SIOUX CITY, Iowa (KCAU) – Everyday, several times a day, meteorologists provide forecasts for the weather during the news broadcasts or digitally on social media, but what isn’t shown is what goes into getting that information and data.
Forecasting takes a bit of work and several different parts that come together. This is known as the forecast funnel. In the forecast funnel method, forecasting starts broad and eventually ends at a local level, starting with the atmosphere across the country, then taking a closer look at a regional level, and moving into the more local level for a specific area.
Most meteorologists will start their forecasting by looking at a website called the Weather Prediction Center, or WPC for short. The WPC has forecasters that provide a synopsis of what is currently going on in a specific region, what is coming to a specific region, and/or what forecast models best represent what is projected to happen. This is not a forecast but rather a general look at the current weather patterns such as frontal systems, pressure systems, and where ridges and troughs are located, all things vital to forecasting. This is known as model diagnostics, which helps meteorologists determine which models are more favorable to use for more accurate forecasting and which ones are the outliers.
The model diagnostics section changes every day depending on what the models are projecting and what is currently happening in a specific region.
This is important to look at first before forecasting because it paints a general picture of current weather patterns in the area.
After looking at the model diagnostics on the National Weather Service’s website, the next step would be to look at the Storm Prediction Center to see if there is a chance for severe weather in the area.
The Storm Prediction Center, or SPC for short, is another team of forecasters that look at many different weather maps and data to determine the most favorable areas for severe weather every day, starting with what day it is (known as Day 1).
Looking at the SPC helps meteorologists prepare forecasts based on the chance for severe weather. There are many different things to look at when severe weather is possible, from the upper atmosphere down to the surface. This can slightly change how the forecasting is done.
If severe weather is possible, meteorologists will focus on slightly different weather-related areas. These areas paint a better picture of thunderstorm production in the area, but if severe weather isn’t a possibility, meteorologists start with the forecast funnel.
The forecast funnel starts with the upper atmosphere and generally covers the country as a whole vs. the location for the forecast.
Starting with the upper atmosphere, it provides meteorologists with information about ridges, troughs, and pressure systems. Ridges and troughs are everyday weather patterns and have different things associated with them:
- Ridges: Typically bring colder, more dense air to the area. We typically see stormy weather or snowy weather when a ridge is over the area.
- Troughs: Typically bring warmer, less dense air to the area. We typically see more fair-weather when a trough is present.
Looking for these features helps determine if the area will see more fair-weather or more stormy-like weather.
The next step would be to look at the synaptic level. This level covers around 620 miles to around 1,500 miles, like a regional area.
The regional area has features closer to the surface. These features include wind speeds, vorticity, and temperature, dew points, and more. These features help determine where:
- Clouds are going to be.
- Storms/rainy/snowy weather may start.
- If there is warm air advection or cold air advection (warm air moving into the area or cooler air moving into the area).
The synoptic level allows meteorologists to see how the upper atmosphere is working with the synoptic level. It also provides a better understanding of what exactly is happening in our atmosphere.
The next step would be looking at the mesoscale level. This level ranges from 50 miles to under 620 miles. The mesoscale level helps meteorologists see the timing of incoming storms, precipitation, cloud coverage, surface temperature and wind speeds, and much more.
All this is a step by step of what meteorologists look at. This doesn’t even include looking at the models in general.
As mentioned above, most meteorologists will look at the recommended models on the WPC model diagnostics page.
This means, as the steps above are being looked through from a broad area to a localized area, meteorologists are looking between the recommended models to compare and contrast what they are showing.
There are several different models that can be used. Most of the models anyone can access for free, but some are harder to come by due to them being run and owned by European countries/countries overseas.
The models typically used include:
- NAM (North American Model)
- HRRR (High-Resolution Rapid Refresh model)
- RPM (Rapid Precision Mesoscale model)
- GFS (Global Forecast System)
- ECMWF (European Centre for Medium-Range Weather Forecasts, also called the EURO for short)
Each model ranges in how much time it covers.
- HRRR covers around 18 hours in the future.
- RAP covers around 39 hours in the future.
- NAM covers around 84 hours into the future.
- GFS covers around 384 hours into the future.
- ECMWF covers around 90 hours into the future.
Every model is programmed to take climatological data, past model runs, and current weather data to come up with new model output. This means a lot goes into the models for meteorologists to look at, which is why some are outliers from time to time. For example, some models may suggest a cold front moving through on a Thursday morning while the others are in agreeance with one another, suggesting the cold front will move through later that night. It can also suggest an earlier time as well. This is why it is important to start with the WPC model diagnostics website. Models also update several times a day, some faster than others. The long-range models (like the GFS and ECMWF) update less than the short-range models (like the HRRR, RAP, and NAM). This helps provide meteorologists with up-to-date data for forecasting throughout the day.
Forecasting takes place through all the steps mentioned above and can take anywhere from a few minutes to over an hour to complete a forecast, depending on how big of an area the forecast is for, how long of a forecast period meteorologists are looking at (is it only for one day or several), and depending on what is happening (like inclement weather or fair weather) it could add time to forecasting.
Forecasting is a science and may not always be 100% accurate as the weather is always changing by the second, minute, hour, day, etc. “Predicting the future” is never easy but with all the knowledge going into forecasting and how much information and data is available, meteorologists are able to provide as accurate as possible forecasts.