7:39AM

We became a meso-scale weather lab experiment on Monday as cool outflow air from thunderstorms exiting Maine into the Atlantic pushed southward as a back-door frontal boundary and moved into southern NH and much of eastern MA, popping some showers and thunderstorms in the process. This boundary cooled coastal areas off from around 80 to near 70, 60s in some cases, while areas well southwest of Boston remained very warm. This boundary which has now cooled off most of the region and even notched-down the humidity (though it is still technically humid) will hang around the region and fall apart today, being only a minor focus for development of showers. We’ll have to wait for another boundary, a warm front, to push through the region early Wednesday, with showers and thunderstorms, introducing very muggy air back to the region from mid into late week. Additional showers/storms are expected Thursday-Friday as a cold front moves into the region from the west and slows down. Its too early to tell how soon this will get out of here, but there is optimism for at least part of the weekend being better.

Updated forecast for southeastern New England…

TODAY: Mostly cloudy to partly sunny. Isolated showers. Highs 70 coast to 80 far inland. Wind light E becoming variable.

TONIGHT: Mostly cloudy. Patchy fog. Showers mainly south and west of Boston late. Lows in the 60s. Wind light variable to SE.

WEDNESDAY: Variably cloudy. Episodes of showers and thunderstorms. Highs upper 70s to middle 80s. Wind S to SW 10-20 MPH.

THURSDAY: Showers and thunderstorms likely. Low 66. High 85.

FRIDAY: Showers and thunderstorms possible. Low 68. High 82.

SATURDAY & SUNDAY: Isolated showers and thunderstorms. Lows 60-68. Highs 78-88.

MONDAY: Sunny. Low 66. High 88.

9:36PM

The heatwave that impacted parts of the region from as early as Wednesday through Sunday is done, but the humid pattern is not going anywhere during the coming week. Though a weak trough will dominate, this trough sits between a ridge to the west and a rebuilding ridge in the western Atlantic, and with no real push of dry air available from Canada, the humidity level will remain rather high right through the next 7 days. It won’t be as hot because of the lack of ridging and limited sunshine through at least the end of the work week. By sometime next weekend, another retrogression or westward movement of high pressure from the Atlantic may heat the region up again. Some signs point to another potential heatwave resulting but not until sometime the following week. We’ll also be eyeing an early-season system in the tropics for development and eventual track.

In the mean time, the updated forecast for southeastern New England goes something like this…

OVERNIGHT: Variably cloudy. Patchy fog valley and swampy areas. Humid. Lows in the 60s to lower 70s, warmest in urban centers. Wind light variable.

MONDAY: Variably cloudy. Showers and thunderstorms developing mid to late afternoon. Humid. Highs 80-85 except 70s South Coast. Wind S to SW 10-15 MPH, higher gusts.

MONDAY NIGHT: Mostly cloudy. Showers and thunderstorms likely early then diminishing. Patchy fog redeveloping. Muggy. Wind light SW to W.

TUESDAY: Partly sunny. Slight chance of afternoon showers or thunderstorms. Humid. Highs upper 70s to middle 80s. Wind W 5-15 MPH.

WEDNESDAY: Partly sunny. Scattered showers/thunderstorms. Low 66. High 84.

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

FRIDAY: Mostly cloudy. Scattered showers/thunderstorms. Low 68. High 81.

SATURDAY: Variably cloudy. Scattered showers/thunderstorms. Low 66. High 83.

SUNDAY: Partly cloudy. Low 67. High 88.

11:44AM

The high pressure ridge that pushed most of the storms back to the west of the WHW forecast area of southern NH, eastern MA, and RI, will start to flatten this weekend, still keeping us in the ongoing heatwave, but allowing a slightly greater risk that a few showers and storms could get into the area. The ridge will weaken and retrograde further to the west during the coming week, as a new ridge re-builds in the western Atlantic. This will leave our area in a weak area of troughing that will bring increase shower and thunderstorm activity, less heat (80s instead of 90s), but continued humidity.

Updated forecast for southeastern New England…

TODAY: Partly cloudy. Isolated late day thunderstorms. Highs 92-97 except 80s to around 90  South Coast, Cape Cod, and Islands. Wind W 10-20 MPH.

