We start by analyzing visible satellite images (“Super HD Smoke Test” – visible smoke and/or dust when using this product) today throughout the Midwest and East. We see a higher-level tornado south of Nova Scotia, and although not obvious there is a ridge (clockwise flow) in the northern Plains. The flow between each feature that helps push wildfire smoke across eastern Canada to the Northeast is represented by the milky white color you see that is not a cloud.

So, how does all of this relate to the heightened fire risk, and even work in conjunction with potential “dry thunderstorms”?

Before going into the explanation, see the current warnings from National Weather Service. We have gray outlining a large part of the Northeast and pink mostly in the mid-Atlantic. As a reference to what each color means, gray stands for “air quality warning” and pink stands for “red flag warning” or heightened fire hazard.

Analyzing the HRRR through tomorrow night, we see that some high-density smog will move into the Northeast and Mid-Atlantic during the day and again tomorrow. In fact, this is why it will be quite faint, as this plume will come pretty close to the boundary layer, if not in it (the lowest part of the atmosphere where we all experience weathering). ). So that’s why we have air quality warnings.

Now, let’s go back to the concept of “dry thunderstorms” and how this relates to today’s smoke and fire hazards. It would be easiest if we studied the elevation of the atmosphere today in the Northeast. From Dupage University, a skew-t shown was selected from the Hudson Valley representing predominantly the entire Northeast. I have sketched as best I can to illustrate this. First, a dry thunderstorm is essentially a storm without rain. It has a high cloud background where rain falls from higher distances measured from the surface. The farther the raindrop falls from the dry air below, the more likely it will evaporate. We know evaporation is a cooling process, so now the evaporated air is denser than its surroundings. Due to the force of gravity acting on it, this denser air falls to the surface hence the potential for strong gusts of wind. Another important ingredient is lightning. We need CAPE so that the updated gas flow reaches vertical to allow charge separation, which is the catalyst that generates lightning. Usually, we want to see CAPE in grades -10 to -20 for hydrometeorology (i.e. rain, hail, hail, etc.) to transfer those charges. When we combine that, we get lightning.

Below, we have a CAPE sufficient for an increasing headwind, a layer of high clouds, and a large area of ​​dry air below the main cloud layer. This will be your “dry” thunderstorm setup. The dry air you see is actually smoke coming from eastern Canada! Finally, check out our heightened fire risk to see how all of this comes together.

Today, we have a moderate wind from the NW. Typically, we want to see wind speeds above 15-20 mph, even though gusts are above 20 mph. With a cold front heading south today, this not only strengthens the winds up front, but also acts as a push to head up, in which we can see storms rising across the country. northeast.

Next, we have a relative humidity value less than 40%. It’s a pity that the area hasn’t had much rain, if any, recently. Combining wind to help spread local wildfires or wildfires and drying vegetation, as well as low humidity values ​​with pre-dry conditions, we have the ideal weather formula. fire. Today, let’s add the full parameters for pop-ups and storms, as well as the risk of dry thunderstorms with smoke rising – now we see why we have a very unusual setup today. now! If one of these cells produces lightning, it doesn’t take much work to start a bushfire or wildfire and let it spread pretty quickly due to the dry vegetation and wind on the spot.

With all these components we can see the word fire weather index parameter via HRRR its spread relative to this region with values ​​above 45-50 mostly confined to the north Mid-Atlantic.

The risk of a dry thunderstorm is mainly for today, although the fog and smoke will continue through the week as the omega block pattern stagnates before it clears later this week.

Again, today’s setup is quite meteorologically appealing. Smoke from wildfires mixes with the atmosphere to enhance the wind gust potential of a storm by evaporating rainwater into dry air (from the smoke as noted above). You combine that with the main fire weather conditions (low relative humidity, wind conditions, lack of rain and sunshine as well as allow for CAPE and concentration of solar radiation), and we get Ideal for fire weather combined with poor air quality. If you are sensitive to harmful particles, please limit all outdoor activities possible (especially if the activity is strenuous) and try to stay indoors mostly if necessary to limit effects.

About the author

Armando Salvador

Hello! My name is Armando Salvadore and I am a Mississippi State graduate with a Bachelor of Professional Meteorology and an Activity Meteorologist working in the Private Sector. Stay tuned if you like technical, exotic, and general weather tweets! Also big on long-range forecasting as well! Twitter: @KaptMands