ITHACA, N.Y. — It would appear we’re in one of those brief transition periods between three months of hot and humid weather and six months of cold weather. Enjoy it for the short time it’s here. Temperatures will be comfortably mild through this week with pleasantly cool nights, though a soaking rain is likely between Wednesday evening and Thursday night.
Your Weekly Weather
It’s a fairly pleasant Sunday evening across the Northeast thanks to an area of high pressure centered overhead, and one can be sure the restaurants are packed with students and parents celebrating Cornell’s pandemic-delayed 2020 commencement ceremony. Temperatures are comfortable if a hair below normal, in the upper 60s and low 70s across the Finger Lakes and Southern Tier.
With that high pressure’s stabilizing effect, tranquil conditions will continue through the night tonight. With the loss of daytime heating, near-clear skies, and low dewpoints, it should cool off fairly quickly after sunset. You might want a jacket if you’ll be out late, as temperatures will drop into the 50s by 10-11 PM, and bottom out in the low 50s along the lakeshore and in Ithaca’s urban core, and some upper 40s in the outlying areas and on the hilltops. Some patchy fog will be possible in the usual valley areas, so use caution if you’ll be out on the roads in the early morning hours.
As the high shifts eastward Monday, its clockwise flow will churn some warmer and more moist air into Ithaca and Tompkins County, though still fairly comfortable with calm conditions. Highs will be in the upper 70s with comfortable humidity and partly cloudy skies. With that southerly wind and partly cloudy skies Monday night, it’ll be quiet and on the milder side, with lows in the upper 50s.
Tuesday will be on the breezy side as southerly winds pick up ahead of a frontal boundary to the west, its parent low passing north-northeastward across Canada. The daytime hours should remain dry, with partly cloudy skies turning mostly cloudy and highs in the mid 70s. After midnight Tuesday night, however, rain associated with that frontal boundary will begin pushing into the region from the west, with scattered showers likely by sunrise. With the thicker cloud cover and growing humidity, lows will only bottom out in the mid 60s.
Wednesday will be an unsettled day as the front continues to push in, with a secondary low likely developing along the frontal boundary to the southwest, in the Ohio River Valley. The frontal trough is quite large but the moisture is fairly confined in a tight “ribbon” of flow, so even as shortwaves or the secondary low approach, the initial rain should be intermittent. Expect highs in the mid 70s with near-overcast skies and periods of light to moderate rain. New rainfall amounts will be between one-tenth and one-quarter of an inch. Wednesday night will see the frontal boundary itself move overhead, and that will bring more persistent rains after midnight. Expect overcast skies with rain and lows in the low 60s.
Thursday is looking like a washout. That Ohio River Valley will become the new primary core as it deepens and moves northeastward into Canada. As it does, it’s going to wrap the moisture around itself, and that’s going to pull bands of slow-moving moderate to heavy rain over the region. Quantified precipitation forecasts indicate that between 8 PM Wednesday and 8 PM Friday, Ithaca and Tompkins County could see 2-3″ of rain. Skies will be overcast and highs will be in the low 70s. The rain will become more intermittent after sunset as the low moves away, and then more scattered and less frequent by the early hours of Friday morning. Skies will begin to clear up, with a few lingering rain showers and partly cloudy skies by morning. Lows Thursday night will be in the mid 50s.
Friday will be cooler as colder air comes in on the counterclockwise northwesterly flow behind the front and its parent low. An isolate shower or two may persist, especially east of Ithaca. Plant for partly cloudy skies otherwise, with highs in the upper 60s. Friday night will be mostly clear as high pressure builds in from the west. Lows will be in the low 50s.
The weekend is looking dry and seasonable. Expect sunny skies and highs in the low 70s Saturday, and sunny skies and highs in the upper 60s Sunday. Lows will be in the low 50s.
Your extended outlook now comes with new and improved graphics courtesy of updates at the NOAA Climate Prediction Center. Generally, the large-scale pattern for the lower 48 indicates a large jet stream ridge over the Great Plains, with drier air advected poleward and bringing warmer and drier conditions to much of the continental United States. Ithaca/Tompkins is far enough downstream to allow for some potential downstream troughing, but modestly warmer and substantially drier than normal conditions are expected as we finish out the month.