NC/VA Sunday Snow Threat

[Poimen]

The nam has really uped the qpf in the RDU area but I just don't trust the nam. It has burned me to many times!

I agree, if it turns out to be on to something then it will be a nice bonus.

[WeatherNC]

I would be pretty flipping stoked if the RAH site, in addition to the national mosaic, looked even close to this at 7pm tomorrow evening...

[rduwx]

If I'm not mistaken the nam has WeatherNC in it's bullseye. To bad the ground is too warm but it'll be nice to see some flakes in the air.

[HKY_WX]

nam wants to spark a coastal low. thus the higher totals from rdu eastward.

[strongwxnc]

Yep..

nam wants to spark a coastal low. thus the higher totals from rdu eastward.

[WeatherNC]

nam wants to spark a coastal low. thus the higher totals from rdu eastward.

Excellent ob, just a little closer to the coast than what the global shows and that accounts for the heavier amounts in the east. Clipper has more moisture on this run too, as evidenced by the increase in amounts up stream.

[FoothillsNC]

the NAM's surface temps are mid 40's over most of NC during the event, to be honest that looks way too warm given the setup and the surface low passing south of CLT . I"m not sure why it is so warm in the boundary layer, I haven't looked about 925 though. Its' 850s though support snow atleast along 40 east of Asheville. AVL itself looks mostly rain with a warm advection going on there to just around CLT.. After this, the NAM has high temps staying below 40 on Sunday from a line Chapel Hill to around Athens....roughly I-85...so temps Sunday look to hardly move at all with strong CAA.

I know I am completely out of the hunt on this one, so I'm pulling for you guys north and east ( and you too ne TN). Whoever ends up beneath the best banding could end up with some sloppy inches. Doesn't even look like a drop of rain here.

[Cold Rain]

the NAM's surface temps are mid 40's over most of NC during the event, to be honest that looks way too warm given the setup and the surface low passing south of CLT . I"m not sure why it is so warm in the boundary layer, I haven't looked about 925 though. Its' 850s though support snow atleast along 40 east of Asheville. AVL itself looks mostly rain with a warm advection going on there to just around CLT.. After this, the NAM has high temps staying below 40 on Sunday from a line Chapel Hill to around Athens....roughly I-85...so temps Sunday look to hardly move at all with strong CAA.

I know I am completely out of the hunt on this one, so I'm pulling for you guys north and east ( and you too ne TN). Whoever ends up beneath the best banding could end up with some sloppy inches. Doesn't even look like a drop of rain here.

The point you raise is the reason we will get very little if any snow from this.

[MillzPirate]

the NAM now has PGV at >.50 qpf.......... there is now officially a trend to a wetter solution on the NAM for each run at PGV... maybe WeatherNC can put together a graphic to highlight this

[FoothillsNC]

The point you raise is the reason we will get very little if any snow from this.

where are you? It would help to have locations listed. I'm pretty positive that north of 40 will see some snow from this but theres a pretty big area right around 40 running east to west that I have a question about. It could come down to rates, wetbulbs at start time ( a clear night all night would help), and what strength and track the sfc low takes. There's decent divergence east of the Apps tomorrow midday (timing of the event is one thing to argue against NC snow) but other things make this an extremely close call, which could very easily switch one way or the other. It's very hard to fx snow east of the mountains in NC, no matter what the pattern or season. There's so many things to consider. Looking back at the best ones, they weren't forecast too well usually. Minor events turned into big ones, and quite often forecast big ones turned into duds. I think its much easier to forecast around the DC area for example.

edit: just saw your location.

[WeatherNC]

the NAM's surface temps are mid 40's over most of NC during the event, to be honest that looks way too warm given the setup and the surface low passing south of CLT .

Checked soundings for this run here and surface temps would wetbulb at or near freezing by 0z, which is when the column is just beginning to become saturated. At 3z, it is isothermal below 900mb.

here is RDU @ 3z also

the NAM now has PGV at >.50 qpf.......... there is now officially a trend to a wetter solution on the NAM for each run at PGV... maybe WeatherNC can put together a graphic to highlight this

waiting on the 0z station reports from Allan's site

[DCMetroWinston]

WBTV Futurecast

[wxologist]

FYI...the CIPS Analog Guidance has been affected by the AWIPS/NOAAPORT satellite issues today. Unfortunately...until these issues are fixed...our data feed and most of our supplemental data sites will be affected. This has affected WFOs in the northern US today as well. Pass the word along if necessary.

