6:52 AM

Winter is not going to go out without a fight, which may mean March comes in like a Lion.  Before discussing the potential of the storm, let’s look at how the cold air gets into the forecast area first.

There is very strong agreement that a strong cold front will drive towards the East coast from the northern Plains.  The brunt of the Arctic air with this cold front will be over the Great Lakes, however strong Polar air does build into the forecast area behind this cold front.  Given the observations of surface temperatures over Canada, I think the low level cold air mass will be slightly stronger than the GFS MOS guidance is giving credit to, so I have gone and will continue to go slightly colder than MOS.  

A strong low level jet at 850 MB ahead of the cold front will bring significant moisture into the forecast area ahead of the cold front.  The combination of this moisture with the strong PVA moving through the forecast area at 500 MB, will support heavy rainfall over the region on Friday.  I think what we’ll see is scattered showers on Friday morning with a heavy band of rain, possibly with some embedded thunderstorms, on Friday afternoon and evening just ahead of the cold front.  

Temperatures will be above normal through much of Friday as I don’t expect the cold front to move through until the evening hours, which means the morning lows will be rather warm for this time of year.  Once the cold front does move through the region, temperatures will crash through the 30′s, 20′s, and even 10′s over the interior.  

By Saturday morning, we’ll have a broad trough in place over the Eastern United States.  Note some key features in this pattern though.  There is no presence of a negative NAO nor a 50/50 upper low structure, which means the Atlantic supports a progressive solution for any disturbance that intensifies in this trough.  Note also, that Pacific jet stream will be strengthening over the central Pacific, which is another telling sign that the Pacific supports a progressive pattern as well.  The ridge over the Western United States would support a low pressure to develop along the coast, however all other features suggest that any low pressure system that does form along the coast would be fast moving, weak, and likely to take a more eastward track.  The key on the degree of amplification of the ridge over the West and the trough in the East would be the development of the upper low off the West coast on Saturday, which frankly does not look very impressive at this time.  So here is how I think this situation will play out.

High pressure will bring clear conditions to the forecast area on Saturday with below normal temperatures.  The high pressure system will move to the north and east of the forecast area by Sunday afternoon, which will weaken the support for any type of cold air damning ahead of this potential storm.  Meanwhile, a southern branch disturbances will dive into the trough and move through the Southeast.  A weak area of low pressure will form along the old cold front boundary and begin to move towards the Carolina coast.  By Sunday evening, the 500 MB trough will tilt to the negative as the low pressure system intensifies off the East coast.  At this time, I think this intensification at 500 MB down through the surface will be slightly too far east given the rest of the set up in the atmosphere, thus leading to most of the precipitation to fall off the coast.  However, even if the storm is closer to the coast, the result would likely be rain or a snow/rain mix.  The reason why is that as the high pressure system slides to the east, due to lack of upper level support (no 50/50 low), there is no mechanism to stop the warming of the boundary layers, especially at the coast.  So if the storm is closer to the coast, then the easterly winds will warm the coastal plain to above freezing, thus rain.  What is needed here is a perfect storm track, and we know how that’s worked out this winter.  

The idea of  developing a storm is not unsupported.  The pattern is changing and when patterns change, storms usually occur.  However, my contention is that this is not a pattern to support a snow storm in any way.  There is no support in the Atlantic and very little support in the Pacific.  The key for any type of significant wintery precipitation will be for this storm to take a perfect track with perfect amplification of the 500 MB pattern at just the right time.  To much has to go right for all of that to occur.  So for now, I am sticking with the idea of a rain/snow shower mix on Sunday into Monday morning.

Once again, there is growing support for a much milder pattern setting up after this weekend as the pattern becomes transient and a strong influence from the Pacific is felt.

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