We are about to head into yet another stagnant pattern of dry air with mostly sunny skies and seasonal temperatures. Whenever we get these long extended patterns of dry air, you can count on the upper level jet stream to be the culprit.
The jet stream is literally a stream of air at about five miles off the ground that is driven mainly by temperature differences in the atmosphere. This stream meanders from west to east across the United States and around the northern hemisphere. The sup-tropical jet and the polar jet both have major influences on weather in the Northeast with a focus on the sup-tropical jet in the summer.
This week the sub tropical jet has a kink across the eastern third of the United States and the Western two thirds is dominated by a massive ridge in the jet. It’s similar to the crest of a wave. This one is traveling from Southern California into Canada and back down to the Gulf States. Underneath it you’ll find warm and stable air. These long stretches can mean brutal temperatures for those underneath the ridge and can mean prolonged drought conditions. See above.
Rochester and much of the northeast will be directly underneath the trough of this blocking pattern. If it’s a shallow trough, weather can be cloudy, cool, and sometimes rainy. Luckily it’s a deep trough allowing for the showery weather to remain along the Eastern Seaboard. We’ll get high pressure at the surface and a dry stretch into August.
The jet stream is the backbone for all forecasts. It’s what college students looking for a meteorology degree spend semesters studying. How they form, how they influence storms, why some might bring sunny skies and others could bring tornadoes. Diffluence and confluence around the jet stream, speed, level in the atmosphere, and much more. We may not talk much about the jet while on TV, but you can be sure we’re thinking about it.
Above is an Omega Block – one of the more common blocking patterns that , when over us, can lead to prolonged drought conditions.