The weather pattern that will be unfolding over the next few days is certainly one that will be keeping us on our toes here in the weather department! The potential exists for several rounds of convection (thunderstorm activity) across the area...a few of which may contain locally damaging winds and hail as well as excessive rainfall. It will be a rather fitting way to conclude what has been a particularly busy weather month throughout the Twin Tiers.
The culprit for all of the active weather will be a deep trough of low pressure digging into the Great Lakes, around which multiple upper air disturbances (referred to be meteorologists as "short waves") will be rotating. Each time one of these small disturbances swings across our area there will be an increased risk of convection...but the real trick for us in the weather department is getting the timing of these short waves just right as this can make a very big difference when it comes to exactly what type of weather we receive. The computer models that we normally use while making our forecasts are not always in agreement when it comes to resolving such small scale features, and this does result in somewhat lower confidence on our part. It's times like these when a careful analysis of the CURRENT state of the atmosphere (using satellite, radar, and data from both surface observations as well as weather balloons) is absolutely essential when making a forecast....and the #1 mistake made by many meteorologists is to blindly follow the computer models without looking at the "real" weather first!.
All of that having been said, here is my stab at things right now! The threat for scattered thunderstorms will certainly be with us from midday Saturday into the early portion of Saturday night. At this point I don't think we'll be looking at anything too terribly widespread as we will still be quite a distance from the developing trough, and any short wave features will likely pass well to our west. There will, however, be other features such as lake breeze boundaries (leading edge of much cooler air flowing inland from Lakes Erie and Ontario)....and even orographic lifting in some of the higher terrain across our area to touch off thunderstorm activity. Weak winds extending very high up into the atmosphere will limit the threat for severe weather to some degree (although isolated severe storms cannot be ruled out as the very warm and humid air will allow storms to develop very strong updrafts)....but those same weak winds will also cause any storms to be very slow-moving which increases the probability of locally excessive rainfall. Storms will likely die out shortly after sunset Saturday evening..
I'm much more concerned about the prospect of severe weather on Sunday. As the trough approaches us from the Great Lakes, winds will be increasing throughout the depth of the atmosphere and it appears that the winds will also be veering (turning clockwise) quite significantly with height. In addition, one or more short waves will be rotating through the area on this day, so I am expecting to see fairly widespread thunderstorm activity. The increasing and veering winds will allow storms to become rather organized, which increases the threat for damaging winds and large hail. I'll be posting updates in this blog from time to time as the event approaches..
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Have a great weekend!