TONIGHT: Partly cloudy. Isolated showers or thunderstorms early. Lows upper 60s to middle 70s. Wind W 5-15 MPH.

SUNDAY: Partly sunny. Scattered afternoon thunderstorms. Highs 90-95 except 80s South Coast, Cape Cod, and Islands. Wind W to SW 10-20 MPH.

MONDAY THROUGH FRIDAY: Daily episodes of scattered showers and thunderstorms. Lows 65-72. Highs in the 80s.

7:31AM

Happy Birthday USA!

This is just a carry-forward of yesterday’s forecast, getting rid of old info. Discussion on previous entry is the same. Have a safe and happy 4th of July everyone!

TODAY – INDEPENDENCE DAY: Partly cloudy. Slight chance of isolated afternoon to early evening thunderstorms north and west of  Boston. Humid. Highs from around 80 South Coast to around 90 elsewhere. Wind SW 5-15 MPH.

TONIGHT: Partly cloudy. Muggy. Lows upper 60s to lower 70s. Wind SW up to 10 MPH.

FRIDAY: Mostly sunny. Humid. Highs upper 80s to lower 90s, cooler South Coast. Wind SW to W 5-15 MPH.

SATURDAY & SUNDAY: Isolated PM thunderstorms. Lows 65-75. Highs 85-95.

MONDAY & TUESDAY: Scattered PM thunderstorms. Lows 65-75. Highs 85-95.

9:21AM

The outline from a few days ago is basically the same. Retrogression of high pressure from the western Atlantic will continue and eventually merge with high pressure from over the southern USA to form a large flat ridge of  high pressure, creating a hot weather pattern that will last well into next week. A little house-cleaning details are being taken care of today before this really gets underway. The back-door cold front that cooled off and in some cases fogged up parts of southern NH and eastern MA is heading back northeastward as a warm front and that cooler maritime air will be a distant memory in a short time. The thunderstorm threat is also diminishing, though we cannot rule out pop up storms from time to time in this pattern. For the next few days, the most likely place to see them would be across interior MA and southern NH in the late afternoon to early evening. Plan on mainly rain-free, very warm to hot, humid conditions. The most cloud cover will probably exist today, as the high pressure ridge continues to push the tropical moisture belt that had been over the region back to the west.

Updated forecast for southeastern New  England (southern NH, eastern MA, and RI)…

THIS AFTERNOON: Variably cloudy. Isolated showers and thunderstorms. Highs upper 70s South Coast to 80s elsewhere. Humid. Wind SW 10-15 MPH, gusting 20-25 MPH.

TONIGHT: Partly cloudy. Muggy. Lows in the 60s. Wind SW 5-15 MPH.

THURSDAY – INDEPENDENCE DAY: Partly cloudy. Slight chance of isolated afternoon to early evening thunderstorms north and west of  Boston. Humid. Highs from around 80 South Coast to around 90 elsewhere. Wind SW 5-15 MPH.

THURSDAY NIGHT: Partly cloudy. Muggy. Lows upper 60s to lower 70s. Wind SW up to 10 MPH.

FRIDAY: Mostly sunny. Humid. Highs upper 80s to lower 90s, cooler South Coast. Wind SW to W 5-15 MPH.

SATURDAY & SUNDAY: Isolated PM thunderstorms. Lows 65-75. Highs 85-95.

MONDAY & TUESDAY: Scattered PM thunderstorms. Lows 65-75. Highs 85-95.

12:51AM

Before I update the coming weather, a quick look back at the surprise “severe weather outbreak” of Monday. I put it in quotes, because it was not a severe outbreak in the classic sense. What these storms were made of was low level wind sheer. The storm tops were not very high. They were not typical storms, producing large hail and widespread damaging winds. Lightning was sparse at best. These storms were more like what you might see in a land-falling tropical storm, producing relatively weak spin ups (very brief and weak tornadoes), still capable of producing damage, however.

The set-up that caused this will still exist today (Tuesday), and though storms and showers may be a little less numerous overall, we will still have to watch for the possibility of isolated flooding downpours and isolated tornadoes and/or micro bursts in rapidly-developing tropical showers and storms. A very warm and humid tropical air flow will provide plenty of fuel for this.