[MillzPirate]

WeatherNC, what are your thoughts on the coastal idea the NAM has been showing. I'm interested in this idea going back to the Innauguration snow of 08. The path of the shortwave came from nearly the same direction (albeit Canada) and redeveloped itself near Myrtle Beach. Mid January vs. Early December, and shortwave vs. established clipper aside, the prospect of a coastal is intriguing.

[Cold Rain]

where are you? It would help to have locations listed. I'm pretty positive that north of 40 will see some snow from this but theres a pretty big area right around 40 running east to west that I have a question about. It could come down to rates, wetbulbs at start time ( a clear night all night would help), and what strength and track the sfc low takes. There's decent divergence east of the Apps tomorrow midday (timing of the event is one thing to argue against NC snow) but other things make this an extremely close call, which could very easily switch one way or the other. It's very hard to fx snow east of the mountains in NC, no matter what the pattern or season. There's so many things to consider. Looking back at the best ones, they weren't forecast too well usually. Minor events turned into big ones, and quite often forecast big ones turned into duds. I think its much easier to forecast around the DC area for example.

edit: just saw your location.

Yeah, I just finally updated my location and stuff. I haven't had a chance before now. Wife wanted to watch Home Alone, so it gave me the opportunity to update my profile, although Home Alone is a decent movie. Anyway, I hope we can squeeze some flakes out of this, but I've seen these things underperform so many times that it's really hard to get excited about, especially this early in the season. If I was confident that the rates would be heavy enough, I would be more bullish on seeing snow. But I've seen the NAM overdo amounts several times over the past couple of years in these situations, so I'm reticent to rely heavily on it.

[Jon]

Yeah, I just finally updated my location and stuff. I haven't had a chance before now. Wife wanted to watch Home Alone, so it gave me the opportunity to update my profile, although Home Alone is a decent movie. Anyway, I hope we can squeeze some flakes out of this, but I've seen these things underperform so many times that it's really hard to get excited about, especially this early in the season. If I was confident that the rates would be heavy enough, I would be more bullish on seeing snow. But I've seen the NAM overdo amounts several times over the past couple of years in these situations, so I'm reticent to rely heavily on it.

"Cold Rain" "Don't pin your hopes on clippers." "Snow shields activated"....you don't have to tell us how your level of confidence...

[FoothillsNC]

Yeah, I just finally updated my location and stuff. I haven't had a chance before now. Wife wanted to watch Home Alone, so it gave me the opportunity to update my profile, although Home Alone is a decent movie. Anyway, I hope we can squeeze some flakes out of this, but I've seen these things underperform so many times that it's really hard to get excited about, especially this early in the season. If I was confident that the rates would be heavy enough, I would be more bullish on seeing snow. But I've seen the NAM overdo amounts several times over the past couple of years in these situations, so I'm reticent to rely heavily on it.

yeah I wouldn't go bythe NAM too much either, but other models are ok and in the ball park as well with this event. What makes it hard is the sfc. temps.....just unsure what they'll be, but overall not a big precip maker anyway...but , when a clipper comes east of the mountains, occasionally there are surprises, its just usually they don't venture down this far south...which makes this one kind of fun to forecast. And H.A. is a great movie.

[WeatherNC]

FYI...the CIPS Analog Guidance has been affected by the AWIPS/NOAAPORT satellite issues today. Unfortunately...until these issues are fixed...our data feed and most of our supplemental data sites will be affected. This has affected WFOs in the northern US today as well. Pass the word along if necessary.

Thanks!

NOUS42 KWNO 040153

ADMNFD

SENIOR DUTY METEOROLOGIST NWS ADMINISTRATIVE MESSAGE

NWS NCEP CENTRAL OPERATIONS CAMP SPRINGS MD

0151Z SAT DEC 04 2010

THE NCEP 00Z MODEL CYCLE STARTED ON TIME WITH GOOD US/CAN UPPER

AIR DATA COVERAGE..

