New Hampshire Weather
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Select a summit. Quick links and plots will automatically update.
Quick Links
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Links to weather forecasts and tools
for specified forecast location.
for specified forecast location.
Quick Overview
This site uses atmospheric model data from NOAA's HRRR, RAP, NAM, and GFS models, the ECMWF open data, and the National Blend of Models (NBM) to generate forecasts for undercast probability at several summits in New Hampshire. Forecast resolution, accuracy, and update frequency vary between the models.
The forecasts you see on NWS and other sites are often based on a combination of these models along with observational data and expert analysis. Trust them, before you trust my plots, which come from individual models and are interpreted by a dumb particle physicist.
I built this to visualize data not readily available from the NWS website. While exact wind speeds from an individual, non-local, coarse-grain model may be inaccurate, larger trends such as sky coverage and cloud elevation can be informative. Full model details can be viewed here.
| Model | Forecast Range (Hours) | Spatial Resolution | Strengths | Weaknesses |
|---|---|---|---|---|
| HRRR | 0-48 | 3 km | High temporal resolution, good for short-term forecasts | Limited range, may struggle with longer-term trends |
| NAM | 0-60 | 12 km | Good for medium-range forecasts, covers larger areas | Lower resolution compared to HRRR, less accurate for local events |
| GFS | 0-120 | 13 km | Long-range forecasts, global coverage | Coarser resolution, may miss localized weather phenomena |
| RAP | 0-48 | 13 km | Hourly regional refresh (HRRR's parent model) | Coarser than HRRR, short range only |
| ECMWF | 0-144 | ~0.25° (~28 km) | Highly skilled global dynamics and thermodynamics | No cloud fields in open data; 3-hourly steps |
| NBM | 0-144 | ~2.5 km | Calibrated blend; direct ceiling & visibility, incl. probabilistic | Surface fields only (no upper-air); blends can smooth extremes |
I built this to visualize data not readily available from the NWS website. While exact wind speeds from an individual, non-local, coarse-grain model may be inaccurate, larger trends such as sky coverage and cloud elevation can be informative. Full model details can be viewed here.
The undercast prediction is only available for Mt. Washington right now. Select Mt. Washington above to see it.
Undercast forecast — Mount Washington
- No undercast
- Undercast
Bar height is the model’s score for that hour as a share of its threshold — the score at or above which it calls an undercast. The dashed line is that threshold.
Model performance
Measured on a held-out year the model never trained on, at the same thresholds the forecast above uses. Pick how far ahead:
