Real-Time Mesoscale Analysis (RTMA)

Description

RTMA (Real-Time Mesoscale Analysis) is NOAA/NCEP's near-real-time, hourly surface analysis designed to provide the best estimate of current weather conditions within about 30-45 minutes of valid time. It uses a two-dimensional variational (2D-Var) assimilation system to combine a short-range model background with surface, mesonet, buoy, ship, and radar-derived observations.

The analysis is generated on the National Digital Forecast Database (NDFD) grids, including the 2.5 km CONUS Lambert Conformal grid, as well as Alaska (~3 km), Hawaii, Puerto Rico, and Guam. Standard RTMA parameters include 2 m temperature, dewpoint, 10 m wind speed, direction, gust, surface pressure, visibility, cloud ceiling, and precipitation fields. RTMA provides high-resolution situational awareness in regions with sparse observations, including offshore waters and complex terrain.

Because RTMA prioritizes timeliness, it does not incorporate late-arriving observations. Instead, its role is to provide provisional “actuals now,” supporting operational dashboards, bias correction, and rapid verification of short-term forecasts. For finalized, higher-quality analyses, see URMA, which reruns RTMA about six hours later with expanded datasets.

• Use cases: near-real-time monitoring, rapid verification, bias correction, energy and aviation operations, emergency response.
• Coverage: CONUS (2.5 km), Alaska (~3 km), Hawaii, Puerto Rico, Guam.
• Latency: ~30-45 minutes after valid time.

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