Unreasonable Heat and Humidity in US Midwest

M.T. Cranium

Over the corn belt of the Midwest U.S., most of IL, IN, IA, MO, s MN, e KS, sWI and that general area, temps today near 35 C and dew points in the range of 27-29 C for humidex readings in the mid to high 40s, even near 50 C locally. Will report later on the extreme values reached as the current time in the Central time zone is 1255. A cold front plowing into this soupy mess will set off tornadic severe storms in parts of WI, MN and IA later today. Radars to follow on that.

The maturing corn crop returns moisture to the lower levels and increases the ambient humidity from the general air mass levels of 24-25 C a few degrees higher still for these exceptional readings. Have seen extremes in 1995 of 30-32 C dew points, maybe this will repeat later today.

I am watching this in comfort here, temp 22 and dew point 12 C. :cool:

M.T. Cranium

This radar should have the main action on it, but you can navigate further east on it too.

http://radar.weather.gov/radar.php?rid=mpx&product=N0R&overlay=11101111&loop=no

Meanwhile, 19z (2 p.m. CDT) readings are in, at Des Moiines IA the temp is 35 C , the dew point 27 C and the humidex 47 C. This is fairly typical of the region, further west into KS there are temps as high as 39 C already.

I think that if you or I walked out into this, we would drop to the ground lifeless in seconds. We used to get heat and humidity almost this bad when I lived in Ontario, but I think only once or twice did it get anywhere near this bad, and one of those times was followed by a notable storm (the July 14-15, 1995 derecho which roared through at 0300 and dropped a tornado near where I lived at that time).

Min

I see on twitter some people complaining about the heat in the US.

We are lucky in Ireland to have it so good.

lonestargirl

M.T. Cranium wrote: »

I think that if you or I walked out into this, we would drop to the ground lifeless in seconds. We used to get heat and humidity almost this bad when I lived in Ontario, but I think only once or twice did it get anywhere near this bad, and one of those times was followed by a notable storm (the July 14-15, 1995 derecho which roared through at 0300 and dropped a tornado near where I lived at that time).

I surprising myself by saying this but you do get used to it. It's still not pleasent but it gets more bareable, and the Oct - May weather is good compensation. There were a couple of days last week when we had humidity >90%, there was condensation on the outside of my windows. The pace of life here is also much slower than northern US, kinda an adaptation to the weather.

M.T. Cranium

There have been a number of repeat episodes of these extreme temp/dew point combinations, to the point where it has become almost a daily occurrence in July. The past few days, stronger fronts have developed along the northern boundary of the hot, humid air mass, and tremendous rains have hit parts of the Midwest (especially Iowa, northern Illinois and southern Wisconsin, but also parts of Michigan, Ohio, Ontario in Canada and New York state).

Here's a link to some news coverage of flood damage in Iowa.

http://www.msnbc.msn.com/id/38395404/ns/weather/

Earlier today (Sat 24th) weather stations around Chicago were reporting 150-200 mms of rain and canals in that city were overflowing too.

Meanwhile the severe heat has hit the east coast (again) and today's high in Washington DC will probably come in at 39 C. In central Virginia, it was 43 C and these are temps without humidex factored in !! The Virginia all-time state record is under threat today (it was 110 F and so far 109 F reported, probably at least a tie in the works).

Danno

I would seriously question alot of the USA data... some apalling setup of stations there... http://surfacestations.org/

pauldry

Twas 49c in Dubai the last day. 2010 has been quite a warm year by all accounts. 2011 could be warmer even still. The downpours and wet n windy and negative NAO are coming to an end for Summers. My sidekick self is telling me that the end of this Summer bes ok and the next 2 esp next yr bes hot n good.

OMG I had too much 2 drink:eek: puke

M.T. Cranium

Yes, Danno, some of the U.S. stations are poorly exposed and they tend to run a bit hotter than others around them, but this has been the warmest July since records began in many places, or top three at least. Parts of inland western Canada on the other hand, have been a few degrees below normal and wet.

Pauldry is sleeping this one off. :cool:

Danno

Paul"dry" LOL!!!

It is a pity MTC that the USA have allowed their stations to fall into such neglect. On that site I posted they showed what a good quality USA station looks like... http://gallery.surfacestations.org/main.php?g2_itemId=56

I was astonished to see a concrete path leading to it, the whole screen sitting on a tripod elevated above a gravel bed, and a concrete block or two left beside it for whatever reason I don't know!

If this is what they are basing readings on and feeding it into climate models, then the whole thing is a joke - for them to come out and say that records are being broken takes the buiscit. They are measuring UHI and no more in 91% of cases FFS!!!

My own PWS here outside Durrow is way way better sited than the "good example" listed above!!!

M.T. Cranium

Danno, there's no doubt that some of the U.S. recording sites are poorly exposed, and some of these are among the hourly reporting sites. This is compromising the exact meaning of "record highs" as you say. However, stations with good and standard exposure are breaking records in this past month's heat wave and the upper level parameters are equal to those that I remember from the summer of 1980 which was quite hot in the same region. One station that looks a bit dubious to me is Williamsburg, VA which has hit 109 F both days this weekend (RIC closer to 105 F). But I hope nobody thinks these readings are really like 92 F heated up by exposure to sun, I can assure you having travelled through that region one summer, 100 F there is super-hot and feels worse than 110 F in Arizona.

I think on balance, it's a case of a few anomalous readings providing extra ammunition to those who like to deal in anecdotal evidence for global warming. I think the question of recent years always coming in "top ten" warmest on record is a wider issue than just U.S. recording sites, after all some of the regions showing the largest increases are in the Eurasian subarctic zone. The more you look into these issues, the murkier it all gets, because there's another factor at play, changes in the definition of climate day that used to take the daily lows from the first 18 hours only. This has led to the practice of "adjusting" modern data upward (or older data downward) which leads to an opportunity for subjective fiddling. But the change in day has a noticeable impact on winter temperatures, just think of the number of times a day records its lowest temperature between 7 p.m. and midnight, and how few times the opposite trend balances that out. I worked out that Feb 1934, the coldest month in the Toronto series, would have come in almost 1.0 C lower if they had used the modern definitions of climate day. But what if some researcher decides the difference is 2 degrees? Then he will introduce a 1 degree upward bias to modern temperature comparisons.

The flip side of the argument (and I am not offering this as a defence for the poor exposures) is that a hundred million people live in a huge "megalopolis" from DC to Boston, and the poorly exposed sites are probably quite representative of their daily environments, for example, Central Park in NYC sometimes runs 3-4 F degrees cooler than the airports during the heat of the day because it is situated in a large oasis of quasi-rural vegetation within the large urban heat island.

For what it's worth, Canadian recording sites are probably maintained at a higher exposure standard and I haven't seen any photographic evidence of poorly exposed sites. There is a tendency for Canadian airports to be further from urban heat islands than U.S. airports where the cities have grown around them. For example, Calgary airport is still quite a way beyond the outer suburbs. Vancouver airport has good exposure (for an airport) but is an odd situation because it's closer to the sea than most of the city, therefore its temperatures in summer can be quite unrepresentative of what 90% of the city is experiencing especially in a heat wave.

Meanwhile, the big heat wave came to a crashing end at Washington DC, where a strong cold front just blased through with gusty thunderstorms, dropping the temperature at DCA from 37 C at 19z to about 24 C at 20z. It is still widely 39-42 C further south in Virginia. Looks like the heat may try to return mid-week but this time will be less intense and quickly replaced by near-seasonable conditions again on Thursday.