2009.02.26
First comes beneficial rain, then, maybe snow
We might be getting a little ahead of ourselves talking about snow. First will come quite a bit of rain ... on Friday with a front, on Saturday with a wave of overrunning moisture in the early stages of the possible winter storm for somebody in the Southeast, Appalachians or Middle Atlantic. The Hydrometoerological Prediction Center is forecasting widespread amounts of an inch or more across Southwest Virginia over the next 3 days. It is possible that some of this precipitation toward late Saturday into Sunday could be sleet or snow, but much more of it is likely to be rain Friday and Saturday before the colder air seeps back in. All of the moisture is needed because, according to the latest U.S. Drought Monitor map, almost all of Virginia is abnormally dry and most of the Roanoke and New River valleys are suffering moderate drought.
As for the snow ... it all depends on what happens with the trailing upper-level low, and the models are still chasing it around like a greased pig trying to get a handle on what it will do. Some of Thursday night's late model runs were again cutting out a strong coastal low, with at least one showing a sweep of snow well inland. This would probably not be an issue for us until Sunday, though some sleet or snow may fall Saturday evening as cold air thickens in the area. I would only say this at this point: As tired as all of us may be with this winter and its persistent weird misfires, this situation bears some vigilance. I will be watching closely with a great deal of interest to see how the pieces come together for whatever happens.
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HPC has the area of 4+" snow now over central/western GA, SC, and NC...
Comment by Julie — February 27, 2009 @ 9:35 am
... but our region is in or near slight risk both Saturday and Sunday:
http://www.hpc.ncep.noaa.gov/wwd/day2_psnow_gt_04.gif
http://www.hpc.ncep.noaa.gov/wwd/day3_psnow_gt_04.gif
Some of SC is in slight risk of 12 inches, though:
http://www.hpc.ncep.noaa.gov/wwd/day3_psnow_gt_12.gif
I expect these areas will shift some more, though I'm not sure which direction ... very honestly, I think it will shift a bit our way later today, but I could be totally wrong.
Also I should point out we are in a slight risk of .25-inch of ice for Saturday:
http://www.hpc.ncep.noaa.gov/wwd/day2_pice_gt_25.gif
Significant ice storms are usually harder to come by this time of year than earlier in the season, because it's harder to maintain a below-freezing surface layer beneath a thick cold layer ... but some freezing rain/sleet in the transition is certainly possible.
Comment by kevinmyatt — February 27, 2009 @ 9:44 am
But Kevin...Julie...have you giggled over the ETA?
http://wxcaster4.com/nam/CONUS1_MESO-ETA212_SFC_ACCUMSNOWFALL-KUCHERA_84HR.gif
Comment by Betsy — February 27, 2009 @ 10:05 am
I think the surface low track may be a little too far south, as well. I think the low ends up cutting more along the NC/SC border than digging into S GA. I also agree we may see the area of significant snow shift a little north (to our favor), but that may well just be wishful thinking. That said, last night's models are still all over the place but seem to be a tad colder in our area. The next few runs will be fun to watch; this is certainly one of the more interesting systems we've had all winter. I did see the ice probability map, and that's always a concern since I'm in a notoriously cold spot.
Comment by Julie — February 27, 2009 @ 10:15 am
I think something like that is still possible, Betsy ... we might get lesser amounts of snow out of Saturday night's overrunning/changeover stuff, but I'm kinda thinking either 4-plus or absolutely nothing for our region from the upper low/coastal low on Sunday ...
Whether it snows or not here, I think this is a much more interesting system to follow than the fare we've sampled this winter so far ... we have a really energetic system digging far to the south with some real moisture to work with ... not some dinky clipper or storm lifting into the Ohio Valley.
