TCs to have their MSW directly sampled on land

[Ubuntwo]

Most TCs never see their MSW (maximum sustained winds) sampled. Even with aircraft reconnaissance, the alpha pattern only inconsistently captures max winds. This uncertainty is just part of tracking cyclones. While recon undersampling is a pretty well-studied topic with understood conversion factors - for the narrow band of max winds to directly strike a land-based observation site? It's pretty rare. But it happens. Its frequency is much more common with weaker TCs, as their areal coverage of max winds tend to be larger (less organized wind core), and the lower winds increase the chances of obs sites surviving peak wind. Here are some recent Atlantic cases:

Hurricane Tammy (2023): A hospital on Barbuda recorded a peak 1-minute wind of 78kt. The operational intensity at the time was 75kt, and by the next full advisory reconnaissance data found it back down to 70kt. This observation led to the TCR bumping this initial peak intensity to 80kt - meaning maximum winds were sampled & above what recon found.

Hurricane Nicholas (2021): As Nicholas approached landfall, a Weatherflow site on Matagorda Island recorded a sustained wind of 66kt at a 6 meter elevation. This supports an intensity of 70kt with correction for station altitude and standard rounding - even with no accounting for undersampling. The NHC kept peak intensity at 65kt due to relatively lower maximum SFMR of 63kt and 850mb winds of 80kt (reducing to 64kt). This is one of the only Atlantic hurricanes I'm aware of where an unadjusted land observation exceeds the official (post-TCR!) intensity and is not associated with a mesovortex or transient feature.

Hurricane Elsa (2021): Grantley Adams Airport reported a 10-minute sustained wind of 65kt as Elsa made its close pass. This led the NHC to operationally jolt the intensity from 50kt to 65kt. The TCR kept this 65kt intensity near Barbados (apparently due to a lack of recon support for higher winds), despite the 10-min to 1-min conversion supporting 70-75kt.

Hurricane Irma (2017): On approach to southwestern Florida, recon data hardly supported a 100-kt intensity. The last VDM had peak FL winds of 93kt and SFMR of 80kt, and the prior VDM 100kt/64kt. The storm was quite poorly sampled at this point. At an exposed site in Marco Island, a spotter recorded impressive sustained winds of 97kt gusting to 112kt. This validated the NHC's "generous" landfall intensity, and was the basis for the 100kt landfall intensity in the TCR.

Hurricane Gustav (2008): Perhaps the holy grail of MSW sampling in the Atlantic. The highest flight-level wind recorded in the leadup to landfall was 143kt at 700mb. This reduces to 130kt, and this was the operational landfall intensity. The highest dropsonde sfc wind was 116kt. At Paso Real de San Diego in Western Cuba - 17 miles from the coast, located on mostly flat land along a lake - a sustained wind of 135kt gusting to 184kt was recorded. It is remarkable the station was able to withstand these winds. In the initial TCR, the NHC kept the 130kt landfall intensity pending WMO confirmation of the observation. They initially attributed these winds to eyewall mesovortices and possibly terrain enhancement. Following WMO confirmation, the NHC increased the landfall intensity to 135kt and removed the aforementioned attributions. This also held the record for the highest gust in a tropical cyclone before reanalysis of observations in Cyclone Olivia. Traditional understandings of inland wind decay would support a landfall intensity of 145kt. It is possible the provided an ocean-like fetch for winds to accumulate along. The lack of recon support is ultimately what prevented a higher landfall intensity, but it is very likely that Gustav at least transiently produced >137kt winds.

This is by no means a complete list - feel free to pitch in additional cases here.

[ljmac75]

10 minutes and not 1 minute but a station on Dominica reported 10-minute winds of 130kts during Hurricane Maria (intensity was judged as 145 kts 1-minute from it).

There was also a 10-minute wind of 54 kts during Tropical Storm Ophelia in 2023, which was converted to 1-minute wind of 60 kts for the wind estimate.

During Hurricane Camille there was a report of a "fastest-mile" wind of 104 kts, which is roughly 99 kts 1-minute, about 4 hours after the storm made landfall. That's not technically what you're talking about I think but it does agree with the NHC landfall intensity of 150 kts from the inland decay rate.

[ljmac75]

I thought of some more.

During Hurricane Ivan in 2004, Grand Cayman Island recorded a sustained wind of 130 kts, which I believe was around the MSW estimate at the time. I think this was land-based, but I'm not sure.
During Hurricane Sally in 2020, there was an observation of 98 kts at 18 meters over Ingram Bayou, reducing to around 93 kts at 10 meters, with the MSW being set at 95 kts in the final NHC report (not a land report but I think it's worth mentioning).

There's some others I can think of that might or might not count for this, wind obs taken at low heights that might translate to the MSW at 10 meters depending on the estimate for roughness length, amateur radio reports that could just be estimates etc.