FallsLake

I remember a few years back we saw the models keep showing warm ups in the LR, but the EPO totally dominated the pattern and it kept us cold. The models would just keep pushing the warm up back. **Ironically opposite of what we're use to where the models keep pushing our cold back.

6z GFS sets up a typical la Nina pattern after the first week of January. Looks like cold shots, warm up with lake cutters, and then cold again. This is where we really need the help of the NAO.

The mountains are definitely our enemy with clippers. For our area (Central / eastern NC), we tend to do better than folks to the south and west of us. Two reasons: 1) Biggest reason is the trajectory of the precipitation over elevated areas to our NW. **draw a line from RDU NW and the elevation of areas through VA and WV are mostly in the 3000 - 4000 range. Draw a line from Charlotte down to Greenville SC NW and you have 5000 - 6000 foot mountains. Basically they have more of a rain (snow) shadow effect. 2) Also for clippers it's just better to be farther north and east because of the traversal of the wave as it goes from NW to SE.

looking at the indices and it would signal a continuation of our current pattern: PNA - Looks to stay positive throughout the LR. Maybe flirting with neutral towards the end. AO - Looks to be predominantly negative in the LR, ensuring cross polar air into NA NAO - Positive, which is now normal for us. **this is hurting our chances of a storm ridding up the coast. EPO - Looks to stay negative LR models (going out 12 days) also indicating a colder than normal LR. But it looks dry. The 6z GFS shows very little precip over the SE. So it looks like our Mongolian cold and dry winter continues.

As I said before, in this pattern of suppression we may have to pin our hopes on a clipper. Usually clippers stay just a little too far north for many on this board but with these massive highs and deep troughs we can now score. The last two runs of the GFS show something at ~ day 9. It's definitely too far out to get excited about but I believe this more that a big storm showing 5 days out. 6z GFS (similar to the 0z):

Yeah, I'm disappointed. Just looked at the Euro and it's just cold and dry for RDU for the next 10 days. We may get some kind of clipper (..never modeled well) give us something but the big storm signal has slipped away. Way out at 10 days it has some kind of system, but that's fantasy range. For folks in the deep south, this might be a good pattern for you. Any waves that do pass to the south could give you some rare wintery preicp.

Mostly sleet again, some flakes mixing in (34.1). After looking at the latest RAP, this might be what I get for the majority of the event. Lots of frames where I'm in the "purple".

The latest RAP is ever so colder for areas to the east. RDU is going to be on the line for some of the heaver amounts (...or should I say rates).

0z NAM hour 21:

Oz NAM better for RDU. Looks like it will flip between snow and rain with heaver rates.

Dealing with the last couple of runs of the HRRR, it backed off on the intensity of precip which then backed off on the cooling. The latest 0z increase precip rates some which then also increases mixing; particularly around RDU. So basically if you want snow, you need heavy precip to occur.

Latest RAP(20z) is out and it continues to show RDU getting hit hard. Hour 19 to correspond to the past post with hour 20:

Here's the latest RAP at hour 20:

I'm really pulling for the HRRR. It along with the RAP look better for our area:

For us RDU folks we need to hope that the 3Km NAM has the right idea about snow on the back end:

The euro would be nice; particularly for the RDU folks. It also shows potential events in the LR. http://wx.graphics/models/ecmwf/ecmwf_usa.php

