A winter-like blast of cold air is headed our way for the middle of this week, bringing with it the threat for frost and freezing temperatures.
A couple of days ago we posed the question of whether snow could wind up in the forecast for Wednesday morning; nothing significant, of course, but just enough flakes flying around to make it seem even more like winter.
The answer to the question is “no.” Snow is not in the forecast — at least not the official forecast from the National Weather Service. The latest model runs have trended drier with available moisture as cold air moves in behind a cold front early Wednesday. Still, we shouldn’t be surprised if we see a snowflake or two floating on the breeze Wednesday morning. And the NWS’s Morristown weather forecast office is even mentioning the possibility of trace accumulations for the highest peaks of the Appalachians.
The bigger story, though, will be the cold air — and the potential for widespread frost and even freezing conditions.
Spring cold snaps aren’t at all uncommon. That’s why we use terms like “redbud winter” and “dogwood winter” and even “blackberry winter” to reference them. As the jet stream moves north and cold air retreats to the polar region, spring is a season of sparring between the pole and the tropics, and lingering intrusions of cold air are inevitable.
This spring’s cold snaps, though, have been particularly voracious. We haven’t seen anything extreme like the Easter weekend deep freeze of 2007, but we’ve seen a greater than usual amount of these cold air intrusions, and as a result our temperatures are running slightly below normal for the spring season.
This week’s temperatures will be as much as 20 degrees below normal. Keep in mind that our average high for this time of year is about 70 degrees. We’ll be lucky to break 50 degrees on Wednesday and Thursday, as the cold air lingers. Nighttime lows are likely to be in the 30s for three consecutive nights — Tuesday night, Wednesday night and Thursday night. It’s those nighttime temperatures that will cause growers to have to take precautions with their susceptible plants for at least a couple of nights this week.
The NWS forecast drops us to 36 degrees early Wednesday morning. But with clouds and showers and a stiff breeze, frost isn’t likely to be a big threat.
The bigger threat of frost will come Thursday morning. High pressure will build in behind the cold front, which will allow for excellent radiational cooling after the sun has set Wednesday evening. We’re likely to see widespread frost Wednesday night, and probably a light freeze, as well. Each carries its own risks for plants. The GFS model output statistics keeps us in the mid 30s Wednesday night into Thursday morning. That might not prevent a widespread frost but it would obviously help us avoid a freeze. But with radiational cooling in control as the sun sets Wednesday evening, there’s not much cause for optimism that the GFS’s warmer temperatures will prove to be correct.
After another very chilly day on Thursday, another widespread frost is likely Thursday night as the high pressure system becomes even more dominant. We may not see temperatures drop quite to the freezing mark by sunrise Friday morning, but it’ll be close. The current forecast calls for a low of 33.
We’ll likely be out of the woods by Friday night. A warming trend will be well underway by that point, and thickening cloud cover — maybe even some rain showers — will help keep temperatures in the 40s Friday night.
The good news in all of this is that we should see 70-degree temps return again by Monday, and this looks like the end of the frost/freeze threats for this spring. Call it a last hurrah by Old Man Winter.
To put this week’s “Dogwood Winter” into perspective: For however cold it might feel, temperatures this cold so late in the season aren’t at all unusual. The NWS forecast drops us to 30 degrees Thursday morning. The average date of our last 30-degree (or colder) temperature readings in Oneida is April 24 — two days later. We aren’t going to be anywhere close to record low temperatures for this time period. But the afternoon temps will be impressively cold. Our record low maximum temperature for Wednesday’s date is 44 degrees (2019). And for Thursday’s date it’s 45 degrees (1991). For the record: Our record low temps on those dates is 20 degrees and 19 degrees.