00Z RAOB RECAP..

LMN/74646 - SHORT TO 446MB

PNI/91348 - SHORT TO 496MB; 10158; FLIGHT EQUIP PROBLEMS..

OTZ/70133 - 10159; NOT AVAILABLE.

GUM/91212 - 10142; GROUND EQUIP PROBLEMS.

OAX/72558 - NOT IN FOR THE NAM.

$$

SHRUELL/SDM/NCO/NCEP

WeatherNC, what are your thoughts on the coastal idea the NAM has been showing. I'm interested in this idea going back to the Innauguration snow of 08. The path of the shortwave came from nearly the same direction (albeit Canada) and redeveloped itself near Myrtle Beach. Mid January vs. Early December, and shortwave vs. established clipper aside, the prospect of a coastal is intriguing.

Just got off the phone with one of our on air Chiefs here in the east. We came to the agreement we are not buying into the NAM QPF totals yet, and the closer to the coast development, if at all. To put >0.5" liquid into perspective, that would be one of our better RN events here in Greenville since the monsoon. Most of the time you will see the banding rapidly erode between the triangle and 95, as the coastal takes over. Seen it numerous times, and seems likely this go around even if a closer to the coast solution verifies. General tenth to maybe a quarter inch liquid, with those along and north of the 264 corridor standing the best chance of a sloppy inch or very isolated two. 0z NAM has a warm nose here around 1 am Sunday, have a look at the text below. Would likely be overcome with heavier rates, maybe, but given I am expecting about half what the NAM is putting out, around 0.2", this may be an issue if the GFS starts showing it.

[Cold Rain]

"Cold Rain" "Don't pin your hopes on clippers." "Snow shields activated"....you don't have to tell us how your level of confidence...

Years of living in the Triangle, my friend. Love your sig, by the way. Went to State for meteorology back in the mid 90s. Not too crazy about the weird looking wolf thing on the field, outside the tunnel, though.

[Cold Rain]

yeah I wouldn't go bythe NAM too much either, but other models are ok and in the ball park as well with this event. What makes it hard is the sfc. temps.....just unsure what they'll be, but overall not a big precip maker anyway...but , when a clipper comes east of the mountains, occasionally there are surprises, its just usually they don't venture down this far south...which makes this one kind of fun to forecast. And H.A. is a great movie.

Yeah, the surface temps are the reason I'm very skeptical at this point. If I knew we were going to be in the mid 30s or lower throughout most of the event, I'd be a bit more optimistic. But 40 or higher surface temps seems like an awful lot to overcome, especially if precip rates are not high. But, as you said, there are surprises. Maybe this will be one. I hope so. By the way, H.A. is good. I like A Christmas Carol...the George C. Scott version best. That's my favorite Christmas movie.

[SBUWX23]

Havent had much time to look at things...have work at 5am tomorrow so wont be up much later but just read RAH evening AFD update and several interesting points were made.

Near term /through tonight/...

as of 1013 PM Friday...

The middle clouds were clearing eastern NC this evening as the weak

upper level disturbance moves offshore. A weak surface trough was

pushing southeast through the Piedmont with a subtle drop in dew points

noted behind the trough. Expect this trough to push through all the

region by midnight with a light north flow continuing mixing near

the surface for several hours. Otherwise... satellite trends

indicate that the skies will be mainly clear overnight with an

increase in clouds from the northwest again near sunrise. This will be

associated with the 130+ knot upper level jet that will be

approaching from our northwest then. Lows generally 25-30 accepted.

Winter storm warnings and advisories continue upstream of northwest NC

tonight. This Alberta clipper northwest flow system is currently aimed

directly for western NC (sat afternoon).

