Weather

Close, but No Cigar...

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At least that's probably the perception of any snow lovers out there regarding the brush with mildly wintry weather we experienced this weekend. Throughout the run-up to the event, we tried to emphasize that this was a borderline case, as so many are for central North Carolina, that was unlikely to produce much in the way of snow on the ground or travel difficulties. For this particular event, we were lacking both a strong high pressure center north of the state to reinforce cold air in the lower atmosphere as moisture aloft approached from the south, and also had only modestly strong surface low pressure and upper level support to generate the sustained significant precipitation rates needed to get snow to the ground without melting, and to cool the lowest levels of the atmosphere, along with ground surfaces, sufficiently to allow for accumulating snow. The end result was a main precipitation shield associated with a low pressure wave south and east of us that pushed into the area Saturday night and pulled out to the east by around 7-8 am Sunday morning, and a trailing band of precipitation associated with both an upper level jet streak to our north and northwest, and enhanced low level northeasterly flow in the wake of the departing surface low. These features kept some precipitation going through late morning, and where the precipitation rates briefly intensified along narrow streaks, we did get reports of wet snow and sleet from parts of Guilford, Alamance, Durham, Person, Granville, Vance, Warren and Halifax counties, but never for long enough to drive surface temperatures below about 34-36 degrees.

Speaking of temperatures, after another 2-3 days at or below normal, we may see a swing, at least briefly, to above normal values late this week and into the Christmas weekend, as a pattern that has featured frequent mid-level troughing over the eastern U.S. "flattens" a bit. For now, it appears we'll also have a quiet lead-in to the holiday weekend, with little chance of precipitation until late Saturday night or Sunday, and that likely in the form of scattered rain showers. There are some indications we could slip back into a cooler pattern after that to finish off the year, but the signals are by no means conclusive.

One result of all that is little aparent chance at a White Christmas for central sections of the Tar Heel state this year. That, of course, is nothing the least bit unusual, as you'll note from these features on the subject recently posted by the National Weather Service office in Raleigh. The second link includes a listing of Triangle area snowfall totals for the past thirteen years, notable for the variability of those totals as much as anything else. For details, see:

http://www.erh.noaa.gov/rah/news/content/white.christmas.2005.html

and

http://www.erh.noaa.gov/rah/news/content/20051219.krdu.RDUPNSRAH.html

Those of you living in the coastal plain a little east of us in the Triangle might recall you missed a White Christmas by just a day or so last year. Details on a storm that left significant snow and ice over much of the coastal plain on 26 December can be found at:

http://www4.ncsu.edu/~nwsfo/storage/cases/20041226/