Doorpath asked in Science & MathematicsWeather · 2 months ago

# why are "1 minute sustained windspeeds" of tropical systems always rounded to a multiple of 5?

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• Anonymous
1 month ago

Short answer: Hurricane intensity is more of an estimate than a known exact value.  In fact, it is not uncommon for meteorological agencies to re-evaluate a storm's intensity after the fact (post-season analysis).

Longer answer: They don't actually measure 1 minute sustained windspeeds with a precision that would enable us to say "this storm has winds of 132 mph and is therefore slightly stronger than this one of 131mph".

In fact, hurricane intensity is assigned as a very well educated estimate. Direct measurements in a storm's core via aircraft recon are not even undertaken for all storms and even when they are- it is sometimes sporadic. Intensity estimates are often assigned through indirect observations such as satellite appearance (in layman's terms, stronger storms often have more robust features on satellite--made formal through the "Dvorak technique" which assigns a number called the "T number" to a storm based on its satellite appearance.... T numbers can help reach an intensity estimate). Buoy, land station measurements, and even ship data may also be used to support an increase or decrease in estimated intensity.

Even when aircraft recon is undertaken (which is pretty much exclusive to storms in the Atlantic ocean), the maximum 1 minute sustained winds are still an estimate. A better estimate, but still an estimate.

Even the 5mph increments are often of dubious precision.

• Jim
Lv 7
2 months ago

Depends on how many categories you want.

• Anonymous
2 months ago

Billrussel42 and TQ have it right. There is no  meaning in a value noted closer than 5.

• TQ
Lv 7
2 months ago

Not rounding one-minute sustained wind speeds of tropical systems to a multiple of five would imply a degree of precision that does not exist in the data.

Source(s): Meteorologist.
• Anonymous
2 months ago

To make it more Exciting.

Most weather records are imprecise, that is why "Global Warming" is a fad & fantasy.

Never wonder why Arabs wear Wool in the Desert? It is not because they herd goats. 110 in the Day, and Freezing at night.

• 2 months ago

probably because the variation in the windspeeds is such that better precision is not meaningful.