6:30PM

Just beyond the mid point of July, it really is still early Summer, and we’ve had some very  nice weekends so far this season. This particular weekend may not have been as nice as many of the others but it wasn’t terrible either. But now it’s time to look ahead to the coming week!

On Monday we will find ourselves under the influence of a building high pressure ridge aloft but still low pressure on an old frontal boundary east of the region over the ocean. This means fair weather but air still modified by the cooler ocean. We get rid of that and get a land breeze going Tuesday and Wednesday, which will be much warmer days, almost hot! Almost… Well it may feel  hot to many because we have not had that many hot days so far this Summer.  Will anyone reach 90? If it is going to happen this most likely day is  Wednesday, which will have a moderate westerly wind ahead of an approaching cold front and high pressure aloft. This approaching front may set off isolated thunderstorms mainly well west and north of Boston late Wednesday with a better chance of more organized shower and thunderstorm activity holding off until late Wednesday night or Thursday, depending on the timing of the cold front. This front is expected to move along enough to allow fair weather and mild to warm, drier air to dominate the end of the week. Though it may not be completely cloud-free as some cooler air will be aloft and can initiate cloud development Friday and Saturday. A larger scale trough is expected to approach from the west and the weather may go downhill again before next weekend is over.

Forecast for southeastern New England…

TONIGHT: Mostly cloudy to partly cloudy South Coast / Cape Cod. Partly cloudy to mostly clear elsewhere. Lows 55-63, coolest interior valleys. Wind light NE to N.

MONDAY: Partly cloudy to mostly sunny. Highs 72-82 from coastal to inland areas. Wind N 5-15 MPH shifting to E.

MONDAY NIGHT: Mostly clear. Lows 56-63, again cooler interior valleys. Wind light E shifting to S.

TUESDAY: Sunny. Increasing humidity. Highs 75-80 South Coast / Cape Cod, 80s elsewhere. Wind SW 5-15 MPH.

WEDNESDAY: Mostly sunny to partly cloudy. Isolated thunderstorm possible late day far NW of Boston, scattered showers/thunderstorms night. Breezy. Humid. Low 66. High 88.

THURSDAY: Partly sunny. Scattered showers/thunderstorms. Humid. Low 70. High 82.

FRIDAY: Partly cloudy. Less humid. Low 64. High 82.

SATURDAY: Mostly sunny. Low 62. High 83.

SUNDAY: Mostly cloudy. Late showers. Low 64. High 80.

10:25AM

High pressure will hold rain off this weekend, but will have a tougher battle keeping cloudiness away. Lots of high-level cloudiness will dominate today, filtering and dimming the sun. It will shine a little brighter at times as clouds are periodically thinning out as they battle high pressure and drier air from the north. Clouds will win the battle a bit more tonight into Sunday, becoming thicker, with more limited sun on Sunday morning into afternoon. The end of Sunday may turn out more like today as cloudiness starts to thin out again. At this time an area of rain from a developing low pressure are to the south is expected to stay just offshore of Cape Cod. With high pressure to the north and developing low pressure to the south, the air flow will be easterly, which will keep coastal areas the coolest, but also preventing inland areas from getting too warm, though it will be comfortable.

High pressure takes over for the first part of next week with more sun and warmer to hotter air moving in. By Wednesday, an approaching front and low pressure trough may set off a few thunderstorms, with more activity likely by Thursday as the front moves through. This front may be slow to exit late next week so a low confidence forecast will have some lingering cloudiness and perhaps a shower in it for Friday, but this may change.

Updated forecast for southeastern New England…

TODAY: Lots of high cloudiness – filtered to dim sun. Highs 72-77 coast, 78-83 inland. Wind light SE to E.

TONIGHT: Mostly cloudy. Lows in the 60s. Wind light E to variable.

SUNDAY: Mostly cloudy with middle cloudiness hiding sun much of time but thinning out later for a little more sun at least interior MA and southern NH later in the day. Highs in the 70s. Wind E up to 10 MPH.

MONDAY: Partly cloudy. Low 62. High 82.

