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.