Forecast NBM
about these numbers
Headline temperatures — NWS. The official National Weather Service forecast for this gridpoint, issued by the local Weather Forecast Office and updated several times a day; the update time is shown above.
NBM line. The raw National Blend of Models — NOAA's bias-corrected blend of models and ensembles on a 2.5 km grid, updated hourly. Values are the grid cell containing the location above, fetched via Open-Meteo. ≠ marks days where the NWS forecast differs from the blend by ≥3 °F.
± values. The NBM ensemble standard deviation of the max/min temperature, from the NBM station bulletins (NBS 3-hourly to ~3 days, extended by NBE 12-hourly to ~day 8) at station , parsed by the Iowa Environmental Mesonet. Station bulletins are extractions of the same NBM grid at airport sites, so σ describes the nearest station's grid cell rather than the exact point. The chart below goes further: it draws the NBM's actual 10/25/50/75/90th percentiles from the probabilistic bulletin (NBP), fetched directly from NOAA's open-data archive.
Precip, Td, wind gust. The precip number is the 24-hour total exceeded with 75% probability, from the NBM percentile bulletin (≥0.0 means the driest quartile of outcomes is dry; the full distribution is in the chart below; a value without the ≥ is the deterministic blend total, shown only when the bulletin is unavailable). Afternoon 2 m dewpoint (Td at the hour of the day's maximum temperature — the mixed-airmass value, not the daily max of Td), and maximum gust.
about this data
Observed radar. The national NEXRAD base-reflectivity composite (N0Q, ~1 km, 5-minute updates), mosaicked from the WSR-88D network by the Iowa Environmental Mesonet. Slider frames run every 10 minutes back 2 hours, each an archived composite stamped with its exact valid time. Rasters render at native grid resolution and are upscaled without interpolation — blocky pixels are the actual data cells.
HRRR forecast. Simulated 1 km AGL reflectivity from the HRRR (NOAA's 3 km, hourly-cycled, convection-allowing model), on the same dBZ scale as the observed radar. All frames come from one explicit model run (labeled, e.g. "13Z run +5h"); the latest run is typically ~1–2 hours behind the clock.
TLE. Time-lagged ensemble: the pixelwise mean over the last 3 or 6 hourly HRRR runs valid at the same time. Tiles are decoded back to dBZ through the exact reflectivity palette, averaged in linear reflectivity ⟨Z⟩ (no echo = 0) or in log space ⟨dBZ⟩ (no echo = −32.5 dBZ floor), and re-encoded with the same palette. Runs missing from the archive are skipped; the label counts the members used.
Precip accumulation. MRMS multi-sensor QPE (~1 km): 24/48/72-hour totals ending at the labeled hour, updated hourly. Legend colors are the exact rendering palette at the documented mm bin edges.
GOES. GOES-West (GOES-18) or GOES-East (GOES-19), auto-selected by longitude; single image at native resolution over its own smaller region, stamped with the scan time. True color is composited client-side: GOES carries no green band, so red (0.64 µm, 0.5 km) and blue (0.47 µm) are combined with a synthetic green G = 0.45 R + 0.10 NIR + 0.45 B (NIR = the 0.86 µm veggie band); blue and veggie are 1 km native, upsampled to the red band's 0.5 km grid. Dark at night — use the clean-window IR (10.3 µm, 2 km), whose color scale is labeled in brightness temperature (°C): the image encoding is exactly invertible (GINI convention), and the colors are IEM's operational IR enhancement.
Hover values. Hovering the map reads the value under the cursor directly off the rendered raster — every palette here is exactly invertible (dBZ for radar and HRRR, mm for accumulations, IR brightness temperature). No value shows where there is no data, or for the true-color composite (which has no scalar).
The grey mask. All products are fetched for a fixed region around the center point (450 km; GOES 250 km) — panning and zooming never trigger new data loads. The grey mask covers whatever is not actually loaded. Tile products overshoot their nominal region (generously at wide zooms), so the clear region grows and shrinks with zoom to match true coverage. A spinner appears while the displayed layer's data is in flight, so an empty map means no returns rather than still-loading. After the radar frames land, the other products (MRMS, GOES, TLE means) preload in the background.
Sources. All imagery via the Iowa Environmental Mesonet's public services (data: NOAA/NWS). Forecast numbers via Open-Meteo (NBM), api.weather.gov (NWS forecast and alerts), IEM's MOS API (NBS/NBE bulletins), NOAA's open-data archive on AWS (NBP percentile bulletins), and NOAA SWPC (Kp forecast, OVATION).
Temperatures & precipitation FORECAST · CLIMO
about this chart
Panels. Daily maximum and minimum temperature on a broken y-axis, and 24-hour precipitation below. Each day's max glyph sits at 17:00 local, min at 04:00. Daily min/max are over the local calendar day (midnight–midnight, NBM hourly values via the daily aggregation); note the bulletin values technically describe the NBM's overnight/daytime window products (TXN), which almost always — not strictly always — coincide with the calendar-day extremes.
NBM temperature distributions. The sienna violins are the NBM forecast density for each day's max/min, drawn through the NBM's own 10/25/50/75/90th percentiles from the probabilistic station bulletin (NBP), fetched directly from NOAA's open-data archive — the shape is the blend's, including any skew, not an assumed form. Between the percentiles the quantile function is interpolated monotonically and the width profile lightly smoothed (hover values are the exact bulletin numbers); beyond the 10th/90th percentiles the remaining 10% per side is drawn as an exponential tail matched to the boundary density. The center line marks the bulletin mean. Density is on one shared scale across all days and both temperature panels. Where the NBP bulletin is unavailable the violin falls back to a Gaussian from the NBS/NBE mean and σ (the legend says which is in effect).
NBM precipitation. The bottom panel shows the NBP 24-hour precipitation percentiles for the periods ending 12Z each day (mm; each violin sits at the true center of its 12Z–12Z window). Zero precipitation carries finite probability, so the violin covers only the wet part of the distribution above 0 mm — its lower edge is the wet/dry boundary and is deliberately sharp. The label is the total exceeded with 50% chance (the median), shown when nonzero. Hover or tap for the 75/50/25%-chance ladder and the chance of no precip implied by zero-valued percentiles. A flat tick at 0 mm means all bulletin percentiles are zero. Precip density is per mm — a different unit from the temperature panels — so it has its own width scale, shared across days.
Climatology. Grey bands are the empirical 5–95% and 25–75% ranges, the grey line the mean, computed per day-of-year with ±7-day pooling for sample size; percentiles are order statistics, nothing fitted. Two baked station records exist — KSLC (ASOS) and Santa Fe 2 (NWS COOP, ~8 km from downtown Santa Fe at city-like elevation) — both over the last 30 complete years (1996–2025, rolling-normal convention, chosen for nonstationarity of the longer records; physical QC on every max/min pair). The chart uses the nearest station within 40 km of the chosen point; beyond that no climatology is shown rather than a wrong one.
NWS dot. The official NWS forecast, same number as the headline on the day cards.
Last 7 days OBS
| day | hi/lo °F | precip | gust |
|---|
forecast verification — NBM day-ahead vs observed
about these observations
The strip at the top of the page is the latest METAR-derived observation at the station shown (via IEM), refetched every 10 minutes. Routine METARs are hourly (KSLC reports at :54) with specials only on significant changes, so an age approaching an hour is the observing system, not staleness. The table is the last 7 complete days at the same station: calendar-day max/min, precip (mm), and peak gust. Sunrise and sunset times in the strip are computed locally from the page's coordinates (standard solar-position equations, ~1 min accuracy); the moon glyph draws the current phase (hover for name and illuminated fraction).