Coastal Snow SC/NC?

[downeastnc]

Gonna be a fun one tonight into tomorrow morning if the models are to be believed then my neck of the woods could see over .50 qpf fall in 6 hrs or less and it will be snow until the last 850-1000 ft. Question is will that be able to overcome temps around 35-40? If it does many of us stand to get a pretty good thump of snow, another thing to look at is how far inland does this snow get the GFS is rather bullish taking snow inland as far as RAH.

[snowlover91]

Going to be interesting. Even the models are having a hard time, GFS is very cold at 850mb around -3C to -5C and then the 925mb level is right around freezing. On the other hand the NAM is showing 850s -1 to -2C and 925mb temps around -2C as well. GFS is a little warmer at the surface, 34-36F with heavy precip (snow or rain?) and the NAM is about 34-35 with heavy precip as well. Most likely would be a very heavy snow if rates are high enough.

[FallsLake]

Looking at Twister.com it shows (for GFS) just over 2" at RDU to near 6" in coastal NC. Then it shows the clipper late Sunday dropiing near 1" near the Va boarder.

[RaleighWx]

It is certainly cold enough aloft through eastern piedmont and coastal plain, but the boundary layer is warm. Upper 30s to mid 40s for many areas. If the precip comes down hard enough snow will mix in, but as of now I just dont think it will get cold enough for any significant snow or accumulation. Too bad it isnt january.

[RaleighWx]

I will post on it later today

[downeastnc]

Going to be interesting. Even the models are having a hard time, GFS is very cold at 850mb around -3C to -5C and then the 925mb level is right around freezing. On the other hand the NAM is showing 850s -1 to -2C and 925mb temps around -2C as well. GFS is a little warmer at the surface, 34-36F with heavy precip (snow or rain?) and the NAM is about 34-35 with heavy precip as well. Most likely would be a very heavy snow if rates are high enough.

GFS totals for here are prolly 7-10 inches so lets hope that one is right lol. What I think is going to happen is when the rates get high we see snow when they let up we get drizzle/light rain....really though since most of this hits in like 6-10 hrs rates should be pretty good given the amount of QPF involved in the models.

For the record MHX doesnt even mention the word snow in any product at all which kinda surprised me, I guess they are going with climo and think the BL will win. Even still Iwould expect them to at least mention the possibilties but whatever....

[snowlover91]

What is interesting to note is the 15Z RUC at 18 hours shows a band of .10-.25qpf per hour riding up the coastal plain with 850s around -2C. Have no idea what the sounding looks like or surface temps, but the key here is it shows a band of heavy precip which if snow would easily be 1" an hour. I know Greg Fishel always mentions with questionable boundary layer temps like this that one thing which plays a key is the rate of precip. Not only does heavy precip help bring the cold air aloft down quicker but it also helps to cool the air down as the snow melts, I forget the name of the process. Basically, the lowest few thousand feet that is above freezing melts the snow and turns it to rain, but in melting the snow the air is cooled down as well. With no WAA and actually weak CAA at the surface, would this process possibly help cool the column more? GFS shows around 6" for the area which seems a little bit overdone while the NAM gives us basically nothing but a dusting. Hard to say what will verify. Going to be watching the HRRR very closely tonight.

[Hugo]

GFS totals for here are prolly 7-10 inches so lets hope that one is right lol. What I think is going to happen is when the rates get high we see snow when they let up we get drizzle/light rain....really though since most of this hits in like 6-10 hrs rates should be pretty good given the amount of QPF involved in the models.

For the record MHX doesnt even mention the word snow in any product at all which kinda surprised me, I guess they are going with climo and think the BL will win. Even still Iwould expect them to at least mention the possibilties but whatever....

MHX's discussion does say Ptype issues tomorrow morning and afternoon, but that air and ground temps should prevent accumulation.

ILM says rain only without mentioning any hint of frozen precip.

[downeastnc]

MHX's discussion does say Ptype issues tomorrow morning and afternoon, but that air and ground temps should prevent accumulation.

