ITHACA, N.Y. — Memorial Day is a day meant for reflection and appreciation. One of the things we can appreciate this year is a beautiful sunny days with temperatures comfortably in the low 70s. As the work week commences, however, a warm front will bring in some unsettled, potentially stormy conditions for Tompkins County, though nothing severe is expected.
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A weak cold front has moved south of the Southern Tier, and behind it, Canadian high pressure will be taking control for Monday. Calm winds and fairly rapid clearing are expected during the early overnight hours, and for those night owls who fancy a very late night walk, expect mostly clear skies after midnight with a low in the low 50s.
Monday will be a gorgeous late spring day by just about any standard. With the high pressure in place to the northwest, Ithaca and Tompkins County can expect mostly sunny skies, comfortable dewpoints, and a high in the low 70s. One small caveat to all this is that clouds will begin to move in by sunset, as the next system approaches the region, but it should remain dry for any evening plans you might have. Expect thickening clouds overnight with overcast skies by morning, and a low around 50 °F.
That next system will be an area of low pressure over the Great Plains with an associated warm front running well ahead of it, extending eastward into Pennsylvania and New York. The unfortunate part is that the front will stall, and waves of moisture will ride along its unstable boundary, keeping showers and thunderstorms an ever-present part of the forecast for the middle of the week. Much of this can be attributed to the “heat dome” over the Southeast, which creates a ridge of hot air that forces the jet stream northward, and contributes to an upstream trough that creates a stormy clash of air masses over the central part of the country. If you think it’s unpleasant for us, imagine how the Great Plains feels; with several inches of rain yet to come, the flooding already underway is likely to worsen.
The wave of moisture should arrive with the warm front Tuesday morning, with rain likely by 7-8 AM (closer to 7 AM if you’re West of Ithaca, closer to 8 AM for Ithaca and communities to the east). Expect a fairly unpleasant day, with overcast skies and periods of rain, and perhaps a weak thunderstorm or two. The scattered showers will diminish somewhat during the afternoon, and a little more so during the evening, but skies will remain overcast. Highs will be in the mid 60s, with winds rotating to a south breeze by afternoon. Rainfall amounts will total between a quarter and a half of an inch in most areas. Tuesday night will be mostly cloudy with scattered showers and a low in the upper 50s.
Wednesday will be considerably warmer as the warm air flows in behind the front, but otherwise conditions will remain unsettled, especially in the afternoon hours as another wave of moisture rolls into the region. With more heat comes more energy in the atmosphere, and the atmospheric instability will be substantial, with wind shear (changes to wind speed and direction with height) conducive to thunderstorm development. Keep an eye out for any strong or severe thunderstorms that may pop up, especially during the later afternoon and early evening. Apart from that, plan for mostly cloudy skies with scattered rain showers, more frequent in the PM hours, and a high in the upper 70s. The dewpoint will be in the mid 60s, so even in the drier period, it will feel kinda muggy. Wednesday night will be mostly cloudy with scattered rain showers, and a low in the low 60s.
A third wave of moisture will come in for Thursday, along with the low pressure culprit, which will pass from the Midwest and over the Northeast as it finally moves out of the continental U.S. Unfortunately, this means another day of warm but stormy weather. Plan for scattered rain showers throughout the day, mostly cloudy skies otherwise, and a high in the upper 70s.Showers should decrease somewhat Thursday night, with mostly cloudy skies and a low in the mid 50s.
The models are in some disagreement on how fast the low pressure center moves out – the American GFS and Canadian CMC weather models has it linger into Friday morning and afternoon, while the European ECMWF has it moving out more quickly, with a more pleasant Friday in store. The ECMWF is generally the more accurate of the two, and NWS Binghamton is going with the ECMWF here, forecasting clearing skies and low 70s for Friday as the cold front clears the region and northwest winds and stable air come in behind the low. In either case, Friday night will be mostly clear and dry, with a low in the upper 40s.
Saturday is looking pleasant enough with sunny skies and a high in the mid 70s, but as the low gets pushed eastward by a pair of lows along different branches of the jet stream, Saturday night will cloud up with mostly cloudy skies and lows in the mid 50s, and Sunday will be mostly cloudy with a chance for some rain showers, and a high in the mid 70s.
Unfortunately, the heat dome will persist into the early part of June, which will contribute to warmer and wetter than usual conditions for the Northeast as we start meteorological summer. The trough over the Western United State should slacken somewhat, which (with any hope) should relieve the Great Plains of its continued stormy weather, at least somewhat. The long-term outlook sees the heat down and the trough both shifting eastward later in June, but Tompkins County is looking to be about normal in terms of temperature and precipitation, though medium-range outlooks are liable to change substantially as time progresses.