Summer Heat Diary… August 17-20

Sunday July 20th…

Dear diary…

It’s T minus one day before the eclipse. The main emphasis for this blog has been forecasting excessive heat along the path of the eclipse. First though, here is a visibility forecast from Michael Palmer because knowing where and how much cloud cover and smoke will affect viewing is really most important:

Here is an updated NOAA graphic for comparison:

Heat and forest fire related smoke will probably reduce visibility in Oregon and northern California. Here is a view from Redding CA on Friday:

Here is a great graphic from Accuweather depicting coverage of the sun by the moon across the country:

Next, weather wise and what this post has been specializing in has been temps. The GFS two meter temps have been fairly consistent for about a week. Here is this morning’s panel:

This GFS forecast surface maximum temperature from Intellicast has many cities above 90F along and near the path of the total eclipse:

Unfortunately east of the Rockies the places with the best visibility along the track of where a full eclipse will be observed will be the hottest. The largest cities that I am concerned with for heat problems at the start of the eclipse are 1) Columbia (around 96F) 2) Nashville (around 94F) 3) St. Louis (around 93F) 4) Charleston (around 90F). Keep in mind that temperatures will fall, refreshingly so, several degrees as skies darken during the eclipse.

Next let’s look at dew points, which will greatly affect heat index values in association with heat wave #7 and, thus; heat index values for eclipse watchers:

Humidity will be a problem in coastal areas of the Carolina’s. Mid-South, and Mississippi Valley, but not so much in the Tennessee  Valley, so Nashville may catch a break.

Here are the current heat advisories (in orange) posted south of the path of the total eclipse:

Its possible that advisories could be posted farther north in the Mississippi Valley on Monday.

Here are some more tips for eclipse viewing from Bob Henson:

Here are Sunday’s maxes:

Low level heat wave #7 was in full swing over the southeastern quarter of the nation where maxes from 90F to over 100F were very common along with heat indexes well over 100F from Louisiana northward through portions of Arkansas and Oklahoma.

The Climate Guy

Saturday July 19th…

Dear diary. Advisories for what I’ve termed heat wave #7 have been posted (in orange) in the south-central U.S. and coastal areas of the Carolinas:

Of the seven heat episodes I have referred to this season, #7 will probably end up being the least significant, but dangerous nonetheless.

By tomorrow widespread highs in the 90’s with high heat indexes above 95F will be widespread from the Plains into the South:

The zenith of this heat wave will be on Sunday and Monday (eclipse day) then a strong front will put a kibosh on the thing by the middle of next week:

By Thursday morning a cool, Canadian air mass will be making inroads through gulf Gulf coastal states.

On Monday the GFS toasty forecast for the eclipse east of the Rockies holds:

Notice that the path of the eclipse goes through Oregon. Rob Elvington has noted that viewing will be affected by smoke from blazes that were a direct consequence of past western heat waves this season. Here is one of Rob’s satellite photos over Oregon:

Here are some good eclipse viewing safety tips from NWS Boise:

Here are Friday’s highs:

Temperatures in the 90’s and 100’s spread north through the Plains. The states with the worst heat indices above 105 were Arkansas and Louisiana.

The Climate Guy

Friday July 18th…

Dear diary. The GFS has been the most consistent model in association with heat wave #7 and the upper air pattern/temperatures along the path of the eclipse during Monday. Usually the meteorological model that is more consistent with an event is the one to be believed and will verify. The scale and orientation of the heat dome has been about the same forecast for Monday for a couple of days:

Here are the associated forecast toasty temps valid at 18Z Monday along the eclipse path from the latest GFS model run:

Here is another chart for the best local viewing times:

To get exact forecasts for sky conditions and temperatures in your viewing area check the NWS site or local T.V. and radio station.

The eclipse should actually aid any overheated viewers. After everyone gets settled in and is hopefully comfortable in their outdoor position, the eclipse itself will cool temperatures. Here is a forecast that includes what I suspect will be a 5-6F cooling from the total eclipse (From Eric Holthaus valid for Nashville TN):

Here is MDA Weather Services forecast temperatures for a few key cities on Monday:

A dying front this weekend will initially prohibit maxes above 90 getting north of Tennessee, but dangerous heat will be building south and west of the boundary on Saturday:

Oops. Looks like heat advisories needed to be expanded north to D.C. today (Image from Topper Schutt):

Just to our north Canada has been experiencing record climate change related heat and forest fire activity this summer where smoke has been extensive, particularly in British Columbia and northern Canada:

I’ll be adding more to this post as relevant information crosses my radar today.

The Climate Guy

Thursday July 17th…

Dear diary. The heat is on! Or, in this case heat wave #7 for this season. With any luck this will be the last dangerous heat wave for the United States this season, and I will end my Heat Wave Diary post for 2017 after the thing ends. Of course, if it looks like more dangerous heat might occur going into September, we’ll continue this post.

Yesterday I was on the fence about arbitrarily declaring a heat wave, but conditions across the South and models suggest that at least a “low level” episode of dangerous conditions will be occurring through at least the early part of next week mainly across the southern half of the U.S. The Northeast may see a taste of this heat for a couple of days as well. I’m not anticipating many records to be set from heat wave #7; thus, my arbitrary designation of the thing being “low level.”

One very important reason that I have chosen to declare that a widespread heat wave is occurring is the area of heat advisories are expanding across the South:

The GFS has been the most consistent model forecasting a strong heat dome over the South with the zenith of the thing coinciding with eclipse day on Monday the 21st and Tuesday the 22nd.

East of the Rockies on eclipse day these two meter temperatures look toasty indeed:

High dew points above 70 should be sending the heat index into dangerous territory across the Southeast Atlantic and from the Gulf Coast northward through the mid Mississippi Valley on Monday:

Here are today’s maxes:

About the same level of heat occurred in the southern tier of the U.S. on Thursday as on Wednesday.

To see all 2017 Heat Diary entries click:

The Climate Guy

Leave a Reply

Your email address will not be published. Required fields are marked *