The latest guidance (12z ec and 00z nam) continue to forecast the northwest

flow or clipper system to track in nearly perfect position to bring

some accumulating light snow to at least our northern Piedmont

counties late Saturday into Sat evening. An upper level vorticity

forecast track over or near the southern Piedmont of NC favors the

northern Piedmont for snow. The weak surface wave track just to our

west and south favors the same region. It appears that the strong

height falls and lift may at least partially offset the lack of deep

moisture (east of the mountains)... and allow for the moisture that

is present to get wrung out.

The partials... if anything... have been coming in colder this

evening for the event. Currently just an model average snow/rain

line also incorporating the wet bulb zero forecasts during the

height of the expected precipitation (21z-03z)... yields mostly light snow

for the northern Piedmont (i-40 and I-85 corridors to near Raleigh

and rwi)... with some measurable snow possible in this zone.

Quantitative precipitation forecast will be problematic... as the new 00z/NAM suggests 0.50 liquid

equivalent which seems high given the northwest flow event. If 0.25 is

realized... and the current partials verify... then a good coating

of snow appears in order in the aforementioned areas in later

forecasts. We will only update the hazardous weather outlook at this

time to enhance the chance of light snow wording especially from

Winston-Salem to Raleigh northward. A Winter Weather Advisory for

some light accumulating snow may be needed once the new data can be

analyzed. There is increasing confidence that some snow will fall

over our Piedmont with this system.

&&

[WeatherNC]

Makes sense given the recent trends over the past 24 and upstream advisories, but it lacks continuity with the afternoon package, j/j

[MillzPirate]

you might be in the Southeast thread when the prospect of getting a 1 or 2 inch snowfall wreaks havoc on the board

[MillzPirate]

looks like the GFS is holding firm with its qpf at around .2

[Jon]

Havent had much time to look at things...have work at 5am tomorrow so wont be up much later but just read RAH evening AFD update and several interesting points were made.

Near term /through tonight/...

as of 1013 PM Friday...

The middle clouds were clearing eastern NC this evening as the weak

upper level disturbance moves offshore. A weak surface trough was

pushing southeast through the Piedmont with a subtle drop in dew points

noted behind the trough. Expect this trough to push through all the

region by midnight with a light north flow continuing mixing near

the surface for several hours. Otherwise... satellite trends

indicate that the skies will be mainly clear overnight with an

increase in clouds from the northwest again near sunrise. This will be

associated with the 130+ knot upper level jet that will be

approaching from our northwest then. Lows generally 25-30 accepted.

Winter storm warnings and advisories continue upstream of northwest NC

tonight. This Alberta clipper northwest flow system is currently aimed

directly for western NC (sat afternoon).

The latest guidance (12z ec and 00z nam) continue to forecast the northwest

flow or clipper system to track in nearly perfect position to bring

some accumulating light snow to at least our northern Piedmont

counties late Saturday into Sat evening. An upper level vorticity

forecast track over or near the southern Piedmont of NC favors the

northern Piedmont for snow. The weak surface wave track just to our

west and south favors the same region. It appears that the strong

height falls and lift may at least partially offset the lack of deep

moisture (east of the mountains)... and allow for the moisture that

is present to get wrung out.

The partials... if anything... have been coming in colder this

evening for the event. Currently just an model average snow/rain

line also incorporating the wet bulb zero forecasts during the

height of the expected precipitation (21z-03z)... yields mostly light snow

for the northern Piedmont (i-40 and I-85 corridors to near Raleigh

and rwi)... with some measurable snow possible in this zone.

Quantitative precipitation forecast will be problematic... as the new 00z/NAM suggests 0.50 liquid

equivalent which seems high given the northwest flow event. If 0.25 is

realized... and the current partials verify... then a good coating

of snow appears in order in the aforementioned areas in later

forecasts. We will only update the hazardous weather outlook at this

time to enhance the chance of light snow wording especially from

Winston-Salem to Raleigh northward. A Winter Weather Advisory for

some light accumulating snow may be needed once the new data can be

analyzed. There is increasing confidence that some snow will fall

over our Piedmont with this system.

&&

RAH seems to change their mind each single model run...wonder what they'll say tomorrow. Funny earlier they said no snow at all, a "non-event" now they say "... with some measurable snow possible in this zone."...this is comical.

