DAYS 1-5 (MAY 14-18)

The process of migrating / breaking down of a Rex Block continues, with slow-motion weather changes the result. Low pressure to our southwest very slowly weakens, broadens, and drifts northeastward over the next several days. Yesterday, high clouds in the sky were battled by drier air and you saw that they had trouble thickening up. Mid level clouds were held off mostly to our southwest. By late-day, if you were sky watching you noticed an increase in clouds, but this morning you notice that hasn’t changed too much – with just some thicker high to mid level cloud cover across our southern areas while to the north the clouds are thin enough to allow some sun. This was my expectation when making yesterday’s forecast, leading to the wording that I used for today (Wednesday) of “limited sunshine / lots of clouds” while other forecasts you may have seen just called for “cloudy”. The latter is now becoming true for southern areas and eventually this will become the case for the region in general as the day goes on, but it’s still a slow process, with intervals of filtered sun still possible into midday at least across areas north of I-90. This may seem like a lot of explanation for one deck of clouds, but my aim is to give people an understanding of how this particular pattern is working on making our changes such a slow process. Anyway, once we get the clouds in, the atmosphere will moisten up enough to allow the chance of showers to increase as we get to this evening and tonight, and in pulses Thursday into Friday as we see our wind flow go from easterly to southerly. The surface humidity will be increasing, and you’ll feel that in the air quite noticeably by Friday, as well as Saturday. Those two days are when we’ll have an air flow out of the south. Saturday also continues the shower chance – although not a “washed-out” day, as there may only be a few hours total where any one area is impacted by rainfall. We do have to get a disturbance through here from west to east at some point Saturday when we can have a heaver bout of shower and thunderstorm activity. I’m still working on tweaking the expecting timing of that and won’t really be certain of it until Friday, but yesterday’s leaning was late-day / evening and today’s is just a little bit earlier (Saturday midday / afternoon). Stay tuned for more about that. Sunday, we’re into a drier western air flow, but upper level low pressure crossing the region can still allow a few showers to pop up with the aid of the sun’s heating, so I can’t leave that as a completely rain-free forecast either at this point.

TODAY: Filtered / limited sun favoring northern MA / southern NH morning, otherwise becoming mostly cloudy. A shower possible South Coast late-day. Highs 60-67 coast, 67-74 inland. Wind E up to 10 MPH.

TONIGHT: Mostly cloudy. Shower chance increases. Lows 52-59. Wind E to SE up to 10 MPH.

THURSDAY: Mostly cloudy. Showers most likely through mid morning, then a lower shower chance thereafter. Highs 59-66 coast, 66-73 inland. Wind SE up to 10 MPH.

THURSDAY NIGHT: Mostly cloudy. Chance of showers. Lows 53-60. Wind S up to 10 MPH.

FRIDAY: Mostly cloudy. Chance of showers. Highs 62-69 South Coast, 69-76 elsewhere. Wind S 5-15 MPH.

FRIDAY NIGHT: Mostly cloudy. Chance of a shower. Patchy fog, Lows 55-62. Wind S 5-15 MPH.

SATURDAY: Mostly cloudy. Showers likely, favoring midday & part of afternoon. Highs 62-69 South Coast, 69-76 elsewhere. Wind S up to 10 MPH becoming variable.

SATURDAY NIGHT: Variably cloudy. Chance of a shower. Lows 52-59. Wind SW to W 5-15 MPH.

SUNDAY: Partly sunny. Chance of a shower. Highs 62-69. Wind W to NW 10-20 MPH.

DAYS 6-10 (MAY 19-23)

This is the period of time where we’ll be in the much-mentioned hybrid block / progressive pattern. The upper pattern will attempt an omega (trough west central North America / ridge Great Lakes and eastern Canada / trough east of New England), with us on the fair weather eastern side of high pressure early next week – dry and seasonable / slightly cool weather. After this we see a progression of features as the pattern begins a transition to ridge western US / trough eastern US. This may cause some unsettled weather in our region by the middle to latter portion of next week, but I’m uncertain of details this far in advance.

DAYS 11-15 (MAY 24-28)

Strongest indications are for a trough of low pressure dominating the eastern US, including New England, including the WHW forecast area. This pattern would feature a couple opportunities for wet weather, but not an excessively wet pattern. Temperatures near to below normal. May 24-26 is the Memorial Day Weekend, where much scrutinizing of the weather expectations is done. I’ll be focusing on this period in detail as it nears.

DAYS 1-5 (MAY 13-17)

A slowly migrating Rex Block will result in slow weather changes heading through the balance of this week. As mentioned in the previous update, high pressure will try to hang on but drift to the northeast into Atlantic Canada. A surface high associated with the upper ridge has driven a weak back-door cold front into the region early today and this will result in a regional onshore (northeasterly) air flow, which will keep the coast cooler than inland areas. The same will generally be true for Wednesday and Thursday while we see the general air flow become easterly to southeasterly. This will be in response to the slow approach of a large but weakening low pressure circulation from the southwest – this being the low pressure portion of the aforementioned block. While the dry air wins the battle for a while, even allowing some sun Wednesday, eventually the moisture will increase enough to bring more dominant cloudiness and a shower chance Wednesday night and/or Thursday, and even more so as we get to Friday. By that time, a southerly air flow will have taken over, and it will become more humid as well. Any warm-up will be modest late week, and a southerly wind off the water south of New England means that it will be the South Coast’s turn to be ocean-cooled more directly on Friday. Saturday’s weather will be unsettled as we still have low pressure around while a disturbance from the west joins the party, increasing the shower chance. This does not look like a wet day from start to finish, but it’ll be a couple days before I can work out the timing of the best rain chances. Initially, I lean toward later over earlier, but don’t make any solid plans based on that idea at this point.

TODAY: Filtered sunshine through lots of high clouds. Highs 60-67 coast, 67-74 inland. Wind variable to NE up to 10 MPH.

TONIGHT: High clouds dominate. Lows 48-55. Wind NE to E up to 10 MPH.