TUESDAY: Mostly sunny. Low 66. High 88.

WEDNESDAY: Partly sunny. Isolated PM t-storms. Low 69. High 89.

THURSDAY: Mostly cloudy. Scattered showers/t-storms. Low 66. High 82.

FRIDAY: Variably cloudy. Isolated showers. Low 62. High 78.

7:38AM

Quick update.

High pressure today – beautiful summer day. Low pressure to the south will get a little closer than previously anticipated, but it will not ruin the weekend. It will add some cloudiness to it, especially Sunday, along with a risk of some wet weather over Cape Cod at that time.

Next week looks a little more typical of mid to late July as high pressure strengthens, adds some heat, and a cold front tries to knock it back down bringing a risk of thunderstorms again by the middle of the week.

Forecast for southeastern New England…

TODAY: Mostly sunny. Highs 70s  Cape Cod and immediate coast, 80-85 elsewhere. Wind light NW early then variable with coastal sea breezes.

TONIGHT: Mostly clear. Lows in the 60s. Wind light SE to S.

SATURDAY: Sunshine becoming filtered by increasing high cloudiness. Highs 70s Cape Cod and South Coast, 80-85 elsewhere. Wind light SE to S.

SATURDAY NIGHT: Mostly cloudy. Lows 60-65. Wind light SE.

SUNDAY: Mostly cloudy. Risk of some rain Cape Cod / Islands. Highs in the 70s. Wind SE to E 5-15 MPH.

MONDAY: Partly cloudy. Low 60. High 80.

TUESDAY: Mostly sunny. Low 64. High 89.

WEDNESDAY: Partly cloudy. Isolated PM t-storms. Low 68. High 90.

THURSDAY: Partly sunny. Risk of showers/t-storms. Low 68. High 84.

9:18PM

After a few eventful days with areas of tropical downpours and some localized severe weather, a cold front is finally, slowly, about to push offshore. A final wave of low pressure sliding up along the front from south to north will prolong showers over Cape Cod tonight. But starting Thursday, and likely lasting into early next week, high pressure will dominate, along with lower humidity Thursday-Friday, and low to moderate humidity over the weekend and early next week. We will have to watch a potential area of low pressure just to the south around Monday, in case it ends up a little further north than currently anticipated. But this forecast will take an optimistic route, and you’ll find a whole lot of nice weather in it.

And here it is, for southeastern New England…

TONIGHT: Lots of clouds, with some lingering showers Cape Cod. Slowly drying out but remaining humid over Cape Cod. Lows in the 50s well inland, 60s near the coast. Wind light N to NW.

THURSDAY: Early clouds Cape Cod, otherwise mostly sunny to partly cloudy with some pop up fair weather clouds. Less humid all areas. Highs middle 70s inland hills and Cape Cod to around 80 elsewhere. Wind NW 5-15 MPH.

THURSDAY NIGHT: Mostly clear. Lows middle 50s inland valleys to lower 60s coast. Wind light NW.

FRIDAY: Mostly sunny. Highs 75-80 Cape Cod, 80-85 elsewhere. Wind variable up to 10 MPH.

SATURDAY: Mostly sunny. Low 63. High 83.

SUNDAY: Partly cloudy. Low 63. High 83, cooler coast.

MONDAY: Partly sunny. Low 64. High 81, cooler coast.

TUESDAY: Partly cloudy. Low 64. High 84.

WEDNESDAY: Mostly sunny. Low 65. High 85.

11:33PM

Tropical air dominates ahead of a slow-moving cold front which will take until late Wednesday to clear southeastern New England. Until then, the threat of showers/downpours and some thunderstorms will continue. A cluster of showers/storms including some downpours will move south southwest to north northeast across parts of the region overnight, but during the day Tuesday only a few pop ups or small clusters of this activity is expected, as a more solid line of convection organizes well to the west. This line brings the best chance of severe storms into western New England during the afternoon, but signs suggest that this line will weaken and start to fall apart as it moves into southeastern New England during the evening of Tuesday. It will have to wait for another impulse coming up along the front to re-energize and bring a final around of downpours for Wednesday morning, impacting the commute. This wet weather may linger through the afternoon over Cape Cod but a drying trend should take place elsewhere as the front begins to push offshore. A shot of modified cool air will arrive late Wednesday into Thursday as the humidity breaks. A warm up will follow on Friday and Saturday as high pressure re-positions itself south of the region. By the middle and end of the weekend, clouds and an eventual shower threat is expected as more tropical moisture returns around the back side of this high pressure area, aided by an approaching low pressure trough from the west.

