Our annual rite of spring, with scratchy throats, itchy eyes and a symphony of sneezes, is underway in New England as tree pollen of all sorts bursts forth – with birch pollen the newest addition to the pollen party that just jumped into the spotlight this past weekend and will continue over the next two weeks, joining already-present pollens like juniper, elm, maple and poplar.
With no soaking rain, no substantial relief from pollen is expected for allergy sufferers, though occasional showers may provide very temporary relief. A daily stream of energetic atmospheric disturbances aloft continue dropping over New England, racing south out of Canada, sailing in the fast jet stream winds aloft – the fast river of air that steers disturbances like these and separates warm from cool air.
With New England under the jet stream winds – and straddling the line between cool and warm air – our chance of scattered showers and thunder rises, particularly during the afternoon when we reach the warmest time of the day, with the warmth capable of feeding the bubbling clouds that can transition to showers and storms.
Because we’re not squarely into warmth and humidity, most storms will fall shy of severe limits, producing briefly heavy rain and a few lightning strikes with some small hail possible, but not the strong storms we can see during hot and humid days.
Nonetheless, while dry air may not provide as much fuel for storms, it can lend itself to not only hail – balls of ice inside storms – but also locally gusty wind, and a couple of severe thunderstorm warnings were issued in Maine on Sunday afternoon and may be required with one or two storms Monday afternoon in New England as well, though the strongest storms will likely stay inland of the coast, given an expected sea breeze Monday afternoon that will cool coastal communities a bit.
With the loss of daytime heating, the scattered showers and storms will wane, giving way to a partly cloudy sky with patchy coastal fog overnight Monday night. Another disturbance drops south from Canada over New England on Tuesday, but the air will remain dry and the jet stream will start a slow shift northward, cutting the chance of afternoon thunder to just an isolated storm or two and marking a transition for New England more firmly into warm air.
By midweek, true early summer warmth will unfold as the jet stream drifts north, allowing temperatures to rise above 80 degrees Wednesday afternoon and keeping the chance of afternoon thunder quite limited through Thursday. By the weekend, the jet stream starts to drift southward slowly over New England once again, simultaneously lowering our daytime temperatures just a bit – but still running warmer than normal – and raising the chance of afternoon thunder each day.
Our prediction last week of a frost-free extended forecast continues, and planting seems safe for all but the North Country of New England with no big intrusions of cold foreseeable through Memorial Day weekend.