ITHACA, N.Y. — It’s not often these weekly weather reports don’t have some degree of meteorological misery attached. Cold, storms, wind, ice, and so on. But once in a while, a fairly nice stretch weather slips in. That’s much of the week ahead is looking like, thanks to late May climatology and a large are of high pressure over Canada. If you wanted a week to do some social distancing outdoors, your wish is granted.
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For what it’s worth, there is still some rain in the forecast, mostly in the next 24 hours. The current synoptic scale setup has three main components – an area of high pressure over the southern edge of Hudson Bay Canada, a strong and deep mid-latitude low pressure storm system currently centered near Chicago, and a budding tropical system, Tropical Storm Arthur, moving NNE off the Florida Coast towards the Outer Banks of North Carolina.
That area of high pressure to our north has kept the atmosphere fairly stable this weekend after the cold front swept through Friday evening. The system over Chicago will make a run into our area, and some of its precipitation shield will sweep in this evening and tomorrow with the warm front associated with the low. However, while the low is deeply stacked, that Canadian high is also large and strong. It’s effectively an elastic wall that the low pressure system can budge but it won’t have the energy to dislodge, and so it’s going to be shunted back by the high and wander southeastward.
As Tropical Storm Arthur moves northeastward and also finds its path blocked by the high, the two areas of low pressure will come close enough that they will begin to interact in a dynamic process known as the “Fujiwhara effect“. The two systems will rotate counterclockwise around a center point between them, before merging their energy together into one storm off the Outer Banks and moving off to the northeast past Cape Cod. This sounds scarier than it is; Arthur will have transitioned from a tropical low to a mid-latitude (extratropical) low by this point, and the merged low will be weak. The point of this explanation is, from Tuesday on the Canadian high and the two lows interacting to our south will result in a quiet, seasonably warm stretch of weather into next weekend.
So with that explanation out of the way, time for the actual forecast. With the Midwest storm system briefly pushing in before the high shoves it back, expect a cloudy and rainy Sunday night and Monday. The first showers will move in around 5 PM, becoming more widespread as they push east-northeastward during the evening. It will be a cloudy, rainy night, and earlier in the weekend models were showing the possibility of excessive rain and potential flooding. However, the latest runs have backed away from that scenario, shifting the precipitation shield northwestward and decreasing rainfall amounts to more modest, safer total. Lows will be in the low 50s, with rainfall between one-tenth and one-quarter of an inch.
Monday will be a grey, showery day, with the low being pushed back by the evening hours, allowing for the showers to taper off. Highs will be in the mid 60s. New rainfall amounts will be between one-tenth and one-quarter of an inch. Monday night will see a few scattered showers early, with mostly cloudy skies after midnight and a low in the low to mid 50s.
The high will firmly be in control of our weather by Tuesday, as it slowly moves southeastward from Quebec into New England during the week. With its clockwise flow, that will result in a warming trend through the week. For Tuesday, it will be mostly cloudy but dry, with highs in the mid 60s. Tuesday night will be partly cloudy and dry, and with somewhat better conditions for cooling off after sunset (dryness/less cloud cover), temperatures will drop into the upper 40s for lows.
Wednesday will be another dry, seasonably mild day, with partly cloudy skies and highs in the mid to upper 60s. Wednesday night will be partly cloudy with lows in the upper 40s.
Thursday is looking a little warmer, with highs in the low 70s with partly cloudy skies. The high will begin to bring some moister and more unstable air northwestward into the Southern Tier, which will allows for a few isolated showers Thursday night. Otherwise, Thursday night will be mostly cloudy with lows in the mid 50s.
Friday sees the high recede northward, and the combined low passing off the coast could bring in more unstable air into the region, allowing for a few more rain showers, but as the models currently have the bulk of precipitation staying on the storm track to our west, these errant showers would be light and scattered. Plan for mostly cloudy skies, a few scattered light rain showers and highs in the low to mid 70s. Friday night will be mostly cloudy with a chance for a few rain showers, and a low in the upper 50s.
Memorial Day weekend’s looking good for any outdoor grilling, hikes or other socially distant activities you might have planned. There will be a chance for a few pop-up rain showers in the wake of the coastal low, so the possibility of rain can’t be excluded, but generally expect partly cloudy skies and highs in the mid 70s Saturday and Sunday.
Looking ahead to the end of May and start of June, the ridge currently in place over the Eastern United States is expected to progress a little eastward, as will the trough over the Mountain West. This will mean continued mild and warm weather, with seasonably normal conditions on the precipitation side. Overall, it’s looking like the second half of May will be meteorological quieter and arguably much more pleasant than the first half.