Another ice/snow risk Thurs PM/Fri AM
Continued best wishes for recovery to WSET (Channel 13) web producer/meteorologist Jamey Singleton and two others injured in a traffic accident Tuesday in Bedford County.
We’re getting something of a booster shot of Arctic air, with highs Wednesday in the 30s to low 40s after lows mostly in the 20s amid breezy northwest winds that have prompted wind advisories. It will warm up just a bit — mostly 40s, maybe a few low 50s — during the day Thursday, before another head-scratching winter weather situation develops Thursday night.
One rule of weather is that if back-to-back weather situations seem almost alike, they usually won’t be. In other words, don’t be fighting the last battle with the new storm system. Once again, we have a low approaching that will track somewhere northwest of us, spreading Gulf of Mexico moisture into and over colder, drier air at the surface,sort of like Tuesday morning’s system that left some slushy snow in areas west of Roanoke but didn’t really live up to even a rather understated billing as a winter weather maker. At first look, though, the storm approaching late Thursday and early Friday appears to have more cold air wedging in to work with and at least somewhat more moisture. The Hydrometeorological Prediction Center — skeptical, to its credit, of our chances of widespread significant snow or ice on Tuesday morning — has already painted our region with 50+ percent chances for getting at least .01 inch of ice (even spreading into much of western North Carolina) AND a 20-30 percent chances of getting an inch of snow (or snow and sleet, as this would more likely be) in the 24 hours ending Friday evening. There is a also a sliver of slight risk for heavy ice — .25 inch or more — in part of the New River Valley and along the I-77 corridor. Eventually, just like on Tuesday morning, most areas will likely go over to plain rain on Friday — though cold air may be stubborn enough to hang on in some colder valleys longer in the day this time around.
While no prolonged Arctic air appears to be in the offing, there is some interest in the Feb. 28-March 2 period, when there are indications that northern and southern branches of the jet stream may phase somewhere east of the Mississippi River for a possible deep low-pressure system and large-scale winter storm. Something to keep an eye on in the long run as this odd winter 2012-13 slides into March.
February 19, 2013 - 8:02 PM
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I’m back. So sorry to hear about Jamey Singleton and even more about the two unfortunate other men. I hope that everyone survives and recovers. Thanks, wd and KM for the praise on the first thread today; my thinking was that the southerly winds at the surface would prevent/delay enough of a temp drop in the floor of the Roanoke valley. And to say the least, I was not only due, but overdue. I have made a lot more wrong predictions on this blog than correct ones. And the person who gets the A+ is Doppler Carol, who confided to me privately last night that she thought that there would be nothing but rain in Roanoke city, which seems to have verified 100%. Nice going, Doppler Gal!!
Run-on comment to keep the number of comments down. I have forgotten who it was last year who came up with the following terrific expression, but I thought of it today. I was delivering near the end of my route when suddenly a big gust of wind came “out of nowhere” and completely blew over empty trash barrels about 2:30. The wind kicked up “like an angry mule!!” I hope whoever first said it comes forward to accept my TYVM!! I think it was someone from the NRV.
Great to hear from you two, Leo Lady and HokieTrax! :>)
About the missing comments on blog threads — those comments have not disappeared from the system, they merely do not display. It appears that each time a blog post reaches 50 comments it rolls over and starts again at 1. Technicians are working on the problem. One problem got solved today, I can wrap text around graphics again. Hopefully this one is corrected soon, too.
Thank you, Kevin. And I have a question for you. From my limited understanding of the oscillations and the polar view stuff, this weekend looks like a dream come true for snow lovers here. Yet the outlook is very iffy at “best” for them. Items: The NAO outlooks continue to show a nosedive. The AO is already quite negative and will drop for another couple of days before starting to rise, albeit still in quite neg territory. The PNA is slightly + and is outlooked to become VERY POSITIVE, which is usually a helpful thing in getting a trough in the East.
