Rainfall Expectations Increased

Based on the most recent data, the NWS has upped the total expected rainfall to 4-6 inches with isolated areas of 8 inches very likely. The axis of heavy rainfall has shifted eastward. This is not even the worst of the rain.

Later on tonight, as the jet stream shifts to an easterly flow triggers the rainfall explosion. An extremely wet atmosphere combined with an endless supply of tropical moisture from the ocean will set up a torrential rain event for the better part of 6 hours. This strong easterly flow will enhance the rainfall right along the coast even more so as a coastal front will likely set up. Any way you cut it, Tuesday morning will be very wet and very dangerous.

Major flooding is expected, the likes of which have not been seen in decades. Pretty much every river and stream will likely overflow, some worse than others. Again, the ground is still very saturated so expect areas that received flooding two weeks ago to flood again. This could happen even quicker than before as the time period for the heaviest rainfall is much shorter than the last storm. What that means is we will see the same amount of moisture a lot faster.

In addition to major flooding, several records will fall including the wettest March on record.Some of these records have stood for close to 70 years! As it stands now, we have received 10.92 inches of rain this month. The next measurement will likely break our all time March record. The all time record is 17.09 inches back in August of 1955 and that was mainly the result of two hurricanes that hit the area. 17 inches is unlikely, but I am almost positive that this month will end up as the second wettest month ever in Boston.

Exciting stuff for weather geeks, but I also recognize the significant damadge this will cause. Be advised, move all valuables from basements and keep an eye on rapidly rising water. We are not very used to seeing this type of rain around here, so flash flooding can happen in areas that people do not expect to see any flooding at all. Do your neighborhoods a favor and try to clear out debris from storm drains so the water can flow smoothly. Overnight tonight and early tomorrow morning will be the best chance for flooding. Stay safe!