The increase in humidity across New England is moving in on a southerly wind, and that new air traveling over cool ocean water creates a more moist, cooler air over Southern New England that allows for clouds to develop and drift north across Southern New England late each night into each following morning. These clouds tend to be shallow, don’t produce any rain and burn off fairly quickly with such strong summer sun, with the Cape and Islands taking as long as late morning to completely burn through the clouds but eventually seeing sunshine with mild and humid air by afternoon. Elsewhere, any clouds burn off quickly and sunshine couples with the new, warm, humid air to lift temperatures to around 90 degrees right on through the weekend. The strong sun angle comes with the Summer Solstice: the first day of astronomical summer on your calendar, but more importantly for us as meteorologists, the strongest sun angle and longest day of the year with just over 15 hours and 17 minutes of daylight for someplace like Boston on Saturday. Of course, the strong sun also means sun safety is important: SPF 30 sunscreen, finding shade when possible around midday, remembering the hat and sunglasses and staying hydrated. One thing notably absent from the forecast is thunder: often a feature of a hot and humid New England forecast, this time around we just don’t see a strong enough feature to trigger thunderstorm development for most of us this weekend. Often, variable heating in the mountains can cause an isolated storm to develop and that probably will happen in the mountains of Northern New England Friday evening, Northern Mountains and perhaps Berkshires Saturday late day and evening, and scattered late day and evening storms that may survive out of the mountains into other parts of Northern and far Western New England Sunday. For the vast majority of New England, the weekend will be storm-free, but heat and humidity continues into next week, with the chance of afternoon thunder growing, especially toward midweek. There are indications the humidity may decrease by late next week into next weekend, but summer warmth is expected to roll on through the end of our exclusive First Alert 10-day forecast.
The first sign of noticeably increasing humidity in New England came in the form of low altitude clouds and areas of fog Thursday morning – set to burn off quickly but coming coincident with dew point temperatures (a measure of the amount of moisture content in the air) rising into the 60s, meaning a humid feeling to the air. The increasing humidity won’t reach Northern New England today, where record warmth is expected exceeding 90 degrees, but that humidity will be felt throughout Southern New England by day’s end and likely will result in many air conditioners running as uncomfortable sleeping weather returns for a long stay. At the seashore, an afternoon sea breeze will likely kick up Thursday afternoon, but not before temperatures exceed 80 degrees for the first time this week at the coast, then the sea breeze is expected to be even more feeble and later in the day if at all on Friday. Inland, temperatures will rise to near 90 degrees Thursday and Friday – by the weekend, just about everyone except Cape Cod and the Midcoast of Maine, Downeast, are expected to near 90 degrees with humidity and some spots will likely record a heat wave of three or more consecutive days of 90+ heat. Of course, Saturday is the summer solstice – the longest day of the year and the strongest sun angle, which is making sun safety an important component of our First Alert Weather Forecast: remember sunscreen, stay hydrated, and anything to limit direct sun will help, from a wide-brimmed hat to sunglasses to finding shade. In this sunny weather this time of the year, sunburn can set in within 10 minutes if we’re not protected! The chance of thunderstorms will remain limited in the coming days, building a bit in the mountains Friday afternoon, then in Northern and Western New England Saturday and perhaps expanding into Central New England Sunday…with the greater chance of scattered afternoon thunder most of next week as heat and humidity rolls on through most of the exclusive First Alert 10-day forecast, with signs the humidity may roll back a bit by the end of next week.
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In an incredible stretch of weather for New England, there are still changes afoot that make each day of the next 10 a little different that the one before it. One thing that stays the same for a couple more days: an extreme ultraviolet index. Full sunshine so close to the strongest sun angle of the year for the Summer Solstice, and longest day of the year at 15 hours and 17 minutes of daylight, this coming Saturday can result in sunburn in only 10-15 minutes of exposure without sunscreen. Aside from some evening and night wispy clouds, mostly clear skies continue right through Thursday, though the sea breezes that have been recurring at our coastlines each day through Wednesday will abate, at least until later in the day, Thursday, allowing temperatures to rise into the 80s at our east-facing beaches Thursday afternoon. With the shift in wind to blow more from the south rather than east by Thursday, this will increase humidity a bit, but it’s Friday when a southwest wind delivers noticeably more humid air for a sticky day with high temperatures 85-90 for most. Showers and thunderstorms should remain south of New England through the end of the week, consolidated around a weakening and very slow moving upper level storm over the Mid-Atlantic, which will eventually drift northeast toward New England. The chance of an afternoon storm in Western New England rises to about 30-40% Saturday afternoon – lower in the eastern half of the six-state region – then, by Father’s Day Sunday afternoon, the chance of thunder rises to 30-40% for many of us, but anything that does develop would be scattered and most likely in Northern and Western New England. Once we jump into this new air of 85 to 90 degree temperatures with humidity, expect it to stick around quite a while: most of next week our exclusive First Alert 10-day forecast keeps temperatures of 85 to 90 degrees with humidity and a chance for scattered afternoon thunder.