There is a fairly strong 50-50 low still in the Newfoundland area. There is greenish air still up near Iceland, just a little bit east of it. I haven’t seen so many hopeful signs in ages, but the details in the continental USA are not cooperating for our long-suffering snow lovers. Why?
Looking at the 500 mb map below projected for Sunday on 12Z Euro,
http://raleighwx.americanwx.com/models/euro/12zeuro500mbHGHTNH120.gif
I woud note:
(1) NAO- is east-based, the green colors poking up toward Iceland, not over Greenland, and
(2) Coldest air is shown on the other side of the pole, so that may be where the core of Arctic air slips with AO-
That said …. there may be that window around the first of March for a larger storm to form.
Time for an early night (for me). Will check back in Wed. AM.
I like the new format. While this winter has been quirky, I’ll take 3 of these winters in a row over the one we had last year which was just pathetic! Except for January 3rd and February 19th of course.
Is there any chance the next system could bring decent snow chances?
Not much chance, Kevin. Lows passing to the northwest spreading warm, moist Gulf of Mexico air on top of cold air at the surface almost always end up as ice or rain, unless the cold air damming is exceptional. In this case, it’s middling … not weak, but not extraordinarily strong.
Not too surprisingly given the setup … HPC has shifted the 1-inch snow chances northward this morning, but increased our region’s ice chances.
http://www.hpc.ncep.noaa.gov/pwpf_24hr/prb_24hsnow_ge01_2013022012f048.gif
http://www.hpc.ncep.noaa.gov/pwpf_24hr/prb_24hicez_ge.01_2013022012f048.gif
http://www.hpc.ncep.noaa.gov/pwpf_24hr/prb_24hicez_ge.01_2013022012f072.gif
http://www.hpc.ncep.noaa.gov/wwd/day2_pice_gt_25.gif
I really dislike ice! I hope we can get more cold air damming in place before this event occurs! The one good thing is that we now have a generator, because when I think of ice, I think of the power going out. And if we have 0.25 inches of ice, I think the Roanoke Valley will be in a world of hurt! I can only imagine how many people would lose power if that verifies.
A quarter-inch of ice is usually about where the widespread power outages and tree limb damage begins. The “major” ice storm stuff with thousands losing power for days is usually when you get to about a half inch or more of ice.
Of course, an ice storm is “major” to you if your power goes out, regardless of the numbers. Most folks who watch the weather have an idea of the threshhold where their power is likely to go out.
Factors that I think will keep this from being a widespread major ice storm in Southwest Virginia, except maybe in a few pockets:
(1) Sleet. There should be a fair amount of it early on. The more sleet (and some snow) falls, the less moisture will be freezing rain.
(2) Warming. Eventually most areas will go above freezing at the surface on Friday morning, turning freezing rain to rain. And even with temperatures right at 32, not everything that falls freezes instantly. Some of it runs off before it can freeze.
(3) Limited moisture. Not as limited as Tuesday, but it doesn’t appear more than a half inch of liquid is likely to fall anywhere, and noted in 1 and 2 above, not all of it is likely to be freezing rain.
safe to say that travel from riner,va to lebanon, va will be safe friday evening since we’ll be getting above freezing?
Kevin, thanks very much for replying to my long question last night. I had noticed that the thumb of the polar vortex had retreated from Michigan in the past few days, but had not noticed that the core of the vortex had also gone onto the other side of the North Pole. I think your explanation about the negative AO affecting the Siberian/Russian/ (Eastern European?) side explains a lot of why a big snowstorm for us is not in the cards for this weekend. And I had forgotten briefly (what a shock! Me forgetting something?) that blocks need to be near Greenland, not Iceland. And of course I do not have access to a future polar view.
I am glad I am not working today. Quite chilly out there, and especially for anyone who has to be outside most or all of the day.
Still one more question, but this one just about everyone will be interested in …. have your shingles cleared up completely yet? Or at least gotten much, much better?