Updated forecast for southeastern New England…

OVERNIGHT: Mostly cloudy. Showers likely, downpours and thunderstorms possible. Muggy. Lows 65-70. Wind S 5-15 MPH.

TUESDAY: Variably cloudy. Pop up showers and thunderstorms with local heavy downpours. Many areas rain-free much of the time. Muggy. Highs 77-85. Wind S to SW 10-20 MPH.

TUESDAY NIGHT: Mostly cloudy. Showers and thunderstorms moving in from the west but becoming weaker and less numerous while pushing eastward through midnight, then increasing again from southwest to northeast overnight with more widespread downpours possibly by dawn. Muggy. Lows 65-70. Wind variable to SSW 10-15 MPH.

WEDNESDAY: Mostly cloudy with showers/downpours and embedded thunderstorms morning-midday most areas, midday-afternoon Cape Cod. Breaking clouds from the west later. Humid. Highs in the 70s. Wind variable 5-15 MPH with higher gusts, mostly from the S trending to W.

THURSDAY: Partly cloudy. Low 55. High 79.

FRIDAY: Mostly sunny. Low 60. High 82.

SATURDAY: Partly sunny. Low 65. High 85.

SUNDAY: Mostly cloudy. Chance of showers. Low 65. High 80.

MONDAY: Mostly cloudy. Chance of showers/thunderstorms. Low 65. High 78.

12:03AM

A frontal system will sit over the region Monday through early Wednesday, finally scooting eastward and offshore during Wednesday. This front separates tropical air flowing up from the south ahead of it from cooler and drier air behind it, including some unseasonably cool air that will be moving southward out of Canada into the upper Midwest. This air will arrive in modified form later Wednesday into Thursday, but before that we’ll have to deal with occasional downpours and thunderstorms. Though widespread severe weather is not likely, some individual thunderstorms could be strong to severe with anything ranging from flash flooding to hail to damaging wind. Again this activity should not be widespread, but all should keep up to date on conditions over the next few days.

Fair weather should arrive by late Wednesday and especially Thursday into late week, with a gradual warming trend following the cool shot. By later next weekend, we may be back into another unsettled weather system with clouds and a shower threat.

Forecast for southeastern New England…

OVERNIGHT: Mostly cloudy. A few showers and an isolated thunderstorm possible. Humid. Lows in the 60s. Wind SW to S 10-20 MPH.

MONDAY: Variably to mostly cloudy. Episodes of showers and thunderstorms. Some storms may be strong to locally severe. Humid. Highs upper 70s to middle 80s. Wind S 10-20 MPH.

MONDAY NIGHT: Mostly cloudy. Showers and thunderstorms, some possibly strong. Muggy. Lows 65-70. Wind S 10-20 MPH.

TUESDAY: Variably cloudy. Scattered showers and thunderstorms. Any storms may be strong. Muggy. Highs 78-85. Wind S 10-20 MPH and gusty.

WEDNESDAY: AM showers / PM breaking clouds. Low 64. High 76.

THURSDAY: Partly cloudy. Low 58. High 79.

FRIDAY: Mostly sunny. Low 59. High 83.

SATURDAY: Partly cloudy. Low 64. High 84.

SUNDAY: Mostly cloudy. Chance of showers. Low 66. High 82.

7:55PM

First, the weekend. Short and to the point. High pressure will be in control Saturday and it will be a wonderful Summer day. On Sunday, it will start very nice but a disturbance rapidly approaching from the west leading humidity back into the region will bring increasing clouds and an eventual risk of some rain from west to east in the afternoon and evening. It won’t turn out to be a wash-out, but some areas are likely to get wet before the end of the day. If the timing of this disturbance is slower than I expect right now, we’ll salvage most of Sunday rain-free. Greatest chance of a completely dry day will be from Rhode Island and far southeastern MA through Cape Cod.