Elizabeth Gardner from WRAL. http://www.wral.com/weather/video/17167486/

If we can get a dusting or a half inch of slush, consider that a victory. Here's RAH's discussion from last night: .SHORT TERM /FRIDAY THROUGH SATURDAY/... As of 425 AM Thursday... ...Some wet snow is still possilbe across portions of Central NC Friday night and early Saturday although accumulations will be limited... An amplifying trough extending from eastern Canada southwest through the Great Lakes/Ohio Valley into Texas on Friday morning will shift east and approach the Southeast coast by Saturday evening. At the surface, a stationary front extending from northern FL northeast just off the Southeast coast lingers through Saturday with a couple of surface waves of low pressure developing and riding up along the front. A secondary cold front with a surge of slightly colder and drier air settles into VA and evntually northern NC from the north on Friday. The persistent southwesterly flow aloft originating in the western Gulf of Mexico with deep moisture including precipitable water values of 1.5 inches or more and multiple disturbances riding northeast will produce a long ribbon of precipitation across the northern Gulf to the Southeast coast. As disturbances aloft move up the coast near the baroclinic zone off the coast, the precipitation shield will buckle northwest across most of the central NC including the Piedmont on Friday and Friday night. The most widespread precipitation and greatest precipitation amounts will be across the coast with 72-hour model consensus QPF amounts ranging around 1.5 inches in the southern Coastal Plain near Goldsboro, with around an inch from Southern Pines northeast to near Raleigh up to Roanoke Rapids. There will be a sharp gradient in the precipitation amounts across the northwestern edge of the precipitation shield with amounts of 0.1 to 0.25 in the Triad. While anticipating the precipitation amounts across the northwestern colder edge of the precipitation shield is challenging enough, handling the mixing with/change to wet snow and then accumulation potential is problematic. The big picture using pattern recognition screams that a lack of a strong cold/dry high pressure system in a favorable position prohibits a higher impact snow accumulation event. What is more likely are narrow, southwest-northeast elongated snow islands where a cold enough boundary layer meets the precipitation axis and produces some snow accumulations. Partial thickness values and forecast BUFR soundings suggest precipitation on Friday will generally be a cold rain as snow falling aloft melts as it enters a warmer boundary layer where air temps are in the mid to upper 30s in the lowest few thousand feet. With time during the day, the warmth in the boundary layer will cool and toward evening, the precipitation across the interior Piedmont will increasingly mix with and then change to snow overnight with the wet snow area expanding southeast. It typically only takes a wrinkle or two to sabotage snow forecast in central NC or to decrease the snow accumulation efficiency, and there are a lot of potential issues with this event including a lack of cold/dry air, a warm boundary layer, warm ground temperatures and questions about how far northwest the precipitation will extend. In the end, we still expect some light snow accumulations, certainly less than an inch and generally a dusting, will occur west of U.S. Route 1, mainly across elevated and grassy locations. The greatest amounts will likely occur in the I-85 corridor from Burlington northeast to the VA border. It is not out of the question that a couple hour burst of heavier precipitation rates could produce some localized greater amounts up to an inch or possibly two, but that is a low likelihood outcome. The precipitation will end from west to west Saturday morning, perhaps lingering into the early afternoon near the I-85 corridor as some light rain. Highs on Friday will only be in the lower 40s (may stay in the upper 30s in a few spots) with lows Friday night in the 30 to 36 range by Saturday morning. It`ll be chilly on Saturday with highs in the lower 40s. -Blaes &&

My grid forecast. even with the better model runs this morning, I would take this and run: Friday Night Rain and snow likely before 1am, then a chance of snow. Cloudy, with a low around 32. Light and variable wind. Chance of precipitation is 60%. New snow accumulation of less than a half inch possible. Saturday A chance of snow, mixing with rain after 10am, then gradually ending. Partly sunny, with a high near 42. Light and variable wind becoming northwest around 5 mph in the afternoon. Chance of precipitation is 30%. New snow accumulation of less than a half inch possible.

From RAH: .LONG TERM /FRIDAY THROUGH WEDNESDAY/... As of 305 PM Wednesday... ...Increasing chance of snow across portions of Central NC between midnight and 7 AM Saturday, with some accumulation on elevated and grassy surfaces possible... Friday and Friday Night: Central NC will be under the influence of deep southwesterly flow aloft as a strong upper level trough to the west swings eastward toward the region. Disturbances in the flow aloft will move over the area, resulting in periods of heavier precipitation. At the surface, Central NC will be sandwiched between the stalled front off the Mid-Atlantic coast and high pressure ridging eastward from the west. With the high in an unfavorable location, the best push of cold air will likely get hung up along the mountains. Expect much of the precipitation to fall as rain, especially early on. Despite the delayed CAA, strong lift in a saturated dendritic growth zone will likely result in precipitation rates strong enough for snow to occur where temperatures are in the 32-36 degree range. This will be an event where the cold air is chasing the precipitation, thus expect most of the precipitation to fall as liquid. Liquid equivalent precipitation totals will range from less than a quarter of an inch in the northwest to nearly 1.75 inches in the southeast. Given the warm ground and boundary layer, snow will have a difficult time accumulating except for on elevated and grassy surfaces and under high precipitation rates. Generally less than an inch of snow is expected at this time, primarily between midnight and 7 AM Saturday. Best chances for accumulating snow along a line from Lexington to Burlington to Roanoke Rapids, generally be along and west of US-1. Highs on Friday in the low to mid 40s with overnight lows in the upper 20s NW to mid 30s SE. Temps are not expected to fall below freezing in the Triad until after midnight. Saturday through Wednesday: As the strong upper disturbance swings through the region Saturday morning, the main precipitation axis will shift east of the area. At the surface, in the wake of the disturbance aloft, west-northwest flow will advect strong cold air into Central NC ahead of a secondary strong vort max aloft diving southward over the area. Saturday and Sunday will be the coldest days Central NC has had in a while, with highs in the low to mid 40s and overnight lows in the low to mid 20s (possibly dipping below 20 in outlying areas Sunday night). Generally dry weather expected for the remainder of the period although a few sprinkles/flurries early next week cannot be ruled out. Temperatures will moderate a bit Monday and Tuesday before another cold front moves through the area. &&

