ITHACA, N.Y. — I could spin some yarn about “April showers bring May flowers” and all that jazz, but cool, cloudy, showery conditions aren’t exactly inviting people outdoors in the meanwhile. While nothing particularly disruptive is on the tap from the weather this week, unseasonably cool, dark and damp conditions over the next several days will invite you to stay in the great indoors while a storm system aloft slowly makes it way out of the region.
Much cooler today with more showers expected. The week ahead will remain cool and unsettled, as an upper level low pressure system will remain nearly stationary over the area. pic.twitter.com/A9Wd4A9Mju— NWS Binghamton (@NWSBinghamton) April 23, 2023
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At present, a large low pressure system is spinning aloft over Northern New York, Ontario and Quebec. Unlike their surface-level counterparts, upper-level lows are, as you might have guessed, anomalously low pressure in the middle to upper troposphere. Structurally, they tend to be cut off from the general flow of the jet-stream (eddies), so they move very slowly. The low pressure aloft also tends to draw in cold air that then works down towards the surface. That cold air in the upper-level low also increases the lapse rate in the atmosphere because it’s an anomalously large change in temperature in height, with colder air than usual in the mid-levels. That increases the formation of clouds and precipitation.
Long story short for those not interested in the meteorology lesson; it’s going to be cool and cloudy for much of the next week as that upper-level low pressure system slowly weakens, eventually merging back into the jet stream and getting carried off to far yonder.
With the primary band of rain over Eastern New York and New England, the rest of your Sunday will have generally cloudy skies with a few scattered rain showers and a few breaks of sun possible before sunset. Temperatures will barely break into 50s, and fall into the mid 40s by sundown. Additional rainfall amounts will be light. less than 0.1″ inches. Rain showers end by midnight as a dry slot works into the region, with only a few passing clouds by sunrise Monday. Lows will be chilly, in the mid 30s.
A shortwave (pulse of instability) spins around the upper-level low Monday, which will trigger another round of showers. Skies will become mostly cloudy by late morning with occasional light rain showers during the afternoon and evening. Highs will be in the mid 50s. Monday night sees showers come to an end as the shortwave departs, with partly cloudy skies and lows in the mid 30s.
With the upper level low still centered to the north, another shortwave will bring another round of showers for the afternoon and evening hours Tuesday. Skies will be mostly cloudy with highs in the lower 50s. (One of the reasons precip peaks during the afternoon and evening is that that’s when surface heating is greatest, leading to the steepest lapse rate and greatest atmospheric instability.) Tuesday night will see showers end before midnight, with lows in the low to mid 30s.
Yet another shortwave spins around the upper-level low Wednesday. Expect partly to mostly cloudy skies, light afternoon and evening rain showers, and lows in the mid 50s. The showers will end after sunset, with partly cloudy skies overnight and lows in the mid 30s.
The cold pool shifts north-northeastward enough on Thursday that, in a change of pace, there are no rain showers in the forecast, though it will remain cool with northwest breezes, driven by a surface high pressure system over the Western Great Lakes. It will be partly cloudy with highs in the mid 50s. Thursday night will be partly cloudy with lows in the mid to upper 30s.
Friday reintroduces the threat of showers, but this time its part of a large area of low pressure moving from the Deep South through the Mid-Atlantic states. Expect partly cloudy skies with a few PM showers and highs in the low 60s. Friday night will host mostly cloudy skies with a few showers, primarily south and east of Ithaca, with lows in the lower 40s.
Looking into next weekend, the low heads out into the Atlantic on Saturday, but models are converging on the development of a surface low pressure system over the Midwest, which is likely to swing through from Sunday through the start of the following week. Temperatures will be around 60 with showers early Saturday, dry conditions overnight Saturday into Sunday with lows in the 40s, and more persistent, heavy rains as the frontal boundary passes through Sunday with highs around 60.
Heading into the start of May, the medium-range shows a ridge of abnormally warm air over the Western United States, with a downstream jet stream trough providing unseasonably cool conditions to the Central and Eastern parts of the Lower 48. The large-scale pattern ushers in cool continental air from Canada, and his dry air will result in decreased precipitation amounts over much of the northern-third of the country. In Tompkins County, with the downstream Atlantic Ocean jet stream ridge, precip will be closer to normal, and not quite as anomalously cold as the Mississippi River Valley, but still below normal with highs in the 50s and low 60s instead of the mid and high 60s we would typically see in early May.