WEDNESDAY: Limited sunshine / lots of clouds. Highs 60-67 coast, 67-74 inland. Wind E up to 10 MPH.

WEDNESDAY NIGHT: Mostly cloudy. Chance of a shower. Lows 52-59. Wind E to SE up to 10 MPH.

THURSDAY: Mostly cloudy. Chance of showers. Highs 59-66 coast, 66-73 inland. Wind SE up to 10 MPH.

THURSDAY NIGHT: Mostly cloudy. Chance of showers. Lows 53-60. Wind S up to 10 MPH.

FRIDAY: Mostly cloudy. Chance of showers. Highs 62-69 South Coast, 69-76 elsewhere. Wind S 5-15 MPH.

FRIDAY NIGHT: Mostly cloudy. Chance of a shower. Patchy fog, Lows 55-62. Wind S 5-15 MPH.

SATURDAY: Mostly cloudy. Showers likely, favoring the afternoon or evening. Highs 62-69 South Coast, 69-76 elsewhere. Wind S up to 10 MPH becoming variable.

DAYS 6-10 (MAY 18-22)

Low pressure shifts east of the area by the end of the weekend with cooler air and only a chance of a few passing showers May 18. High pressure builds in for fair weather May 19-20. Next round of unsettled weather follows for the middle of next week as low pressure returns.

DAYS 11-15 (MAY 23-27)

A cool northwesterly air flow is expected to dominate with mostly dry weather and one or two opportunities for passing showers. This time frame includes Memorial Day Weekend (May 24-26).

DAYS 1-5 (MAY 12-16)

A slow transition of the spring weather pattern continues over the next several days. Last week’s omega block (low West, high Plains, low East), as noted on yesterday’s blog post, transitioned to a rex block pattern (high North, low South). We’re currently under the influence of high pressure, but as we move through this week, the large scale features shift and the high slides to the east while the low to the south drifts northeastward, our way. However, there will be resistance from the high and the overall process will be quite slow to occur. This means that while we see an increase in clouds after today’s abundant sun, the clouds will struggle to thicken up into midweek, and any rain will be held at bay to our south and west as well. Finally by Thursday and Friday as we see the now broad and weaker upper low move further northeast, we’ll see a trend to a more southerly air flow and as a result more moisture with lots of clouds and increased shower chances. Neither of these days look like full on rainy “wash-out” kind of days though.

TODAY: Clouds scoot across southeastern NH / northeastern MA early on, otherwise abundant sunshine. Highs 60-67 Cape Cod / South Coast, 68-75 elsewhere. Wind W to SW 5-15 MPH.

TONIGHT: High clouds fan in from the southwest. Lows 48-55. Wind SW to variable under 10 MPH.

TUESDAY: Sun & high clouds. Highs 63-70 coast, 70-77 inland. Wind variable up to 10 MPH with coastal sea breezes.

TUESDAY NIGHT: High clouds increase. Lows 50-57. Wind SE up to 10 MPH.

WEDNESDAY: Limited sunshine / lots of clouds. Highs 60-67 coast, 67-74 inland. Wind SE up to 10 MPH.

WEDNESDAY NIGHT: Mostly cloudy. Lows 52-59. Wind SE up to 10 MPH.

THURSDAY: Mostly cloudy. Chance of showers. Highs 64-71, coolest coastal areas. Wind SE up to 10 MPH.

THURSDAY NIGHT: Mostly cloudy. Chance of showers. Lows 53-60. Wind S up to 10 MPH.

FRIDAY: Mostly cloudy. Chance of showers. Highs 63-70, coolest South Coast. Wind S 5-15 MPH.

DAYS 6-10 (MAY 17-21)

Continued slow pattern shift as upper level low pressure dominates but the core of which passes to our west then north. This starts us out in a southerly air flow which then trends more westerly. There are shower chances early in the period, the May 17-18 weekend, before a drying trend takes place. Temperatures near to slightly above normal for the period overall.

DAYS 11-15 (MAY 22-26)

Late month pattern features a broad trough of low pressure and mostly west to east flow, with a trend for more cool air from Canada – i.e., temperatures near to below normal, with mostly dry weather interrupted by brief shower chances. Memorial Day Weekend is May 24-26 as part of this expected pattern.

DAYS 1-5 (MAY 11-15)

The large scale pattern has now shifted from one block to another as part of the transition to the “hybrid” pattern I have referenced several times recently. Previously, the Omega pattern existed – cut off low western US, cut off low eastern US, ridge of high pressure between the two. Now, it’s a Rex Block – high pressure to the north, low pressure to the south, located over the central and eastern US. This pattern persists the next few days before itself starting a shift in response to more progression to it west and north. Eventually the features move. The eastern nose of the high pressure area will play a part in giving us fair weather from today through Tuesday, after which it will give way to a northeastward-drifting low pressure area that will increase our clouds and wet weather chances as we head through midweek. I don’t think it will be in a hurry to get all that wet here, though, as the low from the south will be broad and disorganized with no super organized areas of rainfall, instead a more broken rainfall pattern.

TODAY: Lots of sun / few clouds. Highs 65-72. Wind NW 5-15 MPH.

TONIGHT: Mostly clear. Lows 38-45 inland, coolest in valleys, 45-52 coast, mildest Boston. Wind NW under 10 MPH.

MONDAY: Mostly sunny. Highs 68-75. Wind W 5-15 MPH.

MONDAY NIGHT: Mostly clear. Lows 48-55. Wind WSW 5-15 MPH.

TUESDAY: Sun & high clouds. Highs 63-70 coast, 70-77 inland. Wind S to SE 5-15 MPH.

TUESDAY NIGHT: High clouds increase.. Lows 50-57. Wind SE up to 10 MPH.

WEDNESDAY: Limited sun / clouds dominant. Highs 60-67 coast, 67-74 inland. Wind SE up to 10 MPH.

WEDNESDAY NIGHT / THURSDAY: Mostly cloudy. Chance of showers. Lows 53-60. Highs 61-68. Wind SE to E up to 10 MPH.

