Greater Boston, North Shore and Metro West: A blocking pattern over the north Atlantic has slowed systems to a crawl over much of the country, especially here in the Northeastern US. As a result we are the beneficiary of high pressure settling in and bringing us fair skies and dry conditions through Patriots Day. Offshore low pressure has actually retrograded southwestward and will move offshore to our south today and tomorrow. The associated cloud deck remains just far enough offshore today that it will not impact our weather. What will impact our weather are the gusty northeast winds that are going to keep it chilly along the coast. Along with that is a elevated fire danger that brush fires are almost certainly going to be a concern over the weekend with the highest risk on Saturday.
The National Weather Service has issued a Red Flag Warning for Saturday due to the gusty winds and very low humidity values and bright sunshine. The pre green up areas are still quite dry and with several days of dry weather behind us conditions are ripe for brush fires to ignite and spread rapidly because of the wind component.
There will be a wide temperature range today as we experience chilly and raw conditions along the coast with temperatures in the upper 40s, then low 50s just away from the coast and finally to near 60 across inland Merrimack Valley and downward along the Route 495 beltway. Abundant sunshine will make for an excellent mid April day away from the coast. However, clear skies and slackening winds will set us up for a night of radiational cooling so expect the mercury to once again dip back into the 30s, except about 40 in Boston.
With the low moving out of the picture by Sunday high pressure will now be firmly in control. That means a more tranquil day along the coast with lighter winds everywhere, sunshine and milder temperatures. A splendid day to get in some yard work, another practice run for the marathon, a walk along the beach or whatever your fancy is. Although it will remain coolest along the shore temperatures are expected to range from well into the 60s for most, closer to 60 along the shore, perhaps falling back to the mid 50s during the afternoon. Another clear and quiet night follows with cooling temperatures falling into the mid 30s inland to low 40s on the shore.
A cold front approaches for Patriots Day. A big day in these parts with the running of the Boston Marathon. Although the front is not expected to cross the area until very late in the day or into the evening hours we may still have a sea breeze set up along the coastal plain during the afternoon because of a light wind field ahead of the front. This means the runners will be running into the wind as they approach Boston. Although a milder west wind will take hold over the interior, meaning milder temperatures, once again along the coastal plain the ocean breeze likely keeps temperatures 15 to 20 degrees cooler there. Highs across the interior near 70, only in the 50s on the coast. Sunshine prevails with late day clouds moving in ahead of the front.
A few showers are possible Monday night and again Tuesday afternoon. Cooler temperatures for Tuesday and Wednesday. Then fair skies return for mid week with warming temperatures later in the week.