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  • Writer's pictureMeteorologist James. F

Day 3! heatwave status for many.

Monday was hot, Tuesday yesterday was even hotter! and now today, Wednesday.. Day 3 of this heat which will take its sweet time sitting over us, baking us in it's glory.

Highs for many areas again today will manage to hit or exceed 35 degrees.

850mb Temperatures in the Interior will be anywhere from 22 to as much as 25 degrees, even as warm as 27 and 28 degrees near the Border, for towns like Grand Forks, Rossland, Castlegar and Nelson.

Now, these are not the forecast high temperatures, these are temperatures at the 850mb level or at an altitude of near 5,000ft. You may have heard us talk about the 850mb temperatures during the winter time season when talking about the snow/rain line or types of precipitation. But during the summer months, we use these to help tell us how hot the air really is! and depending where you live and on the current weather conditions, it is also good at forecasting afternoon high temperatures!

Here in BC, many of us use the 850mb method to forecast afternoon temperatures, it works great in some mountainous areas, however it does have some flaws! it doesn't work so well under cloudy, rainy, windy days or even high elevation areas. it works best in sunny, windless days and areas near sea level or low elevation areas, in BC this method works great for the Interior, because they are a semi-desert climate and have the most sunshine and light winds than all of Canada.

During summer months, we take the 850mb temperatures from the models we use and we add 15 degrees to account for air to surface. this will give us our forecast high temperature, for example...

Let's say one of the weather models forecast a 850mb temperature of 21*C for Kamloops, BC.

The forecast high would be: 21*C + 15*C = 36*C.

Now, let's take a look at the ECMWF forecast 850mb Temperatures for Today!

Kamloops: 24*C + 15 = a forecast high of 39*C

Kelowna: 25*C + 15 = a forecast high of 40*C

Lillooet: 23*C + 15 = a forecast high of 38*C

Nelson: 26*C + 15 = a forecast high of 41*C

4 of these towns and many more have already had 2 days of 32*C or higher, if temperatures get to or exceed 32 degrees again today, that will make it an official heatwave. Which would make it the 4th one this summer.

Temperatures in the Interior are expected to stay in the 35-40*C range through Thursday, but stay above 32 through Friday. making it a 5 day heatwave for many.

Heat warnings remain in place for the following areas:

~ Central Coast: Inland sections

~ North Coast: Inland sections

~ Fraser Canyon.

There are also Extreme Heat Advisories in effect for:

Arrow Lakes - Slocan lake


Kootenay Lake

West Kootenay


North Thompson

South Thompson

Okanagan Valley


Temperatures will cool down slightly by the weekend as a trough makes it way inland, bringing showers and storms to the area along with cooler temperatures in the mid-20's, Although mid-20's is warm! Temperatures normal for the area of the Interior ranges from 29 to 31*C.

Seasonal temperatures into the low-30's will return next week.


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