Next week? Spare me the drama. Ok, yes there will be a somewhat significant trough of low pressure which includes an closed upper level low pressure area somewhat resembling the infamous “polar vortex” of this winter-past. But don’t let the media’s depiction of this slightly anomalous feature (for July) get to you. These features do occur in Summer, and one will take place next week, setting up a chilly outbreak of air, in comparison to average, coming out of Canada into the Midwest, eventually making its way to the Northeast in modified form. Before that happens, there will be a clash of air masses, with that cool air advancing in from Canada clashing with the warm/humid air that will be lead in by  Sunday’s approaching disturbance. This will set up a chance of showers and thunderstorms in the Monday-Wednesday period. This far out, it’s impossible to time these and also nearly impossible to predict the intensity of showers/storms. Suffice it to say, there is some risk for significant rain and even some severe weather, but I’m not going to alarm anybody this far out by predicting some giant long lasting event of severe storms and flooding. I’ll watch the potential as it gets closer and update accordingly.

By late next week, we should go from a dry/cool day Thursday to a dry/warmer day  Friday as things move along in the atmosphere.

Forecast for southeastern New England…

TONIGHT: Any scattered clouds vanish with a clear sky and bright full moon. Lows 55-64, coolest interior valleys, mildest urban areas. Wind light variable.

SATURDAY: Sunny. Highs 70s South Coast & Cape Cod, 80-85 elsewhere. Wind S 5-15 MPH.

SATURDAY NIGHT: Mostly clear. Lows 58-66. Wind S under 10 MPH.

SUNDAY: Mostly sunny start then increasing clouds west to east. Chance of light rain or showers by mid to late afternoon especially north and west of Boston. Highs 70s  South Coast & Cape Cod, 80-85 elsewhere. Wind S to SW 10-20 MPH.

MONDAY: Mostly cloudy. Numerous showers/thunderstorms. Low 68. High 82.

TUESDAY: Variably cloudy. Scattered showers/thunderstorms. Low 67. High 83.

WEDNESDAY: Partly sunny. Isolated showers/thunderstorms. Low 66. High 80.

THURSDAY: Partly cloudy. Low 54. High 75.

FRIDAY: Mostly sunny. Low 59. High 83.

7:18AM

A final round of thunderstorms held together late Wednesday night to bring a brief soaking, some gusty wind, vivid lightning, and big thunder rumbles to areas of north central and northeastern MA and southern NH. The front responsible for this is now settling just offshore and will be located fairly close to the coast through early Friday. A couple of low pressure waves moving up along the front will likely remain far enough east to keep most wet weather offshore (except Nantucket this morning), but some cloudiness may slide up across the area, especially southeastern MA including Cape Cod, at times through early Friday. The front will finally push far enough east for all areas to enjoy a fantastic Saturday with lots of sun and warm air as high pressure dominates. This will quickly give way to a disturbance approaching from the west on Sunday, which will bring clouds and eventually a chance of showers. Unsettled and more humid weather is expected Monday and Tuesday as a broad trough approaches from the west. A shot of unseasonably cool air will be moving out of Canada into the north central US during this time and some of that air is due by the middle of next week here in the Northeast.

Updated forecast for southeastern New England…

TODAY: Clouds southeastern MA and RI especially morning-midday including showers Nantucket, with more sun to the northwest, then mostly sunny afternoon. Highs upper 70s to middle 80s. Wind NW 5-15 MPH.

TONIGHT: Clouds return to southeastern  MA, mostly clear to the northwest. Lows upper 50s to middle 60s. Wind N under 10 MPH.

FRIDAY: Clouds depart southeastern MA morning, otherwise mostly sunny. Highs upper 70s to middle 80s. Wind variable up to 10 MPH with coastal sea breezes.

