2009.01.05
Winter storm watch two counties north of Roanoke
A winter storm watch has been issued for Alleghany, Rockbridge and Amherst counties and all points northward for the threat of heavy icing late tonight and Tuesday. The National Weather Service in Blacksburg has noted in a morning forecast discussion that locations south of there may be placed under a winter weather advisory later. Right now, it looks like the Roanoke Valley is likely to escape this event with a barely-above-freezing rain, maybe mixed with some sleet as it begins. It is still a close call, and there will probably some locations not far from the valley that get ice out of this event. The New River Valley and locations along the Blue Ridge from Bent Mountain to Floyd Countain will be more likely to see a light glaze. Though buildup on trees and power lines and other above-ground objects will be the main concern, keep a close eye out for icy patches if you travel late tonight or Tuesday.
Latest advisories from the National Weather Service at Blacksburg
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Two things:
I will be completely honest and say that I am almost hoping for a sleet storm. That doesn't cause too many problems and at least it's white. Sad, isn't it?
Also.. I hate to be asking this already, but what is the lowest snow total ever on record for Roanoke?
I know we stand at 0.4 right now and I almost think we won't get more than that. Seriously.
Comment by Brandon R. — January 5, 2009 @ 9:44 am
Not only is sleet white, it officially counts as "snowfall" ... sleet also takes longer to melt, as it's a more concentrated form of ice than fluffy snowflakes with air pockets ... I don't think the cold air will be deep enough for more than just a brief period of sleet with this ...
As for least snow in a season, that would be 1975-76, when Roanoke got 2.3 inches ... 0.1 inch in December and then 2.2 inches on March 12 ... must have been quite a shock to have that almost-no-snow winter in the middle of an era of very snowy winters in the 60s and 70s ... and it came close to being an essentially snowless winter, considering that it was mid-March before the first halfway decent snowfall (0.1 inch rounds down to zero in my book, as does our current 0.4 inch that didn't even cover the entire Roanoke Valley)
It's WAY WAY too early to be giving up on snow for this season ... it's looking more and more like we will have the cold air in place for much of January, it's just a matter of getting some kind of storm system to track the right way ... doesn't take a lot of moisture to top 2.3 inches of snow (that's not even a quarter-inch of liquid)
Comment by kevinmyatt — January 5, 2009 @ 10:04 am
Since the chance of snow is essentially nill, I'll take a steady, cold rain to continue helping the drought situation. It's starting to look like after a promising start to the winter that we'll be hard-pressed to get any decent winter weather for the foreseeable future. Long-range trends and models show a storm or 2 with some potential, then a warming trend later in the month. And given the trend for winter storms the past couple years, I'm not holding my breath for those at this point. It may be mid-February before we have a shot at cold after this current period breaks, so it's starting to look more and more like the best way we would get a decent snow is a clipper with some strong upper-level dynamics like in 2007, or a very strong surface low cutting out of the gulf that somehow defies the 2-3 year pattern and goes up the coast rather than cutting west of the mountains. This is shaping up to be a 3rd straight disappointing winter for snow, but at least we're getting some drought-easing rains this year.
Comment by Other John — January 5, 2009 @ 10:11 am
Kevin-is there such thing as a dew point forecast? If so, do you have a link? I think it will be interesting to watch the dew points as this storm develops...
Also, someone made a comment on one of the weather forums that I watch that Richmond is the new Atlanta in terms of climate...any thoughts?
Comment by Betsy — January 5, 2009 @ 10:33 am
Not aware of a dew point forecast product, other than some of the technical model stuff ... you can watch the actual dew point change here: http://weather.noaa.gov/weather/current/KROA.html
I don't think 1 degree of worldwide warming over a century is enough to shift Atlanta's climate to Richmond ... the new Raleigh, maybe ... I think the climate is slowly warming and man probably has a role in that, but I don't believe the recent years' pattern of little snow/little rain in our particular region is strongly connected to that, but rather finds its origin more in cyclical patterns in the Pacific ... those same cyclical patterns are bringing repeated excessive snow and cold to other areas of the country, including some that don't typically get it ... but if this goes on for 30 years rather than 12, perhaps I could be wrong about that ...
Other John: There are some indications the cold might hold longer and even be more severe than earlier thought, with strong high pressure developing in the West. The problem is, it would mostly be cold and dry, so there go even the drought-easing rains. I think the models do a poor job picking up the kind of disturbances we usually get our 2-4-inch type snows from more than 5 days out. So I still think a small to medium-sized snow is at least 50-50 shot by Inauguration Day.
Comment by kevinmyatt — January 5, 2009 @ 11:13 am
I am going to go figure out how to hook up the generator, just in case. The last model run has the 32F line just a little south and east of me (Floyd Co.), and I'm above 2500' elevation, so I typically see 2 or 3 deg. lower than guidance - just enough of that razor's edge to warrant being as prepared as I can be...
Kev, WRT longer range models, there certainly does appear to be a trend towards deep, lasting cold. The dip in the jet will certainly deflect any moisture away, and looks to shut off the GOM completely (for us). Also, I meant to ask if you noticed how squarely the polar vortex was located right over Alaska earlier this weekend with all the record cold in the midwest - talk about a picture-perfect example to use in a meteorology class!
Comment by Julie — January 5, 2009 @ 12:54 pm
Hey Kevin - Thanks for all you do! Is there an update on this storm? Do you think it will likely be icy in the Roanoke area tomorrow morning?