While the fantastic stretch of weather will continue for several more days in New England, there are plenty of subtle features that are noteworthy. The cool start this morning was certainly one notable item, with low temperatures in the 40s for many, cooling under clear skies and a calm wind with dry air. While dry air cools easily under clear and calm conditions at night, it also warms quickly during the day with sunshine…and we’ll have plenty of sun with nary a cloud in the sky Tuesday. Of course, the ample sunshine will deliver an extreme UV index so New Englanders are encouraged to remember sunscreen to avoid sunburn in the coming days, through the end of the week. As was the case Monday, Tuesday and Wednesday will bring a sea breeze off the 60 to 65 degree ocean water to keep temperatures about 5-10 degrees cooler in coastal communities than inland, and this light flow of wind and associated ocean moisture will make early morning clouds a possibility on Cape Cod and perhaps Cape Ann Wednesday and Thursday mornings, but whatever gray sky develops would be thin and burn off quickly. Otherwise, comfortable air continues until the wind becomes more southerly Thursday, bumping humidity up just a bit ahead of noticeably stickier air Friday into the weekend, with temperatures nearing 90 for the Summer Solstice – the first day of astronomical summer - Saturday. Even as humidity and heat increases and temperatures reach 90 degrees for some of New England Friday through the weekend, the storm chance remains fairly limited until later in the weekend and early next week, when leftover energy from the persistent rains in the Southeast and Mid-Atlantic rides northward and brings an increased chance of afternoon scattered showers and thunder from Father’s Day afternoon onward in the exclusive First Alert 10-day forecast.
Clouds over Eastern New England Monday morning were the result of a cool ocean flow of air but melted away quickly for most, thanks to dry air aloft and the strongest sun angle of the year as we approach the summer solstice on Saturday. With a trend toward sunshine, the ocean flow will still have some influence on Monday’s weather as ocean temperatures are only around 60 degrees, meaning it will be hard for coastal communities to warm past the 60s while inland cities and towns eclipse 70. A cool overnight Monday night shouldn’t yield as many clouds Tuesday morning, though a few pockets are possible near the coast, with more sunshine expected Tuesday. In fact, with an upper level storm nearly stalled over the Mid-Atlantic and Southeast U.S., the shower chance remains south of New England through the week, with wind direction determining each day’s high temperatures dependent upon how much ocean wind there is on any given day. Our First Alert weather team is forecasting a southerly wind to take hold later this week, by Thursday and Friday into the weekend, delivering warmth to nearly all of the area with highs in the 80s to around 90 except on Cape Cod. As humidity slowly builds, the chance of showers and thunder gradually increases, but at this point it looks as though we may wait until Sunday afternoon for the next noteworthy chance, with heat and humidity continuing into early next week with a building chance of showers and thunder in our exclusive First Alert 10-day forecast.
Although humid air lingered in Southern New England with Cape Cod rain showers Friday morning, drier air is arriving aloft, and the combination of a light breeze and heating of the day from the sun will allow that drier air to mix down to ground level, noticeably lowering the humidity in the air as the day progresses. The slow nature of the arrival of this new air means there’s not a lot of cooling of the atmosphere going on, so temperatures will still rise into the 80s for many, making for a rare treat of low humidity and summer warmth in most spots by Friday afternoon, though the Cape may hang onto a twinge of humidity through the day. A partly cloudy sky will allow the new, dry air to cool overnight Friday night into the 40s north and 50s south, setting up a great Saturday. Earlier in the week, we carried a low chance of a Saturday afternoon shower for much of New England with an upper level disturbance moving over New England, but now it appears the air will be dry enough that any chance of a scattered shower Saturday afternoon will be confined to the far North Country of New England. Another disturbance Sunday will also be fighting dry air, along with a stabilizing wind off the ocean, meaning the chance of any pop up showers Sunday afternoon is pretty small. Next week, the trend has been for strengthening of the high pressure, or fair weather, dome moving over the Northeast United States, meaning the bulk of moisture lifting up the Eastern Seaboard will remain south of New England for much of the week, ensuring a fairly benign weather pattern with the tendency for a wind off the ocean to keep coastlines a bit cooler than the interior, but pleasant weather is expected overall. Eventually, the moisture and warmth to our south will start to push northward by week’s end, and while it’s unclear exactly how much of the moisture holds together and whether the chance of showers and thunder will rise all that much, we do expect temperatures to rise for the end of next week into next weekend in our exclusive First Alert 10-day forecast.
