January 25th Winter Weather Event
We have a complicated weather system coming up for tomorrow into tomorrow evening. Overall, this event will likely not be a big storm. It is a northern branch upper level disturbance that is strong and will have some decent lift associated with it, but it will not tap the Gulf of Mexico and only briefly the Atlantic Ocean. Thus I do not expect heft QPF totals with this system, especially east of the mountains. However, a pool of very cold air will be waiting for the arrival of this system and a hybrid or in-situ damming event will occur east of the mountains.
The model trends since yesterday have been for less QPF overall and for the snow/ice line to shift north somewhat. In some ways as far as travel and life disruption goes this is a worse scenario as a little bit of ice can cause more problems than a light snow event. Overall, my forecast is a blend of the various model guidance. I think the GFS is likely too dry with its QPF totals, as most of the higher resolution models, (NAM, RGEM, SREF, our in-house high resolution models) show more QPF than the global GFS model does or the ECMWF does for that matter. However, I did trim the high-resolution models QPF forecasts back a little to give respect to the drier GFS/ECMWF.
I have updated my forecast map and even added some zones as this event will likely have a good deal of complexity to it. So, let’s get to each zone.
Zone A:
This area looks to be mostly snow, although some areas in this zone on the western and southern fringes could mix with ice. It also appears to be the area with the best chance to get 0.25 to 0.5 inches of QPF if not a little more. Snow ratios will be probably better than 10:1 and so 3-6 inches seems like a good call here, with locally higher amounts in the higher elevations. Areas in the eastern fringe of this zone could see the lower parts of these totals.
Zone B:
This area will also be mostly snow it appears but it is the amount of QPF that is in question. The 12z GFS is bone dry with less than a 0.1 of an inch, while some of the other model data shows between 0.1 to 0.25 inches. Since this area will be mostly snow, I would think 1-3 inches even with low QPF values could be a good call. The area of SE Va, and the lower Delmarva is the place to watch for potentially hitting the high end of these totals. We will likely see an area of low pressure start to crank east of the Tidewater and this could enhance the precipitation in those areas. The Virginia piedmont is the area that could bust on the low side.
Zone C:
This as always is a very tricky area. NAM and GFS BUFKIT soundings show the potential for some decent ice in areas like Chattanooga before a changeover to rain may occur. The various valley and peaks in these areas of TN/NC/Ga also make it tricky to forecast. I think in general, this area will see some ice that may change to rain as it ends. It is possible that a decent accrual of ice (0.1 to 0.2) could occur before any changeover happens. Again, this area is tricky as usual.
Zone D:
This zone has the potential to see a significant to major ice storm. Again we have complex terrain involved here in NE TN, eastern KY, and SW Va, but in general this area could see up to 0.5 inches of liquid QPF falling in the form of sleet and freezing rain. Again microclimate factors may dictate otherwise in some areas, but in general we have to watch this area for ice.
Zone E:
This area looks to see mostly a mix of sleet and freezing rain and which p-type is the most prevalent will likely determine the impact of this event. Most of the model data shows around 0.1 to 0.2 inches of liquid QPF, with the GFS the lightest more around 0.05 inches. However, if a majority of this falls as freezing rain we could see some glazing issues. If the majority falls as sleet, the sleet will accumulate and cause slick spots, but will likely not make as much an impact as the freezing rain would. The higher resolution models show more precip than the GFS does, so I am going with a general 0.1 to 0.25 inches of liquid QPF in this area. It is likely that someone in this area will see a ¼ inch glaze of ice on trees and power lines which could cause some issues. The areas mostly likely to see this are from the Raleigh area N and NE.
Zone F:
I highlighted this little area as it could see a wintry mix. If the aforementioned coastal cranks a bit, areas like Elizabeth City could pick up a couple of inches of snow from it.
Zone G:
I expect this area of Kentucky will see some accumulating snow from this system.
Zone H:
This area will likely see mostly rain or little precip. However, I cant rule out a period of wintry precip at the start of the event, mostly likely in the form of sleet or freezing rain, however, I don’t see a major impact for these areas at this time.
So there you have it. I may tweak this map tonight or tomorrow morning if the data/ideas change, but this will probably be what I go with. Again, this will likely not be a major event, but with temperatures likely to be below freezing for many areas from east TN to NC north, what does fall will likely be frozen or freezing and could cause issues.
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