Another warm storm?
2012-01-26 23:39:45.000 – Mike Carmon, Weather Observer/Meteorologist
A Typical Low Pressure System
Are you a snow-lover?
If so, I regret to inform you that you will most likely be disappointed with this latest round of winter weather.
The jet stream continues to be positioned such that the seasonal parade of winter storms is passing directly over or just to the west of New England, instead of to our east. This is a perfect scenario for a storm producing milder conditions and a wintry mix of precipitation, rather than a colder system harboring an all-snow event.
The reason for this takes us back to Meteorology 101. Low pressure systems, like the one currently making its way through the Ohio Valley and northeastward towards New England, feed off of stark changes in temperature, or a temperature gradient. The stronger the gradient (the quicker/greater the temperature change), the more fuel a low pressure system has to develop.
Due to certain forces governing the flow of air at and above the surface of the earth, wind flows counter-clockwise around a low pressure system, which grabs colder air from the north and pulls it southwards. On the other hand, the same mechanism also takes milder air on the southern side of the low and dredges it northward, all of which can be seen in the diagram above.
Thus, looking at the diagram and taking into the account the explanation, you can imagine why a storm passing to our west would result in a warmer precipitation type scenario. Although cold air may be in place to start, the approaching warm air in advance of the low, which is led by a warm front, prompts wintry precipitation to gradually mix with warmer types as warmer air moves in behind the front. In contrast to this, should the center of the low pass to the east, as it would during a Nor’easter, the region in question would be spared the effects of the warm sector, and precipitation would come primarily in the form of snow.
This winter has certainly seen its fair share of storm systems passing through the center of the country and traveling directly into New England over land, which puts us right in line for the stream of mild air.
There is still plenty of winter left, though, and the pattern could change at any time.
Mike Carmon, Weather Observer/Meteorologist