A stream of disturbances aloft are moving over New England Tuesday, dragging a ribbon of clouds southeast out of Canada to blot out the sun for the majority of the day, with only splashes and breaks of sun expected from time to time. The air is still comfortable, though, dry in nature which not only allows temperatures to rise well into the 70s for most but the dry air also has meant these clouds have trouble producing more than a few sprinkles in the morning and evening. Partial clearing Tuesday night will leave a blend of clouds and sun Wednesday, but the wind is likely to persist from the east and southeast, meaning the cool ocean water will influence not only immediate coastal communities, but those farther inland, as well, holding temperatures in the 70s for most and even some 60s for highs right at the beaches. The delay in switching the wind to blow form the south means the air stays fairly comfortable Wednesday, with deeper humidity and warmth waiting until that wind switch overnight Wednesday night into Thursday, when a morning shower is possible and an evening shower or thunderstorm should bubble up in the sticky air. Friday brings drier air, though, interestingly, there’s not a lot of cooling expected Friday – so, given the tendency for dry air to warm easier than humid air and expected Friday sunshine, it’s entirely possible Friday ends up warmer (and certainly should be brighter and much less humid) than Thursday’s muggy air. This weekend, the jet stream wind – the fast river of air aloft that steers disturbances and separates northern cool air from southern warmth – will be flowing through the sky directly above New England, meaning any strong enough disturbances could touch off showers. At this early juncture, our First Alert Team sees a low chance for showers later Saturday and a more elevated, moderate chance of showers Sunday, with neither day at this point looking like a washout. That said, the jet stream remains near to New England through the first half of next week, keeping an elevated chance of showers through the midweek and keeping us on guard for the potential of steadier or heavier rain if enough moisture should push north out of the Gulf of Mexico. Temperatures this time of the year should normally reach the middle to upper 70s by day and, although we’ll have some days warmer than others, we don’t see any exceptional heat or chill in our exclusive First Alert 10-day forecast.
The dramatic change of air in New England behind Saturday evening’s cold front and associated thunderstorms is palpable - dew point temperatures that measure the amount of moisture in the air have dropped from humid 60s to dry 40s. Even with the substantially drier and cooler air, scattered sprinkles and showers remain in the forecast - nowhere near as strong as Saturday’s storms - driven by the same atmospheric energy aloft that prompted yesterday’s storms, but devoid of the energy needed to become anything more than sprinkles, showers and perhaps an isolated embedded downpour from building, puffy cumulus clouds that are otherwise picturesque. A Sunday sea breeze will hold coastal community temperatures in the 60s Sunday afternoon, though inland - particularly Central and Western New England where the chance of showers is quite low - high temperatures will break 70. Skies clear Sunday night with low temperatures in the 40s and 50s, headed for a day of abundant sunshine Monday with highs in the 70s, even at the coast where a sea breeze likely waits until afternoon to kick up. Dry weather lasts through Wednesday as the wind gradually turns to blow from the south by midweek, bringing an incremental increase in temperatures each day, with daily sea breezes likely abating by Wednesday. An approaching disturbance Wednesday night and Thursday brings our next chance of scattered showers as the jet stream - the fast river of air high in the sky that steers disturbances - shifts over New England, raising the chance of showers again for the upcoming weekend, though at this point it’s too early to deem any of these days a washout, with scattered showers or thunder the more likely outcome in our exclusive First Alert 10-day forecast.
Early morning showers and thunder heralded the arrival of sticky air that will remain in New England until the passage of a cold front Saturday afternoon. For the time-being, clouds are stubborn Friday morning and midday, and won’t give way to sun in far Southern New England today…though communities farther north will find sun burning through the clouds to bump temperatures into the 80s for a warm and sticky Friday afternoon. The chance of thunder rises not so much Friday afternoon, but rather Friday evening into the first part of the night as a disturbance aloft moves through the New England sky. Fed by the humidity, these storms may actually take the unusual trend of continuing to expand and strengthen a bit even after sunset, eventually settling onto Cape Cod as rain that will last into early Saturday morning on Cape, while the rest of New England finds partial clearing particularly after midnight and some areas of fog. Saturday likely sees sunshine burning through the fog patches for another sticky and warm day – but change will be on the map in New England and moving south in the form of a well defined cold front that marks a wind shift and the start of new air. Along the wind shift – the front edge to the new air – we’ll see some showers in the far North Country of New England Saturday morning, sinking south through Northern New England during the morning and reaching the Maine coast by 2 PM…while Southern New England sees showers and embedded thunder with about 50% coverage moving from Manchester, NH, around noon to Cape Cod by 4 PM or so. Behind the cold front, a new, northerly wind will send the dewpoint temperature – the measure of the amount of moisture in the air – tumbling, and comfortable air will take over on a steady breeze Saturday evening for a comfortable night of sleeping Saturday night. The new air will be dry by nature, affording Sunday sunshine mixed with puffy, fair-weather cumulus clouds – a few of which may build just tall enough to drop a few isolated sprinkles Sunday afternoon, but nothing too impressive is expected. The comfortable air lingers through the start of next week, eventually giving way to returning warmth and humidity by week’s end with a building chance of showers and thunder toward the end of our exclusive First Alert 10-day forecast.