Spring into the season like Jeremy Burlando! Photo: Samuel Cardenas / Slingshot
Spring weather can be very changeable and, in fact, is even difficult for meteorologists to predict at times, which is why it can make for some crazy kiteboarding
In his regular column to enhance our understanding of the wonderful world of wind, iKitesurf meteorologist, Shea Gibson, picks over some of the things weather forecasters have to consider when trying to predict where exactly a weather effect will hit. It all seems to simple when you see it presented on TV!
WORDS: iKitesurf meteorologist Shea Gibson
SPRING STORM WEATHER AND KITEBOARDING: WHAT TO WATCH FOR
Spring into summer seasonal change always gets us stoked to see the warming weather patterns. However, before Old Man Winter finally lets go, spring is also a time where we still have cold air clashing with warm air to create a few hazards. This difference in temperatures of air masses brings rather volatile weather across our ride zones in the form of cold fronts, which bring storms and rapid transitions of winds behind them. Storms occur ahead of and along the cold fronts due to the sharp increase of instability, which in many cases delivers big winds to those areas that fall in the pre-frontal zone, while post-frontal winds can also ramp up quickly behind them. There’s so much to consider when deciding if it’s safe or too dangerous to go out on the water along the pre-frontal builds. Usually we are all more comfortable and feel safer with post-frontal winds in most scenarios. We generally coin the term ‘convergent winds’ for (usually warmer) winds that are blowing into a system - such as a front or an area of low pressure. At times this is aided by ‘low level jetting’, where higher wind speeds aloft are forced down to the surface, potentially creating some intense pre-frontal winds. Conversely, as cool air sinks and disperses, sometimes at a rapid rate, we have ‘divergent winds’ that go out and away from areas of high pressure. These are usually comprised of cooler air from an entirely different direction. The gradient between these lows and highs can be very steep with strong and / or damaging wind speeds, depending on the size and strength of each. Bearing that in mind, let’s discuss a primary and sinister entity in some of our weather hazards.
Ominous shelf cloud
What they call a bolt from the blue! Photo: Scott H Murray / Media Drum World
WHERE THINGS GET WEIRD
Many areas around the world are systematically affected by what is known as an outflow boundary or ‘gust front’ for short. These are caused by a separation of cold air from a thunderstorm with the release of energy when a storm’s core draws in warm air up-drafting. Ice to melts at a rapid rate and drops a massive amount of moisture all at once. This release of energy can also can create an outward arc of clouding that forces cool air down. This drafting appears as the well known ‘shelf cloud’ and advances quickly away from the storm. If rear-inflow jetting (influx of warm air aft of the storm cloud, building in behind it) is really strong at the time, then the outward arc can be driven for long distances for up to hundreds of miles, catching many off-guard in the process. Generally, the closer the gust front is to the parent storm or cluster, the more powerful the winds. The storm cells they originate from can sometimes create microbursts or macrobursts, which contain very powerful straight-line winds in all directions. Microbursts are generally smaller in size and less than four kilometres across, whereas macrobursts are greater than four kilometres. Speeds can escalate as high as into the 90’s and even over 200 kilometres-per-hour with microburst or macroburst energy. As many of us will have seen out on the water, these shelf clouds initially pack strong winds that can shift directions 90 - 180 degrees at times (with a rapid air temperature drop and cooling I might add). However, the longer the distance, the weaker the surge of energy becomes, but it still holds properties that would interrupt surrounding atmospheric conditions, such as low level jetting and sea breezes. So, if you see a shelf cloud coming, get ready because the winds ahead of it will eventually shut down then switch quickly (and sometimes violently) from a different direction.
Rear inflow jet
Rear inflow jet – detailed
Another known issue on the water is lightning; one of the least understood topics in meteorology from a physics standpoint, because we can never tell exactly where it will generate from and where it will strike. We have a good idea of the large area where it will be produced, but it all depends on the ice column in a storm cell. The deeper the column, the more friction and the more lightning we will see. We see anything from cloud-to-cloud, intracloud and cloud-to-ground strikes. We are most concerned with cloud-to-ground when it comes to kiting. When storms are near, lightning can strike anywhere. Although many riders associate lightning as being close to the storm and try to squeeze out those last few minutes, it can strike outwards to beyond 40 miles away from the parent cloud. Hence the term ‘bolt out of the blue’. This type of lighting has tragically claimed many lives in the past, so be aware of its possibility. Many riders have experienced static shock in the kite lines as a storm is approaching, so if you are feeling it, get off the water right away because you have just become a likely grounding unit for a lightning bolt to connect with. Other hazards include water spouts and tornadic waterspouts, which are interesting features that occur with rotation of the air column just ahead and/or under the storm cell. Waterspouts are generally pretty calm when over water, but don’t let them fool you. If your kite gets near, you’ll get thrown pretty hard and fast. Waterspouts can at times spin up very quickly and become violent over the water, as we have seen with tropical systems, or if popping onto land within a storm cell and then holding form to become an actual tornado. Either way, if a waterspout / tornado watch or warning are issued, then take heed. All of these hazards present lots of challenges in our forecasting efforts, with so much criteria to look over before making a high confidence forecast during pre-frontal and post-frontal events. Models are getting better and better and they do serve as a huge help in guidance in many cases, but the human element is still the best for interpreting and interrogating this data. We have a way of filling in the gaps with local knowledge that the models cannot see. Also, the way that models are depicted in many apps can be showing the same sets, but just packaged differently. Many models miss the coastal and maritime nuances that many of you know in your own riding spots, so be sure to toggle all of the models to gain more perspective. iKitesurf has multiple global, national and regional models available to make for an entire suite to take a look at each day, every day. It’s like having a 3rd, 4th and 5th opinion from doctors on your health and mental well being - the more the better! After all, as kiters we need more and more time on the water to have that lovely sense of mental well-being. Stay safe and stay in the wind! Shea Gibson
Make sure to check the multitude of weather stations in the iKitesurf network to determine the best quality stations for your area. IKitesurf’s +50,000 sensors across the world, including some of their own sophisticated weather stations in the US and surrounding territories, will help you to see the local observations in near-real-time for the best outcomes. Each spot also provides additional forecast data for your needs.