DAYS 6-10 (MAY 16-20)

Pattern shift is slow, still in the hybrid block – low pressure not completely connected to the jet stream which becomes more progressive overall. The low pressure area that dominates the eastern US looks weaker than the one associated with the recent omega pattern. This pattern for us would deliver a southerly air flow shifting more westerly with time, but occasional shower chances with fair weather being dominant the majority of the time. Temperatures, while variable, would average near to slightly above normal.

DAYS 11-15 (MAY 21-25)

Heading into late month, the strongest indications are for a progressive pattern – general west to east flow – but with a mean trough in eastern Canada and the northeastern US, making us more susceptible to a shot or two of cool Canadian air with temperatures near to below normal. Overall pattern looks drier.

DAYS 1-5 (MAY 10-14)

Today is the day the current storm system departs, but it’s not going to be a quick process. In a blocking pattern, we often see surface lows interacting with their upper counterparts in such a way that they do cyclonic loops or such things. If you look at the radar, you can see the maturing surface low sending one more lobe of moisture into the region – steadiest rain north of I-90 – early this morning. As I type this blog update, the classic pivot of the precipitation area is already underway, where as the low wraps up and starts to move out, the precipitation instead of moving north and west pivots back around to the east and south, pulling it back across the same areas it already had visited. So we’ll go through that process this morning to midday before we finally dry things out. The heavy overcast associated with the rain-producing portion of the low will thin out from northwest to southeast and other lower clouds will scurry across the sky, born of low level moisture left behind by the rain. But the general trend will be for clearing later today and definitely tonight as dry air finally moves in. This sets us up for a stretch of dry weather Sunday through Tuesday as high pressure builds toward the region Sunday and sits near to just south of our area Monday and Tuesday. We can still see some fair weather clouds sharing the sky with the sun on Sunday as a little colder air lingers aloft. Wednesday, a more general southeasterly air flow arrives ahead of the next low pressure area, but it will still be a generally nice day, with some increase in high cloudiness filtering the sun.

TODAY: Cloudy morning – steadiest rain north of I-90, a break to the south before more showers move through. Breaking clouds / slow clearing trend afternoon from northwest to southeast. Highs 57-64, occurring late-day. Wind variable becoming NW 5-15 MPH, a few higher gusts.

TONIGHT: Mostly clear. Lows 45-52. Wind NW 5-15 MPH.

SUNDAY: Sun / passing clouds. Highs 65-72. Wind NW 5-15 MPH.

SUNDAY NIGHT: Mostly clear. Lows 46-53. Wind NW 5-15 MPH.

MONDAY: Mostly sunny. Highs 68-75. Wind W 5-15 MPH.

MONDAY NIGHT: Mostly clear. Lows 48-55. Wind WSW 5-15 MPH.

TUESDAY: Mostly sunny. Highs 70-77, cooler South Coast. Wind SW 5-15 MPH.

TUESDAY NIGHT: Clear. Lows 50-57. Wind S up to 10 MPH.

WEDNESDAY: Sun and high clouds. Highs 65-72, coolest coast. Wind SE up to 10 MPH.

DAYS 6-10 (MAY 15-19)

A hybrid blocking / partially progressive pattern is expected at mid month. The first half of this period is most likely to be unsettled with fair weather returning thereafter. Temperatures near to slightly above normal.

DAYS 11-15 (MAY 20-24)

Transition from the hybrid pattern mentioned above to a more progressive pattern with a drier trend – brief unsettled episodes – and variable temperatures but no extremes expected.

DAYS 1-5 (MAY 9-13)

Over the next few days we’ll see a break-down of the omega block pattern that’s been in control of the weather. But to get there, we have to go through another bout of wet weather. This started somewhat last evening especially north and west of Boston with a band of rain and thunderstorms, that later on lifted northward and away, but today, low pressure approaching from the southwest brings the rain back during the course of the day, especially midday and afternoon, into evening. Tonight it becomes more showery, lasting into early Saturday as the low pressure area cuts right across our region from southwest to northeast. Ahead of it blows a genearlly easterly wind, keeping us cool today. The wind goes variable as the low crosses the region. On the back-side of the low we get into a westerly flow Saturday, but wrap-around moisture can still cause scattered showers for a part of the day, and complete clearing won’t take place until Saturday night. This does set up a splendid Sunday (Mother’s Day) with sunshine and pleasant air as low pressure pulls away through eastern Canada and high pressure builds our way from the west. This high will sink to our south early next week with continued fair weather and a warm-up.

TODAY: Cloudy. Areas of fog and a few patches of drizzle during the morning. Rain arrives southwest to northeast midday on. Highs 50-57. Wind NE to E 5-15 mph.

TONIGHT: Cloudy. Rain evening. Numerous to scattered showers overnight. Areas of fog. Lows 46-53. Wind E to SE 5-15 MPH, becoming variable.

SATURDAY: Areas of fog until mid morning. Mostly cloudy to partly sunny. Scattered to isolated showers. Highs 57-64. Wind variable to W 5-15 MPH.

SATURDAY NIGHT: Clearing. Lows 48-55. Wind NW up to 10 MPH.

SUNDAY: Mostly sunny. Highs 65-72. Wind NW up to 10 MPH.

SUNDAY NIGHT: Mostly clear. Lows 46-53. Wind NW 5-15 MPH.

MONDAY: Mostly sunny. Highs 68-75. Wind W 5-15 MPH.

MONDAY NIGHT: Mostly clear. Lows 48-55. Wind WSW 5-15 MPH.

TUESDAY: Mostly sunny. Highs 70-77, cooler South Coast. Wind SW 5-15 MPH.

DAYS 6-10 (MAY 14-18)

A hybrid blocking / partially progressive pattern is expected at mid month. This period should see the return of some unsettled weather, but timing and details are TBD. Temperatures near to slightly above normal.

DAYS 11-15 (MAY 19-23)

Transition from the hybrid pattern mentioned above to a more progressive pattern with a drier trend – brief unsettled episodes – and variable temperatures but no extremes expected.

