Q&A of the Day – What’s the Deal with Heat Advisories?
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Today’s Entry: Brian, what’s the deal with heat advisories? Just about every day we seem to get them now. When I see them or hear about them I always think duh! It’s summer! Seriously though, I get that it’s been a bit hotter than usual but it seems like the weather people have gotten carried away with heat advisories.
Bottom Line: No doubt, heat advisories have certainly become the norm in South Florida and for much of the country this summer. And given that we’ve had multiple weeks which have produced record high temps worldwide, advisories being issued have become more common as well. Like other weather advisories, heat advisories are official advisories issued by the National Weather Service. In fact, a heat advisory is actually just one of four heat related declarations by the National Weather Service. The NWS’s four heat designations are these:
- Excessive Heat Watch: Heat watches are issued when conditions are favorable for an excessive heat event in the next 24 to 72 hours. A Watch is used when the risk of a heat wave has increased but its occurrence and timing is still uncertain.
- Heat Advisory: A Heat Advisory is issued within 12 hours of the onset of extremely dangerous heat conditions. The general rule of thumb for this Advisory is when the maximum heat index temperature is expected to be 100° or higher for at least 2 days, and night time air temperatures will not drop below 75°; however, these criteria vary across the country, especially for areas that are not used to dangerous heat conditions.
- Excessive Heat Outlooks: The outlooks are issued when the potential exists for an excessive heat event in the next 3-7 days. An Outlook provides information to those who need considerable lead-time to prepare for the event.
- Excessive Heat Warning: An Excessive Heat Warning is issued within 12 hours of the onset of extremely dangerous heat conditions. The general rule of thumb for this Warning is when the maximum heat index temperature is expected to be 105° or higher for at least 2 days and night time air temperatures will not drop below 75°; however, these criteria vary across the country, especially for areas not used to extreme heat conditions.
Because the system includes watches and outlooks in addition to the advisories and warnings, there is a good chance to have at least one of those in play during any given summer day in South Florida. And speaking of SFL... One of the reasons many South Floridians have been subjected to more of them than ever this year isn’t just due to hot weather. It’s due to an experiment the National Weather Service has been conducting.
As of June 1st, the NWS kicked off what they call their “New Experimental Heat Advisory/Warning Criteria for Miami Dade County”. The experiment lowered the threshold for heat advisories and excessive heat warnings by 3 degrees. So naturally there are going to be more of those than ever this summer in Miami-Dade. The reason given for the experiment is to see if there’s a measurable health impact by issuing advisories and warnings at lower temperatures. If they determine that there is a perceived health benefit, you could expect to see and hear about even more in the future just about everywhere that experiences hot weather across the country.
So that’s the low down on heat advisories, watches and warnings. The combination of what has the potential to be the hottest summer on record with four different types of heat related alerts that are issued by the National Weather Service and a South Florida experiment at lower temps than before has led to more of those alerts having been issued than ever before. Like you, my knee jerk reaction to the regular alerts being issued is that it feels like overkill. But at the same time there’s this somewhat significant factoid. Heat almost always kills more Floridians than hurricanes. A University of Florida study showed that in the previous decade 215 Floridians died due to environmental heat. A twenty-year historical analysis conducted by the National Weather Service found that Floridians were nine times more likely to die from environmental heat than from the impact of a hurricane. That perspective might provide non-hype related insight into why there’s so much emphasis on the related heat alerts.