The field guide
Reference explainers on how forecasting tools and data work, written to support the instruments on the map.
SoundingsHow to read a skew-T sounding
The temperature and dewpoint traces, CAPE, the cap, inversions, the dendritic growth zone, and the hodograph.
VerificationHow forecast verification works
What MAE, RMSE, and bias measure, why verification uses analyses like RTMA as truth, and two common scoring pitfalls.
ModelsA field guide to the weather models
GFS, Euro, HRRR, NBM, GEFS, and the AI models: what each one is, its resolution and update cycle, and where it performs best.
The deskThe subseasonal desk: reading all six drivers together
The MJO, Kelvin waves, Rossby wave trains, mountain torque, the SSW gauge, and cyclone phase space, with the lags that connect them.
Global driversWhat is the MJO?
The eastward-moving tropical convection cycle behind week-2 and week-3 forecast skill, and how to read the 8-phase diagram.
AI modelsHow AI weather models actually work
GraphCast, Pangu, and AIFS: trained on decades of reanalysis, run in minutes, and their known smoothing bias.
SeasonalEl Niño and La Niña, explained
How Pacific sea-surface temperature anomalies shift the winter jet, historical US impacts by phase, and the limits of the signal.
WinterWhat is the polar vortex?
What the stratospheric polar vortex is, what a sudden stratospheric warming does to it, and why surface cold lags by weeks.
RadarHow to read weather radar
Reflectivity, velocity couplets, debris balls, correlation coefficient, and the common false echoes that mimic weather.