HRRR vs. URMA: Wind Gust Model Analysis
By StormAuditor Editorial Team · Published 2026-07-16 · Updated 2026-09-30
Based on public NOAA and National Weather Service records, published under StormAuditor's methodology and data-source standards. Radar-derived hail sizes are estimates unless attributed to a ground report.
Damage-threshold ranges in this article are general guidance synthesized from industry and federal research — IBHS building-performance research, NWS severe criteria, and product standards such as UL 2218 (hail impact resistance) and ASTM D3161/D7158 (shingle wind ratings). Actual performance depends on product rating, age, installation quality, exposure, and impact characteristics — thresholds describe when damage becomes possible, not when it occurs.
High-Resolution Rapid Refresh (HRRR) and Unrestricted Mesoscale Analysis (URMA) are advanced weather models that provide detailed insights into conditions like wind gusts, crucial for historical storm assessments and property damage investigations.
HRRR and URMA in Storm Analysis
When you look into past storms, mainly damaging wind and hail, the data sources matter. Tools like StormAuditor depend on them. Two key sources give high-resolution weather data: the High-Resolution Rapid Refresh (HRRR) and the Unrestricted Mesoscale Analysis (URMA). Both capture detail over smaller areas and shorter time spans than global models.
What Are HRRR and URMA?
HRRR (High-Resolution Rapid Refresh) is a NOAA real-time weather model.
- It updates every hour.
- It gives forecasts and analyses for the continental United States.
- Its fine grid shows local weather, like thunderstorms, wind shifts, and temperature changes, in more detail.
- In StormAuditor's method, HRRR is the fallback background wind field for our SAWE-2 (Storm Auditor Wind Estimate) system. We use it when the URMA analysis is not available.
URMA (Unrestricted Mesoscale Analysis) comes from the National Weather Service (NWS). It is another set of high-resolution data.
- HRRR focuses mainly on fast forecasts. URMA is about analyses.
- URMA pulls in many kinds of observations, including surface stations, radar, and satellite data.
- The result is a very accurate picture of the weather at a given time. Researchers rely on it to rebuild past weather with the best available data.
- URMA is the NWS analysis of record and the main background for SAWE-2. Each day's peak-gust analysis is the starting point. Measured station gusts then correct it.
How Do HRRR and URMA Differ?
The main difference is purpose and how often they update.
HRRR updates hourly to give _short-range forecasts_ and analyses. That makes it excellent for fast-changing weather. Its strength is showing current conditions and the very near future.
URMA is the NWS analysis of record: an hourly, 2.5-km grid built after the fact from observations. HRRR has an analysis part too. But URMA is valued for how it blends in observed data. It aims for a "best fit" to what was observed, which suits research and after-the-storm analysis.
For storm damage work, both help build a more accurate picture. URMA's peak-gust grid gives StormAuditor the regional wind pattern. Local station data and measured storm reports then correct it. HRRR fills in when URMA is not available.
How StormAuditor Uses High-Resolution Data
Wind. StormAuditor's Storm Auditor Wind Estimate (SAWE-2) starts from the URMA analysis of record for each day's peak gusts. HRRR is the fallback. We then improve this field with a two-pass objective analysis. That step adds gusts measured at NOAA ASOS/AWOS stations and NWS LSRs (Local Storm Reports) marked as measured. These layers keep our wind estimates sound across a region and precise at each place. They give valuable insight for date-of-loss research.
Hail. StormAuditor relies mainly on MRMS MESH (Maximum Estimated Size of Hail) radar products. SPC storm reports and NWS severe thunderstorm warnings back them up, as our Storm Auditor Hail Estimate (SAHE-2) explains. HRRR covers how the air moves, including wind. MESH uses advanced radar algorithms and excels at mapping hail swaths and estimated sizes.
Practical Guidance for Property Owners, Contractors, and Adjusters
Anyone in a property damage claim should understand the weather data behind it. Tools built on URMA and HRRR help show what conditions were likely at a property, such as gusts above the severe level of 58 mph.
- Property owners: If you suspect hail or wind damage, weather reports like StormAuditor's give key context. Knowing the estimated wind speeds and hail sizes helps in talks with contractors and adjusters. For example, 1.00" quarter-size hail is where asphalt shingles often show functional damage. Do a first visual check for creased or missing shingles, fascia damage, or dents in soft metals.
- Contractors: Detailed weather data lets you talk with clients and insurers from facts. If a StormAuditor's /address-lookup report shows sustained winds or significant hail at a property, it supports your assessment of storm damage. Functional hail damage to asphalt shingles often begins with hail about 1.00" to 1.25" across. Older or softer shingles can show damage from smaller hail.
- Adjusters: High-resolution model data plus observed reports helps you judge whether reported damage fits the weather. Tools using URMA/HRRR wind analyses and MESH hail swaths show a storm's footprint in space and time. That can speed up claims. On aged or poorly fastened asphalt roofs, shingles can lift with gusts of 46–57 mph. Shingle loss is possible from 58 mph, and widespread roof-covering loss is possible from about 74 mph.
Limitations
HRRR and URMA have excellent resolution. But they are still models, not perfect measurements.
- HRRR can have local errors. Complex terrain and fast, small events like microbursts between stations are the hardest cases.
- Our wind method relies on station data. That data may miss some intense, local gusts.
- Radar hail estimates (MESH) can under-estimate wet hail. They can over-estimate in very strong reflectivity cores.
- A property inside a severe weather warning area was under a warning. That does not mean it got the storm's peak.
- StormAuditor gives estimates, not absolute measurements, and cannot prove what caused damage.
For the full list, see our Limitations page.
Related StormAuditor Tools
- Property History Report: Get a detailed weather history for any address.
- Wind Explorer: Explore past wind events and severe wind warnings.
- Hail Explorer: See past hail swaths and reports for specific areas.
- Storm Auditor Methodology: How we process and present storm data.
- Date of Loss Weather Research: Research before you file a claim.
FAQ
Q: What is HRRR and how does it help with past weather?
A: HRRR (High-Resolution Rapid Refresh) is a fast-updating NOAA weather model. It gives detailed weather conditions, including wind fields. StormAuditor uses HRRR as the fallback background wind field when the URMA analysis of record is not available.
Q: How does URMA differ from other weather models?
A: URMA (Unrestricted Mesoscale Analysis) means high-resolution analyses. They pull in many kinds of observations to rebuild the exact state of the weather. Compared with slower global models, URMA gives finer detail over smaller areas. That detail is key for understanding local weather events.
Q: Can HRRR tell me the exact wind speed at my house on a specific date?
A: HRRR gives very detailed estimates of wind speed. StormAuditor's base is the URMA analysis of record, with HRRR as the fallback. We then refine these estimates with gusts measured at ASOS/AWOS stations and in NWS Local Storm Reports. The result is a station-corrected estimated wind speed at your location, validated against held-back measurements under the published methodology.
Q: Is HRRR used to estimate hail size?
A: HRRR gives general weather conditions. For hail size, StormAuditor mainly uses MRMS MESH (Maximum Estimated Size of Hail): radar hail swaths built for this purpose, combined with SPC storm reports.
Q: Why do high-resolution models like HRRR matter for property damage claims?
A: They show local events, like strong gusts, more accurately than broader models. This detail helps owners, contractors, and adjusters see whether severe weather likely hit a property, such as winds above 58 mph or hail of 1.00" or larger. That context is key for damage assessments.
Q: Where can I learn more about StormAuditor's data sources?
A: See the full list of our data sources, including NOAA, NWS, SPC, IEM, and NCEI, on our Data Sources page.