ITHACA, N.Y. — On the one hand, the temperatures Friday night through Sunday morning were quite unpleasant. Binghamton set a new record low for the month of April. Agricultural damage has been reported in the Midwest due to the late freeze. Temperatures from the Dakotas down to Oklahoma and Florida are 10 °F to as much as 30 °F below normal. (In contrast, those in Seattle are well into the 80s and 30 °F above normal, because you can’t have a huge trough in the jet stream without a ridge.)
On the other hand, despite the frosty temperatures, widespread snowfall and biting wind, it’s not as bad as some of the models were showing a week ago. Plus, the future is looking up. Or at least, the temperatures are. After a reinforcing push of cold for Tuesday, temperatures will steadily climb from the 50s, to the 60s and well into the 70s by next Saturday.
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Being on the backside of the high pressure area associated with the arctic cold pool means that Sunday has been somewhat milder as southerly winds are channeled up the rear flank of the high’s clockwise flow. However, just to our north where the winds are more westerly due to a very strong low pressure system over Newfoundland, temperatures remain in the 40s and even the 30s in some spots, and the lake effect is going in full force, though the relative warmth means most of it is falling as rain. Both downstream effects from Lake Erie, as well as more unstable air channeled up by the high, have contributed to a fairly cloudy Sunday across Tompkins County, with a few breaks of sun on occasion.
The remainder of Sunday should be quiet for most. North of Ithaca, it will be a little cloudier with the chance for a stray lake effect rain shower, and highs will be in the low 50s to around 50 °F, with west-northwesterly winds. Ithaca southward will have a few more breaks in the clouds and a lower risk for showers, with highs in the mid 50s and west-southwesterly winds.
By Sunday evening, clouds will begin to thicken as a shortwave (pulse of instability) approaches from the west. While not especially strong or long-lasting, it will result in overcast skies Sunday night, and light rain across most of the region Monday morning. For tonight, expect overcast skies, with the chance for rain showers increasing by daybreak. With the insulating effect of the clouds, temperatures won’t fall too much, with lows in the low 40s.
Monday will be a grey and wet day as the shortwave closes off into a weak low pressure system as it passes over upstate New York. Behind it, more cold air will be channeled into the region, though nothing quite as bad as Saturday. Expect cloudy skies and light rain from sunrise through late afternoon, with one-tenth of an inch to one-quarter of an inch of rain in most areas, and temperatures topping out around 50 °F. With that colder air coming in and skies clearing Monday night, temperatures will steadily drop off, with lows in the upper 20s in Ithaca and mid 20s elsewhere in the county. With temperatures that cold, there will be a risk of a damaging freeze in areas where the growing season has already started, in the more urban areas and along Cayuga Lake, so hold off on our outdoor plantings until mid-week, or bring your plants inside if possible.
Tuesday will be a chilly day, as diurnal heating helps to drive up strong winds from the northwest in the wake of Monday’s low. This northwest wind will also help churn up lake effect activity downwind of Ontario, though it should at least be warm enough to remain all-rain. Expect a windy, chilly, partly cloudy days, with a few rain showers north of Ithaca, and highs in the upper 40s. As the heat of the day wanes and the low pulls further east, the winds will calm and cloud-cover should clear up. Tuesday night will see decreasing clouds, with mostly clear skies by morning and a low in the low 30s.
Wednesday will see some improvements as a high pressure system moves eastward over the Ohio River Valley. This will result in sunny skies and milder temperatures, if still well below normal, with highs in the mid 50s. Wednesday night will be mostly clear as the high passes to the south, with lows in the mid 30s.
The high shifts eastward for Thursday, and on the backside of its clockwise flow, temperatures will climb with the southerly wind, into the low 60s. However, while the temperatures are more pleasant, the active wave pattern will rain on our parades. An area of low pressure will move from the Great Lakes into Southern Canada, and the southern lobe of that will result in widespread light to moderate rain from late Thursday afternoon through the overnight hours. So while it will be partly cloudy in the morning, skies will be mostly cloudy by lunch, overcast with the first showers by about 2-4 PM (earlier to the west of Ithaca, later to the east), and rain overnight with lows in the low 50s.
One of the benefits of that low passing to the north, however, is that it will draw in even warmer air into the region for Friday, effectively shunting some of the jet stream ridge eastward. It will be an unsettled day, as showers will persist, and that warmer air may even provide enough energy for some thunderstorms. But temperature-wise, it’ll be in the low 70s. Friday night will see scattered showers, maybe a thunderstorm or two, and lows in the low 50s under mostly cloudy skies.
Saturday and Sunday will continue the warm, unsettled pattern, as it looks like we’ll be entering a regime change with the jet stream, putting us under a ridge but close enough to its edge that storms will rise up from the Mississippi River Valley and through the Midwest and Great Lakes, potentially bringing rain showers and pulses of unstable air into our warmer environment. We’re not looking at anything like a washout those, this is more like an active summer pattern where you have lots of convective “pop-up” activity in a warm, moist environment. Expect partly cloudy skies and pop-up showers and thunderstorms Saturday with highs in the mid 70s, partly cloudy skies and showers Saturday night with lows in the mid 50s, and partly to mostly cloudy skies with convective rain showers and thunderstorms Sunday with highs in the mid 70s.
You know how there’s something of a running joke that we don’t have spring anymore, it’s more like a switch that flips from winter to summer? The upcoming pattern is going to give that joke legs. With the ridge shifting to the east and a new jet stream trough settling in over the West Coast, we will see a warmer than normal conditions (upper 60s is our normal this time of the year) as well as a continued wet pattern through the second half of the month. It won’t be a perfect stretch of weather by any means, but at least you’ll have some chances to break out the shorts and sun dresses.