Sunday July 16th…
Dear diary. Red alert! This morning’s run of the models is now forecasting a significant heat wave starting in the Plains then spreading eastward this week. The first heat wave of the season mainly affected the Eastern Seaboard in early June. The second and third heat waves mostly set records in the Southwest from late June into early July. This fourth heat wave will be more widespread than the prior ones this season across the nation affecting a very large area by Thursday the 20th. I think that #4 will be the big one for this year unless models are way off today.
In a warming world due to carbon pollution heat waves, such as the one now forecast, will become more likely. Unfortunately, the synoptic pattern looks anomalously toasty for most of the U.S. during what is typically the hottest time of the year, climatologically, in late July.
Yesterday I indicated that most guidance was trending cooler with this fourth heat wave event… not so today. We are seeing that 597 decameter circle again:
The corresponding 2 meter temperatures look frightfully hot:
The coming heat wave is likely to be prolonged with the heat dome lasting at least into the fourth week of July. The Southeast has not been exceedingly hot this summer, but that’s probably going to change be late this week… particularly if we see the 500 Mb heat dome ridge progress eastward and set up like this:
I’m going to state that the first day of heat wave #4 will be tomorrow, Monday the 17th, due to widespread maxes above 90 in the Plains and lower to middle Mississippi Valley. Declaring a start or end to a heat or cold wave can be sketchy since there usually are leftover small areas of residual anomalous temperatures… in this case the high temperatures in the Plains and Southwest today. While hot, I don’t see any spot on this map close to record levels valid for tomorrow:
I’ll be adding to this post with updates later today.
To see all 2017 Heat Diary entries click:
https://guyonclimate.com/category/heatdiary2017/
The Climate Guy
Saturday Evening Updates…
Dear diary. I took a look at the GFS two meter temps valid only four days from now on Wednesday the 19th, which are quite toasty in the Plains and South. Looks like the break from extreme heat won’t last long. Am sharing the panel:
Here are the maxes for Saturday:
Their were numerous reports of maxes around 100 in Texas and the Plains. Las Vegas got hot enough to tie their record high of 114. A comfortable summer continues from the Great Lakes eastward to New England.
The Climate Guy
Saturday July 15th… Dear diary. Most of the U.S. will be catching a break from intense heat the next couple of days. At the same time I don’t think there will be any widespread record cool areas. Here are the GFS numbers for Tomorrow:
By Sunday a front will take the edge off the heat that was in the Mid-Atlantic and South this week. The Southwest will be the only area affected by well above average heat.
Models and ensembles now have a high probability of that fourth heat wave I’ve been harping on by the middle of next week in the Plains and portions of the East. It’s too early to tell how intense or how prolonged the heat wave will be, though. The orientation of the 594 decameter height line (or oblong circle) across the nation’s mid-section during the middle of the summer depicted here is not that uncommon but not very frequent either:
Notice that there is not much of a positive (or hot) height anomaly color in association with this pattern… just a tiny bit of orange shading in Iowa.
I’ll be adding to this post with updates later today.
To see all 2017 Heat Diary entries click:
https://guyonclimate.com/category/heatdiary2017/
The Climate Guy