ILM says rain only without mentioning any hint of frozen precip.

LOL it does but I didnt read it since I stopped after I read the part covering thru 6pm Sunday since the event would be over by then ( I thought ), they do mention it in the Sunday night thru Friday segment which would be after the event ( I thought )...really its confusing as hell to read its like they are talking about two systems one tonight and another Sunday afternoon...

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/...

AS OF 350 AM SATURDAY...BULK OF THE PRECIP WILL ACTUALLY OCCUR ON

THE COLD SIDE OF THE BOUNDARY TONIGHT. PRECIPITABLE WATER IN

EXCESS OF 1.25 INCHES AND SPECIFIC HUMIDITY VALUES OF 8 TO 10 G/KG

WILL LINGER ALONG THE COAST FOR MOST OF THE NIGHT. HAVE

CATEGORICAL POPS CONTINUING OVERNIGHT FOR THE EASTERN THIRD

TAPERING BACK TO HIGH CHANCE OVER THE NORTHWESTERN COUNTIES WHERE

LOWER DEWPOINTS WILL START TO ADVECT IN LATE TONIGHT. A CHILLY

NIGHT IS IN STORE WITH THE LOW-LEVEL COLD AIR ADVECTION WITH MIN

TEMPERATURES IN THE 36 TO 43 DEGREE RANGE.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...

AS OF 215 AM SAT...UPPER TROUGH TO THE WEST WILL SWING THROUGH

EASTERN NORTH CAROLINA DURING THE DAY ON SUNDAY. FRONT OFFSHORE.

SOME TIMING AND STRUCTURE DIFFERENCES BETWEEN MODELS ON WAVE ALONG

THE FRONT SUNDAY. THIS WILL AFFECT WIND DIRECTION AND POSSIBLY SPEED

SUNDAY AS WAVES LIFTS TO THE NORTHEAST OF THE AREA. WAVE WILL

CONTINUE TO PUMP MOISTURE ONSHORE AS FRONT REMAINS OFFSHORE AND

UPPER TROUGH SWINGS THROUGH. BEST CHANCES WILL BE ALONG THE COAST

DURING THE MORNING AND EARLY AFTERNOON AS MAIN PIECE OF UPPER LEVEL

ENERGY SWEEPS ACROSS THE AREA. CHANCES AND QPF DECREASING WEST TO

EAST ON SUNDAY AS UPPER LEVEL ENERGY MOVES ACROSS. ATMOSPHERE

REMAINS QUITE STABLE DURING THE DAY SUNDAY WITH STRONG CAA BEHIND

THE FRONT SETTING UP DEEP INVERSION. FORECAST SOUNDINGS AGAIN

SHOWING PTYPE MIGHT BE AN ISSUE SUNDAY BEFORE PRECIP ENDS SUNDAY

AFTERNOON. LOWEST FEW MBS ABOVE FREEZING. GROUND IS WARM AFTER MANY

DAYS OF WARM ATMOSPHERIC TEMPERATURES SO IF ANY FROZEN PRECIP

FALLS...DONT EXPECT ANY ACCUMULATIONS. MODEL PTYPE ALGORITHMS

SHOWING ALL LIQUID.

[Lookout]

GFS totals for here are prolly 7-10 inches so lets hope that one is right lol. What I think is going to happen is when the rates get high we see snow when they let up we get drizzle/light rain....really though since most of this hits in like 6-10 hrs rates should be pretty good given the amount of QPF involved in the models.

For the record MHX doesnt even mention the word snow in any product at all which kinda surprised me, I guess they are going with climo and think the BL will win. Even still Iwould expect them to at least mention the possibilties but whatever....

That is not going to happen. Despite cold mid levels, boundary layer temps are way too warm at first to be snow..even with the heavy precip rates, it's going to take some time to cool the boundary layer because the warm layer is not only very warm to start but rather deep on the 12z run. To be honest, the 12z runs are not as favorable as prior runs as both runs are warmer with 925mb to surface temps and the greatest threat has shifted to far eastern nc on this run. Looks like the greatest chance of a changeover before ending on this run is from rocky mount eastward to the nc coast.