SATURDAY: Sunny. Low 64. High 84, cooler coast.

SUNDAY: Increasing clouds. PM showers possible. Low 64. High 81.

MONDAY: Mostly cloudy. Scattered showers/thunderstorms. Low 66. High 80.

TUESDAY: Mostly cloudy. Scattered showers/thunderstorms. Low 64. High 80.

WEDNESDAY: Partly sunny. Low 58. High 76.

5:17PM

A very warm to hot, humid southwesterly flow will continue through Wednesday. A trough will bring a risk of showers and thunderstorms as it moves west to east across the region in the early hours of Wednesday, then a cold front will slide across the area from west to east Wednesday night with less fanfare, but still a risk of a few showers and thunderstorms. The front will be a little sluggish to get too far off the coast so we’ll have to watch for a wave of low pressure on it that may throw some clouds back over the region Thursday night or Friday morning, especially southeastern areas (Cape Cod, southeastern MA). But during Thursday and into the weekend some nicer air will dominate with warm temperatures and lower humidity.

Forecast for southeastern New England…

EVENING: Partly cloudy and hazy. Slight chance of isolated showers and thunderstorms. Most areas rain-free. Humid. Temperatures falling through the 80s. Wind SW 10-20 MPH.

OVERNIGHT: Variably cloudy. Scattered showers and thunderstorms, a few possibly heavy. Muggy. Lows upper 60s to middle 70s. Wind SW 5-15 MPH, gusty near storms.

WEDNESDAY: Mostly cloudy with any showers and thunderstorms exiting early morning. Partly sunny and hazy afternoon. Highs near 80 South Coast/Cape Cod, middle 80s to lower 90s elsewhere. Wind SW 10-20 MPH with higher gusts.

WEDNESDAY NIGHT: Variably cloudy and hazy with isolated showers/thunderstorms early. Partly cloudy overnight. Humid early, drying out late. Wind SW 5-15 MPH shifting to NW.

THURSDAY: Mostly sunny to partly cloudy. Highs upper 70s to middle 80s. Wind W 5-15 MPH.

FRIDAY: Clouds SE early otherwise mostly sunny. Low 60. High 82.

SATURDAY: Sunny to partly cloudy. Low 62. High 86.

SUNDAY: Partly to mostly cloudy. Chance of showers PM. Low 66. High 82.

MONDAY: Mostly cloudy. Chance of showers. Low 64. High 78.

TUESDAY: Cloudy. Chance of showers. Low 64. High 74.

7:20AM

Disturbance moves through this morning with clouds but no rain. A warm and humid southwesterly flow becomes established by tonight and lasts through Wednesday with a few fronts trying to push through. This combination will result in thunderstorm chances at times from tonight through Wednesday. Drier air should arrive during Thursday and remain into the start of the weekend before the next trough approaching from the west returns unsettled weather to the region later in the weekend.

More detail in the next post.

Forecast for southeastern New England…

TODAY: Lots of clouds morning, more sun afternoon, clouds return evening. Highs in the 80s, some 70s South Coast/Cape Cod. Wind SW increasing to 10-20 MPH with higher gusts.

TONIGHT: Variably cloudy. Slight chance of showers/thunderstorms. Lows 65-70. Wind SW 5-15 MPH.

TUESDAY: Partly sunny. Isolated to scattered showers/thunderstorms mainly afternoon. Highs middle 80s to lower 90s. Wind SW 10-20 MPH.

WEDNESDAY: Variably cloudy. Episodes of scattered showers/thunderstorms. Low 69. High 86.

THURSDAY: Partly cloudy. Low 62. High 83.

FRIDAY: Mostly sunny. Low 61. High 82.

SATURDAY: Mostly sunny. Low 65. High 85.

SUNDAY: Mostly cloudy. Chance of showers/thunderstorms. Low 68. High 86.

11:41AM

Just a forecast update. Full discussion tonight with The Week Ahead post.

THIS AFTERNOON: Sunny. Highs 78-85. Wind W 10-20 MPH.

TONIGHT: Clear. Lows in the 60s. Wind WSW 5-15 MPH.

