The 2021 Sturgis Rally long range forecast and early August outlook

Sturgis Rally and the August Outlook -Look to the Pacific.

GOES-16 satellite image of the Black Hills nestled between Wyoming and South Dakota Saturday morning around 9:30 AM MDT.

Immediately you notice the milky white blur covering large sections of the area – smoke from wildfires in Canada and the Pacific Northwest.

There is hope that conditions will improve over the next 48 hours… but there will always be more chances for thick smoke so long as wildfires continue as large and as widespread as they are.

This years Sturgis Rally could be one of the smokier ones we experience. Saturday’s smoke event was fairly significant for the Black Hills Area – considering the smoke came initially from the East (still from fires out west that settled east of the hills)… even during the Schroeder Fire I don’t remember having such stagnate and unhealthy conditions.

The first Week of August (this next week) looks to be right on the mark for this time of year. 80s to 90s during the day, with a chance for a thunderstorm or two in the afternoon right around 2-3 PM… particularly in the higher elevations of the Black Hills. Any of these storms could be strong and produce larger than quarter sized hail and monsoonal wind/rains events. These storms sometimes rumble their way to the plains, but generally fizzle out sometime around 8-10 PM.

The pattern so far shows this continuing into the second week of August… perhaps even warmer and drier. This is the easy forecast – but can this pattern be broken?

It is likely that this forecast will not help you determine if you should go to the Badlands 10 days from now. What it can do is prepare you to pay more attention to the forecast as we approach Rally – because it now looks as though there is a likely chance the forecast will be -frequently- changing as opposed to staying relatively stable. That is to say, it’s no longer a safe bet that hot and dry conditions will persist through the Sturgis Rally.

If we want to break this pattern – and get some much needed water in the area along with cooler temperatures, we will have to fight against three major factors;

• Our entrenched drought
• Climatology
• The Gulf of Alaska

Our severe to extreme drought conditions can act as a feedback, discouraging precipitation and perpetuating a dry disposition. Soil devoid of water will lead to lower surface dew points. Dew point measures the amount of surface based fuel available for thunderstorms. You don’t necessarily need high surface dew points to get thunderstorms, (see elevated thunderstorms), but it can tip the balance in your favor.

Dry surface conditions can absorb rain from elevated thunderstorms, sapping its strength and evaporating large portions if not all the precipitation for a given area. You need storms that are heavy enough to break through this initial barrier. We can sometimes break through this pattern if the climatology supports several large scale systems.

Climatology dictates that we are generally hot and dry in August – our dry season. You can pepper in a few large isolated thunderstorms here or there, but overall your typical drenching rain producing systems are out the window. This is because upper level systems still have a hard time pushing into our area as the residual heat dome of summer locks in place. Hot, stale  and sinking air circulates clockwise around a great area of high pressure. The location of this summer heat dome has a great impact on our overall chances for precipitation… any slide to the East or West changes our weather.

This year, we’ve had a bit of luck as High Pressure has locked in to a location good enough to bring a fetch of Arizona’s monsoonal moisture into our backyards from time to time (and its’ heat).

If we want a better chance at multiple cold fronts and upper level systems to come through and breaking the climatological norm for this time of year, we need the jet stream to cooperate and to break up the heat dome of high pressure. The Gulf of Alaska can be used as a makeshift crystal ball.

When a ridge of heat and high pressure pushes into the Gulf of Alaska – this signifies a whiplash of energy through the jet stream. This is no different than whipping a rope and watching the ridge of energy pass all the way down the rope towards the end – (don’t be at the other end!).

Right now, there is an entrenched upper level low pressure system in the gulf of Alaska for basically 3 months… the counter clockwise spin lifting dry heat into the West coast and the intercontinental Western Basin. If we start seeing a disruption of this pattern, that usually signals a noticeable shift in the weather in the Black Hills about a week later. Its not a perfect science, but its proven to be a useful tool when hedging bets for long range forecasts.

Now that you’ve been sandblasted with more than you ever wanted to know about jet stream dynamics…

Long range jet stream models indicate that the upper level low pressure system in the Gulf of Alaska is expected to shift Southeast as a appreciable ridge of high pressure pushes up into Alaska accordingly. This in turn should disrupt the heat dome into several smaller waves and push it south – allowing a more dynamic forecast to evolve.

This encourages more short waves, which encourages more fronts and disruptions in the overall weather pattern. With the ridge forced southward, this will bring upper level dynamics currently in Canada closer to the Black Hills, along with the *possibility* of cooler temperatures.

In conclusion… although the climatology for the region dictates a hot and dry Sturgis Rally for the Black Hills – there are signs that this pattern could be disrupted in the 7-14 day time frame due to synoptic scale models in the Pacific Ocean, more specifically the Gulf of Alaska.

• Better chances of day to day changing weather rather than a stagnate, persistent forecast.
• Thunderstorm activity would increase, with more than just an isolated storm in the afternoon.
• Days of high heat are not eliminated, but are more likely to be broken up by several small shortwaves.
• Any smoke that moves through the area will also be frequently broken up into smaller spaces of time.
• Larger systems capable of overcoming drought conditions and providing beneficial rain in small bursts.

There is a cult within the locals here in the Black Hills that the Sturgis Motorcycle Rally, through supernatural forces, actually brings huge storms to the Black Hills. The Rally occurs just as daylight hours are starting to decrease rapidly, cooler air aloft is starting to creep back into Canada and the Northern Plains. Perhaps there is science to this…

We will be having lots of intricate discussions about the forecast for Rally Week – this is just one of many. Stay tuned for more forecast and updates – have a wonderful weekend

Brant