DAYS 1-5 (MAY 8-12)

The easternmost upper low of an omega block still controls our weather, but this pattern will be gradually breaking down and shifting during the coming several days. Initially, we have a surface low to our east today and we’ll be in a light north to northwest air flow with somewhat drier air for several hours. As the day goes on and we approach evening, we’ll start to see the air flow shift to easterly as a boundary settles just to our south and we begin to feel the effect of developing low pressure to our southwest. Rain chances go up as we reach evening but first in the form of isolated to scattered showers. As we move through the nighttime hours and into Friday, a steadier rainfall is likely. The movement of the new low pressure area will determine how quickly we break out of the steadier rain and see improvement. Right now, I lean toward a slightly quicker scenario in which the steadiest rain exits the region around or prior to dawn on Saturday, with the daytime hours just having the chance of additional passing showers as the low pulls away via the Gulf of Maine. High pressure then builds in with a stretch of fair weather for Sunday (Mother’s Day) and Monday, including a warming trend.

TODAY: Sun/cloud mix, then clouds overtaking the sky toward evening. Isolated to scattered showers by evening. Highs 65-72. Wind NW up to 10 MPH shifting to NE late-day.

TONIGHT: Cloudy. An episode of more numerous showers in the evening including some thunderstorms, especially in central MA. Patchy drizzle and scattered showers overnight including areas of fog. Lows 50-57. Wind NE 5-15 MPH.

FRIDAY: Cloudy. Periodic rain. Areas of fog and drizzle. Temperatures steady 51-58. Wind NE to E 5-15 MPH.

FRIDAY NIGHT: Cloudy. Chance of rain. Lows 45-52. Wind NE 5-15 MPH.

SATURDAY: Mostly cloudy to partly sunny. Chance of showers. Highs 57-64. Wind NE to NW 5-15 MPH.

SATURDAY NIGHT: Partly cloudy. Lows 48-55. Wind NW up to 10 MPH.

SUNDAY: Partly sunny. Highs 65-72. Wind NW up to 10 MPH.

SUNDAY NIGHT: Clearing. Lows 46-53. Wind NW 5-15 MPH.

MONDAY: Mostly sunny. Highs 68-75. Wind W 5-15 MPH.

DAYS 6-10 (MAY 13-17)

A gradual shift in the wind flow from westerly to southerly early to mid period with fair weather to start then a chance of showers as moisture increases. The unsettled weather may continue into late period as some additional blocking is indicated with low pressure nearby.

DAYS 11-15 (MAY 18-22)

A hybrid pattern – partially blocking / partially progressive. Hard to pick up dominant weather systems but the overall trend is for less rain and near to slightly above normal temperatures.

DAYS 1-5 (MAY 7-11)

Upper level low pressure continues to impact our weather, but there will be a different overall feel today as we’re now in a warmer southerly air flow. We’ll also see breaks in the clouds and partial sun but this will fuel some convective showers and a few thunderstorms that can move across the region from mid afternoon through early evening. Activity can occur anywhere but will favor areas north of I-90, from west to east, and can produce brief downpours. A surface low associated with the upper low will wander eastward and we’ll find ourselves in slightly drier air behind it on Thursday. During that day, the shower chance will be minimal and we’ll have a northerly air flow, albeit light. But we’re not completely done with the foul weather associated with our blocking pattern, and another surface low will be evolving and moving into our area for late week. I’ve been leaning toward a slightly faster evolution and timing of this system. This means that the rain chance would increase as early as Thursday evening, and then be with us mostly during the day on Friday. What happens as we get to the weekend depends on the progression of low pressure. Some guidance has it slower-moving and wet weather lasting into Saturday. Other guidance keeps the system more progressive and moves it out more quickly. Either can occur, and I’m leaning toward a split with a slight tilt toward the quicker solution. I realize this goes against the general rule of thumb for spring blocking, so yes it’s a bit of an “out on the limb” prognostication. However, if this proves to be how it does go, we’d have improvement Saturday with just a possible lingering shower, and great weather Sunday, so the weekend would turn out pretty decent.

TODAY: Clouds break for sun at times. Scattered showers and isolated thunderstorms mid afternoon on. Highs 58-65 South of I-90, 65-72 I-90 northward. Wind SE to S up to 10 MPH.

TONIGHT: Variably cloudy. Patchy fog. Chance of a shower. Lows 50-57. Wind variable up to 10 MPH.

THURSDAY: Variably cloudy. Chance of a shower. Highs 65-72. Wind NW to N up to 10 MPH.

THURSDAY NIGHT: Cloudy. Showers likely. Lows 51-58. Wind N to NE 5-15 MPH.

FRIDAY: Cloudy. Rain likely. Temperatures generally steady 51-58. Wind NE 5-15 MPH.

FRIDAY NIGHT: Cloudy. Chance of rain. Lows 45-52. Wind NE 5-15 MPH.

SATURDAY: Mostly cloudy to partly sunny. Chance of showers. Highs 57-64. Wind NE to NW 5-15 MPH.

SATURDAY NIGHT: Partly cloudy. Lows 48-55. Wind NW up to 10 MPH.

SUNDAY: Partly sunny. Highs 65-72. Wind NW up to 10 MPH.

DAYS 6-10 (MAY 12-16)

No big changes to the previous outlook which suggests the blocking pattern reorganizes and coexists with some progression of the large scale features. This should give us a period of fair and milder weather early to mid next week before an unsettled weather threat evolves.

DAYS 11-15 (MAY 17-21)

Continuing to lean toward a hybrid partial blocking / partial progressive pattern. Overall this is a drier pattern with variable but mostly near normal temperatures, and no sharply defined weather systems in control.