This run doesn't match up with prior runs as far as temps go so we will see if it turns colder but I'll be honest, looking at the soundings, precip rates, etc, this model run has caused my confidence to decrease a lot. It really is going to take a lot of heavy precip to overcome such a warm boundary layer...temps on the nam and gfs have surface temps in the mid to even upper 40s as late as 06z and only cooling to the upper 30s to low 40s by 12z. Models have a hard time with dynamical cooling so these temps are not necessarily set in stone for those areas that are in the heart of it.

I'm sorry to say but The 12z run of both models suggest, at best, a brief changeover or even just a mix before ending without much chance of accumulation..while prior runs showed a real chance of some accumulations.

[WeSuck]

I think the SE VA and Interior NE NC stand the best chance at something in regards to this storm. Whether heavy snow falls or not, accums will be very limited. However, I will take snow falling over no accums any day!

[shaggy]

The best part is that we haven't spent a week tracking this possible event. No matter what happens I don't have much invested in it and i'll take any token flakes if I can get them. Then bring on spring and fishing weather!

Its better to have snow overhead and and hope we overcome warm surface temps than to have it right at freezing at the surface and too warm aloft.

[downeastnc]

That is not going to happen. Despite cold mid levels, boundary layer temps are way too warm at first to be snow..even with the heavy precip rates, it's going to take some time to cool the boundary layer because the warm layer is not only very warm to start but rather deep on the 12z run. To be honest, the 12z runs are not as favorable as prior runs as both runs are warmer with 925mb to surface temps and the greatest threat has shifted to far eastern nc on this run. Looks like the greatest chance of a changeover before ending on this run is from rocky mount eastward to the nc coast.

This run doesn't match up with prior runs as far as temps go so we will see if it turns colder but I'll be honest, looking at the soundings, precip rates, etc, this model run has caused my confidence to decrease a lot. It really is going to take a lot of heavy precip to overcome such a warm boundary layer...temps on the nam and gfs have surface temps in the mid to even upper 40s as late as 06z and only cooling to the upper 30s to low 40s by 12z. Models have a hard time with dynamical cooling so these temps are not necessarily set in stone for those areas that are in the heart of it.

I'm sorry to say but The 12z run of both models suggest, at best, a brief changeover or even just a mix before ending without much chance of accumulation..while prior runs showed a real chance of some accumulations.

I know thats why I had a LOL at the end of the sentence...it wouldnt surprise me though to see 2-4" in some spots IF the rates are high enough to overcome the BL issues since to do so would mean pretty heavy rates and with those rates it could cool to 32 all the way to the surface for the duration of that kind of rate. It all comes down to how much CAA we get at the surface behind the front I think it has got to be mid to upper 30's to pull it off anything above 40 would be hard to overcome...that said the latest GFS QPF outlook is sick, with PGV getting 1.63" over the next 72 hrs so we shall see if those rates happen or not.

[WeatherNC]

I think shaggy nailed it, not a typical SN event in that we have not really tracked this one so not much is invested in it. If anything, this is more of a novelty event, with some consistency in the American guidance showing a slgt potential for ptype issues here tomorrow morning. As stated, last 600-1k' are going to be an issue. Unusual for the heaviest precip occurring on the cold side of the boundary, we usually see it happen the other way around. MHX is pretty mum about SN chances, stating that all ptype algorithms are liquid. Just based on thickness plots from the 12z, borderline between measurable SN with RN, indeterminate, and all SN tomorrow morning. Granted not the best tools, i.e. soundings, but even they show a shallow layer at the surface between 2-5C here tomorrow. Hopefully this low tracks far enough west to keep the moisture rolling in here tomorrow through mid day. Best guess on any chance of seeing frozen would be from 5am-noon. I had a thunderstorm this morning btw, and almost hit 80 on Thursday, so we have 2 things going for us right there.

