DAYS 1-5 (MAY 22-26)
“Uh-oh”, or something more colorful I can’t type here, may be the first thought of someone rising around or just after dawn from Cape Ann MA to NH Seacoast, under a blanket of stratus with temperatures in the upper 50s. Even Boston and immediate North Shore sits in the upper 50s with a light east wind, although without the stratus. Are you thinking – “here we go again, no warm-up today either”? Today will be different. Most of the remainder of the region is already in a southwesterly air flow, and this will finally make its way across the eastern coastal areas of MA and NH and areas that were stuck in the 60s to around 70 yesterday will make a significant jump today. But as I cautioned and also forecast yesterday, today’s temperatures right at the shoreline will be cooler, probably under 90 in many locations for high temperatures, and certainly so along the South Coast and across Cape Cod where the southwest wind is a “sea breeze” by default. So not everybody will be baking in the early heat. Where that heat was yesterday, this will be day 2 and the final day of a short spell of it, where as other areas will have the warm to hot weather for today only. A cold front crossing the region tonight is going to put an end to any heat. Other than an isolated air mass thunderstorm that may pop up well ahead of this front in a couple areas today, it’ll be dry during the daylight hours. Tonight, after sunset, a remnant line of showers and maybe embedded thunderstorms will cross the region from west to east, but it will have lost a lot of the punch it will have to our west where the timing will favor stronger storms. We’ll have lost some of our dynamics (which were around but capped from activating yesterday) and will be losing daytime heating, so we will miss out on big storms but also be gypped of any beneficial rain, as just brief showers will pass by. We’re back to dry weather Monday behind the front, along with cooler air and lower humidity. The high pressure area supplying the cooler air is going to drift eastward but with its center staying to our north, so we’ll see our surface wind here turn northerly to northeasterly as we get to Tuesday and Wednesday, and we’ll also have to watch for a couple of waves of low pressure passing by on the front that goes by Sunday night, which will sit not far to the south for a few days. This could bring occasional cloudiness back into the region, and while it’s not shown by guidance at this point, even a shield of rainfall may try to work into at least southern portions of the region sometime Tuesday or early Wednesday. Right now though, odds favor it staying rain-free and it’s just something to keep an eye on. When we get to Thursday though, that frontal boundary will start lifting back to the north in response to an approaching trough from the west, so regardless of what happens prior, we may end up with lots of clouds and the threat of some rainfall by then.
TODAY: Low clouds parts of Cape Ann MA to NH Seacoast dissipating by midday, sunshine elsewhere. A few clouds may build and an isolated thunderstorm or two is possible mainly southwestern NH, central MA, and eastern CT, this afternoon. Highs 74-81 South Coast, 82-89 just inland from South Coast as well as along East Coast shoreline, 90-97 elsewhere with hottest over interior valleys. Humid – dew point middle to upper 60s. Wind SW 5-15 MPH, higher gusts by late-day, but still some weak sea breezes for a while along some immediate East Coast shores.
TONIGHT: Clouds move in evening – a round of showers with possible thunder west to east. Clearing overnight. Humid through midnight, drying overnight. Wind SW 5-15 MPH and gusty shifting to NW.
MONDAY: Sun/cloud mix. A passing shower possible South Coast / Cape Cod. Highs 72-79. Wind NW-N 5-15 MPH.
MONDAY NIGHT: Variably cloudy. Lows 48-55. Wind N-NE 5-15 MPH.
TUESDAY: Mostly cloudy. Slight chance of rain favoring the South Coast. Highs 66-73, coolest east-facing shores. Wind NE 10-20 MPH.
TUESDAY NIGHT: Mostly cloudy. Slight chance of rain favoring the South Coast. Lows 49-56. Wind NE 5-15 MPH.
WEDNESDAY: Variably cloudy. Chance of rain near the South Coast early. Highs 66-73. Wind NE-E 5-15 MPH.
WEDNESDAY NIGHT: Mostly cloudy. Lows 50-57. Wind E-SE up to 10 MPH.
THURSDAY: Mostly cloudy. Chance of showers. Highs 63-70. Wind SE-S 5-15 MPH.
DAYS 6-10 (MAY 27-31)
A lot of scrutiny will be on this period of time with Memorial Day Weekend sitting right in the middle of this period (May 28-30), so the entire period is important for planning including people who may be traveling regionally a little early or extending the weekend an extra day. Obviously a forecast for days 6 to 10 is not going to carry with it a guarantee of accuracy or be made with very high confidence, given its time in the future, but here’s my best early guess… Friday May 27 we see showery weather as a trough and cold front move through. Saturday May 28 is dry with high pressure moving in. Sunday May 29 and Monday May 30 will see high pressure in eastern Canada and high pressure to our south battling for control – a common theme of spring. This puts a frontal boundary between the 2 and possibly in our vicinity. This increases the chance for cloudiness and at least the possibility of a period of wet weather, but given the overall pattern and tendency to be dry, I’d favor the drier side winning out with the temperature forecast being a toss-up and dependent on which side of a frontal boundary wet sit on or whether or not we’re bisected by it. The same will hold true for Tuesday May 31 looking that far out as well. Obviously, a great deal of fine-tuning will need to be done to this forecast.
DAYS 11-15 (JUNE 1-5)
Early June pattern looks like it wants to be somewhere between weak zonal flow and weak omega blocking with us on the drier side of the pattern overall, along with mostly seasonable temperatures. This is just a general idea and a lot more looking is needed.