DAYS 1-5 (MAY 6-10)

We’re still being dominated by an imposing letter from the Greek Alphabet. Yep, the Omega Block continues – not highly unusual for spring, in fact, fairly common for this season – more so than any other season (watch social media posts / headlines that try to tell you otherwise). This pattern often keeps the weather similar for several days. Sometimes, you can be in the fair weather sandwich in between two lows, underneath an upper ridge. We’re not. This time, we’re under the easternmost upper low, and it gave us a cool, wet Monday, and will do the same to our Tuesday. Yesterday, the main rain area got pushed back westward somewhat due to high pressure in Atlantic Canada. Today, that high gives ground and the rain wheels back through our region. Some embedded thunderstorms can also occur with it. Wednesday, we start to see less concentration of the moisture with slight weakening of the pattern, and with surface low pressure to the west we’ll have more of a southerly air flow. Result: Wednesday is still a mainly cloudy and occasionally showery (and chance of a thunderstorm) kind of day, but a little milder than today in general. The surface low makes its way across the area then east of our region Thursday. While I cannot rule out a shower that day, this looks like a drier day overall, but without complete clearing of the sky as clouds remain dominant. The puzzle to solve for late week is how much impact another low pressure area has on our region. Most guidance shows low pressure bringing another rain event sometime Friday into Saturday. Timing and magnitude varies from model to model, run to run of course. Nothing new there. The thing to watch when using guidance is the trend, and keeping a real-world eye on the pattern. For now, I remain of the meteorological opinion that we’re still under the gun for some additional wet weather there, favoring Friday with s-l-o-w improvement following. There’s the chance that the evolution of that system is further south and east, which would lessen the chance of a more pronounced impact.

TUESDAY: Cloudy. Shower coverage increases again – a few may be heavy with a slight chance of thunder. Areas of fog / drizzle. Highs 53-60. Wind E to SE 5-15 MPH.

TONIGHT: Cloudy. Showers likely. Areas of drizzle and fog. Lows 45-52. Wind E up to 10 MPH.

WEDNESDAY: Clouds break for sun at times. Scattered showers and isolated thunderstorms. Highs 56-63 South of I-90, 63-70 I-90 northward. Wind SE to S up to 10 MPH.

WEDNESDAY NIGHT: Variably cloudy. Patchy fog. Chance of a shower. Lows 50-57. Wind variable up to 10 MPH.

THURSDAY: Variably cloudy. Chance of a shower. Highs 60-67. Wind variable to N up to 10 MPH.

THURSDAY NIGHT: Mostly cloudy. Chance of a shower. Lows 48-55. Wind NE 5-15 MPH.

FRIDAY: Cloudy. Chance of rain. Highs 52-59. Wind NE 5-15 MPH.

FRIDAY NIGHT: Cloudy. Chance of rain. Lows 45-52. Wind NE 5-15 MPH.

SATURDAY: Mostly cloudy. Chance of showers. Highs 52-59. Wind NE to N 5-15 MPH.

DAYS 6-10 (MAY 11-15)

The blocking pattern relaxes and breaks down partially, but remains somewhat intact and coexistent with some pattern progression. May 11 (end of weekend / Mother’s Day) looks OK but not perfect, maybe a sun/cloud mix with a pop up shower, but this forecast will be fine-tuned. Fair weather more likely early to middle of next week including a warm-up, as high pressure should be in more firm control here.

DAYS 11-15 (MAY 16-20)

Continuing to lean toward a hybrid partial blocking / partial progressive pattern. Overall this is a drier pattern with variable but mostly near normal temperatures, and no sharply defined weather systems in control.

DAYS 1-5 (MAY 5-9)

The large scale omega block (low pressure western US, high pressure middle US, low pressure eastern US) configuration is the weather pattern during the next 5 days, and this is an unsettled / wet pattern for our area. The good news is we’ll get some additional drought relief. It’s not going to rain every moment of the next 5 days. There will be drier episodes, but you’ll have to get lucky to be able to take advantage of them. The steadiest rain in the area this morning gets pushed back to the southwest during the day today leaving us with drizzle and a few showers, but the rain makes a comeback tonight into Tuesday as the high pressure area in Canada that helped nudge it away relaxes enough to let it back in again. A surface low associated with the upper low controlling our weather will lift to the north and east midweek. Wednesday our air flow becomes more southerly and the rainfall turns more to a scattered shower / isolated thunderstorm pattern with milder air. We end up in a westerly to northerly flow on Thursday, and while there is still a shower threat, it may be the driest day of the five, because yet another low pressure area associated with the upper low will make a run at the region Friday with the opportunity for additional rainfall – coverage and timing TBD. There’s a slight chance that one stays further east and south, but don’t bank on it right now.

TODAY: Cloudy. Showers diminish north to south but areas of drizzle and a few showers continue. Highs 53-60. Wind NE 5-15 MPH.

TONIGHT: Cloudy. Showers regain coverage south to north. Patchy drizzle / fog. Lows 45-52. Wind E 5-15 MPH.

TUESDAY: Cloudy. Better chance of showers in all areas. Areas of drizzle and fog. Highs 53-60. Wind E 5-15 MPH.

TUESDAY NIGHT: Cloudy. Showers likely. Areas of drizzle and fog. Lows 45-52. Wind E up to 10 MPH.

WEDNESDAY: Clouds break for sun at times. Scattered showers and isolated thunderstorms. Highs 58-65 South of I-90, 65-72 I-90 northward. Wind SE to S up to 10 MPH.

WEDNESDAY NIGHT: Variably cloudy. Patchy fog. Chance of a shower. Lows 50-57. Wind variable up to 10 MPH.

THURSDAY: Variably cloudy. Chance of a shower. Highs 60-67. Wind variable to N up to 10 MPH.

THURSDAY NIGHT: Mostly cloudy. Chance of a shower. Lows 48-55. Wind NE 5-15 MPH.

FRIDAY: Cloudy. Chance of rain. Highs 55-62. Wind NE 5-15 MPH.

DAYS 6-10 (MAY 10-14)

The blocking pattern is expected to finally relax and break down during this 5-day period, which starts with the May 10-11 weekend. Will it happen fast enough for a beautiful weekend? Probably not. Expect additional unsettled weather, the details of which will be fine-tune later this week. Drier, mild weather is expected early next week.

DAYS 11-15 (MAY 15-19)

Going with a hybrid partial blocking / partial progressive pattern. Overall this is a drier pattern with variable but mostly near normal temperatures, and no sharply defined weather systems in control.

