11:13PM
The “South Wind Storm Killer” has been at work tonight, keeping organized storms from reaching the coastal plain in eastern MA, RI, and the Seacoast region of NH. Often, a straight southerly wind will keep the atmosphere too stable to support strong storms, and only isolated heavy downpours pop up in the tropical air that is over us. A subtle shift in conditions over the next few hours may allow a line of storms currently entering east central NY State (as of 10:30PM) to make it most of if not all of the way across MA by 3:00AM. Winds should shift to the southwest ahead of this line, and the sooner that happens the better the chance is that these storms survive the trip. If the winds remain more southerly, then this line will also weaken as it moves into the stabilized air in place. So don’t be totally surprised if you hear at least heavy rain falling and possibly some booming thunder sometime between 2:00AM & 4:00AM, earliest to the west, lastly in areas southeast of Boston. All of this activity should be pushing eastward offshore by dawn.
Looking ahead into the new week, we still have a little bit of an upper level trough to cross the region on Monday, and perhaps also one weak wave of low pressure rippling along the front that will have just passed by, so we cannot completely rule out a shower or thunderstorm through Monday evening, though widespread activity is not expected.
High pressure will dominate Tuesday and Wednesday with 2 splendid late summer days being the result.
By Thursday, we’ll be back into return flow on the back side of high pressure, and will see an increase in temperature and humidity, and also the chance of showers and thunderstorms, most likely later in the day or at night, as a cold front moves into the region. This front should push offshore Friday with a return to fair weather, which should last through Saturday as well. Things become tricky by Sunday as that could be when we’d be hearing from Irene, currently a tropical storm and expected to become a hurricane. I could outline multiple scenarios, based on computer model forecasts, but at this point I will just say that the storm will likely impact somewhere along the Southeast US Coast as a hurricane late in the week, and it should arrive in the Northeast via south to north steering currents by late in the weekend. What form Irene will be in when it gets here? It is simply too early to tell, and this will be something to follow during the week.
A peek a little further ahead into the last few days of August: Looks great behind Irene for the last couple days of the month, and there are even some early signs of a bout of late summer heat as we head toward the Labor Day Weekend. More in the days to come…
For now, the latest Boston Area Forecast…
OVERNIGHT: Mostly cloudy, mild, and muggy. Isolated to scattered showers and thunderstorms through 2AM, then a chance of a broken to solid line of showers and storms moving west to east across the region between 2AM & 4AM. A follow up shower or storm may visit areas especially along and east of Route 95 toward dawn. Low 64-69. Wind S 10-15 MPH with higher gusts, shifting to SW, then W toward dawn.
MONDAY: Mostly cloudy to partly sunny with a lingering shower possible in the morning. Mostly sunny to partly cloudy in the afternoon then variably cloudy late in the day with a risk of a passing shower or thunderstorm. High 80-85. Starting humid then slowly drying. Wind W 10-15 MPH with gusts around 20 MPH, shifting to NW.
MONDAY NIGHT: Partly cloudy. Cooler and drier. Low 60-65. Wind NW 5-15 MPH.
TUESDAY: Mostly sunny and comfortable. High 75-80. Wind NW 5-15 MPH.
WEDNESDAY: Mostly sunny. Low 60. High 81.
THURSDAY: Partly cloudy. PM thunderstorms. Low 66. High 88.
FRIDAY: Partly sunny. Low 64. High 82.
SATURDAY: Mostly sunny. Low 64. High 84.
SUNDAY: Clouding over. Rain/wind arriving (Irene)? Low 66. High 77.