DAYS 1-5 (JUNE 27 – JULY 1)
There are a lot of little details to get to, and I want to keep the explanation as simple as possible, without taking up the entire weekend to try to explain the weekend’s weather. 😉 … Today, a warm front approaches (again) more a dew point boundary since we’re not going to warm up significantly behind it, but getting it through here may be a bit of a process. An initial impulse races east southeastward into New England today and turns our sunny start into a mainly cloudy afternoon with a shield of rain and possible embedded thunderstorms. This will also be fighting dry air as it arrives so it may “look” worse on radar than what actually occur at ground level in most areas. Where the front itself is located, near the South Coast, is where we may see some heavier surface-based convection and stronger storms. I do not expected widespread big boomers in the area today. That activity will be limited. It may even be limited to southwestern CT and never quite get into the WHW forecast area at all. This little wave of low pressure that forms on the front as it tries to cross the region will give us a lesson in mesoscale meteorology, as it likely turns the surface wind to the east over southern NH and adjacent far northern MA, eventually to shift more to the north as it moves offshore. This will cause a notable cool-down in these areas after they reach their high temperatures late this morning and midday, just prior to the heaviest clouds arriving and eventual wind shift. To the south of here, the winds will be more variable to southwesterly on the other side of the boundary, but may shift more to the northwest for a while this evening with a less-dramatic cool down there. Eventually, the boundary lifts back to the north once it’s free of the small low pressure area’s influence, and we get a light but more regional southwesterly flow and rising humidity overnight. A wild card during this process is whether or not there will be additional showers and thunderstorms. History shows this set-up can pop them, but history also shows when we’re in a developing or existing drought, any rain is hard to come by. I’ll leave them in the forecast, isolated in nature, overnight. And now to Sunday, the same boundary that goes through today / tonight comes back again as a cold front, but slowly, and will be the focal point for episodes of showers and thunderstorms. Expect this activity to occur mainly during the afternoon and evening hours. So there’s your weekend in a very large nut shell, sounding a lot worse than it will actually be, as the majority of the time at any one location will be rain-free. So what about early next week? As we wrap up June and begin July in the Monday-Wednesday period, an upper level low pressure will be over the region as part of a blocking pattern, and with general surface high pressure to the north, the general air flow will be northerly to northeasterly at times. This pattern is cooler for temperatures, but enough daytime heating with cold air aloft is a set-up for instability showers and thunderstorms. When this set-up occurs, showers and storms don’t even have to be that strong to produce hail. So we will have to watch for that. More fine-tuning to come with the early next week situation…
TODAY: Sunny start, then rapidly clouding over late morning-midday. Generally cloudy this afternoon with a period of rain and embedded thunderstorms. A heavier thunderstorm is possible south of I-90 as well. Highs 78-85 by midday. Temperatures falling gradually at first this afternoon then a little more quickly later in the day, especially in southern NH and far northern MA so by evening 60-68 should be common, with coolest readings southern NH. Wind SW up to 10 MPH through early afternoon, shifting to E briefly in southern NH and northeastern MA and becoming variable most other areas except staying SW near the South Coast during mid afternoon into evening.
TONIGHT: Mostly cloudy. Isolated showers and thunderstorms. Humid. Lows 57-64, coolest in southern NH. Wind N-NW north of I-90, NW-W south of I-90 up to 10 MPH, shifting to SW overnight.
SUNDAY: Variably cloudy. Scattered showers and thunderstorms, mainly during the afternoon and evening. Humid. Highs 78-85. Wind SW 5-15 MPH.
SUNDAY NIGHT: Mostly cloudy evening with showers and thunderstorms possible. Partly cloudy overnight. Lows 58-65. Wind W-NW 5-15 MPH.
MONDAY: Partly sunny. Scattered afternoon showers and thunderstorms. Highs 77-84, coolest coast. Wind N-NE 5-15 MPH.
MONDAY NIGHT: Partly cloudy. Risk of a shower early. Lows 56-63. Wind NE under 10 MPH.
TUESDAY: Partly sunny. Scattered afternoon showers and thunderstorms. Highs 76-83, coolest coast. Wind NE 5-15 MPH.
TUESDAY NIGHT: Partly cloudy. Risk of a shower early. Lows 56-63. Wind N up to 10 MPH.
WEDNESDAY: Partly sunny. Isolated afternoon showers and thunderstorms. Highs 75-82. Wind N 5-15 MPH.
DAYS 6-10 (JULY 2-6)
High pressure shifts over and then briefly southeast of the region with fair and a little warmer weather July 2-3. A new high pressure area from eastern Canada may bring a batch of cooler air down for the Independence Day Weekend, but this is a low confidence forecast. Inconsistent guidance ranges from a quick turn to cooler/dry weather with a warm-up by July 6 to a period of unsettled and cool weather all of those days. This far in advance I’m somewhere in between, and will try to add a bit more detail next update. One thing I am more confident of is that I see no widespread beneficial rain.
DAYS 11-15 (JULY 7-11)
Continuing to cautiously lean toward a shift to a more zonal flow pattern with minor disturbance, mainly dry weather, and temperatures near to above normal.