MONDAY: Sunny start, variably cloudy finish, chance of showers/thunderstorms at night. Highs in the 80s. Wind SW 10-20 MPH>

TUESDAY: Partly cloudy. Isolated to scattered showers/thunderstorms mainly afternoon. Low 66. High 88.

WEDNESDAY: Variably cloudy. Episodes of showers/thunderstorms, mainly morning. Low 68. High 82.

THURSDAY: Partly cloudy. Isolated showers/thunderstorms, mainly afternoon. Low 63. High 81.

FRIDAY: Mostly sunny. Low 64. High 84.

SATURDAY: Mostly sunny. Low 63. High 83.

10:25AM

With the midweek bout of heat and humidity, the severe thunderstorms, and the heavy rain and areas of flooding associated with the passage of Hurricane Arthur all behind us (except for recovery in southeastern MA where some of the flooding was very significant), it’s time to look ahead to the remainder of the “Fourth of July” Weekend.

As the cyclone that was once Arthur moves away, now without tropical characteristics, its wind field has expanded as it typical of these storms, and up against high pressure building in from the west, we have a tightened pressure gradient which translates to a gusty wind for today. This will keep up into the afternoon before diminishing by evening. So you may need some help keeping your cookout stuff from blowing off the tables outside. A benefit of this air flow is the transportation of refreshing air into the region. But lingering moisture on the ground from yesterday’s rain will be heated by the sun, rise skyward, and will result in some pop up fair weather clouds that will share the sky with the sun midday and afternoon. Once we get to Sunday, high pressure sinks to the south of the region, the remains of Arthur are long gone, and we’re into a dry and warmer westerly air flow. We should see about 100% of the possible on on Sunday – a great day to end the weekend.

Looking into next week, humidity comes back Monday through Wednesday, and it gets a little hotter, but not majorly so. A frontal system wavering around in the vicinity late Monday through Wednesday will result in opportunities for showers and thunderstorms from Monday night through Wednesday, but expect it to be rain-free the majority of the time. By Thursday-Friday, drier air should win out as high pressure returns to the Northeast.

Detailed forecast for southeastern New England…

THIS AFTERNOON: Sun  mixed with passing clouds. Highs 75-82. Wind NW 10-20 MPH, gusting as high as 30 MPH, diminishing late.

TONIGHT: Partly cloudy early, then clear. Lows 55-60 except 60-65 coast and urban areas. Wind W up to 10 MPH.

SUNDAY: Sunny. Highs 78-85. Wind W 10-20 MPH.

MONDAY: Sunny start, variably cloudy finish, chance of showers/thunderstorms at night. Low 62. High 87.

TUESDAY: Partly cloudy. Isolated to scattered showers/thunderstorms mainly afternoon. Low 66. High 88.

WEDNESDAY: Variably cloudy. Episodes of showers/thunderstorms, mainly morning. Low 68. High 82.

THURSDAY: Partly cloudy. Low 63. High 81.

FRIDAY: Mostly sunny. Low 64. High 84.

1:04PM

Hurricane Arthur is attempting to take over the day but nothing takes away from the fact that it’s the birthday of the United States of America! Happy Birthday!

Arthur is weakening while accelerating northeastward and will pass just southeast of Cape Cod tonight as a category 1 hurricane. As previously mentioned, heavy rain will be the main impact of the system, 1-3 inches in most of the area but 3+ inches possible in some parts of east coastal MA/NH, but especially southeastern MA including Cape Cod. Strongest winds remain offshore, but tropical storm force wind gusts are possible over Cape Cod and the Islands. The best chance for gusts of wind at or above 40 MPH will be from the Cape Cod Canal eastward with a risk of 50 MPH gusts on the Outer Cape and Nantucket. Arthur’s rain scoots out rapidly from west to east overnight tonight followed by clearing. This sets up a fantastic weekend with warm and dry air dominating both Saturday and Sunday. The warmest of the 2 days will be Sunday. There may be some fair weather clouds popping up Saturday as the air above will be slightly cooler and there will be moisture left behind on the ground for the sun to heat up. Sunday will probably be 100% sunny.

