ITHACA, N.Y. — For those looking to get outdoors or enjoy the long holiday weekend coming up, you’re in luck. Generally speaking, apart from a few mild showers the week will be sunny and reasonably pleasant. Thursday’s cool temperatures, however, are but a taste of what’s to come as the days get shorter and the calendar relentlessly creeps towards winter. C’mon folks, you’re not reading the forecast for its ebullient optimism.
As us customary for the first weather forecast of the month, let’s open up this week by taking one last look at September 2020 now that it’s in the record books.
Generally speaking, the story of September wasn’t the temperature, but the dryness. According to the Northeast Regional Climate Center based out of Ithaca, the average temperature for the month at the Dryden Game Farm Road meteorological station was 59.1°F, about 0.9°F below normal. Interestingly, average high temperatures were actually 0.5°F above normal, while low temperatures were 2.3°F below normal. This all ties back to the dryness experienced through much of the month. When the air has less moisture in it like it does on dry days, it heats up and cools down more quickly because moist air takes more time to absorb and release heat energy than dry air does.
Across the Northeast, temperatures were generally within a few degrees of average, with no stations significantly below normal, and only a handful of stations reporting values significantly above normal (Portland, Maine had its 7th warmest September on record, but that’s about it for notable values).
On the precipitation side, however, September was pretty darn parched. The Game Farm Road site recorded 1.82″ of rain in September, less than half of the 3.69″ usually recorded during the month. On that note, three-quarters of that (1.44″) fell during the day on the 29th. 1.82″ places September 2020 at a tie for 19th for driest Septembers in Ithaca’s 128 years of records. Had it not been for that late-month soaker, it would have been the driest ever recorded.
Across the Northeast and Mid-Atlantic, 10 of the 30 first-order weather stations received 50% or less of their normal rainfall. Portland and Caribou, Maine had their 8th and 2nd driest Septembers on record, but no one else was in a top-ten driest. Like Ithaca, Binghamton also had their 19th driest September on record. The National Drought Monitor out of the University of Nebraska-Lincoln has much of the Southern Tier classified under moderate drought conditions, so be mindful if you have well water prone to running low.
Don’t expect this pattern to change anytime soon, either, It’s been a fairly dry start to October as well, and looking at the next seven days dryness will generally prevail, although a few showers may pop up here and there. At least it won’t be especially warm; the cool to mild conditions we will see in the week ahead will wick away moisture more slowly than a summer heat would.
Your Weekly Weather
It’s a cool, generally quiet night for the Southern Tier this Sunday evening. A weak surface low is trekking across the region, but there’s not much moisture available to it, and the atmospheric dynamics aren’t favorable, which has resulted in extensive mid-level and upper-level cloud cover and a few sprinkles and isolated showers, but generally nothing substantial. Skies will stay mostly cloudy as the system continues to move eastward during the overnight hours into Monday morning, and a few light showers will be possible, but measurable precipitation will certainly be less than one-tenth of an inch in the few places it does occur. With mostly cloud skies and dewpoints in the mid 40s, lows overnight will generally stay in the mid to upper 40s across our region – a little warmer in Ithaca’s urban core and by Cayuga Lake, a little cooler in the higher elevations and outlying towns.
The weak frontal boundary pushes through just after sunrise Monday, but the change in winds will hardly be noticeable and the air mass behind it isn’t sensibly different from the air currently overhead. Showers will end by sunrise, and skies will progressively clear from mostly cloudy during the morning to partly cloudy by late afternoon. Highs Monday will be in the mid 60s. Monday night will be dry, and that drier air aloft will allow temperatures to slide back a little further, cooling to the low 40s overnight with partly cloudy skies.
Tuesday will see southwesterly flow develop thanks to an area of high-pressure building in from the Ohio River Valley into the Mid-Atlantic, and this will raise the high temperatures while keeping conditions dry. Expect only a few passing clouds Tuesday with highs around 70°F, with a few more clouds later in the day as a shortwave (pulse of atmospheric instability) passes to the north. Tuesday night will be partly cloudy and dry with lows in the low 50s.
Wednesday will be a little unsettled as the high slowly shifts southeastward, while a stronger area low low pressure passes to the north from Ontario into Maine. Most of the precipitation will stay to the north, but a few showers are likely to swing through during the afternoon and evening hours. The low’s counterclockwise flow will also enhance the southwesterly flow ahead of its cold front, so it will be breezy, close to 30 MPH at times. Apart from the showers and gusty winds, expect partly cloudy skies and highs in the low 70s. The cold front should push through a little after sunset, which will end most of the showers but the winds will still gust as they turn to the northwest, finally quieting down after midnight. Lows will be in the upper 40s with partly cloudy skies.
Thursday will be substantially cooler as that low ushers in brisk Canadian air in its wake. A stiff northwest wind will keep temperatures in the mid 50s for highs Thursday, with partly cloudy skies and a few lake effect rain showers to the north of Ithaca. The winds will slacken Thursday night, and the skies will clear up, and that will set Tompkins County for some rather chilly conditions overnight, with lows Thursday night in the upper 30s in Ithaca, and some mid 30s in the outlying areas. Some patchy frost will be possible.
Friday is looking warmer as that northwest wind lightens up and an area of high pressure moves in from the Upper Midwest. Expect sunny skies and highs in the low 60s. Friday night will be calm and quiet, good for stargazing, with mostly clear skies and lows in the low 40s.
The holiday weekend forecast is going to come with a little bit of hedging. Right now, expect mostly sunny skies both days as that high shifts eastward and the winds turn southerly, with low 70s for highs both days, and upper 40s Saturday night. However, Sunday night and the start of next week are complicated by model runs showing what would be a hurricane (“Delta”, because we ran through the assigned names and had to go into the Greek alphabet) making landfall on the central Gulf Coast and its remnants trekking into the Northeast. Ostensibly, a lot can happen between now and then, but given the potential for heavy rain and gusty winds during what is for many a three-day holiday weekend, it’s something to keep an eye on as we move through this week.
Potential tropical impact noted, mid-October is looking to be on the warm side as a ridge develops over the eastern two-thirds of the continental United States. The relative coolness and dampness in the Southeast is tied to the tropical event, and the possibility its counterclockwise circulation draws cooler air southward after it makes landfall and transitions to an extratropical system (a typical mid-latitude low, albeit one with tropical moisture). Precipitation for the period as a whole is expected to be about normal for the Southern Tier.