DAYS 1-5 (MAY 12-16)

A disturbance that passed by our region overnight is moving offshore this morning with just some patchy clouds in eastern areas and a couple of light showers clipping the outer portion of Cape Cod before 8 a.m. After this, high pressure dominates and today turns out to be quite a nice day for mid May with sunshine, eventually sharing the sky with diurnal clouds as the sun-heated ground sends moisture into the sky that condenses in colder air aloft. These clouds will dissipate this evening but while that happens we’ll see an increase in high clouds from the west ahead of warm front from low pressure moving into the Great Lakes. Clouds thicken into Wednesday morning and as that front moves through, a period of light rain is possible. After the warm front goes by, while clouds remain abundant, it should be generally rain-free outside of a shower chance in central MA and southwestern NH later in the day, ahead of a cold front. As this front enters our region at night, the shower chance increases, but the front does not make a clean pass through. The upper level low that is driving the system is going to be drifting east southeast instead of traveling with its companion surface low into southeastern Canada, the latter eventually dying and giving way to a new surface low to the south, which quickly is caught under the upper low, becoming quasi-stationary for about 24 hours (Thursday to early Friday). This is when our wettest weather will occur, along with a cool-down due to thick overcast and an air flow off the still-chilly Atlantic waters. Double good news though: 1) The low does bring some beneficial rainfall to aid in keeping the dry conditions and areas of moderate drought from worsening too much. 2) It moves eastward enough so that we start to see improvement later Friday and most certainly in time for the start of the weekend, although we will still be on its western periphery Saturday with a sun / cloud mix and an active breeze and at least a pretty cool start to that day.

TODAY: Patchy clouds NH and eastern MA until mid morning including a brief shower Outer Cape Cod. Abundant sun mid to late morning. A sun / cloud mix midday and afternoon. Highs 60-67. Wind NW to W 5-15 MPH.

TONIGHT: Partly to mostly cloudy. Lows 43-50. Wind variable up to 10 MPH.

WEDNESDAY: Mostly cloudy. Chance of rain favoring areas north and west of Boston morning to midday. Highs 55-62 occurring by midday then may turn cooler especially coastal areas. Wind variable to E up to 10 MPH shifting to S 5-15 MPH.

WEDNESDAY NIGHT / THURSDAY: Mostly cloudy. Showers likely. Slight chance of a thunderstorm. Lows 48-55. Highs 55-62. Wind S shifting to E 5-15 MPH, higher gusts.

THURSDAY NIGHT: Cloudy. Widespread showers. Slight chance of a thunderstorm. Areas of fog forming. Lows 47-54. Wind E to NE 5-15 MPH.

FRIDAY: Cloudy with showers / drizzle through midday, then tapering off with breaks in the clouds later. Highs 55-62. Wind NE to N 5-15 MPH.

FRIDAY NIGHT: Variably cloudy. Lows 42-49. Wind N 5-15 MPH.

SATURDAY: Partly sunny. Highs 65-72 except cooler Cape Cod. Wind N to NW 5-15 MPH.

DAYS 6-10 (MAY 17-21)

High pressure dominates with fair, milder weather early to mid period. A brief shower chance around May 20 leads to slightly cooler but fair weather to end the period.

DAYS 11-15 (MAY 22-26)

This period encompasses from the Friday leading into Memorial Day Weekend to the Tuesday after it. Typically there is a lot of uncertainty in a medium range forecast in general, most especially spring time. Current trends indicate that this period of time features mostly dry weather and somewhat variable temperatures, with an increase in wet weather returning toward the end of the period.