As the precipitation intensified and the low pressure system became more intense, basic physics said more cooling was on the way.

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Meteorologists were blaming the nor'easter on the collision of two storm systems: cold air traveling south from Canada bumping into a moist low pressure system heading north from the Carolinas.

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There's this low pressure system sitting out in the Bay of Bengal which is sort of nudging up exactly to the same area which is going to dump, I think it's 200 millimeters of rain, a huge amount of rain.

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When there is no wind, for example, heat builds up in a city, creating a low-pressure system that pulls air into the city.

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The past two years it got stuck on top of southern England - and that locked a low-pressure system in place which in turn brought misery and rain.

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Miles below, another low-pressure system is brewing.

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He forecast a cold, frosty and mainly dry night in Britain and warned that the system of low pressure was likely to wreak more havoc in Germany and Poland overnight.

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