Excessive Heat Watch—Dead on Arrival

It was hard not to notice that the NWS office of the Twin Cities stood tall with the issuance of an Excessive Heat Watch some 60 hours before the time it went into effect. On Monday evening, the NWS advised us that excessive heat levels might be reached during the day on Thursday. It may not have been an unprecedented amount of warning, but it’s not something we don’t see often. One would guess that the issuance of a watch so far in advance would suggest the likelihood of serious heat, but that does not appear to be the case based on the “regular” hot forecast in effect as of this writing (6 p.m. Wednesday)

Something seemed amiss about this watch from the start. When the watch went into effect the only counties within many miles (five states perhaps) of the Twin Cities were Hennepin and Ramsey. This suggested it was a marginal at best. And even while the forecast temps at that point were close to 100, the dew point forecast did not go above 60—hardly oppressive.

We understand that a watch does not always mean a warning will follow. But for the NWS to trumpet the heat watch so many hours in advance suggested a certainty and confidence that didn’t bear out. In the end, the NWS/Twin Cites looks a little silly.

File Under: Things That Don't Seem Logical

Here is a depiction of the latest heat watches and warnings. The red-shaded areas represent Excessive Heat Warnings; the lighter-colored shading represents Excessive Heat Watches. It makes some sense that the always-cooking urban core could be under a warning when surrounding areas are under watches. But what makes less sense to us is why there would be a warning for two counties (one in Minnesota, one in Wisconsin) that are midway between the Twin Cities in Duluth. Is the heat really expected to arrive in such an unusual arc pattern? Or is the thinking that the two counties didn't receive much rain today and thus will heat up faster? Hmm.... Professional meteorologists, what can you tell us?