[WeatherNC]

12z Euro looks good for ~1/2" here with 850's <0C, -2 to -3 range here between 24 and 30 hrs. Storm total liquid is between 1.5-2" for most of enc over the next 48hrs. Very wet run for sure.

[WeSuck]

12z Euro looks good for ~1/2" here with 850's

What does euro have for SE VA? All I have on me is my phone atm. In line more with NAM or GFS?

[downeastnc]

12z Euro looks good for ~1/2" here with 850's <0C, -2 to -3 range here between 24 and 30 hrs. Storm total liquid is between 1.5-2" for most of enc over the next 48hrs. Very wet run for sure.

Imagine the radar returns will look sick tomorrow especially with a low melt layer, either way its going to be one of those things where its gonna be feast or famine, with that much QPF if it does changeover who knows what it will happen. me and Shaggy are gonna be out and about you want us to pick ya up or try to meet somewhere if we do get into the snow....might have to sled in the slush out there on the bypass.

[WeatherNC]

So your saying there's a non-zero chance...

[downeastnc]

So your saying there's a non-zero chance...

Now if only they are right......still its nice to see every single one of them show snow here thats kinda hard to ignore. It would be nice to have one of these oddball events break our way for once....still WOW at the QPF

[WeSuck]

12z NAM is sick nasty wet with precip!

http://raleighwx.americanwx.com/models/nam/18znam850mbTSLPp06NAMLoop.html

[WeatherNC]

PGV based on the 18z NAM, last 600 or so ft is going to be an issue, 2-3C, and it is really a shallow surface layer, 900' is around 0.5C, 200' 2C. You can see on the 12z sounding that the model attempts to take the bl isothermal, note how the temp/dp/wetbulb all straddle the 0C line between about 925 and 975mb, indicative of a melting layer.

[WeatherNC]

Good rn event regardless of what happens with frozen type

[WeSuck]

I imagine this is what the radar may look like tomm. I am using this for radar purposes and not comparing to the event.

http://www4.ncsu.edu/~nwsfo/storage/cases/20041226/regradloop/regrad.loop.html

[WeatherNC]

MHX AFD, only WFO I have seen this afternoon that mentions the chance of a rogue SN-flake reaching the ground, ILM and RAH went all liquid, as did MHX for the most part. Interesting snip-it at the end about temps tomorrow, may not get out of the upper 30's.

.SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/...

AS OF 415 PM SATURDAY...A WIDESPREAD COLD RAIN WILL BE OCCURRING

AREA WIDE SUNDAY MORNING WHILE TEMPERATURES CONTINUE TO DROP ON

STRONG NORTHERLY FLOW WITH LOW PRESSURE MOVING NORTHEAST OFF OF THE

COAST. THIS COLDER NORTHERLY FLOW WILL BE DEEPEN THROUGHOUT THE

DAY SUCH THAT MOST OF THE PRECIPITATION FALLING THROUGH THE CLOUDS

WILL BE SNOW...HOWEVER...THE BOUNDARY LAYER IS FORECAST TO REMAIN

DEEP ENOUGH ABOVE FREEZING SO THAT MOST OF THE SNOW IS EXPECTED TO

MELT AND CHANGE OVER TO RAIN. A FEW SNOW FLAKES MAY MAKE MAKE IT

TO THE SURFACE...MIXING WITH THE RAIN SO HAVE INCLUDED A SLIGHT

CHANCE OF SNOW IN THE FORECAST BUT NO ACCUMULATIONS ARE ANTICIPATED.

THE RAIN WILL BEGIN TO TAPER OFF FROM WEST TO EAST AFTER 18Z AND

THE FORECAST WILL REFLECT DECREASING CHANCES OF RAIN ESPECIALLY

WESTERN ZONES DURING THE AFTERNOON. SIGNIFICANT RAINFALL AMOUNTS

OF 1 INCH OR MORE ARE EXPECTED ACROSS EASTERN NC BY EVENING. MOS

TEMPERATURES LOOKED TOO WARM FOR HIGHS SO TRENDED TOWARD THE

COLDER SIDE OF GUIDANCE WITH HIGHS IN THE LOWER TO MIDDLE 40S BUT

THESE READINGS MAY BE TOO HIGH AND I CAN ENVISION TEMPERATURES IN

THE UPPER 30S ALL DAY.