Next week, warm, muggy, periods of thunderstorms as we get into a Summery southwesterly flow and a frontal system tries to press into the region from the northwest.

Updated forecast for southeastern New England…

THIS AFTERNOON: Cloudy. Showers/rain and embedded thunderstorms becoming widespread, heavy at times. Muggy. Highs in the 70s. Wind variable 5-15 MPH but becoming NE to N 15-25 MPH with higher gusts Cape Cod and the Islands.

TONIGHT: Cloudy with rain and embedded thunderstorms, heavy at times especially east coastal MA through Cape Cod, ending west to east overnight followed by rapid clearing. Humid. Lows in the 60s. Wind N to NW 5-15 MPH inland, 15-30 MPH coast, gusts 40 MPH or higher possible Cape Cod and Nantucket.

SATURDAY: Clouds Cape Cod at dawn then clearing. Sunny start elsewhere, then some fair weather clouds popping up for a mix of sun and clouds before they dissipate late day. Highs 75-83. Wind NW 10-20 MPH with higher gusts.

SATURDAY NIGHT: Mostly clear. Lows 55-62. Wind NW 5-15 MPH, diminishing.

SUNDAY: Sunny. Highs 83-88 except cooler Cape Cod. Wind W 5-15 MPH.

MONDAY: Mostly to partly sunny. Chance of showers/thunderstorms evening and night. Low 64. High 87.

TUESDAY THROUGH THURSDAY: Partly sunny. Daily risk of showers/thunderstorms. Lows in the 60s. Highs in the 80s.

8:38AM

The tropics chose to get active early in the season and the result is Arthur, which will pass just southeast of southern New England as a strong tropical storm or more likely a category 1 hurricane on the evening of Independence Day, forcing many changes to plans to celebrate this birthday. The problems will come in 2 forms: 1) Heavy rain that will result from tropical moisture interacting with a slow-moving cold front, and 2) Gusty winds over Cape Cod and the Islands which will be closest to the storm center as it passes. The time frame for the heaviest rain is  Friday afternoon and evening from the Boston area southeastward through Cape Cod. The strongest wind would take place Friday night, again confined mainly to the Cape & Islands region. But let’s back up a bit. Before that, we have another muggy and very warm day for today, and with the approaching slow-moving frontal boundary, scattered showers and thunderstorms can erupt any time from midday on. These will be mostly scattered or in clusters, so while it is possible that some areas escape them, anywhere that does see activity can experience a strong thunderstorms with torrential downpours and possible flooding. With a little luck, as far as eastern MA and RI and the NH Seacoast is concerned, any activity will lift to the north and push back a bit to the northwest in the evening, allowing a better chance to get fireworks displays completed in the cities/towns that are holding them, Boston included. Once we get beyond that threat and the Friday “fun”, drier and warm air will spill in from the west making for a fabulous weekend (Saturday-Sunday).  Some heat and humidity returns early next week but is quickly broken by another cold front and a risk of showers/thunderstorms later Monday and especially Tuesday. Drier air arrives by the middle of next week.

Updated forecast for southeastern New England…

TODAY: Sun & clouds. Muggy. Scattered showers and thunderstorms possible any time from 11AM on. Highs upper 70s South Coast, 80s elsewhere. Wind S 5-15 MPH.

TONIGHT: Mostly cloudy. Areas of fog especially South Coast & Cape Cod/Islands. Cluster or line of showers/thunderstorms may form in east central MA into southern NH but should remain west of the Boston area where only isolated showers/storms are possible. Activity diminishing late. Humid. Lows in the 60s to around 70. Wind S 5-15 MPH.

FRIDAY: Cloudy. Rain and embedded thunderstorms redeveloping from SW to NE during the morning-midday, heaviest during the afternoon-evening especially in a band along and E of I-495. Humid. Highs in the 70s. Wind variable up to 10 MPH, becoming N 5-15 MPH most areas but 15-25 MPH with possible stronger gusts over Cape Cod.

