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Tag: Storm Season 2020

  • Taking spaghetti models with a grain of salt

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    During hurricane season, spaghetti models are a frequently cited resource for helping forecast tropical systems. But there’s a lot you should know about spaghetti models and specifically, when and how best to use them.


    What You Need To Know

    • Spaghetti models plot individual computer forecast models on one map
    • They can be a very useful tool for forecasting tropical systems
    • There are key limitation to spaghetti models, however
    • Be careful with how you use and interpret spaghetti models

    Spaghetti models – also commonly referred to as spaghetti plots – can offer easy-to-digest (no pun intended) insight about a tropical system’s potential path. 

    They’re often cited by meteorologists during hurricane season, but there are also important distinctions about when and how best to use them.

    First things first, the spaghetti models show a series of individual computer forecast models, all overlayed together on one map. Each line on the map represents a separate computer forecast model or simulation.

    Spaghetti models are a key tool to help forecasters determine where a storm might be headed, and how much confidence those forecast models might have on a given storm. 

    But with all the help spaghetti models can offer a forecaster, they can also be equally as deceptive, or even misleading, to the untrained eye.

    Spectrum News chief meteorologist Mike Clay offered a strong word of caution on spaghetti models, along with when and how best to interpret them.

    “The only thing the spaghetti [model] is good for is telling how much confidence we have in the models,” Clay said. “If all of the lines are on top of each other, it tells you the atmosphere is in a state that can be modeled and you should have greater confidence.”

    “If the lines are all over the place,” Clay continued, “It tells you there is low confidence and pay attention to changes.”

    In particular, there is one individual ‘model’ that is actually a climatological representation of where a storm should go. However, that model, the so-called CLIP model, appears as a single line. But, this isn’t really a forecast model.

    The CLIP, because it’s exclusively based on climatology, fails to take into account current weather conditions and factors. Because of that, it often shows up as an outlier.

    Other models, like the Global Forecast System (GFS), are known for being not as strong at forecasting tropical systems. Some of the spaghetti models may be better with track, while others may specialize in intensity. 

    In other words: take the spaghetti models (and especially outliers) with a grain of salt, and leave the interpretations of them to the experts.

    Italian for dinner?

    If the spaghetti models look like, say, a messy bowl of linguine pasta (like the example map below), that’s usually an indicator that there’s overall lower confidence about where the storm might be headed.

    On the other side of things, if the spaghetti models resemble a straight line, that’s a good sign that the models may have a better idea about a storm’s possible path. 

    Think of it like an unopened package of grocery store spaghetti, a clustered, linear shape to the models is a signal of a higher confidence forecast.

    In the map below, the initial clustering of lines shows a stronger confidence forecast. Later on, in the Caribbean Sea, the divergence of the models shows a lower confidence forecast.

    Use with caution

    Another key reminder about spaghetti models is that they are purely in reference to a specific storm’s track. They don’t, for example, consider a storm’s potential strength or other possible impacts, like flooding or storm surge. 

    “The spaghetti [models] have nothing to do with intensity,” Clay said.

    When you see a spaghetti model map, also consider the other factors that could potentially make a storm dangerous, like intensity, forward speed and potential flooding, and storm surge.

    So the next time you see spaghetti models, use them, but use them wisely.

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    Spectrum News Weather Staff

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  • How to understand tornadoes and stay safe

    How to understand tornadoes and stay safe

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    Not every thunderstorm spawns a tornado, but when they do, the strong rotating wind can really wreak havoc. So what causes a tornado to form?

    There are multiple variables that go into the development of a tornado that are not available in every storm.


    What You Need To Know

    • About 1,200 tornadoes hit the U.S. each year
    • There are different tornado seasons for different regions
    • Tornadoes are classified on the EF (Enhanced Fujita) scale

    What is a Tornado?

    A tornado is a violently rotating funnel of air that extends from a thunderstorm to the ground.  Sometimes a tornado can be confused with a hurricane, which is also a rotating storm, but on a larger and slower scale. Tornadoes are narrow and faster, making them much harder to prepare for and take cover.  

    Where Tornadoes Occur

    According to the National Severe Storms Laboratory, about 1200 tornadoes hit the United States yearly and can occur in all 50 states.

    They are more common along the Gulf Coast in early spring, May through June for the southern plains, and June through July for the northern plains and upper Midwest.

    The reason for the higher frequency during these months is because conditions for tornado development are more common. Conditions include an unstable atmosphere, sufficient moisture, and sufficient vertical wind shear, which is the change in wind speed and direction as it rises.

    These conditions are typically found along a boundary, such as a cold front, dryline, or sea breeze.

    These boundaries indicate an area where cold and warm or moist and dry air masses meet. This will cause air to rise and thunderstorms to form. If the vertical wind shear is then present, the thunderstorm will start to rotate and a tornado can spin down to the surface.

    Determining the Tornado Classification

    Tornadoes can come in all shapes, sizes, and strengths. It’s not until a tornado has weakened that a determination can be made on how strong it was.

    This is different than a hurricane that immediately gets ranked a category 1-5 based on wind speed. The EF Scale (Enhanced Fujita) is based on the damage that the tornado caused and can be as weak as an EF-0 or as strong as an EF-5.  

    No matter the strength of the tornado, it is important to take cover when a warning is issued.

    A warning means that a tornado is likely occurring and you’ll need to get to your safe spot immediately.

    How to Stay Safe During a Warning

    Safe locations include a basement or an inside room without windows on the lowest floor. Try and grab something to protect your head from falling debris, like a helmet, and wait for the threat to completely pass before leaving.

    Remember that tornadoes can occur at any time of year and during the day or night.

    If the ingredients are there, a spin-up may occur fast, so it’s important to have a way to be alerted wherever you are. If a warning is issued, have a plan in place to quickly respond and get yourself to safety.

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    Meteorologist Mallory Nicholls

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