Another splendid day is unfolding for New England with plenty of sunshine and dry air. While the biggest result of this weather setup is a delightful day regionwide, the dry air and an active breeze from the northwest for the first half of the day has driven our brush fire danger to high and has released lots of pollen into the air for another day of sniffles and sneezes for allergy sufferers. With daytime high temperatures about room temperature at either side of 70 degrees both Wednesday and Thursday, with an overnight in the 40s and 50s between, there will be one big difference between the two days: Thursday brings many more clouds and, eventually, raindrops. The culprit is the big storm responsible for recent severe weather in the nation’s midsection, now breaking into pieces and sending rounds of atmospheric energy east. The first energetic disturbance to reach the Northeast arrives Thursday morning with a round of early downpours and thunder, but likely only clips southwest Connecticut as the bulk of the disturbance misses New England to the south. Thursday afternoon brings the next piece of energy to the Northeast, sparking severe thunderstorms in New York and Pennsylvania, and some of those storms – though likely in weakened form – will arrive from west to east, late Thursday into Thursday night. Showers will be gone by Friday as the aforementioned energetic disturbance spawns a quickly strengthening storm south of Nova Scotia, affording some sunshine and a dry wind to start Friday in New England, but possibly turning the wind from the northeast by afternoon with cooler ocean air and clouds making a run toward the coast. If they arrive, Saturday could dawn gray, but we expect to wait until late day or evening before the next disturbance arrives – one of several in an active but fast-moving weather pattern that features the jet stream winds directly over New England. Each time a disturbance moves overhead – late Saturday, Sunday night and again late Monday – the chance of showers or thunder is elevated but also should keep moving along, so while the Holiday Weekend forecast isn’t devoid of showers, it’s a nice looking forecast in our exclusive First Alert 10-day.
Dry, fresh air has swept across New England and the result is evident in both the look and feeling: splendid sunshine with an invigorating breeze sweeping through pleasant temperatures. About the only thing a New Englander could complain about today would probably be the soaring pollen count and high ultraviolet index making sneezing and sunburns more likely, but with highs around a room temperature 70 degrees and winds gusting to 40 mph unlikely to do damage but enough to put a spring in our step, this is consummate New England spring weather. Not only is today beautiful, but there’s good reason to believe we have rounded the bend into the warm season – a time for planting, pool opening and tuning up the air conditioner and boat, as we unfold an exclusive 10-day forecast that keeps daily high temperatures either side of the lower 70s and nighttime lows safely above frost values. So…with that knowledge our attention turns to sensible weather: what will have an impact on our daily plans. For the next few days, sunshine rules and the weather will be dry all the way through most of Thursday. Thursday evening and night, a powerful upper level storm dives southeast over New England and should prompt the development of rain and thunder Thursday evening and night, eventually organizing into a strong storm south of Nova Scotia. Normally, a storm east of New England over the ocean this time of year means an onshore wind for cool clouds and drizzle, which would happen on Friday if not for the fact that this storm seems so energetic – so strong – that it appears it should draw air into its center so quickly the wind will blow from the northwest over New England on Friday, instead allowing for sunshine except for Northern mountain showers. The jet stream winds aloft that steer storms across the country will flow directly over New England this weekend, meaning multiple disturbances for the holiday weekend but all are likely to be quick moving and timing will be key for these. At this point, we see no reason for too much worry, as the chance for scattered showers or thunder will be elevated Saturday, Sunday night and later Memorial Day if our estimate on timing of these disturbances is correct, but none appear to be a washout at this point.
Another day of scattered showers with embedded downpours and thunder is ending our New England workweek Friday, slowly settling southeast across the region from morning to mid-afternoon. Scattered showers and thunder will continue into the evening, but after dinnertime these showers will start weakening and evaporate entirely shortly after dark. Friday’s showers are the product of a storm center moving near the Canadian border and launching what is technically a cold front south across the region, but there isn’t much cold air with it – in fact, the air behind this system is dry, allowing for plenty of sun Saturday with a northwest wind sloping down off the mountains and hills, helping to further dry and warm the air as high temperatures reach the 70s. By late Saturday, not only will some clouds start filtering into New England’s sky from the west, but the northwest breeze will weaken enough that a late day sea breeze will probably develop, cooling the coast by evening. A storm center moving through the center of the country will spark severe thunderstorms in the Plains States this weekend and some of the clouds well ahead of the system will dim New England’s sun on Sunday, and increasing warmth and moisture moving into the Northeast may even result in a few showers Sunday, with the highest chance the farther north and west one is. For Boston, it’s likely the weekend stays dry, which would be an accomplishment – we haven’t had a totally dry weekend in the City since St. Patrick’s Day in mid-March. If all goes as planned, an increasing southwest wind will boost Monday’s high temperature over 80 degrees, providing fuel for an incoming cold front to spawn strong thunderstorms, so our team has hoisted a First Alert for Monday for potentially damaging storms – if the heat backs off and the storm threat lowers, we’ll take the alert down. Even as the air cools behind Monday’s storms, the week still looks mild, overall, with the best chance of renewed scattered thunder on Thursday and again on Sunday of Memorial Day weekend in our exclusive First Alert 10-day forecast.
A brilliant start to our Thursday marks an easing of the unsettled weather pattern of late, but it’s not completely gone yet. A series of energetic upper level disturbances are lined up across Southern Canada, diving southeast and poised to move over the Northeastern U.S., each resulting in a weak surface-level storm center and each capable of producing scattered showers with their passage. The next disturbance set to cross New England arrives Thursday afternoon, prompting showers first in the hills and mountains, then spreading those showers across the remainder of the region, fueled by the temperature difference between a warming ground and cold sky. Some Thursday afternoon showers may grow hearty enough to not only produce downpours, but even some lightning and thunder! While none of the thunderstorms are expected to become damaging, some may contain some small hailstones and all lightning is dangerous if outside – so keep in mind the phrase “When Thunder Roars, Go Indoors.” Showers and embedded thunder will diminish quickly after early evening, leaving a partly cloudy sky for the start of the night before fog develops and clouds start filling back in from north to south. The period of clearing tonight in the North Country is important, because a recent solar flare has ramped up the energy colliding with earth’s atmosphere from space, meaning the Northern Lights will glow more than usual tonight. While most of New England probably is too far south to observe the Aurora Borealis, Northern Vermont, far Northern New Hampshire and Northern Maine all may see some faint glow in the northern sky, through any breaks in the clouds that emerge. Another disturbance and weak storm center is forecast to cross New England Friday with rain most of the day in Northern New England and a chance of morning, then evening showers in Southern New England, with a rumble of thunder again possible in the evening round. Saturday looks incredible – sunny and mild – while Sunday should be mostly dry but perhaps not entirely, as increasing humidity arrives aloft first, bringing increased clouds and a low chance of showers for some, higher in the North Country. Next week looks likely to be mild, but with cool Canadian air nearby we are both tenuous on just how warm, and wary of thunderstorms in the exclusive First Alert 10-day forecast.