There are two players in the weather the next 48 hours and both will produce some rainfall. Last night heavy showers and storms rumbled east from the Berkshires. Severe thunderstorm warnings popped up, but as the storms moved east they weakened. By the time they reached route 495 they had all but fallen apart and eastern areas of the region saw little or no rain at all.
Some of us would love a good healthy dose of rain and that is still likely going to happen tomorrow. As you know, Hurricane Arthur is moving slowly up the coast and will impact southern New England tomorrow. The confidence in heavy rain tomorrow afternoon and evening is high enough so the Pops Concert was moved to this evening.
While itís not 100% sure there wonít be any storms this evening, the chances are very high the weather stays dry in the 8 PM to 11 PM time frame. A flood watch is up for the Berkshires today and could be expanded later today.
The map below is from one the newer hi-resolution models I like to review. What this is telling me is that around 7PM tonight most of the showers and storms will still be well west of the coastal plain and capitol areas. This doesnít mean this model is 100% correct, but the idea here is the bulk of the morning is certainly dry and we could get by with much of the afternoon and evening being dry as well. As the evening goes on that line pushes east and weakens. I think it will not move through Boston until after the Esplanade has cleared.
Overnight this line of showers will push through and itís possible you might be awakened by the rumble of thunder overnight, unless of course the hum of your air conditioner drowns out the noise. Now, any time you have a very humid and tropical air mass in place there can be showers and storms that pop-up outside of the main line. This is possible later this morning and even into the afternoon, but 80% of us stay dry.
Tomorrow is the day we watch Hurricane Arthur move up the coastline and bring with it a slug of rain. The image below shows the radar projection late morning Friday. Notice the circular blob of rain with the clear center off the coast of Maryland, which is Arthur.
A band of rain protrudes northward form the center and is what will bring us some heavier downpours later Friday morning and through at least the first half of the night. Right now, I would say there is a high likelihood any outdoor event in the afternoon and evening will be cancelled as the rain moves in if they havenít been already. The Red Sox play at 1:30 and even if there aren't showers at the start, it should be becoming increasingly wet.
Between 7PM and 3 AM is when the heaviest rain will occur. Letís look at projected radar for 11PM July 4th.
I'll be updating the forecast on Twitter @growingwisdom frequently.
Notice all the rain over the area as the center of Arthur comes closest to southern New England. At this point there is a chance winds will increase along the immediate coastline to over 20 miles per hour, but the strongest and damaging winds arenít going to make it to land.
The map below shows the projected winds at about ground level. Notice the most intense winds with the hurricane remain well off the coast. Tropical storm force winds can reach Nantucket, Marthaís Vineyard and even parts of the outer Cape, but this term just means winds of 39 miles per hour or higher and you should think of it as a typical noríeaster.
Unlike winter, when snow can shut down airports, an offshore hurricane won't have the same impact to air travel. However, these systems do produce thunderstorms and heavy rain and these can delay flights. The most likely period of delay from Arthur is Friday afternoon and night. Other delays from thunderstorms might occur this afternoon especially around New York, New Jersey and Philadelphia.
Skies will quickly clear from southwest to the northeast Saturday morning and leave us with a beautiful weekend of sunshine and pleasantly warm, but dry air. If you are headed to the beach, the surf will be quite rough and you should heed any warnings about the conditions. Every time we get a hurricane or tropical storm passing by someone ends up taking too big a risk and injuring them or dying. Letís hope this storm is different.
A bit of heat and humidity return early next week before another front brings back some drier and slightly cooler air. I donít see any heat waves on the horizon as we head into the first full week of July.