At least they mention that "Quantitative precipitation forecast will be problematic...", which they could've mentioned when they practically wrote this off earlier today. Funny how even the NAM can turn the NWS sideways!

[Brick Tamland]

Looks like things are getting very interesting for here.

[superjames1992]

RAH seems to change their mind each single model run...wonder what they'll say tomorrow. Funny earlier they said no snow at all, a "non-event" now they say "... with some measurable snow possible in this zone."...this is comical.

At least they mention that "Quantitative precipitation forecast will be problematic...", which they could've mentioned when they practically wrote this off earlier today. Funny how even the NAM can turn the NWS sideways!

Tomorrow, they'll be issuing blizzard warnings! Haha.

I've met some of the guys at the RAH NWS, though, and they're good people, though I do have to wonder why they changed their forecast so dramatically in such a short time.

[NCSNOW]

This is a healthy (wide spread qpf ) looking clipper, Looks to have enough push to overcome the apps/downsloping effect. Should be interesting. Got mostly clear skies out now. Looking at the radar link, I expect a solid deck by sunrise.

http://www.accuweather.com/us/radar/sir/ne/radar.asp?play=true

[Bozart]

Tomorrow, they'll be issuing blizzard warnings! Haha.

I've met some of the guys at the RAH NWS, though, and they're good people, though I do have to wonder why they changed their forecast so dramatically in such a short time.

Wake County forecast for Saturday night, issued at 10:33 a.m. today:

A CHANCE OF RAIN SHOWERS IN THE EVENING. CLOUDY WITH A CHANCE OF SNOW SHOWERS. COLD WITH LOWS IN THE LOWER 30S.

LIGHT AND VARIABLE WINDS...BECOMING NORTHWEST AROUND 5 MPH AFTER MIDNIGHT. CHANCE OF PRECIPITATION 40 PERCENT.

Wake County forecast for Saturday night, issued at 3:31 p.m. today:

CLOUDY WITH A CHANCE OF RAIN AND SNOW SHOWERS. COLD WITH LOWS IN THE LOWER 30S. LIGHT AND VARIABLE WINDS...

BECOMING NORTH AROUND 5 MPH AFTER MIDNIGHT. CHANCE OF PRECIPITATION 50 PERCENT.

Wake County forecast for Saturday night, issued at 10:33 a.m. today:

CLOUDY WITH A CHANCE OF RAIN AND SNOW SHOWERS. COLD WITH LOWS IN THE LOWER 30S. LIGHT AND VARIABLE WINDS...

BECOMING NORTH AROUND 5 MPH AFTER MIDNIGHT. CHANCE OF PRECIPITATION 50 PERCENT.

I guess I'm not yet seeing any big forecast changes at all, let alone in a short time.

[MillzPirate]

Wake County forecast for Saturday night, issued at 10:33 a.m. today:

A CHANCE OF RAIN SHOWERS IN THE EVENING. CLOUDY WITH A CHANCE OF SNOW SHOWERS. COLD WITH LOWS IN THE LOWER 30S.

LIGHT AND VARIABLE WINDS...BECOMING NORTHWEST AROUND 5 MPH AFTER MIDNIGHT. CHANCE OF PRECIPITATION 40 PERCENT.

Wake County forecast for Saturday night, issued at 3:31 p.m. today:

CLOUDY WITH A CHANCE OF RAIN AND SNOW SHOWERS. COLD WITH LOWS IN THE LOWER 30S. LIGHT AND VARIABLE WINDS...

BECOMING NORTH AROUND 5 MPH AFTER MIDNIGHT. CHANCE OF PRECIPITATION 50 PERCENT.

Wake County forecast for Saturday night, issued at 10:33 a.m. today:

CLOUDY WITH A CHANCE OF RAIN AND SNOW SHOWERS. COLD WITH LOWS IN THE LOWER 30S. LIGHT AND VARIABLE WINDS...

BECOMING NORTH AROUND 5 MPH AFTER MIDNIGHT. CHANCE OF PRECIPITATION 50 PERCENT.

I guess I'm not yet seeing any big forecast changes at all, let alone in a short time.

its the change in their forecast discussion.... very different from earlier in the day