[RaleighWx]

The 18z NAM, looking at BUFKIT soundings would be possibly a 2-4 inch snow for RDU between 3-8am.

[downeastnc]

MHX AFD, only WFO I have seen this afternoon that mentions the chance of a rogue SN-flake reaching the ground, ILM and RAH went all liquid, as did MHX for the most part. Interesting snip-it at the end about temps tomorrow, may not get out of the upper 30's.

.SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/...

AS OF 415 PM SATURDAY...A WIDESPREAD COLD RAIN WILL BE OCCURRING

AREA WIDE SUNDAY MORNING WHILE TEMPERATURES CONTINUE TO DROP ON

STRONG NORTHERLY FLOW WITH LOW PRESSURE MOVING NORTHEAST OFF OF THE

COAST. THIS COLDER NORTHERLY FLOW WILL BE DEEPEN THROUGHOUT THE

DAY SUCH THAT MOST OF THE PRECIPITATION FALLING THROUGH THE CLOUDS

WILL BE SNOW...HOWEVER...THE BOUNDARY LAYER IS FORECAST TO REMAIN

DEEP ENOUGH ABOVE FREEZING SO THAT MOST OF THE SNOW IS EXPECTED TO

MELT AND CHANGE OVER TO RAIN. A FEW SNOW FLAKES MAY MAKE MAKE IT

TO THE SURFACE...MIXING WITH THE RAIN SO HAVE INCLUDED A SLIGHT

CHANCE OF SNOW IN THE FORECAST BUT NO ACCUMULATIONS ARE ANTICIPATED.

THE RAIN WILL BEGIN TO TAPER OFF FROM WEST TO EAST AFTER 18Z AND

THE FORECAST WILL REFLECT DECREASING CHANCES OF RAIN ESPECIALLY

WESTERN ZONES DURING THE AFTERNOON. SIGNIFICANT RAINFALL AMOUNTS

OF 1 INCH OR MORE ARE EXPECTED ACROSS EASTERN NC BY EVENING. MOS

TEMPERATURES LOOKED TOO WARM FOR HIGHS SO TRENDED TOWARD THE

COLDER SIDE OF GUIDANCE WITH HIGHS IN THE LOWER TO MIDDLE 40S BUT

THESE READINGS MAY BE TOO HIGH AND I CAN ENVISION TEMPERATURES IN

THE UPPER 30S ALL DAY.

P&C for Greenville I guess MHX feels they got climo on their side and will stick to their guns IF they are wrong they gonna look kinda bad doing quickie WWA or WSW at first light when folks wake up to go to church and its snowing lol

Tonight: Showers and thunderstorms likely before 7pm, then a chance of showers. Cloudy, with a low around 41. Calm wind becoming north around 6 mph. Chance of precipitation is 60%. New rainfall amounts between a quarter and half of an inch possible.

Sunday: A chance of showers, mainly before noon. Mostly cloudy, with a high near 53. Northwest wind between 6 and 9 mph. Chance of precipitation is 50%. New rainfall amounts between a tenth and quarter of an inch possible

[RaleighWx]

MHX AFD, only WFO I have seen this afternoon that mentions the chance of a rogue SN-flake reaching the ground, ILM and RAH went all liquid, as did MHX for the most part. Interesting snip-it at the end about temps tomorrow, may not get out of the upper 30's.

.SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/...