REVIEW OF SATURDAY

A very busy agenda for yours truly didn’t allow me to be on the blog as much as I’d like to have been, so I wasn’t able to comment during and shortly after the occurrence of strong to severe thunderstorms in the area. It’s important to remember something. Just because your area is in a warning for a storm does not necessarily mean your driveway ends up getting the strongest wind gust, the largest hail, the most damage, and consider yourself lucky if you miss out. There were some areas of pretty significant wind damage from this event, including right here in Woburn. Further west, I witnessed live wires down and entangled in down tree branches with the whole mess on fire in the middle of a road in Lexington. There were other significant damage reports, including but not limited to Newton MA and Hampton NH. A pretty impressive event for early in the season.

DAYS 1-5 (MAY 4-8)

Now, onto prognostication of the next 5 days, as we continue in a complex pattern which includes some blocking, quite typical for springtime. The large scale pattern features a closed low / high pressure ridge / closed low configuration from west to east across the Continental USA, with our area impacted by the easternmost upper low. Our summerlike air of yesterday is only a shadow of its former self as we start the day today, with it still quite mild, but a cool-down is in-bound, to be triggered by a southward-moving cold front that slides across the region during the day. The means much of the region will see high temperatures occurring this morning to midday. Additionally, we can see some rain showers around northern MA and/or southern NH to start the day, and a late-day return of showers, more numerous to the north and west of Boston while areas to the south see only isolated activity. Some consolidation of shower activity means most areas get wet Sunday night into Monday. As part of the blocking pattern, high pressure resides in Atlantic Canada, and it should exert enough push on our area to suppress the rain area to the southwest during the day Monday, which while remaining cloudy, will feature a trend to less rain / mainly dry. The high pressure area will lose its grip and the low will regain its influence on our region heading into Tuesday – a day likely to feature widespread showers. As we reach midweek, more changes come about as the blocking pattern loosens up and the upper low starts to lift north northeastward. This should allow our surface wind to shift from easterly to more southerly, but clouds and additional showers are possible as this transition occurs. By Thursday, a weaker version of the upper low will be over our region, and the sensible weather should feature lots of clouds and a few showers. There’s still some uncertainty in the midweek details, so check updates!

TODAY: Mostly cloudy. A spot shower possible. Highs 63-70 by midday, followed by a cool-down north to south. Wind SW to variable to N 5-15 MPH.

TONIGHT: Cloudy. Showers likely. Lows 46-53. Wind NE 5-15 MPH.

MONDAY: Cloudy. Showers diminish north to south but patchy drizzle. Highs 53-60. Wind NE 5-15 MPH.

MONDAY NIGHT: Cloudy. Showers regain coverage south to north. Patchy drizzle / fog. Lows 45-52. Wind E 5-15 MPH.

TUESDAY: Cloudy. Better chance of showers in all areas. Areas of drizzle and fog. Highs 53-60. Wind E 5-15 MPH.

TUESDAY NIGHT: Cloudy. Showers likely. Areas of drizzle and fog. Lows 45-52. Wind E up to 10 MPH.

WEDNESDAY: Clouds break for sun at times. Chance of a shower. Highs 58-65 South of I-90, 65-72 I-90 northward. Wind SE to S up to 10 MPH.

WEDNESDAY NIGHT: Variably cloudy. Patchy fog. Chance of a shower. Lows 50-57. Wind variable up to 10 MPH.

THURSDAY: Variably cloudy. Chance of a shower. Highs 60-67. Wind variable to N up to 10 MPH.

DAYS 6-10 (MAY 9-13)

Blocking remains dominant at least at first. Been trying to figure out if fair weather overtakes the region sooner or is delayed by another low pressure area early in the period. Leaning toward the latter, then a drier trend after. Further adjustment / fine-tuning will be needed for this part of the outlook. This is a slower pattern evolution than prognosticated on the previous blog post.

DAYS 11-15 (MAY 14-18)

Hints for a more progressive pattern though I’m not sold on a complete pattern switch. Current indications are for no well defined weather systems, but overall pattern more “dry” than “wet” and no temperature extremes.

DAYS 1-5 (MAY 3-7)

Another taste of summer will be with us today on the warm side of a frontal boundary that will take until sometime Sunday to make its way across the region from north to south. This will take place as high pressure in eastern Canada gains strength as part of a battle between Canadian cool air and southeastern US warmth that we often see in spring here in New England. But the warm side is in control today, and while it is, we’ll have to watch for some afternoon and evening showers and thunderstorms. But the timing of these seems late enough that areas that do see them still get through the bulk of the day rain-free. The focus for this activity will be west of I-95 late afternoon into early evening, with weakening remains swinging eastward during the evening. As is often the case at this time of year, the activity is likely to diminish as it approaches the coast due to marine stabilization and the loss of daytime heating. A few more showers may traverse the region tonight. As we move through Sunday, clouds are likely to be dominant, and while we’re still “in the warm air” initially, it won’t get as warm as today. The temperature rise will be thwarted and reversed during the day from north to south as the aforementioned frontal boundary moves through. However, I do think we are going to make it through much of Sunday’s daylight hours free of much rainfall too. It is at night when some overrunning over the boundary will likely create a ribbon of rainfall that wets the region down. The push of Canadian high pressure should be strong enough to get rid of most of that rain Monday, while we keep the clouds, and continue the cooling trend. This is part of a blocking pattern evolution that will find two closed lows (eastern and western US) sandwiching a ridge of high pressure (central US). The easternmost low will be what gives us additional unsettled weather Tuesday and Wednesday of next week with occasional showers. Still working out the finer details of those days…

TODAY: Sun/cloud mix, but clouds more dominant southeastern MA and South Coast along with areas of fog . Isolated to scattered showers and thunderstorms will favor areas west of I-95 mid to late afternoon, with a few storms possibly strong to (isolated) severe. Highs ranging widely from 56-63 South Coast to 78-85 inland areas mainly west of I-95. Wind S to SW 5-15 MPH.