Hey, I just had a great idea for the letter carriers on walking routes. In case we do get a lot of icing on sidewalks, outfit them with ice skates! I admit going up steps will be a challenge, as well as driving …. :>) :>)
I hope you’re right on this one Kevin! Ice becomes problematic for everyone, very quickly. You won’t often hear me say I’d rather have rain than wintery “stuff”, but if it’s rain or ice, I’ll take the rain LOL
Here is a rare explanation of weather radar. It is specifically for an aircraft, but the principles apply to all Wx radar. Scroll about halfway down this guide and you will find an interesting technique for locating bad thunderstorms – looking for the shadow behind the storm rather than the reflection from the front. NEXRAD ground based radars have so much power that we don’t often see shadows.
http://code7700.com/radar.html
Scott: The whole region should rise above freezing Friday afternoon, moving from southwest to northeast.
Doug: Some of those teleconnections you mention do look to start March somewhat colder than normal, with some storm systems moving through from time to time. I think the “winter is over” refrain we’ve been hearing will prove to be untrue, again, though that’s far short of a guarantee that we’ll see a large snow event.
I know not to close the book on winter until late March, and only then when the pattern looks favorable for long-lasting warmth. Since moving here, I’ve seen enough bouts of wintry weather and cold later in the spring that always give me pause. So before the calendar hits mid-March, I always know there is a possibility.
As for tomorrow’s system, if we won;t see snow, let the temperatures stay above freezing and just let a cold rain fall. I just don’t like the possibility of ice on the roads…
@Doug G.
Doug, all joking aside, Dick’s sells an ice cleat that goes over your shoe/boot called Yaktrax for about 30 bucks. I don’t own a pair but looks like they could be a real charm for a letter carrier.
I will own a pair before my next winter hike to the Cascades.
Scott, I just watched Leo H on WDBJ7, and their model does show a warm-up during midday Friday, but a resurgence of wintry mix (especially for ROA and points NE, so maybe it won’t affect the NRV) in late afternoon Friday and early evening. I was surprised by that, and hopefully later runs will eliminate that outlook.
And folks down in Carroll and Grayson Counties, be particularly watchful and aware. His model showed your counties as being most likely to get pre-dawn and early morning mix. Which could be ice. I am sure that the NWS and Kevin and Quags and joe and lots of others will be all over this during the next 36 hours.
One other thing: looking back, not only was Doppler Carol all over (as in “very correct”) yesterday morning’s forecast for Roanoke city, but so was The Weather Channel. Twice during late Monday I looked at the hourly forecast on weather,com for 24017 zip, and both times it showed temps never falling below 37*. I dismissed it as another badly wrong (and optimistic from my POV) forecast by them, so did not mention it here, but it nailed the forecast big time.
Polar view has just been updated to today, and sure enough, the core of the strongest vortex is in the Eastern Hemisphere. And the most recent 50-50 low, with no block to hold it there, is also migrating eastward, well south of Greenland. There is another tiny area of slightly colder air in SE Ontario, SW Quebec, upstate New York, and northern New England, but it is not even bright blue in color. Will probably also move east over the next couple of days.
Looks like a moderate trough in the West, a ridge in the central US, and a very weak trough in the NE.
Models have flirted off and on with a second wave of precipitation Friday night into Saturday. Was leaning away from it, but it appears Channel 7′s model may be bringing it back. Will take a closer look at it later today when I get a chance.
Kevin,
I’ve been one your blog’s biggest fans for years but it seems I remember many times over the years that when the NWS calls for temperatures to rise above freezing after the onset of precip, the wedge effects seem stubborn to break down and let the warm air nose in. I know its true at my location primarily due to elevation because decending only 500 feet in less than a mile creates warmer precip types. Is this something you’ve noticed and is the NWS just trying to cover all the bases?
Merle: It’s very situation and topography dependent. On Tuesday morning, for instance, exactly the opposite happened, and temperatures climbed above freezing before precipitation began in most locations. The elevation factors get confusing because there are certain situations where low valleys hang onto the cold longer and others where higher elevations are colder. This situation does not look to be like Tuesday, though, with temperatures warming into the 40s and 50s, but only struggling upward into the 30s. The wedge will not break so much as modify. if enough ice is laid down at the outset, that can help keep temperatures down in some locations for a while longer.