AS OF 415 PM SATURDAY...A WIDESPREAD COLD RAIN WILL BE OCCURRING

AREA WIDE SUNDAY MORNING WHILE TEMPERATURES CONTINUE TO DROP ON

STRONG NORTHERLY FLOW WITH LOW PRESSURE MOVING NORTHEAST OFF OF THE

COAST. THIS COLDER NORTHERLY FLOW WILL BE DEEPEN THROUGHOUT THE

DAY SUCH THAT MOST OF THE PRECIPITATION FALLING THROUGH THE CLOUDS

WILL BE SNOW...HOWEVER...THE BOUNDARY LAYER IS FORECAST TO REMAIN

DEEP ENOUGH ABOVE FREEZING SO THAT MOST OF THE SNOW IS EXPECTED TO

MELT AND CHANGE OVER TO RAIN. A FEW SNOW FLAKES MAY MAKE MAKE IT

TO THE SURFACE...MIXING WITH THE RAIN SO HAVE INCLUDED A SLIGHT

CHANCE OF SNOW IN THE FORECAST BUT NO ACCUMULATIONS ARE ANTICIPATED.

THE RAIN WILL BEGIN TO TAPER OFF FROM WEST TO EAST AFTER 18Z AND

THE FORECAST WILL REFLECT DECREASING CHANCES OF RAIN ESPECIALLY

WESTERN ZONES DURING THE AFTERNOON. SIGNIFICANT RAINFALL AMOUNTS

OF 1 INCH OR MORE ARE EXPECTED ACROSS EASTERN NC BY EVENING. MOS

TEMPERATURES LOOKED TOO WARM FOR HIGHS SO TRENDED TOWARD THE

COLDER SIDE OF GUIDANCE WITH HIGHS IN THE LOWER TO MIDDLE 40S BUT

THESE READINGS MAY BE TOO HIGH AND I CAN ENVISION TEMPERATURES IN

THE UPPER 30S ALL DAY.

The 18z NAM is much colder in the boundary layer at RDU, with the surface actually right around freezing from 5-8am.

[WeatherNC]

The 18z NAM is much colder in the boundary layer at RDU, with the surface actually right around freezing from 5-8am.

Colder air is inbound, Roxboro 52/32 as of 4:15p, Henderson also with a dp in the 30's. I noticed that also, this run takes any sn chances and pushes them on the NW side of the precip shield, RDU up through Oxford area. 12z Euro sn algorithm from wunderground confined 1" accum to the inner banks, around Washington, none here, or at RDU. That 12z GFS ens graphic I posted while cool to look at, is a case of low resolution wreaking havoc on SN output, not likely to be even close. The 18z NAM did have a 2mT min of 35 centered near Edenton tomorrow around 1pm. Expecting to wake up with temps in the 30's, but we are likely to need around 35-36 at the surface to start mixing. Timing is just about perfect, and thickness crashes as the heaviest moisture comes through. Could go either way but i am leaning towards the last 600-1000' being too warm.

[downeastnc]

Colder air is inbound, Roxboro 52/32 as of 4:15p, Henderson also with a dp in the 30's. I noticed that also, this run takes any sn chances and pushes them on the NW side of the precip shield, RDU up through Oxford area. 12z Euro sn algorithm from wunderground confined 1" accum to the inner banks, around Washington, none here, or at RDU. That 12z GFS ens graphic I posted while cool to look at, is a case of low resolution wreaking havoc on SN output, not likely to be even close. The 18z NAM did have a 2mT min of 35 centered near Edenton tomorrow around 1pm. Expecting to wake up with temps in the 30's, but we are likely to need around 35-36 at the surface to start mixing. Timing is just about perfect, and thickness crashes as the heaviest moisture comes through. Could go either way but i am leaning towards the last 600-1000' being too warm.

That is really it too.....gotta hope that weak CAA is enough to creep us down so the snow can reach the surface once it does we should be good as long as the rates keep up.....just need it a tad bit cooler but most likely if anything it will be a bit warmer than progged so

[WeatherNC]

I do think RDU sees about 1" liquid equiv out of this, and that is based namely on the 12z Euro, HPC thinking the front would be further east than what the guidance showed, and numerous WFOs mentioning such is likely going to be wrong. Should be a healthy QPF producer for areas along 95 in the Carolinas, even CAE and CLT could see 1/4-1/2" out of it.