On another front (quite literally) ... rain, some of it heavy, is moving through our area now:
http://radar.weather.gov/radar.php?rid=fcx&product=N0R&overlay=11101111&loop=no
Comment by kevinmyatt — February 27, 2009 @ 10:21 am
I'm not buying the south Georgia snowstorm, either, Julie. If we miss, I think it'll be through the central and eastern Carolinas (which would be about the fourth time in the last 10 years). I just don't see that upper low digging that far south and closing off down that far like that in this pattern. The NAM, Euro and Canadian models are all farther north than the GFS right now, which is the model most stubbornly clinging to the Great Savannah Blizzard of '09.
At this point I'm leaning toward significant snowfall in our area on Saturday night and Sunday, but I'm not sure how much comes from the overrunning wave Saturday night and how much we actually get from the upper low. I think we're still very much in the game for a possible significant to even major winter storm ... but this is the winter of '08-'09, and that alone warrants a lot of skepticism.
Comment by kevinmyatt — February 27, 2009 @ 10:39 am
Let's introduce some real life considerations into the mix. My soon-to-be 8 yr old's outdoor birthday is Saturday at 1 PM with some olympic-style events (race around the house, baseball hit, basketball shot, etc.) They're game to a bit of drizzle and some cool temperatures, but it's the torrential downpour I'm concerned about. Does this system have the capability of washing us out?
Comment by Scott — February 27, 2009 @ 11:42 am
Scott: It probably will be cold and rainy Saturday afternoon, and some sleet, even wet snow is not out of the question,though that will probably come later. I don't think it'll be heavy rain at that time, and if you're blessed, you might catch a break in the showers. So my best guess right now: Not a washout, but chilly and damp.
Comment by kevinmyatt — February 27, 2009 @ 11:57 am
THe GFS still keeps almost everything well south and east of here, while the folks at Accuweather produced a map showing the bulk of the heavy snow in the NE, again. I don;t think anyone or any model has a firm grip on this system at all, the forecasts are all over the place.
Comment by Other John — February 27, 2009 @ 12:54 pm
Agreed, Other John. Still, the latest GFS has taken a step our direction from previous runs, with the snow shield edging into the eastern flank of our region. One of the difficulties will not only be the track of the storm, but how far west the snow shield extends. There will probably be a sharp cutoff at the western edge, so the difference in a 4-plus snow and nothing could be 50 miles. And we still have the cold air moving into Saturday's overrunning moisture to contend with even before the main show begins.
Comment by kevinmyatt — February 27, 2009 @ 1:04 pm
I was looking around at the snow/precip forecasts for the entire storm, and it is looking like the dry slot theory that Julie (I think) mentioned in another thread a couple days ago might happen. It seems to show a healthy dose of snow in WV, and another healthy dose down in the piedmont area eastward, with the lack of snow right along the Blue Ridge (with almosdt the entire area less than an inch). It also showed our area with less than an inch of total precip, with 2-3+ inches west and east of here. I think it's going to be impossible to know what we're going to get until it's over.
Comment by Other John — February 27, 2009 @ 1:07 pm
Seems to me that every time we get a rain to snow event, the two never link up.
That could air usually ends up coming in from the northwest and so it dries the air out in Roanoke and points just east of the mountains.
Comment by Brandon R. — February 27, 2009 @ 1:37 pm
The 12Z Euro has the low much further north than the GFS at 72 hrs, just above Charlotte, NC. This would be good news for us.
Comment by Julie — February 27, 2009 @ 1:40 pm
Hopefully we'll know more from the Blacksburg NWS soon.
If watches/advisories are going to be issued, we're getting close to that time..
Comment by Brandon R. — February 27, 2009 @ 1:59 pm
Brandon: The first part on Saturday is a possible rain to snow event. But the second part on Sunday, the upper low/coastal low, will be just about all snow, it's just a matter of whether it's over us or not.
Julie: I think the Euro coming into line with that kind of solution is a positive development for SW Va. snow lovers. It's far from a lock yet, but I also think the GFS is close and several of the other models seem to show this thing coming farther north and west. Forecast models tend to do a better job on something as dynamic as this system than they do with the puny little clippers and upper disturbances we've dealt with most of this winter, so we'll see if we can get some better agreement now that we're going to be under 48 hours by tonight.
