DAYS 1-5 (MAY 1-5)
May’s here, and this week our pattern will be dominated by the eastern low pressure area in an upper level omega-style blocking pattern. For a more complete picture, the other upper low is over California and a ridge of high pressure is centered over the Plains, and very little movement of the large scale features, only an eastward drift, will take place as we move through the next 5 days. This will result in a slow transition in our weather during this time, not a situation where every day has the same weather. Today, we’ll be in a southwesterly wind flow as surface low pressure that went by our region last night wheels northwestward and gets pulled underneath the upper low that’s initially centered in the Great Lakes region. That feature wobbles its way east southeastward Tuesday through midweek, moving overhead Wednesday then finally off to the south and east of the region by Thursday and Friday. But by that I don’t mean “away” yet. That just gradually shifts our wind from south and west initially to more easterly by later Wednesday and the northeast to north Thursday and Friday. As was previously prognosticated, I still think Thursday will be our coolest day. Backing up a bit for a sensible weather summary – today starts with abundant clouds and some last lingering light showers, especially northwest of Boston, then sun takes over, but more clouds pop up and a stray shower may visit western reaches of the forecast area later in the day. Tuesday, more widespread showers move in from the west and will be around off and on during the day. We may see a break and some clearing early Wednesday before another batch of clouds and possible showers, even some drizzle as we see the wind transition to more of an onshore (easterly) by later in the day. Any showers later Tuesday and Wednesday can contain graupel or small hail due to the cold air aloft. Additional showers and drizzle can be around Thursday, the coolest day with a broad northeasterly air flow, and still some additional pop up showers can occur on Friday as well as we’re still well within the influence of the upper low, even though it’s starting to move further away by then.
TODAY: Mostly cloudy start with a few showers mainly northwest of Boston from north central MA into southwestern and south central NH, then a sunnier interval before more clouds pop up during the afternoon hours, and a stray shower is again possible in the CT Valley to Monadnock region later in the day. Highs 60-67 except 50s South Coast. Wind SW increasing to 10-20 MPH with some higher gusts.
TONIGHT: Variably cloudy. A quick shower possible early in southwestern NH. Lows 47-54. Wind SW 5-15 MPH.
TUESDAY: Mostly cloudy. Scattered to numerous showers, some of which may contain graupel and/or small hail by later in the day. Highs 55-62. Wind SW 5-15 MPH, higher gusts.
TUESDAY NIGHT: Mostly cloudy with showers likely during the evening. Partly cloudy overnight. Lows 43-50. Wind S up to 10 MPH.
WEDNESDAY: Partly sunny early, then mostly cloudy. Scattered to numerous showers, possibly mixed with graupel and/or small hail. Areas of drizzle especially in eastern coastal areas later in the day. Highs 53-60. Wind S up to 10 MPH shifting to E.
WEDNESDAY NIGHT: Mostly cloudy. Chance of showers and drizzle. Lows 43-50. Wind NE 5-15 MPH.
THURSDAY: Mostly cloudy. Chance of showers and drizzle. Highs 46-53. Wind NE 5-15 MPH, higher gusts especially in eastern coastal areas.
THURSDAY NIGHT: Mostly cloudy. A passing shower possible. Lows 40-47. Wind N 5-15 MPH.
FRIDAY: Variably cloudy. Chance of showers. Highs 51-58. Wind N 5-15 MPH.
DAYS 6-10 (MAY 6-10)
May 6-7 weekend looks dry with a slight warming trend, but still coolest at the coast, as upper level low pressure pulls away to the east and high pressure builds to the north of the region. High pressure brings dry weather mid period before the next disturbance brings back the chance of unsettled weather by the end of it.
DAYS 11-15 (MAY 11-15)
Overall pattern looks dry and somewhat milder for this period of time into the middle of the month but may start out with some unsettled weather at first.