As we have been discussing, the retrogression (westward movement) of the ridge of high pressure in the western Atlantic Ocean is underway and will continue through this week. After today, it means a decrease in thunderstorm activity, coverage-wise, though the threat will still exist at times, mainly in isolated form. It also means an increase in heat, and a continuation of humidity. This will include the Independence Day holiday and through the extended weekend following it. Anybody with outdoor plans should take precautions to stay protected from the sun, stay hydrated, and watch for any thunderstorms that develop or move into the region.

Updated forecast for southeastern New England (RI, eastern MA, southern NH)…

TODAY: Mostly cloudy with scattered to numerous showers and embedded thunderstorms. Isolated storms may produce damaging wind and local flash flooding. Very humid. Highs middle 70s South Coast to 80-85 interior areas. Wind SW 10-20 MPH.

TONIGHT: Mostly cloudy. Areas of fog. Lingering showers becoming isolated then ending. Very humid. Lows middle 60s to 70. Wind SW 5-15 MPH.

WEDNESDAY: Mostly cloudy with patchy fog early, then partly sunny. Isolated to scattered thunderstorms during the afternoon. Humid. Highs upper 70s to middle 80s. Wind SW 5-15 MPH.

THURSDAY – INDEPENDENCE DAY: Partly cloudy. Isolated thunderstorms mainly late day and early evening favoring far northern MA and southern NH. Low 70. High 87.

FRIDAY: Partly cloudy. Isolated late-day thunderstorms. Low 70. High 90.

SATURDAY: Mostly sunny. Isolated late-day thunderstorms. Low 71. High 91.

SUNDAY: Mostly sunny. Isolated late-day thunderstorms. Low 70. High 90.

MONDAY: Sunny. Low 69. High 88.

2:08AM

With no major changes to the forecast, this is basically a re-issue of the last blog with tweaks for timing and a few added details, and of course updated for the time period.

2:30AM

Here is my best guess at the weather pattern and resultant day-by-day weather through the first week of July, including the Independence Day holiday (and 2 weekends either side of it).

The battle between a high pressure ridge over the western Atlantic Ocean and low pressure trough centered near the Great Lakes will continue this final weekend of June and the first 2 days of July, with a retrograding ridge eventually being the victor. The result will be mild to warm air, high humidity, and episodes of scattered showers and thunderstorms through Monday, with less shower activity but still a shower and storm threat lingering Tuesday. Many areas will see lengthy stretches with no rain, but any tropical showers and storms may produce drenching downpours. At this point, I expect the day with the most numerous shower activity in southeastern New England to be Monday.

High pressure will continue to drift westward over the western  Atlantic and US East Coast through much of next week, only weakening a little as disturbances try to ride over the top of it from the west by the first weekend of July. The overall pattern for this area will become hotter and continued humid. Shower and thunderstorm activity will be isolated, increasing to scattered in some areas with passing disturbances later in the period.

Updated forecast for southeastern New England (RI, eastern MA, southern NH)…

TODAY: Mostly cloudy morning with isolated to scattered showers. Partly sunny afternoon with isolated to scattered showers and thunderstorms. Humid. Highs middle 70s to lower 80s. Wind S 5-15 MPH, up to 20 MPH some coastal areas.

TONIGHT: Variably cloudy. Isolated showers/thunderstorms early. Patchy fog overnight. Muggy. Lows in the 60s. Wind S under 10 MPH.

SUNDAY: Variably cloudy. Isolated to scattered showers and thunderstorms redeveloping. Humid. Highs upper 70s to lower 80s. Wind S to SW 10-20 MPH.

MONDAY: Mostly cloudy. Scattered to numerous showers/thunderstorms. Low 66. High 77.

TUESDAY: Partly cloudy. Isolated to scattered late-day showers/thunderstorms. Low 67. High 83.

WEDNESDAY: Partly cloudy. Isolated late-day thunderstorms. Low 68. High 84.

THURSDAY: Partly cloudy. Isolated late-day thunderstorms. Low 68. High 86.

FRIDAY: Partly cloudy. Isolated late-day thunderstorms. Low 69. High 88.

SATURDAY: Partly cloudy. Isolated to scattered afternoon thunderstorms. Low 70. High 90.

SUNDAY: Partly sunny. Scattered showers/thunderstorms. Low 70. High 88.

