Upper levels give clues, too!
Normally, my weather maps focus on the lower levels of the atmosphere where the fronts are, the precipitation falls, and the temperatures we experience are felt.
However, looking at the upper levels of the atmosphere is another vital piece of the forecasting process. This is especially true on a day like today, where the lower levels are disorganized and messy with few clues on what the weather may have in store.
The main things to note on this map are the black lines, which roughly equate to pressure (its a lot more complicated than that, but that simplification works) and the ribbon of blue shading, which on this map blends in a bit with the blue shading I added over the western US to indicate cold air. This is the jet stream- strong winds aloft that direct the weather patterns, separate warm and cold air and move weather systems across the globe.
For our weather today, we need to focus on an area of low pressure just to the southeast of the Finger Lakes. Often times, the upper level low is further west than the surface low pressure, which in this case, is a weak, ill-defined area of low pressure well off the east coast. With the upper low still hanging around though, clouds will have a definite presence today and there may even be a shower east of Cayuga Lake as some energy rotates around the low and gets thrown back into central New York.
Temperatures will still be mild today, with highs in the low 70s, thanks to a ridge building to our west. The ridge can be identified by the upward bulge in the black lines. Warm air resides within a ridge and well above normal temperatures will continue across the eastern half of the nation today.
The opposite of a ridge is a trough, and the downward bend in the black lines over the western US show a strong trough moving in. Along with the trough is cold air, with well below normal temperatures for the western half of the country. The bigger these troughs and ridges get, the more extreme the weather in between becomes as the cold and warm air interact.
That is exactly what will happen here as well. The strong trough will spawn an area of low pressure over the Great Plains which will move east, producing severe weather across the middle of the country and rain, some heavy, over our area. This rain will move through the Finger Lakes Friday night and early Saturday. Behind the rain, the trough will settle over us, bringing its cold air with it for the weekend and early next week.