ITHACA, N.Y. — As much as we’d really like to be able to banish snow from the forecast for the next six months, we can’t. An unseasonably cold pattern will result in a widespread if modest snowfall through tomorrow morning, with a couple more brisk days in store before temperatures begin to return to more seasonable values.
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With Monday’s sharp cold front and high winds past us, a cooler regime has settled in across the Great Lakes region. A fast-moving but rather disorganized Alberta clipper-type low is ushering another round of cold air into the Southern Tier, and should have enough moisture with it to drop some light snowfall accumulations across most of the region this evening and through tonight.
In terms of overall accumulations, there will be a modest topographic effect as the hilltops will cool a little more than the valleys, and the chance of snow turning to rain before it hits the ground is more likely in Ithaca proper than on the hills. Generally speaking, most places will see rain and snow showers begin shortly, with at least 2″ of snow between 9 PM tonight and 2 AM Thursday, with perhaps 3″ on the hills and 4″ in some isolated spots. Most of that will like fall in a moderate frontal band lasting only an hour or two. It’s not enough to wreak havoc, but it is enough that, being mid-April, we’ve had it up to *here* with the snow. Lows tonight will be in the mid to upper 20s with clearing skies after the clipper’s passage, and mostly clear by daybreak.
Thursday will be fairly dry if still a bit unsettled. With the northwest winds gusting behind the clipper and enhanced by a high pressure system to the south, some scattered lake-enhanced rain and snow showers are likely, with the greatest chances for showers closer to Lake Ontario (i.e. northwest of Ithaca). Those northwest winds will also keep things fairly brisk, with mostly cloudy skies temperatures only topping out in the low 40s, a good 15-20°F below normal. Thursday night will see the rain and snow showers wind down as the high shifts and the wind slackens over Lake Ontario, and with that, skies will clear up somewhat, to partly cloudy conditions and lows in the upper 20s.
Skies begin to cloud over again Friday morning as the next system approaches, a more organized short wave (pulse of instability) that will track to the south, along the bottom of the jet stream trough. A couple snow showers might start this event off, but generally the timing is looking like it’ll make for what’s primarily a rainmaker, with perhaps one-tenth to one-quarter of an inch. Expect scattered rain showers and cloudy skies with highs in the low to mid 40s, and as temperatures dip back below freezing after dark, a few snow showers will persist into the early AM hours with lows around 30°F
Your Saturday is looking somewhat nicer as a fast moving area of high pressure over the Tennessee River Valley brings mostly sunny skies and somewhat milder air as it takes an elongated shape and brings in some air from the southwest in its clockwise flow. Highs will be around 50°F. Saturday night will be partly cloudy with lows in the low 30s.
Sunday will see partly cloudy skies become mostly-cloudy as a weak frontal boundary pushes in with an area of low pressure trekking eastward across the Ohio River Valley. The clockwise flow around the low will bring the temperatures up into the upper 50s, with scattered light rain showers in the afternoon and evening. These will taper off after dark, with mostly cloudy skies after midnight and lows in the upper 30s.
Monday should be quiet around here as a large storm system passes through the south and a small but notable clipper pushes over the Northern Great Lakes – for once we’re not in the line of fire. Plan for mostly cloudy skies and highs in the mid 50s. Monday night will be partly cloudy with a low in the mid 30s.
Tuesday could be a bit more unsettled as that clipper passes and channels colder air in over Ontario, once again setting off some lake-enhanced showers. Highs will be in the low 50s. Tuesday night will likely see rain or snow showers ahead of the next system, with a low in the mid 30s. Wednesday is looking warmer, with mostly cloudy skies and highs near 60°F.
Oh, look how lucky we are. The persistent trough in the jet stream is expected to continue into the last third of the month, with slightly elevated chances of precipitation to go with it, as storms traverse the trough to the south. In fact, the NOAA Climate Prediction Center is noting slightly elevated chances for a damaging freezing event and elevated chances for a damaging wind event late in April.
If this is spring, I can only imagine what summer’s going to look like. The one saving grace is that it gets harder and harder for the atmosphere to keep up this level of cold, as the influx of solar energy per square foot of ground grows with the rotation of the earth’s axis into Northern summer. This more direct beam of radiation results in a great concentration of solar energy per inch, and makes it harder to maintain this degree of cold.