Up and Down

Thu. 2/28

Surprise snow showers this morning - water vapor imagery shows a piece of upper level energy moving across New England and its this feature that combined with the cold temperatures to squeeze out some snow showers around the area. While most spots saw less than an inch, the Outer Cape saw a bit more. This area of light snow will diminish and shift offshore allowing for improving conditions through the day on Thursday.

Cold Temperatures - It's cold. Temperatures this morning have started off in the upper 10s and lower 20s around the Cape and will struggle to climb much above 30 today thanks to a new surge of very cold air that moved in over night Wednesday. Such a cold day will set us up for a very chilly night tonight as cold high pressure moves eastward towards the area, carrying the core of the coldest air into New England. Computer guidance wants to send temperatures well down into the 10s on parts of the Cape tonight, in fact, some guidance says we hit 10F on the Upper Cape. However, with the area of high pressure still to our west, preventing winds from going calm, I'm not certain we can get quite THAT low, but 12 to 14F on the Upper Cape is possible, with upper 10s to near 20F on the Outer Cape.

Friday Night/Saturday System - a clipper system is currently dropping south and eastward through the Northern Plains and into the Midwest. While the feature is moisture starved because of its origins over the plains of Canada, it is a fairly dynamic little storm center and is already producing a decent area of precipitation relative to its latitude and source region. As the storm system slides eastward, it will begin tugging milder air north and eastward, sending it up and over top of the cold arctic air in place over the Great Lakes and Northeast. This lifting will allow the precip. shield to grow and intensify over the next 24 hours. In addition, as the system heads eastward it's upper level energy will dig and sharpen, supporting further precipitation enhancement over the Northeast. So what is currently a somewhat disorganized area of snow over the plains/midwest will grow into a solid shield of snow by Friday morning.

For us, this adds up to increasing clouds on Friday, with snow developing late Friday night. However, with a surface low track from near Lake Ontario to the Gulf of Maine, we will eventually see southerly winds take over which should force warmer air northward, changing snow over to rain. This is an interesting little storm center from a meteorology standpoint. Climatologically, this is not a low track that supports heavy accumulating snow on Cape Cod. We will be in the storm's warm sector and the brunt of the heaviest precip. is likely to be to our north - closer to the surface low pressure. The interesting feature to this event, however, is that nearly all of the atmosphere will be cold enough to support snow through the entire event - mainly due to the speed of the system and the very cold air it is running into. This is seen in an inspection of the critical thickness values at all levels. The exception to the cold will be right here near the ground where southerly winds blowing in off of the milder waters to our south will allow temperatures to climb through the 30s. Heavier precipitation could potentially overcome some of this warming, but it still appears that after an initial burst of snow, things will go over to rain, with showers continuing into the first part of Saturday. A quiet and cool Sunday is expected after the unsettled start to the weekend.

The weather pattern for next week (and the week after) is looking very interesting with lots of things to watch. As is typical for March, late winter cold will be battling the developing warmth of spring, setting the stage for some potentially strong storm centers. The first system to watch will be a closed upper level low pressure center heading northeastward from the Deep South up the Eastern Seaboard, interacting with a surface cold front dropping south and eastward across the Northeast. The timing and interaction of these two features will be fun to watch and could spawn quite a storm Tuesday or Wednesday. Early indications are that mild air would win out ahead of this storm, meaning a sizable rain storm could be in the cards. But it is still pretty early in the game and there's plenty of time to watch it. Plus, closed cold upper level storm centers can be tricky creatures.

Looking further down the road, the 500 mb height anomalies on the GFS centered on Day 8 and Day 11 show below normal heights (implying a cold pattern) over much of the Eastern US and the 850 mb temperatures appear quite chilly. Add this up with an active jet stream and the makings are there for some interesting weather the first two weeks of March.