Comment by Brian — January 5, 2009 @ 1:16 pm
My gut feeling is that Roanoke's lack of major snows in the last 12 years is partially related to global warming. I also think that the string of snowy winters in the 1960s and 1970s had something to do with the minor global cooling of 1945-1975. Though, random chance and variability plays such a big role that I doubt either hypothesis could be proven.
I've downloaded some data from the Utah State website that were used to populate the "Datasphere" tool and plan to play around with it to see if some of my hunches about how weather has changed in Roanoke is correct.
It would be interesting for someone to do a city comparison to see if the weather in Roanoke/Richmond today is similar to Raleigh/Atlanta's of 20, 30, 40, 50 years ago. It'd also be interesting if, say, Roanoke were more akin to Raleigh now and Washington 20-30 years ago as I suspect.
Comment by Kevin — January 5, 2009 @ 1:17 pm
I plotted the average highs and lows in January from 1948 to 2007. The lines are pretty jagged due to variations in individual years. Nonetheless, there's a very steep decline during the 1950s and 1960s. There's not much of trend in the 1970s and most of the 1980s. By the late 1980s, there's a gradual warming trend through the present. I'm not well versed in the statistical functions of Excel, but I think a line of best fit would have about the same values in 1950 (upper 40s for highs, upper 20s for lows) and the present.
Comment by Kevin — January 5, 2009 @ 1:43 pm
I do not expect Roanoke to be icy in the morning. The cold air damming setup is far from textbook and the cold air isn't that thick anyway. We typically have a hard time getting to freezing in this kind of setup. I would really only expect spotty ice anywhere in Southwest Virginia south of I-64.
As for recent trends ... I just don't think the pattern has gone on long enough to establish it as a kind of "new normal" yet ... what we've experienced in the 2000s is not much different than what the 1950s brought, and that ended suddenly with the 1960s ... a few years of low-snow winters are just a blip on the climatic history of the area ... if this goes on another decade or so, I would be more inclined to wonder about a bigger-picture reason for the rain/snow decline (it's all year, not just winter) rather than merely atmospheric/oceanic cycles playing out ...
And this winter's not over yet ...
Comment by kevinmyatt — January 5, 2009 @ 3:40 pm
kevin & betsy
Follow this link to NWS forecast page for Roanoke:
http://forecast.weather.gov/MapClick.php?site=rnk&FcstType=text&map.x=191&map.y=122&site=RNK
(sorry, I couldn't convert this to an actual link, but put it in your browser and go there)
In the lower right-hand corner of the page is list of links titled "Additional Forecasts & Information" Select the link "Hourly Weather Graph". This page shows a 48-hour forecast of weather parameters, with an option to further extend the forecast.
Fletch
Comment by Fletcher Hinson — January 5, 2009 @ 3:53 pm
I've been watching the ever-changing forecasts for the storm. Earlier, there was a good swath of the area covered by ice potential on the NWS maps. Now, it's just showing some splotchy areas of ice, mostly higher peaks it appears, with almost no widespread coverage. Also, the counties to the north now show some sleet mixing in with the rain, rather than freezing rain, so they have cut some areas out of the advisory/warning listings they issued earlier. And for Blacksburg, they had showed around 0.2 inches of ice from the storm...now calling for just rain with temps in the mid-30's, rather than the low 30's they indicated just this morning. Because of the total precip amounts, I hope it stays just a cold rain.
Comment by Other John — January 5, 2009 @ 4:54 pm
Hey Fletcher...that's cool...thanks for pointing that out...I've been on that site a million times and never clicked on that link! Kevin-check it out.
Comment by Betsy — January 5, 2009 @ 5:05 pm
I don't think we'll be looking at an icing problem at all. NWS canceled the winter storm watch in favor of a freezing rain advisory just to our north at higher elevations in a few select counties. I suppose that's good news; we don't need ice.
There is some very interesting information in these comments.
Comment by Brandon R. — January 5, 2009 @ 5:33 pm
Correct me if I'm mistaken, but don't some of the biggest snowstorms on record (at least for us)
tend to happen in late February and the first two weeks of March. I'm reminded of the '93 and '96
storms plus that crazy snowy winter in the late 1970's.
Comment by Love NRV — January 5, 2009 @ 7:32 pm
The '93 storm was March 13 ... but the biggest storm in '96 was Jan. 6-7. Large snows over history dot the calendar from November to March, even April in 1987. Our region's largest snowfall month, historically, is February. There are some late-season atmospheric dynamics that sometimes that can lend themselves to quick, large dumps of wet snow. (March '93 was really a different species altogether, a once-in-a-lifetime "superstorm" setup that pulled below-zero temperatures all the way to Alabama a week before spring)
Comment by kevinmyatt — January 5, 2009 @ 9:24 pm
It appears the wedge is starting to come in. Winds from the NE, dropping dew points, lowering temps, etc.
I'd say we get down to about 36 or so.
Comment by Brandon R. — January 5, 2009 @ 10:06 pm
My temp has dropped 8 degrees in the past hour and a half.
I'm at 36. Same temp is being reported at VWCC.
Comment by Brandon R. — January 6, 2009 @ 4:53 am
I'm hovering at 33 degrees right now with light drizzle. Looks like some of this moisture is being forced southward; could that high pressure be a bit stronger than expected?
Comment by Brandon R. — January 6, 2009 @ 5:46 am
I think this is about what was expected. We've probably about bottomed out in temperature.
Comment by kevinmyatt — January 6, 2009 @ 9:38 am
Temp here went below 32 around 6:45 a.m. Still at 29, with light icing on trees, porch railing, etc.
Comment by Julie — January 6, 2009 @ 10:24 am