Jet Stream- High speed wind current in the upper atmosphere that is responsible for steering storms and effecting temperatures across the United States.
Jet Stream Trough- When the jet stream sinks below a given region creating a trough like shape in its wave length. When there is a trough in the east this means colder conditions in the winter due to the jet stream allowing cold air to flow into the surface area inside the trough. In most cases we need a trough over the east to get a big winter storm
Jet Stream Ridge- The opposite of a trough. This is when the jet stream moves above our area in a reverse trough like shape, allowing warm air from the south to flow into our region. This is not a stormy setup.
North Atlantic Oscillation (NAO)- Large scale climate pattern that relates to the pressure level over Greenland. In its negative phase high pressure is centered over Greenland and in general creates a cold and stormy setup for the East Coast not allowing storms to easily escape from this track. The positive phase is defined when there is lower pressure over Greenland resulting in less chances for storms to develop and turn up the East Coast.
Pacific North American Pattern (PNA)- Large Scale climate pattern that if I reference in its positive phase combined with a negative NAO could spell trouble for the North East. The positive phase is when there is a high pressure center off the coast of California creating warm conditions in the west and cold conditions in the east.
Heights- heights are a meteorological term that in a sense mean pressure level in the atmosphere. Cold air is heavier than warm air so we can measure air temperature based on how many meters it takes to get up to a given pressure level in the atmosphere.
Pressure Level- Pressure levels in storm systems are measured in millibars (mb). A weak storm has a low pressure of around 1000 mb while a very strong winter storm will range in pressure from 970-990 mb. In extreme cases we will see pressure levels below 970 with massive winter storms. The lower the pressure the more intense the storm is overall.
Difference between Sleet and Hail- Hail occurs in the summer time and its the result of a very strong updraft in a severe thunderstorm throwing small ice pellets back up into the storm letting them accumulate and grow until they are heavy enough to break through the updraft and fall to the ground. Sleet occurs when it is snowing in the upper atmosphere but the snow then melts in a layer of warm air on its way down then finally refreezes again in the form of a ice pellet before it hits the ground. When sleet mixes in with a winter storm it can significantly cut down on snow accumulations.
Negatively Tilted Trough- Basically if I mention a storm is going to go into negative tilt over our region it will mean that the storm will be reaching a peak intensity in our area.