More wintry weather possibly the week of 2/29 - 3/6

A chance of light freezing rain is possible late sunday night through Monday morning as an in situ cold air damming event.  Cold high pressure will be sliding off the New England coast Monday morning as precip increases in the triangle region from the west.  The moisture will encounter cold dry air.  Due to the dryness of the air, much of the initial precip will fail to reach the ground.  But a light icing event for the triangle is not out of the question.  A winter weather advisory may need to be issued for Monday morning.

Another chance of wintry precip will be possible later in the week as a very cold arctic front moves very slowly east of the triangle.  It's possible that a wave of low pressure will develop along this front and bring some wintry precip to the triangle.  This storm is too far out to determine what if anything will occur, but the possibility certainly exists for another wintry storm and possibly another significant winter storm.

2/25-2/26 Major Winter Storm Update

Every single weather model now has RDU getting at least 8.5 inches of snow with one model showing over a foot.  Each model is also showing at least one inch of liquid equivalent precip.  Of course most of that will be snow with rain possible at the onset and some sleet/freezing rain mixing in during the latter half of the event.  Looks like the snow and snow/sleet mix line will set up around the HWY 64 corridor. This again could cut back the totals.  So I'll stick with my original forecast of 4-8 inches of snow and sleet for the triangle with higher amounts north and especially north east.  Up to a foot of snow is possible in some spots.

2/25-2/26 Winter Storm update

A major winter storm is now highly likely for the triangle.  Winter Storm Warnings have been issued by the NWS.  And every weather model is now predicting at least 6 inches of snow.  I'm still concerned with the ability of the models to pick up on the chance for sleet and or rain mixing in a bit.  With that in mind I am upping totals for the triangle to 4 to 8 inches.  With 10+ inches possible in spots.  Right now I do think we end up on the higher side of my accumulation prediction.

2/25-2/26 winter storm update.

No change to my previous thinking.  I still think 3-5 inches is a safe forecast at this time.  I do think there will be a relatively narrow band of heavy snow set up close to the rain/snow line.  It does look like the heavy snow band could set up over the triangle area into northeast North Carolina.  But it's too early to tell for certain.  But I would be surprised at this point if we did get less than three inches.  The GFS is the least wet, but has been trending wetter with each run.  The European model seems like the best bet, but is likely missing some convective banding features with this storm.  Get under one of these bands and you could pick up 2-3 inches in an hour.  I expect there to be a swath of 6+ inch snowfall setting up on a SE to NE line somewhere near the Highway 64 corridor.  Higher resolution models will be able to pick up on the banding, but those only go out to 18 hours.

2/25 - 2/26 potential winter storm

The potential for significant snowfall accumulations across the triangle is increasing.  A moderately strong low pressure system will develop along the gulf coast and transition off the southeast Atlantic coast Wednesday night.  In the mean time the arrival of cold arctic air today, currently in place and the cause of the today's accumulating snowfall, will remain in the area, albeit dampended, overnight Wednesday.  Models are now converging on a wetter solution.  The potential for heavy snow exists within the triangle area with an isothermal layer potentially developing near the surface.  An isothermal layer is a vertical column of at freezing air caused by the dynamics of the falling snow.  It's still too early to tell where any heavy banding will set up.  But the presence of an isothermal layer along with the presence of strong snow flake growth in the upper levels of the atmosphere often equates to large snow totals.

So right now I think it's safe to go with 3-5 inches of snow for the triangle.  Sleet and rain mixing in with the snow could certainly be an issue and I've included that possibility in my accumulation forecast.  If the precip does stay all snow and if the wetter trend continues then the triangle could potentially get close to ten inches.

2/25 - 2/26 Potential snow

The potential for a significant snowfall occurring mainly during the overnight hours Wednesday night into Thursday morning is increasing for the Triangle.  Models are coming into agreement on a low pressure tracking just off the cost of South Carolina and North Carolina before moving ENE.  

There are still questions in regards to the intensity and exact location of the path of the low pressure.  Rain mixing with the snow at the onset of the event could be a limiting factor in any accumulations.  If the low tracks offshore then expect the rain to quickly change to snow or perhaps be all snow.  If the low tracks closer to the coast then a changeover to snow will take more time.  

But again the potential exists for a significant snowfall Wednesday night.

2/16 -17 Winter storm update

I have made some fairly significant changes to the timing of the event as well as updated most likely precip types as the even unfolds.

Monday - A chance of snow and sleet after 5 PM.  

Monday night - Snow and sleet changing to sleet/freezing rain by midnight.  Total snow and sleet accumulation of 1/2 inch to 2 inches possible.  Also .25 - .5 inches of ice accrual possible.

Tuesday morning - Sleet/freezing rain before 10 AM.  

Expect the vast majority of the precip to fall between midnight and 7 AM.  While the roads may be a bit slick due to potential sleet/snow accumulation it shouldn't get really bad until after midnight when the heavier precip works its way to the triangle.

2/16 - 2/18 2015 Winter Storm

A significant winter storm is becoming likely for the Triangle.  Expect light snow to to begin late Monday night mainly after midnight.  Expect any snow that fall to easily accumulate due to the cold air temperature and cold ground temperature.  1-3 inches of snow is possible over night monday.  I expect the the snow to transition mainly to sleet early Tuesday morning before changing to freezing rain or rain Tuesday afternoon.  A total accumulation of 2-6 inches of snow and sleet is possible by the end of the day Tuesday.  Significant ice accrual is also possible.  The sleet will transition back to light snow Tuesday night where another 1-2 inches of snow will be possible.  Bitterly cold temperatures will also be a factor with this system.  Expect temps to dip into the single digits Wednesday and possibly Thursday night.  It's also likely temperatures will not rise above the mid 30's until Saturday.

While a major winter storm does look likely at this time the system is still a few days out.  The type of frozen precip is still a big question mark.  It's possible we could get more snow, sleet or freezing rain depending upon the propagation of the surface low.  This would effect accumulation totals as well as the severity of the impacts of the storm.  Also if the low tracks well onshore, rain during the day on Tuesday is not out of the question.  Winter Storm Warnings should not be issued this early because of the aforementioned possibility.