Tuesday, July 17, 2012

Dubious Heat Advisories

In a season when heat advisories and excessive heat warnings are making regular appearances in Twin Cities forecasting lexicon, we’re starting to wonder whether they serve much purpose or at least question the proper use of them. A comparison of today’s weather with yesterday’s provides a good example.

On Monday, the Twin Cities was under a heat advisory. The temperature reached 98 degrees but the humidity was only moderate, and the heat index never reached advisory levels. And while it doesn’t figure in to the formal mathematical calculation of heat index, a persistent, gusty southwest wind made the heat more tolerable than it might otherwise have been.

In contrast, today’s high temperature reached 94 but the humidity was more oppressive. Toss in light and variable winds and it’s fair to say that most people would think today was more uncomfortable. The NWS did not issue a heat advisory and the heat index technically touched advisory levels (100). On June 27, a formal heat advisory was issued, yet the heat index never reached 100.

With the benefit of hindsight, an advisory (technically) should have been issued for Tuesday rather than Monday. And when you throw in the ill-advised heat advisory on June 27, that’s three days where the issuance/nonissuance of an advisory was wrong. To us, this merely points up the dubious nature of the formality of heat advisories in the first place. Throw in the oddly worded “excessive heat warning” and you’ve got even more confusion.

It’s simply very hot and uncomfortable weather! Nothing more, nothing less. In our minds, the advisories and warnings that occur in winter have far more relevance and significance to our daily lives. If the windchill is a gazillion degrees below zero and you take a long walk without being properly dressed, you’re going to suffer frostbite at a minimum and you could potentially freeze to death. If heavy snow arrives, particularly during rush hour, it’s going to mess with your commute and you might need to plan accordingly. But if the heat index one day is 100 and another day is 98, is that really much of a meaningful difference? And more importantly, is one day more worthy of a heat advisory than the other? We think not.

If you're curious to see official definitions for advisories, warnings, watches and the like for the Twin Cities, click here.

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Monday, July 2, 2012

One Hot Week

A hazy, smoke-enhanced sunset heralded the end of a 99-degree day in St. Paul.
Whether it's labeled with "excessive heat warning," "heat advisory," or merely "stinking hot," it's hot, headline-stealing hot. The only suspense, it would appear, is whether the mercury will hit the century mark this week.