9:31AM

The battle will be on between a Great Lakes trough and a western Atlantic ridge for several days. The ridge will eventually win out for much of southern New England, but enough of a battle from the trough will be given to result in a continued threat of showers and thunderstorms for several days. The thing is, there will be high variability in rain coverage. Widespread wet times will be few, scattered to isolated coverage will be much more common.

First, we have a wedge of cooler air that came southwestward last evening behind a disturbance and pseudo-back-door cold front. It has left low clouds and areas of fog in much of the region and it will take a while to burn that away today. During this time, a band of heavier clouds just to the south as indicating the position of a boundary between this cooler air and the return push of warm and humid air from the south. This boundary will be a focus for generation of some rain as we go through today and this evening, but there is some question as to exactly how much rain will generate and fall in the region. I’m banking on less than some have advertised. So today may feature more “bark” than “bite” in terms of clouds and rainfall. By later tonight, we will see a heavier band of rain and embedded thunderstorms move in from the west with a trough line swinging out from a low pressure center passing northwest of New England. The axis of this heavy rain should time through southern New England between midnight and mid morning Friday. The remainder of Friday may not feature all that much in the way of widespread rain, but we’ll still have to look for isolated to scattered showers and thunderstorms. This boundary will be close to the coast or maybe just offshore, and along with a more established southerly flow of tropical air, showers and thunderstorms will be possible any time during the weekend, favoring Saturday over Sunday, but it’s quite possible that long rain-free periods will take place as well.

Retrogression (westward-movement) of the ridge of high pressure in the western Atlantic will take place during the first half of next week, putting the region into hotter conditions, still humid, and still with a threat of showers and storms, but more isolated with time as the axis of most likely activity shifts to the west.

Tomorrow, a special 10-day forecast looking out through the entire first week of July.

Updated forecast for southeastern New England…

TODAY: Low clouds and areas of fog through the morning. Remaining mostly cloudy midday through afternoon however breaks of sun and isolated showers both possible. Highs in the 70s, upper 60s few coastal points. Wind E 5-15 MPH.

TONIGHT: Mostly cloudy. Areas of light rain possible in the evening, favoring southern NH. Widespread showers/thunderstorms arriving west to east mainly after midnight. Lows in the 60s. Wind E to SE 5-15 MPH.

FRIDAY: Mostly cloudy with showers and embedded thunderstorms ending west to east in the morning. Partly sunny with isolated to scattered passing showers and thunderstorms in the afternoon. Highs 80-85 except 70s some coastal areas. Wind SE to S 10-20 MPH.

SATURDAY & SUNDAY: Variably cloudy. Episodes of scattered showers/thunderstorms. Lows 65-70. Highs 75-85, coolest south-facing coastal areas.

MONDAY-WEDNESDAY: Partly cloudy. Daily risk of isolated to scattered thunderstorms. Lows 66-72. Highs 77-90, coolest south-facing coastal areas.

8:52PM

The hot stretch that began Sunday will give way to slightly more moderate temperatures from mid week through the coming weekend as high pressure ridging, though still off the East Coast, is a bit weaker and battles a trough setting up in the Great Lakes. In addition to a little less heat for southern New England, this also means continued humidity and episodes of showers and thunderstorms, some producing tropical downpours. It will not rain all the time, but expect that many areas will get wet, sometimes quite wet, at times, during the next 5 days. Looking ahead a bit further, there are signs that retrogression (westward movement) and strengthening of high pressure off the East Coast will return our region to hotter weather with less numerous showers and storms as July begins early next week.

Forecast for southeastern New England (southern NH, eastern MA, and RI)…

TONIGHT: Showers and a few thunderstorms mainly in northern MA and southern NH early,  with fading showers south of Boston, otherwise variably cloudy, warm, and muggy. Lows from the middle 60s to lower 70s. Wind W 5-15 MPH.

WEDNESDAY: Variably cloudy with episodes of showers and thunderstorms midday on. Any storms may produce very heavy rain and gusty wind. Warm and humid. Highs in the 80s. Wind SW 5-15 MPH.

WEDNESDAY NIGHT: Partly to mostly cloudy. A few showers and thunderstorms possible. Warm and humid. Lows in the 60s. Wind light SW to variable.

THURSDAY: Variably cloudy. Episodes of showers favoring morning and midday, and a few additional showers or thunderstorms possible in the afternoon. Mild and muggy. Highs in the middle 70s to lower 80s. Wind variable to S 5-15 MPH.

