DAYS 1-5 (JUNE 12-16)
The first half of Saturday morning and Sunday evening / night will be the wettest parts of the weekend which will otherwise feature mostly dry weather, below normal temperatures today and a warm-up for Sunday. A vigorous disturbance is moving rapidly southeastward through the region early this morning with numerous showers, but as I write this, the showers have already exited southern NH and northern MA and will be making their way out of the remainder of the WHW forecast area into mid morning. After that, it’s a dry day, but clouds will be a little stubborn to give up for a while as it takes some time for drier air to work into the region from north to south. With a light and variable wind, as we get the subtle solar heating we do end up with, a light sea breeze will develop in most coastal areas. So, outdoor plans today are best executed from late morning on with a light jacket or sweatshirt handy. If you have Saturday evening plans, a jacket or sweatshirt is recommended for outdoor time as it will be on the cool side, but dry. A small area of high pressure to the east of the region on Sunday will help warm up up with a south to southwest air flow. An approaching and weakening cold front from the west will hold off its arrival until sometime in the evening or at night, when a round of numerous showers and possibly a few embedded thunderstorms will move into the region. This activity may linger into early Monday before it exits with the passage of the weakening front, but a stronger cold front will approach later Monday and trigger another round of at least scattered to possibly a broken line of showers and potential thunderstorms. The intensity of this activity will be determined by the amount of daytime heating that can occur before it, and this will be a function of how much sun occurs during the day. I expect a variable amount of cloudiness so if there is limited sunshine Monday this can limit the potency of showers and storms heading in from the west. That stronger front will move offshore later Monday night, ending that threat, but a pool of cold air above still has to move across the region Tuesday, and this will be a set-up for pop up instability showers and perhaps a thunderstorm that afternoon, but this activity will be more isolated. By Wednesday, the lingering cool pool aloft should be weaker so that we just see some clouds popping up, but no shower activity here, with any of that likely confined to the mountains north and west of the WHW forecast area.
TODAY: Cloudy start with numerous showers ending from northwest to southeast into mid morning. Clouds eventually break for sun north to south. Highs 67-74, coolest coast. Dew point lower 50s. Wind E 5-15 MPH.
TONIGHT: Partly cloudy. Areas of fog especially lower elevations. Lows 52-59. Dew point lower 50s. Wind SE under 10 MPH.
SUNDAY: Partly sunny. Highs 76-83. Dew point middle 50s. Wind S 5-15 MPH.
SUNDAY NIGHT: Mostly cloudy. Showers likely and possibly a thunderstorm late evening and overnight. Areas of fog. Lows 56-63. Dew point middle to upper 50s. Wind S up to 10 MPH.
MONDAY: Variably cloudy. Showers most likely early morning. Chance of showers and thunderstorms west to east late-day. Highs 70-77. Dew point near 60. Wind SW 5-15 MPH.
MONDAY NIGHT: Variably cloudy with showers likely and a chance of thunderstorms evening. Partly cloudy with patches of fog forming overnight. Lows 52-59. Dew point falling to lower 50s. Wind W up to 10 MPH.
TUESDAY: Sun/cloud mix. Isolated afternoon showers and possibly a thunderstorm. Highs 71-78. Dew point 50s. Wind W 5-15 MPH.
TUESDAY NIGHT: Partly cloudy. Patchy ground fog forming. Lows 51-58. Dew point lower 50s. Wind W under 10 MPH.
WEDNESDAY: Sunny to partly cloudy. Highs 74-81 but may turn cooler in some coastal areas. Wind W up to 10 MPH but possible coastal sea breezes.
DAYS 6-10 (JUNE 17-21)
Overall pattern features a low pressure trough in southeastern Canada and a mostly west-to-east air flow over New England. Temperatures near to slightly below normal but will spike briefly around June 18 possibly into June 19. The greatest risk of showers and thunderstorms will occur around June 19 when a frontal system is expected to move through the region from west to east. The summer solstice occurs late evening of June 20.
DAYS 11-15 (JUNE 22-26)
The west-to-east (zonal) flow pattern should continue to start this period with a shower/thunderstorm threat with a frontal passage June 22 or 23. Later in the period we may start to transition to a warmer/hotter set-up, but sometimes this is indicated by guidance earlier than it actually takes place, so this is a low confidence mention at this point.