MESH Explained: Hail Size Estimation for Property Claims

By StormAuditor Editorial Team · Published 2026-07-14 · Updated 2026-08-26

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.

Maximum Estimated Size of Hail (MESH) uses advanced radar data to estimate the largest hailstone size that may have occurred at a location. This data is a valuable tool for understanding potential hail-related property damage.

Introduction to MESH (Maximum Estimated Size of Hail)

When severe weather strikes, especially hailstorms, property owners, contractors, and adjusters need to understand the possible impact. A key piece of information is the size of the hail that fell. That is where Maximum Estimated Size of Hail, or MESH, becomes a critical tool.

MESH is an estimate of the largest hailstone size at a specific location. It comes from sophisticated Doppler radar analysis. Observed hail reports can be scarce or inaccurate. MESH, by contrast, provides a comprehensive, objective dataset with broad geographic coverage — though radar coverage has real gaps at long ranges, in complex terrain, and for shallow storms, and MESH is an estimate of hail aloft rather than a ground measurement. StormAuditor uses MESH data, among other datasets, to provide historical weather analysis for property claims.

What is MESH and How is it Calculated?

MESH stands for Maximum Estimated Size of Hail. It is not a direct measurement of individual hailstones. It is a radar product that infers hail size from the radar's observed reflectivity and other storm characteristics.

Here is how MESH is generally calculated and what it represents:

Doppler Radar Basics: Doppler radar emits microwave pulses. These bounce off precipitation (like rain, snow, or hail) and return to the radar antenna. The strength of the returned signal (reflectivity) gives clues about the size and type of precipitation. The Doppler effect also lets the radar measure how these particles move. That reveals wind speed and direction inside the storm.
Reflectivity and Hail: Larger particles, like hailstones, produce stronger radar reflectivity values. But not all strong reflectivity means hail. Heavy rain can also produce high reflectivity. Telling heavy rain from hail requires more advanced radar products.
Radar reflectivity and temperature profiles: operational MESH is computed from the Severe Hail Index — reflectivity weighted through the sub-freezing layer (Witt et al. 1998) — not directly from dual-polarization variables. Modern dual-polarization radars transmit pulses in both horizontal and vertical orientations. By comparing how these two wave types interact with precipitation, meteorologists can better tell precipitation types apart. For instance, raindrops are usually wider than they are tall. Hailstones are often more spherical or irregular. This shape difference changes how the radar waves reflect.
Advanced Algorithms: MESH uses complex algorithms that analyze several radar parameters:
Reflectivity
Differential reflectivity (ZDR – the ratio of horizontal to vertical reflectivity)
Correlation coefficient (CC – how uniformly shaped the particles are)
Specific differential phase (KDP – how much the horizontal and vertical waves slow down differently)

These algorithms also consider the storm's vertical structure. Updraft strength and the height of the storm's echo tops are essential for hail growth.

Estimating Hail Size: The algorithms combine these radar insights to estimate the maximum hailstone diameter within a radar resolution volume. That estimate is then projected to the ground. The result is an estimate of the largest hail likely to have fallen at a specific location.

Understand this clearly: MESH is an estimate of the maximum hail size. It does not mean every hailstone was that large. It does not guarantee that hail of that exact size hit a specific point on the ground. It indicates the potential for hail of that size within the storm's path.

MESH Methodology Tie-In with StormAuditor

StormAuditor builds MESH data into its historical weather reports. This gives a robust view of past hail events. When you request a historical weather report for a specific address and date of loss with our /date-of-loss-weather-research tool, we use multiple data sources. High-resolution MESH products are among them. Together they help reconstruct the storm's characteristics.

Our methodology, described in detail at /methodology/hail, explains how we use these radar-derived estimates alongside other weather data. We combine MESH with observed hail reports (where available) and other radar parameters. That gives a full overview of the hail threat at your location of interest. This multi-layered approach paints a clearer picture of a past storm than any single data point could.

Honest Limitations of MESH Data

MESH is a very valuable tool, but you should understand its limits:

Estimation, Not Measurement: MESH is an estimate derived from radar, not a direct measurement of hailstones on the ground. Actual hail size at a specific point can differ. Hail growth/melt, wind drift, and small-scale atmospheric changes not captured by radar all play a role.
Radar Beam Height: The radar beam scans at higher altitudes the farther it travels from the radar site. Near the radar, the beam stays close to the ground. That gives a better estimate of what is falling. Far from the radar, the beam sits higher in the atmosphere. The estimated hail size may not perfectly match what reaches the ground.
Atmospheric Conditions: Strong winds aloft can carry smaller hailstones away from the strong reflectivity cores the radar sees. That causes discrepancies. Melting can also shrink hail as it falls through warmer air before it reaches the surface.
Resolution: Radar data has a defined resolution. MESH estimates represent areas within a radar's resolution volume, typically a few square kilometers, not individual points.
Data Availability: Older events may rely on less sophisticated radar technology, if any radar data exists at all. Their MESH estimates are less precise than recent ones, which benefit from modern network upgrades and dual-polarization quality control.

StormAuditor aims to provide the best possible historical weather context. We discuss these limitations openly in our /limitations section, so our users fully understand the data's scope.

Related StormAuditor Tools

StormAuditor offers several tools to help you investigate hail events and other weather questions:

/date-of-loss-weather-research: Get a comprehensive historical weather report for a specific address and date.
/address-lookup: Quickly check basic weather information for any address.
/hail: Learn more about our hail analysis methodology and how we determine hail presence and size.
/methodology/hail: Dive into the specifics of how StormAuditor analyzes and presents hail data.
/data-sources: Understand the various reliable meteorological data sources we use.
/sample-report: View an example of a detailed StormAuditor report.

FAQ: Understanding MESH and Hail

Q: Does MESH account for hail melting before it reaches the ground?

A: MESH algorithms mainly estimate hail size within the storm cloud. Some algorithms may include models for hail melting during its fall, but melting is a complex process. The estimated size aloft can still differ from the actual size observed at the surface due to melting.

Q: Can MESH tell me the exact number of hailstones that hit my property?

A: No. MESH estimates the maximum size of hail and shows the potential for hail in an area. It says nothing about the number of hailstones, the density of the hailfall, or the exact path of individual hailstones over a specific property.

Q: Is MESH data always available for any date in the past?

A: The availability and quality of MESH data vary by date. More consistent MESH products — aided by network-wide upgrades including dual-polarization quality control — are generally available from the early 2010s onward. Older events may rely on less sophisticated radar data. For very old events, radar data may not exist at all. In that case, other meteorological data sources are used.

Q: If MESH shows large hail, does that guarantee property damage?

A: No. Large MESH values indicate a high potential for damaging hail, but they do not guarantee damage. Other factors matter too: construction materials, the angle of impact, wind speed, and how long the hail lasted. MESH provides crucial evidence of hail potential. A physical inspection remains essential to confirm damage.

Q: How does StormAuditor use MESH data differently from other weather services?

A: StormAuditor combines MESH data with a suite of other weather datasets. These include observed hail reports, radar reflectivity imagery, and storm track information. Our goal is a comprehensive historical context. That allows a more nuanced view of a hail event at a specific location and time, as detailed in our /methodology/hail.