TONIGHT: Mostly cloudy. Showers and thunderstorms likely north of I-90 early. A few additional showers possible late evening and overnight. Patchy fog. Lows 52-59. Wind SW up to 10 MPH.

SUNDAY: Mostly cloudy. A spot shower possible. Highs 63-70 by midday, followed by a cool-down north to south. Wind SW to variable to N 5-15 MPH.

SUNDAY NIGHT: Cloudy. Showers likely. Lows 46-53. Wind NE 5-15 MPH.

MONDAY: Cloudy. Showers diminish north to south. Highs 53-60. Wind NE 5-15 MPH.

MONDAY NIGHT: Cloudy. Showers possible mainly South Coast. Lows 45-52. Wind E 5-15 MPH.

TUESDAY: Cloudy. Better chance of showers in all areas. Highs 53-60. Wind E 5-15 MPH.

TUESDAY NIGHT: Cloudy. Showers likely. Lows 45-52. Wind E up to 10 MPH.

WEDNESDAY: Cloudy. Chance of showers / drizzle. Highs 53-60. Wind E up to 10 MPH.

DAYS 6-10 (MAY 8-12)

Blocking early to mid period but southward shift of features to allow high pressure to build in with drier weather, then a more progressive pattern evolves later in the period when we’ll have to watch for the arrival of a cooler airmass from Canada.

DAYS 11-15 (MAY 13-17)

More progressive pattern but overall this area in a trough position which allows for more Canadian cool shots with brief warm-ups between. The pattern can feature brief unsettled spells amidst mostly dry weather.

DAYS 1-5 (MAY 2-6)

We’re in an unsettled weather pattern, but that term “unsettled” is often misunderstood to mean days of rain, or miserably cool weather, etc. Clarification: Unsettled weather can describe changeable weather with several “systems” – high pressure / low pressure / fronts – impacting sensible weather conditions. This is also typical of springtime here in New England, whether in a progressive pattern where weather systems move right along, or a blocking pattern where they are in less of a hurry to move much. Over the next 5 days, we’ll see our set-up shift from progressive to blocking, and endure some changes that go along with that transition. Some of you may have been awoken by rumbles of thunder, or in some cases, crashes of it if it the triggering lightning was close enough, as a warm front moved through from west to east, bringing showers and thunderstorms with it. These have exited over the ocean, and our day today will feature clouds breaking for sun at times, except clouds more stubborn near the South Coast with a stronger direct low level moisture feed off the cooler ocean waters. A weak trough of low pressure approaching from the west can trigger isolated showers and a very low risk of a thunderstorm any time this afternoon or evening, but coverage on these is expected to be quite low. We stay in this “warm sector” with a southwesterly air flow through Saturday. It does appear we can make it through the morning and midday hours with minimal shower threat, but I cannot rule a few stray passing ones out completely – so keep this in mind if you have outdoors in your plans (sports, walks, yard sale hopping, etc.). We will have to keep a closer eye out for the development of showers and thunderstorms, particularly west of I-95, during the afternoon hours. A few of these could be strong with an isolated severe thunderstorm not out of the question. These would likely weaken / fall apart as they migrated closer to the coast late in the day. Part of the trigger of these will be an approaching cold front. The question the last couple of days has been what the timing of that front will be. It’s been a tough one to answer, but I do think it will slide southward across the region on Sunday, with a shower threat. Also, the timing of that front is critical to Sunday’s temperature forecast. A slower-moving front would allow Sunday to be a warmer day for a while with a cool-down coming later. A little quicker movement on the front will take the warmth out of the picture and Sunday will be a cooler day overall. I’m going for a slightly slow, but not too slow movement, so kind of a split between those 2 potentials. This is part of the evolution of blocking which will then put a closed upper level low over the northeastern US early next week, with cooler, mainly cloudy weather. The next question to answer will be how much rain to expect early in the week. There are some indications that eastern Canadian high pressure – part of the blocking pattern – will be strong enough to keep most rain to our south Monday, but may not quite have that ability to do so during Tuesday. So for now, I’m leaning toward less rain for “day 4” and more for “day 5”. Don’t hang your hat on this outlook yet though, because it’s not high confidence, and updates may very well result in notable adjustments in expectations for those days, but that’s the way it goes here in springtime.

TODAY: Clouds break for sun at times – least sun South Coast / most sun north of I-90. A stray shower and very slight chance of a thunderstorm, especially late-day, west of I-95 / north of I-90. Highs ranging from 55-62 Cape Cod / Islands to 73-80 inland with warmest north of I-90 / west of I-95. Wind S to SW increasing to 5-15 MPH with a few higher gusts.

TONIGHT: Mostly cloudy. A shower possible early. Fog patches. Lows 55-62. Wind SW 5-15 MPH.

SATURDAY: Partial sun but lots of clouds. Isolated to scattered showers and thunderstorms will favor areas west of I-95 during the afternoon, with a few storms possibly strong to (isolated) severe. Highs 58-65 Cape Cod, 66-73 remainder of South Coast region, 74-81 elsewhere. Wind SW 5-15 MPH, higher gusts.

SATURDAY NIGHT: Mostly cloudy. A chance of showers. Lows 50-57. Wind variable 5-15 MPH.

SUNDAY: Mostly cloudy. A chance of showers. Highs 58-65. Wind N 5-15 MPH.

SUNDAY NIGHT / MONDAY: Cloudy. Chance of rain, favoring southern areas. Lows 48-55. Highs 55-62. Wind NE 5-15 MPH.

MONDAY NIGHT / TUESDAY: Cloudy. Better chance of rain in all areas. Lows 46-53. Highs 53-60. Wind E 5-15 MPH.

DAYS 6-10 (MAY 7-11)

While there are indications of blocking continuing, enough of a shift in features should result in a drying trend. Temperatures start out below normal then moderate, more aggressively inland than near the coast.

DAYS 11-15 (MAY 12-16)

Current indications are a transition from blocking to progressive, but trough position with a tendency for Canadian cool shots. Brief wet weather interrupting an overall dry pattern.

