-level scale factors eliminate thin-cloud radiation biases.
Fixes a known problem with global model initialization: IFS/ECMWF encodes glacier ice as snow depth, and coarse-resolution snow fields miss valley-to-peak gradients. Our seasonal snow cap removes glacier artifacts hemisphere-aware, while TPI + elevation-based redistribution shifts snow from valleys to peaks — critical for surface energy balance and near-surface temperature accuracy from hour zero. No awkward preprocessing of the ECMWF data needed. WRF EXTREME handles that automagically. And improves spatial distribution of the snow cover at the same time. Yes, automagically, again.
Removes glacier ice that IFS/ECMWF encodes as snow depth — before the model touches it.
Shifts snow mass from valleys to peaks based on Topographic Position Index and elevation — restoring the true valley-to-peak gradient even with low-res data inputs (like 0.25° grids from GFS or ECMWF Open Data).
Critical for surface energy balance and near-surface temperature accuracy from the very first integration step.
Deep modifications to YSU and MYNN-EDMF. Subgrid terrain drag (topo_wind) ported to MYNN for the first time. Dynamic friction velocity floor over snow-covered ridges prevents surface decoupling. Moisture-heat entrainment coupling reworked. Both schemes now share the same terrain-aware capabilities.
Physics-based 2-metre temperature diagnostic with wind-speed and stability-dependent mixing, adjustable bias, and temporal smoothing to eliminate timestep-to-timestep noise. Tunable cool-skin and warm-layer SST coefficients for accurate sea surface representation. All that gives total control over how the model calculates 2m temperature. No more weird noise in 2D fields within extremely stable airmass, unavoidable from the vanilla WRF code.
A specifically developed state-monitoring module that continuously tracks the model's internal fields during integration, detects deviations from a physically consistent state, and corrects errors before they have a chance to propagate and degrade the modelled solution. Result: no unphysical model state, which means, much better forecasts.
WRF-EXTREME is not a configuration — it is a fundamentally re-engineered atmospheric model built on thousands of hours of code-level modifications to the WRF core. Every patch targets a specific, documented failure mode of the standard model.