ITHACA, N.Y. — If someone complains about the rain, feel free to splash a puddle at them.
As of 4 p.m. Thursday, the airport has picked up 0.38″ since the morning. Not a washout by any means, but the region could use any rain that it gets. Luckily, there’s more showers and frequent light rain in the forecast for the next few days.
That’s an important detail to note. If you get a lot of rain in a very short period, say for instance a torrential downpour in a strong thunderstorm, then a lot of it just flows right off the soil because it doesn’t get a chance to absorb. It also opens up the risk for flash flooding.
Thankfully, that won’t be the case for Ithaca and vicinity this week. The constant battle with dry air over New England and Quebec will result in frequent dry periods, alternating with light rains coming in on plumes of moisture from Ithaca’s south and southeast. High temperatures Friday and Saturday will be in the low to mid 60s in the city proper, and low temps in the low to mid 50s tonight, Friday night and Saturday night. Those of you at higher elevations can take a few degrees off of those figures.
The source of our liquid sunshine is two-fold. A large cut-off low is spinning to our southwest, and due to diverging upper-air flow drawing up warmer, moister air from near the surface, it will provide unsettled conditions that allow showers to develop in the destabilized local atmosphere. Because the low pressure area is cut off from the jet stream (hence the name), it will move very slowly, and the chance for more rain will persist for at least the next couple of days.
As the cutoff low slowly moves, the eastern flank of the counterclockwise flow is rotating to draw more moisture off of the Atlantic and into the Mid-Atlantic and lower Great Lakes. Moisture + instability = a rainmaker. In Washington D.C., this will cause 6-10″ of rain in just a few days, and substantial flooding is already being reported. There’s probably a joke somewhere involving washed-up or all-wet politicians. Here, further from the Atlantic, much of the moisture has been wrung out and we’re not as well-aligned with the upper-level flow, so we will see less than an inch of rain when all is said and done. Areas in the southwest part of the county (Enfield, Newfield, Danby) are expected to see higher amounts overall, while Lansing and Dryden will probably finish this event with less than half an inch.
While we won’t be getting too much of a good thing, we could afford to be a little greedy. Cornell’s Game Farm Road weather station reported an average September temperature 2.9 F above normal, with 1.98″ of rain compared to the normal 3.57″ by this date. From March 1st to September 20th, Ithaca only received 64% of its normal rainfall, 14.76 inches vs. the average of 22.98″, the 4th driest for the period in the 123-year record. That eight-inch deficit has had widespread detrimental impacts, from farming needs to fire bans to the city’s water woes.
Looking at the longer-period, things are looking warm and sunny, which means that the future for our drought problem isn’t so sunny. NOAA’s Climate Prediction Center calls for a strong likelihood of warmer conditions in the Ithaca region, and near-normal precipitation during the first half of October. While great for early autumn picnics and outings, warmer temperatures allow the ground to dry out faster, which means it takes more rain to get the same moisture benefits. Drought conditions are expected to persist through the fall, which is unfortunate for you leaf-peepers, as droughts cause leaves to drop before they’ve really had a chance to change color.