Ask the Meteorologist: Forecasting

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“How can you estimate the amount of rain and snowfall we will receive from a storm?”

Chase Tiffany, Ashland Middle School

When putting a forecast together, meteorologists look at computer models. These models generate a forecast (that requires modification & many changes) based on the current conditions of our atmosphere. These parameters include temperature, moisture content, wind speed, wind direction, etc. All of these parameters are plugged into very complicated equations that then allow these computer models to generate a forecast.

Every morning we look at these computer generate forecasts and build our own based off of their data. These computer forecasts are shown in four panel charts. These four charts show the different levels of our atmosphere all for the same time period — and together, the four panels can be viewed for different time periods of every day. More specifically, when forecasting precipitation we look at a chart that shows “6 hour surface precip.”

This map will show coloring that indicates different precipitation amounts (both in the form of rain and snow). Comparing different time periods of the day to the precip & key (which indicates how much rain/snow is expected to fall) allows meteorologists to arrive at rain and snow totals.

It can be much more complex than this to arrive at a very accurate answer but this is the gist of it. We also have graphics that are used on air which indicate an actual number of how much measurable precipitation is forecasted. These numbers are generated directly from the computer models. This saves us the trouble of doing math and also making mistakes however it is still model data — which means it’s a forecast and must be taken with a grain of salt. In other words, it is an estimate!

Meteorologist Alyssa Caroprese