GENERAL WEATHER TERMS (AN ONGOING LIST)

WEATHER MODELS

Weather models are a system of math equations that use current atmospheric conditions to plot out future weather. In general, the further out a model plots, the more inaccurate it tends to be. There are thousands of weather models, short range models, long range models and foreign models. Each model has slightly different equations which place more or less weight on certain characteristics of the atmosphere.

Here is the website I use for models

COD: Forecast Models

There are five main models or so 1. GFS model (Global Forecasting System) A long-range model sometimes called the "American" model. Good for forecasting for events between 2 - 14 days out. 2. European model Another long-range model with a great reputation for performing well. Good for forecasting 2 - 14 days out. 3. GEM model (Global Environmental Multiscale Model) A medium to long range model sometimes called the "Canadien" model. Good for forecasting 2 - 10 days out. 4. NAM model (North American Model) A short to medium range model. Goof for forecasting 1 - 3 days out. 5. HRRR model (High Resolution Rapid Response) A short-range model with high resolution that factors in subtilties like landscape and bodies of water. Good for forecasting from 0 -1 day out. THINGS TO LOOK OUT FOR IN MODELS Trends - At times a model might produce products that trends in a certain direction. When looking for trends, you would compare how the past model runs have plotted out weather conditions for an area and time. Trends could be like the following: Storm track shifting, Storm strengthening and more. Trends are used to analyze how models deal with an event and how its thoughts change on an event. Convergence/Divergence Among Models - When looking at model products it is important to look at other models to see if models agree or disagree. When they agree, models converge on a certain outcome and when they disagree, models diverge on an outcome.

COLD AIR DAMMING

This is a phenomenon that occurs all year long but is most potent during winter. Cold air funnels down from the north and is jammed and kept in by the windward side of the mountains. The windward side is the side being hit by the wind and is the east side in this case because the wind comes from the northeast. Cold air at the surface effectively dams in this region even when warm air passes over. Cold air damming aids in keeping the cold air in our region longer when a winter storm comes. Sometimes if a storm tracks closer and throws warm air overhead, the phenomenon creates conditions for freezing rain.

First you need a north easterly wind, most of the time from a high-pressure system in place in southeastern Canada or the New England States. This brings the cold air in and pushes it against the mountains

This image shows cold air damming before a winter storm that brought extensive freezing rain and snow for the regions along and east of the mountains. You can see warm air west of the mountains unable to cross, and you can see the cold air funneling in and standing its ground.