Here's the NAM at hour 75 (Kuchera):

I'm nor sure they updated their long range (which includes Friday onwards). .SHORT TERM /THURSDAY AND THURSDAY NIGHT/... As of 110 PM Wednesday... Forecast remains nearly unchanged with a persistent southwesterly flow aloft, deep moisture, and multiple disturbances riding northeast over a baroclinic zone off the southeast coast. Light rain is expected on Thursday and Thursday night across the Coastal Plain and Sandhills, mainly south and east of Raleigh. With colder air working into the region, there is a chance that some of the precipitation will mix with or change to snow. It`s important to note that the pattern suggests an active period with widespread precipitation across coastal NC and decreasing amounts and coverage to the north and west in the more climatologically colder region of the northwest Piedmont. In addition, there is no well defined surface high to support the delivery of cold and dry air into central NC to support more than a low end event. Still, partial thickness values and forecast BUFR soundings support some wet snow across the northwest and northern Piedmont including the Triad area Thursday night with surface temperatures dropping into the 32 to 36 range. But given these areas are on the northwest fringe of the precipitation shield and PoPs are in only the chance range, no snow accumulation is expected. && .LONG TERM /FRIDAY THROUGH TUESDAY/... As of 430 AM Wednesday... ...Potential continues for some wet snow Friday night and very early Saturday although the potential for accumulating snow is limited... As disturbances aloft move up the coast Friday, the precipitation shield will buckle northwest across most of the central NC including the Piedmont on Friday and Friday night with the most widespread precipitation and greatest precipitation amounts to the south and east of Raleigh. The precipitation will shift east late Friday night and Saturday morning with just some lingering, light spotty precipitation across the Coastal Plain expected early Saturday. A better chance for wet snow is expected Friday night and early Saturday morning across much of the Piedmont including the Triad and Triangle areas when the air mass will be a little colder. Air temperatures will fall into the lower 30s in these areas by Saturday morning which could support some light accumulations, on the order of a dusting, mainly across elevated and grassy locations in the general region of the I-85 corridor from Burlington northeast to the VA border. The warm boundary layer and ground temperatures combined with the limited precipitation amounts in the cold enough for snow areas should limit the amount, extent, and impact of snow accumulations. Highs on Thursday will range in the mid 40s with lows Thursday night in the 31 to 38 range. Highs on Friday will only in the lower 40s (may stay in the upper 30s in a few spots) with lows Friday night reaching 28 to 35 by Saturday morning. Cully on Saturday with highs in the lower to mid 40s. Another potent short wave trough and potent lobe of vorticity will swing through the mid-Atlantic late Saturday and early Sunday. This feature will bring some enhanced cloud cover although moisture appears limited enough to preclude any precipitation. A northwest flow develops behind the trough on Sunday and continues into late Monday with dry and below normal temperatures. Another impressive trough approaches on Tuesday with a southwesterly flow ahead of the system that should allow temperatures to moderate and could bring some spotty precipitation before temperatures crash behind the trough on Tuesday night into Wednesday. -Blaes &&

12z GEFS snow depth at hour 72:

It really does matter where you live in the Triangle area. When I bought my house I actually drew a map and told the realtor where I would consider (basically Wake Forest SW to Apex - north/westard). I've been on the line many storms since I move to my location. The last one was the January storm and it looks like I could do it again with this one. Nerve racking...

You guys saw the CMC snowfall maps. Here's the freezing rain (I guess it's pulling more cold air in):