Comment by kevinmyatt — February 27, 2009 @ 2:05 pm
Excellent.
Let's just hope it doesn't go too far north and west.
Probably a long shot, but since it is the winter of 08',09'....
Comment by Brandon R. — February 27, 2009 @ 2:07 pm
I think the NWS will probably not fire any watches for the second part of this storm, as that's not until Sunday and probably late Sunday. There may be some advisories or even winter storm watches related to the first part on Saturday night, and I think those would probably be mostly north and northwest of Roanoke. I have no insider information as I haven't talked to NWS folks today, just an educated guess. We should know in 90 minutes to 2 hours or so.
Comment by kevinmyatt — February 27, 2009 @ 2:10 pm
Ugh! Just what we need, Roanokers flocking to Walmart to grab their rock salt, milk, bread and beer!
Comment by Chelsey Cummings (Hunting Hills) — February 27, 2009 @ 2:35 pm
I don't know about the accuracy of their weather alerts and 5-day forecasts, but Accuweather shows around 4-5 inches of snow in most places in the NRV, and about a slushy inch for Roanoke.
Comment by Other John — February 27, 2009 @ 2:49 pm
Other John, I have not given up completely on the notion we get dry-slotted. Right now we are truly on the fence with a 50/50 scenario; there's a 50% chance we get a good snow (notice I didn't say no snow) and a 50% chance we get dry-slotted. As Kevin mentioned, this evening's model runs will be crucial as this system jumps from mid-range models to short-range models. Also of note: the temps did not get as warm today as projected; so, we are starting tomorrow's dynamics with 5-8 deg. lower temps. Could play a part in the grand scheme of things. But - IWBIWISI!!!
Comment by Julie — February 27, 2009 @ 3:35 pm
The NWS seems to be buying the GFS solution of mostly south and east of us (while allowing for possible changes in the next 48 hours) ...
HPC on the other hand, well, check it out:
http://www.hpc.ncep.noaa.gov/wwd/day3_psnow_gt_04.gif
Comment by kevinmyatt — February 27, 2009 @ 3:39 pm
The NRV section of the NWS discussion seems to center around "This could be really bad and this could be really nothing". I hate when they do that. I talked to a NWS person about my hiking trip in Giles County on Saturday and he mentioned "hypothermia".
Comment by Henry — February 27, 2009 @ 4:31 pm
Hypothermia is actually a little bit bigger problem when it's rainy and cold than when it's sleet and snow ... sleet and snow bounce off of you, rain soaks in.
Comment by kevinmyatt — February 27, 2009 @ 4:40 pm
If Southside gets a significant winter storm out of this, I'm going to throw a fit. A really, really big one.
Comment by Brandon R. — February 27, 2009 @ 4:40 pm
I think the latest discussion on NWS/BBG is a bit odd... No Wx advisory necessary, but 4-5" snow possible in the mountains?? Where are they considering the deformation zone to take shape? Please Note - I am a firm believer in our local NWS office's capabilities, but this latest discussion seems a little disjointed. Perhaps due to a lack of model consensus at this point?
Comment by Julie — February 27, 2009 @ 4:41 pm
Looks like the cold front has cleared Charleston WV:
27 15:54 NW 20 G 33 10.00 Mostly Cloudy SCT022CB BKN035 BKN060 57 48 29.89 1011.8
Comment by John-From Charlottesville — February 27, 2009 @ 4:42 pm
We will be on the trail from 10AM to 4PM on Saturday. That seems to be the rain and 38 degrees period as best I can tell.
But I swear it looks like it is running east of us.
Comment by Henry — February 27, 2009 @ 4:47 pm
Saturday's isn't running east of us ... just a question of when the cold arrives.
Sunday's ... we'll see ... even if it runs east of us, how far west does it throw back a precip shield?
Comment by kevinmyatt — February 27, 2009 @ 4:49 pm