By James M. Arnold, Weather Specialist
The ECMWF (European) model has an amazing output forecast for the next 48 hours for this area, and it is seen below from the WeatherBell Analytics site.
While the 2 to 3 inches of snow in our near future the model sees might be a bit overdone, I do see some wintry mix or a short period of snow as the precipitation shield moves away to our east.
What I am becoming concerned about is that we could see a “Flash Freeze” as the front passes to our east early tomorrow morning.? The timing is such that it is likely to pass our area during tomorrow's pre-dawn hours, and without the heating of the sun to help keep temperatures up, readings could go as low as the high 20s!? This could create conditions where any snow or moisture left on paved surfaces could rapidly freeze, even though pavements are now warmed by the recent high temperatures, before winds dry those surfaces.
As far as today is concerned, it is pretty much what you see is what you will get.? Temperatures will remain in the high 50's to low 60's throughout much of the day before beginning to fall by late afternoon.? Rain will be showery and generally on the light side until early this afternoon when it will become steadier and heavier.? Our rain will be driven almost horizontally at times by high winds from the south and southwest throughout the day and into the evening, reaching speeds of 20 to 30 mph with some gusts to 45 to 55 mph likely.? Some isolated tree and power line damage is possible should gusts reach the upper end of the forecast.? Rain will be moderate to heavy throughout much of the night and there is a good chance that we will also see some imbedded thunderstorms thrown in for good measure.? A general 1 to 1.5 inches of rain seems quite likely, and up to 2.5 inches is possible where thunderstorms are in the mix.
Early tomorrow morning as the front passes our area, precipitation should change to a short period of wintry mix or snow before ending.? Flooding should not be an issue except for some urban and street flooding in the usual areas, but some of the smaller streams that react quickly to heavy rain will need to be watched as they could go over their banks should any thunderstorms linger over a given area.? Although there will be some severe weather well to our south, I do not expect any here.? Our heavy rain, high winds and a spectacular frontal passage are enough.
The rest of the week should average out to be partly cloudy and cool, with daytime temperatures if the high 40's to low 50's and nighttime lows generally in the high 20's to low 30's.
As of right now, Marathon Monday looks to be partly cloudy and cool, with temperatures reaching the mid 40's by 9:30 and the low 50's by noontime.? There will likely be a light to moderate westerly wind, serving as a bit of a tailwind for the runners.
James M. Arnold is a Weather Specialist working with Shrewsbury Emergency Management Agency; town of Princeton; Worcester Emergency Communications and Emergency Management Agency; Southborough Emergency Management Agency; town of Grafton and Wachusett Mountain Ski Area