FRIDAY THROUGH SUNDAY: Daily episodes of scattered showers and thunderstorms. Lows in the 60s. Highs upper 70s to middle 80s.

MONDAY & TUESDAY: Isolated showers and thunderstorms possible. Lows 65-75. Highs middle 80s to lower 90s, some cooler areas mainly South Coast.

12:12AM

Summertime and the weather matches it, and will for the entire week ahead. In the Northeast we will sit in a weakness between ridges to the West and East. This will result in some episodes of showers and thunderstorms, but much of the time it will be rain-free. The dominant weather will be warm to hot, humid conditions, the heat being more dominant through Wednesday before relaxing some later in the week.

Forecast for southeastern New England…

OVERNIGHT: Variably cloudy. Patchy fog. Lows in the 60s. Wind W 5-10 MPH.

MONDAY: Partly cloudy to mostly sunny. Isolated to scattered showers and thunderstorms mainly in the afternoon and mainly over northern MA and southern NH. Highs around 90 except cooler some South Coast areas. Wind W 5-15 MPH.

MONDAY NIGHT: Partly cloudy. Lows from the middle 60s to lower 70s. Wind light W.

TUESDAY: Mostly sunny to partly cloudy. Isolated thunderstorms northern MA and southern NH in the afternoon. Highs around 90, cooler South Coast. Wind W 5-15 MPH.

WEDNESDAY: Partly cloudy. Low 68. High 88.

THURSDAY: Variably cloudy. Isolated showers/thunderstorms. Low 65. High 80.

FRIDAY: Variably cloudy. Scattered showers/thunderstorms. Low 64. High 79.

SATURDAY: Partly sunny. Isolated showers/thunderstorms. Low 64. High 81.

SUNDAY: Partly cloudy. Isolated showers/thunderstorms. Low 66. High 83.

2:46PM

This update is to adjust the forecast for the remainder of Friday afternoon, as a weak surface boundary sitting along the Mass Pike may trigger a few isolated to scattered showers and thunderstorms from mid afternoon through early evening. The remainder of the forecast is unchanged at this time.

Updated forecast for southeastern New England…

THIS AFTERNOON: Mostly sunny to partly cloudy. Slight chance of an isolated shower or thunderstorm central and southern  MA and northern RI. Highs 73-78 South Coast, 78-83 elsewhere. Wind W 5-15 MPH.

TONIGHT: Partly cloudy to mostly clear. Lows 60-65. Wind light SW.

SATURDAY: Mostly sunny to partly cloudy. Isolated showers or thunderstorms possible in NH and MA in the late afternoon. Highs 75-85, coolest South Coast. Wind SW 5-15 MPH.

SATURDAY NIGHT: Partly to mostly cloudy. Isolated thunderstorms southern NH early. Lows 63-68. Wind light SW.

SUNDAY: Mostly cloudy to partly sunny. Isolated showers or thunderstorms southern NH and northern MA in the afternoon. Highs 75-85 again coolest South Coast. Wind SW 5-15 MPH.

MONDAY: Partly sunny. Low 67. High 84.

TUESDAY: Partly cloudy. Low 68. High 88.

WEDNESDAY: Mostly cloudy. Scattered showers/thunderstorms. Low 68. High 82.

THURSDAY: Partly sunny. Low 63. High 78.

6:41PM

Summer “officially” begins at 1:04AM Friday, and Summertime weather of the generally favorable kind will be with us for several days to come. A frontal system will be draped across northern New England and will trigger showers and thunderstorms across that region Friday through Sunday. I cannot rule out a stray one making it into southern NH or MA any of the next 3 afternoons or evenings as the air will be warmer and increasingly humid, but for the most part we’ll be seeing dry weather in the WHW forecast area. By early next week, it will be a bit hotter with continued increased humidity.

Updated forecast for southeastern New England…

TONIGHT: Clear. Lows middle 50s interior valleys to middle 60s urban centers. Wind S to SW under 10 MPH.

FRIDAY: Mostly sunny to partly cloudy. Slight chance of an isolated shower or thunderstorm northern MA and southern NH late day. Highs 73-78 South Coast, 78-83 elsewhere. Wind W 5-15 MPH.