DAYS 1-5 (MAY 1-5)

We’ll witness the evolution of a blocking pattern over the first 5 days of May. For our weather, it means a fair amount of spring variety upcoming. Today, we start the month with a pleasant day – a sun/cloud mix, not much wind but a coastal sea breeze, and dry weather. Clouds increase tonight and a few showers and perhaps a thunderstorm can visit ahead of a warm front. This front will push through, making our Friday warmer and more humid, with a chance of an additional shower or thunderstorm late in the day. A cold front will get close but initially won’t make it through here Friday night and Saturday, so we stay on the warm side of it, but with the opportunity for additional showers. The front should then be helped through with stronger high pressure in eastern Canada as we get to Sunday, making that a much cooler and still unsettled day as the shower threat lingers. Low pressure evolves south of our area Sunday and Monday, and while Monday looks like a cool day too (at day 5), the question is do we dry out with high pressure to the north being stronger, or see more wet weather with a weaker high and the ability of low pressure to the south to be closer? That question will be answered over the next few days…

TODAY: Sun/cloud mix. Highs 67-74 except cooler in most coastal areas. Wind variable up to 10 MPH with coastal sea breezes.

TONIGHT: Becoming mostly cloudy. A few showers and a slight chance of a thunderstorm overnight. Lows 53-60. Wind SE to S up to 10 MPH.

FRIDAY: Mostly cloudy to partly sunny. A shower or thunderstorm possible first thing in the morning favoring eastern areas, and later in the day favoring western areas. Highs 72-79 except cooler along the South Coast. Wind SW 5-15 MPH.

FRIDAY NIGHT: Mostly cloudy. A shower possible early. Lows 55-62. Wind SW 5-15 MPH.

SATURDAY: Mostly cloudy. Scattered showers. Highs 68-75, cooler South Coast. Wind SW 5-15 MPH.

SATURDAY NIGHT: Mostly cloudy. A chance of showers. Lows 50-57. Wind variable 5-15 MPH.

SUNDAY: Mostly cloudy. A chance of showers. Highs 58-65. Wind N 5-15 MPH.

SUNDAY NIGHT / MONDAY: Cloudy. Chance of rain, favoring southern areas. Lows 48-55. Highs 55-62. Wind NE 5-15 MPH.

DAYS 6-10 (MAY 6-10)

Uncertainty remains, but what is likely is the blocking pattern continues. Leaning wetter early, then a drying trend, with temperatures near to below normal.

DAYS 11-15 (MAY 11-15)

Expecting a blocking pattern to be dominant heading into mid May. Day-to-day details can’t be determined this far in advance, but our overall trend looks cooler and still somewhat unsettled.

DAYS 1-5 (APRIL 30 – MAY 4)

We’re about to say goodbye to April and this last day of the month will feature breezy, mild, but dry conditions behind a cold front. We’ll have some clouds, both patchy mid level leftovers drifting southeastward in the air flow behind the front, and some high cloudiness fanning up in the higher level southwesterly winds over the region, so sun will not be unlimited today. High pressure builds in tonight and Thursday. Thursday’s weather will be quite nice – more sun, less wind, mild, but a cooling sea breeze near the coast. High clouds do increase again later Thursday ahead of a warm front. Our next unsettled weather stretch is poorly timed for Friday into the weekend, but there are going to be some “nicer” times embedded in that stretch – a matter of working out the details in the shorter term over the next couple days to highlight them. The best guess at this point is that warm frontal showers (and a possible thunderstorm) occur in a several hour window Friday morning, and the approach of a cold front can trigger another shower or thunderstorm later in the day from west to east. The problem: This cold front is not likely to make a clean pass through the region, but get hung up, and allow another wave of low pressure to come up along it during Saturday. Some guidance holds rainfall back until later Saturday, or at night, while other guidance brings it in more hastily. I’m leaning toward the quicker scenario for this at the moment, with occasional showers any time that day. The front should be pulled through for a cooler Sunday, but it may remain somewhat unsettled as upper level low pressure swings through the region – so I can’t leave out the shower threat that day in the current version of the forecast.

TODAY: Sun/cloud mix. Highs 70-77. Wind NW 10-20 MPH, higher gusts.

TONIGHT: Mostly clear. Lows 46-53. Wind NW 5-15 MPH.

THURSDAY: Sunny through early afternoon, then increasing high clouds. Highs 67-74, cooler coast. Wind variable up to 10 MPH with coastal sea breezes.

THURSDAY NIGHT: Becoming mostly cloudy. A few showers and a slight chance of a thunderstorm overnight. Lows 53-60. Wind SE to S up to 10 MPH.

FRIDAY: Mostly cloudy. Chance of showers, favoring early-morning and late-afternoon, including a slight chance of thunderstorms. Highs 65-72. Wind S 5-15 MPH.

FRIDAY NIGHT: Mostly cloudy. A shower possible early. Lows 51-58. Wind SW to variable 5-15 MPH.

SATURDAY: Mostly cloudy. Additional showers likely. Highs 62-69. Wind variable 5-15 MPH.

SATURDAY NIGHT: Mostly cloudy. A chance of showers. Lows 50-57. Wind variable 5-15 MPH.

SUNDAY: Variably cloudy. A chance of showers. Highs 58-65. Wind NW 5-15 MPH.

DAYS 6-10 (MAY 5-9)

There’s a lot of uncertainty in the forecast for next week. Our various sets of guidance show different details, but the general idea is the evolution of a blocking pattern. The set-up of low pressure vs. high pressure determines wet weather (and magnitude of it) vs. dry weather, air flow and temperature. Current leaning: Fair weather May 5. Unsettled with marine air flow middle of next week. Fair weather end of week.

DAYS 11-15 (MAY 10-14)

Expecting a blocking pattern to be dominant heading into mid May. Again, unsettled weather vs. fair weather TBA, but suspect as features shift slightly we’ll have a bit of both. Some recent indications of wetter weather being pushed to the south and a drier, cooler scenario for this region. Will monitor trends on reliable guidance.