The snow-in-May forecast is getting old.
I wrote about it concerning this weekend back on April 29: “I can’t rule out some flakes falling at high elevations around that time, but these same models don’t think much of any accumulation potential."
The problem is, this unusual event has not disappeared from the forecast. If any measurable snow falls at the airport, it will be the first measurable snow in May since 1989, when a whopping 7.9 inches fell on May 7. That’s a 31 year stretch, which makes this a rare event.
Even before the snow arrives, Western New York will have dealt with a freeze warning due to clearing skies behind still another cold front late Thursday night into early Friday. I hope no one decided to take a wild chance on plantings after the freeze warning early in the week. It’s still too early to plant.
After an entirely chilly and mostly dry Friday, the chill builds. Fortunately, an area of low pressure going by will be far enough to our south to leave us out of its precipitation shield. (On Monday, it appeared we could receive some snow and rain from this low on a closer track.)
Behind this low, clearing and freezing temperatures return with Saturday morning low temperatures in the upper 20s. It’s on Saturday when our meteorological mettle will be tested. It will be the most uncomfortable of the next few days, with a strengthening northwest wind adding plenty of wind chill to the unseasonable temperatures. To go with that, moisture will be drawn from Lakes Huron, Ontario, and Erie to produce scattered and occasional snow showers across the region. As depicted here in the European/ECMWF model, you can see coverage will be fairly sparse and shovel-free.
Saturday high temperatures will range from near 35 in the hills to near 40 at lower elevations, with a wind chill in the 20s. When all is said and done for the snow, accumulations will be hard to come by and mainly in the hills, even in the overdone (IMO) ECMWF.
By overdone, I mean the ECMWF has too broad a coverage for even minor accumulations compared to the sparse coverage of actual depicted snow showers. There is also the daytime melting that occurs in May from the higher sun angle and marginal temperatures. On the other hand, if we get just 0.1 inches of snow at the airport, that would break the 31 year streak I mentioned earlier.
Mom fares a bit better on Sunday. There will be limited sunshine and less wind chill than on Saturday. A few light rain showers may arrive later in the day, but most of the day will be dry. Temperatures should make it to the mid-upper 40s (the Sunday average high is 64). Monday brings a fresh batch of chilly air. It will be partly sunny and mostly dry, but a few stray light showers can’t be ruled out. Similar conditions follow on Tuesday.
All in all, there are no major storms that will be impacting us for at least a week, which enhances drying in yards and fields. Beyond midweek, the upper air pattern begins to evolve into something far more tolerable. In fact, the ECMWF goes gung-ho on warming at the surface for next Friday.
Other models skip the gung-ho, but do bring more seasonable temperatures in our direction. In the upper air pattern, there is a progression that will begin later next week, flattening out our cold upper low and pushing it off to the east, allowing more frequent visits from warmer upper level ridges of high pressure. For example, here is the ECMWF ensemble mean for late next Thursday at upper levels. The shape of the flow and coloring should catch your eye as a distinct departure from the cold pattern.
Craning our necks out to around May 23, the American GFS ensemble mean shows a basically west-to-east upper level flow, flooding most of the nation with milder Pacific air masses in place of air masses with northwest Canadian sources. In this pattern, it wouldn’t be balmy every day, but passing cold fronts will usher in Pacific air masses, which are much milder than what we have these days. Although my confidence level on this transition is fairly high, as usual there are no implied warranties and batteries for hand warmers are not included.