FRIDAY NIGHT: Partly cloudy to mostly clear. Lows 60-65. Wind light SW.

SATURDAY: Mostly sunny to partly cloudy. Isolated showers or thunderstorms possible in NH and MA in the late afternoon. Highs 75-85, coolest South Coast. Wind SW 5-15 MPH.

SATURDAY NIGHT: Partly to mostly cloudy. Isolated thunderstorms southern NH early. Lows 63-68. Wind light SW.

SUNDAY: Mostly cloudy to partly sunny. Isolated showers or thunderstorms southern NH and northern MA in the afternoon. Highs 75-85 again coolest South Coast. Wind SW 5-15 MPH.

MONDAY: Partly sunny. Low 67. High 84.

TUESDAY: Partly cloudy. Low 68. High 88.

WEDNESDAY: Mostly cloudy. Scattered showers/thunderstorms. Low 68. High 82.

THURSDAY: Partly sunny. Low 63. High 78.

8:22PM

One more low pressure wave riding along a front will continue the chance of wet weather through the night. It won’t rain all places at all times, but some significantly heavy rain will be around the South Coast including the Islands off Cape Cod at first. Eventually all of this will pull out to sea as low pressure wraps up and moves away. A northeasterly flow has developed in much of the region, dragging cooler air in along with the damp weather. This northeast flow will continue into Wednesday, but drier air will return sunshine to the region. This drier spell will continue through late week, but the air will be warming with time. Humidity will eventually come into play as we reach the weekend, at which time isolated showers or thunderstorms cannot be ruled out. However, we won’t see a return to the soaking wet pattern we have been in recently.

Updated forecast for southeastern New England…

TONIGHT: Cloudy with areas of fog. Rain, some heavy, near the South Coast and Islands, with isolated to scattered showers elsewhere. Slight risk of thunderstorms. Lows 55-60. Wind NE 5-15 MPH.

WEDNESDAY: Clouds linger very early otherwise turning mostly sunny. Highs ranging from the middle 60s over the Islands to middle 70s interior MA and southern NH. Wind NE 10-15 MPH shifting to N.

WEDNESDAY NIGHT: Clear. Lows ranging from the upper 40s inland valleys to middle 50s coastal areas. Wind N diminishing to under 10 MPH.

THURSDAY: Sunny. Highs from near 70 South Coast to near 80 inland locations. Wind S up to 10 MPH.

FRIDAY: Mostly sunny. Low 60. High 81.

SATURDAY: Partly cloudy. Low 64. High 82.

SUNDAY: Partly sunny. Isolated thunderstorms. Low 66. High 83.

MONDAY: Variably cloudy. AM showers. Low 64. High 84.

TUESDAY: Partly cloudy. Low 66. High 88.

11:08PM

A low pressure trough and associated disturbances will move across the northeastern USA bringing a few episodes of showers and thunderstorms to southern New England through Tuesday. This will not be a repeat of the washout rains of last week, however.

High pressure will dominate mid to late week and into the start of the weekend, delivering a  pleasant air mass at first, which will then turn warmer and more humid with time as high pressure sinks to the south toward the end of the week. An approaching front by the end of the weekend may trigger more showers and thunderstorms.

Forecast for southeastern New England (southern NH, RI, and eastern MA)…

OVERNIGHT: Partly cloudy. Lows middle 50s to lower 60s. Wind W around 10 MPH.

MONDAY: Partly cloudy. Isolated showers and thunderstorms during the afternoon. Highs in the lower 80s, 70s some coastal areas. Wind W to SW 5-15 MPH.

MONDAY NIGHT: Variably cloudy. Chance of showers early. Patchy fog in valleys late. Lows 60-65, few upper 50s interior valleys. Wind W under 10 MPH.

TUESDAY: Mostly cloudy. Scattered showers and thunderstorms during the afternoon. Highs in the upper 70s, cooler some coastal areas. Wind variable 5-15 MPH.

WEDNESDAY: Mostly sunny. Low 56. High 76.

THURSDAY: Mostly sunny. Low 56. High 79.

FRIDAY: Partly cloudy. Low 60. High 82.

SATURDAY: Partly cloudy. Low 66. High 84.

SUNDAY: Partly sunny. PM thunderstorms. Low 67. High 83.