FRIDAY NIGHT: Cloudy. Rain/thunderstorms especially southeastern NH, eastern MA, RI early, ending west to east, lastly over Cape Cod. Patchy fog. Humid. Lows in the 60s. Wind N to NW 5-15 MPH except 15-25 MPH Cape Cod.

SATURDAY: Clouds and a shower possible Cape Cod early, clearing at dawn elsewhere. Clearing Cape Cod and mostly sunny to partly cloudy elsewhere midday. Mostly sunny afternoon. Drier. Highs 75-80 Cape Cod, 80-85 elsewhere. Wind NW to W 10-20 MPH.

SATURDAY NIGHT: Clear. Lows middle 50s to lower 60s. Wind W 5-15 MPH.

SUNDAY: Sunny. Highs in the 80s, 70s Cape Cod. Wind W 5-15 MPH.

MONDAY: Partly cloudy. Isolated showers/thunderstorms. Low 66. High 88.

TUESDAY: Partly sunny. Scattered showers/thunderstorms. Low 68. High 87.

WEDNESDAY: Mostly sunny. Low 64. High 82.

9:43PM

The middle month of Meteorological Summer is underway, and starts with several important days for outdoor activity leading up to and through the Fourth of July Weekend. Weather, always critical to plans, becomes even more so during such a period. Instead of launching into a marathon-read, I’ll get to the point with what I expect to take place through the week and into early next week.

We’ve established a very warm, humid southwesterly flow which will last into Thursday. A cold front will approach from the west and slow down through Thursday then slowly slide across the region early Friday. Timing and positioning of this front will be the big decider of what happens here. In addition, the forecast of Tropical Storm Arthur (possibly even a minimal hurricane) is critical. This early-season tropical system is expected to move northward from the US Southeast to Middle Atlantic Coast through Thursday then turn northeast and accelerate  into the waters just southeast and east of New England during Friday (Independence Day). What hasn’t changed with the thinking is that Arthur will stay just far enough offshore to only impact Cape Cod and the Islands with some rain and a gusty breeze for a while, with little or no impact elsewhere. What has changed a little bit is that I now feel that the cold front will stall for a while to the northwest of the Boston area. This front, which will set off scattered thunderstorms well to the west and northwest of Boston Wednesday afternoon, will do the same again Thursday and again they may remain well to the west, finally ambling across the region from west to east in weakened form later Thursday night and early Friday. This is a touchy and uncertain part of the forecast and will be monitored. Many towns have fireworks displays and other celebrations on July 3, so this forecast is important. Regardless of the front and Arthur, it appears we’ll end up with a wonderful couple days of weather Saturday and Sunday, seasonably warm and dry, with lots of sun both days. Heat returns early next week along with a thunderstorm threat as the next front approaches.

Forecast for southeastern New England…

OVERNIGHT: Partly cloudy. Mild and muggy. Lows 65-73. Wind SW 5-15 MPH.

WEDNESDAY: Partly cloudy and hazy. Hot and humid. Highs 77-85 South Coast, 86-92 elsewhere Wind SW 10-15 MPH gusting 20-25 MPH.

WEDNESDAY NIGHT: Partly cloudy and hazy. Warm and humid. Lows 66-74. Wind SW 5-15 MPH.

THURSDAY: Partly sunny. Isolated showers and thunderstorms. Greater chance of showers/storms north central MA and south central NH late day or evening, pushing eastward later at night. Warm and muggy. Highs 70s  South Coast/Cape Cod, 80s elsewhere. Wind SW to S 10-20 MPH.

FRIDAY – INDEPENDENCE DAY: Cloudy start with showers/rain southeastern MA. Clearing trend west to east afternoon. Lows 65-70. Highs 80-85 except 70s Cape Cod.

SATURDAY: Sunny to partly cloudy. Lows 60-65. Highs 80-85.

SUNDAY: Mostly sunny. Lows 63-68. Highs 83-88.

MONDAY: Partly cloudy. Lows 65-70. Highs 85-90.

TUESDAY: Partly sunny. Scattered showers/thunderstorms. Lows 70-75. Highs 85-90.