Raleigh Weather Discussion
It appears we will have some issues with precipitation type overnight tonight and into the morning hours tomorrow. The main question though is how much precipitation will actually fall during the time when the atmosphere would support frozen/freezing precipitation. It appears that the northern and northwest piedmont, mostly the counties near the Va border will be most apt to see precipitation and that fall in the form of a wintry mix. The 12z NAM is now showing no appreciable precipitation in the Triangle through 7am, while the GFS brings in more moisture sooner. The trends on the arrival time of the precip will be a key thing to follow.
Partial thicknesses as well as all the dry air present in the lower levels of the atmosphere which would support a precipitation type of a wintry mix transitioning to freezing rain and then rain through the early morning hours with a changeover to all rain most everywhere by mid-morning in the Triangle to lunch time to the NW. I think close to 0.25 inch of QPF could fall in areas from the Triad to the escarpment. I think those areas could see a dusting of snow/sleet with a light glaze of freezing rain before a changeover. I have included a map with the expected effects. IN general I do think there will be some sleet/snow accumulation although light in the Va border area and in the northern foothills/NW piedmont before a changeover to some freezing rain with a light glaze and then to all rain. Travel could be somewhat tricky there late tonight and early tomorrow.
For the Triangle, I expect some sleet early in the morning with a changeover to freezing rain possible through the early to mid-morning. However, I expect QPF totals generally around 0.1 inch or less before a changeover to rain by late morning. This will mean little in the way of impact, but there could be some icy spots on bridges tomorrow morning.
A 2nd round of moderate to heavy rain will move through Friday night and the first half of Saturday. We warm up some for Sunday and Monday with another storm system on the way for Monday night/Tuesday. Right now, this looks like a little warmer version of this current system, with rain likely the predominant p-type, although I will keep an eye on Tuesday morning.
We then see a very anomalous pattern for mid to late next week with a cold closed 500mb low over New England which will lead to much colder than normal for temperatures for early March. Although there is not a concrete storm on the models in the first few days of March, I am still weary with this setup one will form. So I will monitor closely.
National Extended Weather Discussion
As I have been writing all week, a cold pattern seems very likely for early to mid march, as we see blocking and ridging in western Canada combining to lead to a cold pattern for much of the central and eastern US, centered over the lower Appalachians. It looks to be well supported by the modeling guidance at least and will likely cover much of the first half of March it appears. So no early spring!
With such an anomalous pattern, it seems likely that there could be a significant winter storm sometime in the early part of March, so we will have to watch each storm and setup continually.