Models have indeed trended significantly west with the second slug of moisture Friday night into Saturday. This could provide a nervously close situation for substantial ice in at least some of our region, with temperatures expected to be hanging in the 30s.
No, no ice! I’m like Dopp Carol – ready to find a fork or maybe one of those long BBQ grill forks or skewers and poke this winter done. I like winter and snow but I’m really done with all the back and forth business. Already thinking of the beach.
Thanks Kevin. I do remember times where we never got above freezing as it was forecast but the temps never fell much either. They pretty much remained steady through the entire event.
Yeah, I don’t see anyone liking the weather Friday-Saturday. Ice and cold rain don’t excite snow or spring fans. We don’t even need the rain anymore for the drought.
I know winter is far from over. After living here for nearly 20 years, one comes to realize that March and April are particularly mean months for SW VA.
However, one must not discount the feel of spring around the corner. Longer day light, more direct sunlight, and the buds on the trees are really starting to swell.
The change of the seasons is always a weird/remarkable time. Just think 3-4 weeks from now most of us will be mowing grass and looking at blooms on forcythia and on pears. Fall is just as eerie as one week leaves are on trees, the next everything is bare.
Either way, I hope we get enough cold weather in March to prevent any premature start to spring growth.
A golf tournament got suspended today for snowfall — in Tuscon, Arizona. Reports of thundersnow and “graupel” around Phoenix now.
This is the atmospheric energy that makes the central US storm go boom tomorrow with amazing amounts of snowfall on extreme drought regions — on the whole, a welcome sight, short-term hardships notwithstanding. I talked to ranchers in Kansas last May who will definitely be happy about their snowstorm.
Nate: There are some large signs that we will NOT have a runaway greening in early-mid March like in some previous years. Spring is right around the corner, but it’s a pretty large, dark, cold corner.
Speaking of March, is SW Virginia ever LOOOOONNNNNGGGG OVERDUE for a cold one.Most recent year that ROA was even a little cooler than normal was way back 8 years ago, 2005! It was 3.1 degrees colder than normal. March 2007 was exceptionally warm, a +6.0, followed by the killing frosts around April 9th. And last year was really ridiculous, one of the highest variance months since 2000, an eye-popping +10.1 (mean temp was 57.4, which is almost what April normal mean temp is). But just like with a hitter in baseball, just because an entity is “due” doesn’t mean that he/it will get a hit. But I have a feeling that this will be the streak-breaker, and that we will get a cooler than normal March.
So what you’re saying Kevin is that March looks to be a cold, wet one? Or possibly the potential for lots of borderline situations? Finally! I mean, I’d like to start playing tennis and golf again but I’m tired of these Marches where everything blooms early and gets very warm. It’s not good for my allergies either. If I recall correctly, the last dank March we had was March 2008 I believe. That was a strange month with a few borderline winter weather situations. March 2007 was blast furnace. March 2009 might’ve been normal. March 2010 was normal I think until warmth “from hell” came in April 2010, March 2011 was a roller coaster with 80s one day and a few moderate busted snow chances, and last March was horribly warm.
Kevin, comment 32. Or maybe spring will also be a “white” corner, too ….
Haha I will hold your word for it Doug! WOW! Did not know March 2012 was that warm and a LOT warmer than March 2007 which is surprising! Doug, isn’t March 2008 slightly below average? I remember spring 2008 being an odd one because…well, it was just remarkably normal! Had some rain and lots of normal temps in April too! It was one of the normal springs…so rare nowadays when we have 80s in March too frequently! Or sometimes snow in April!
I will discuss it a little in my upcoming post, very soon, but early March, at least, does appear very likely to begin with a blocking pattern that will favor colder than normal temperatures in our region and a possible southern jet stream track.
I’d also like to stick a fork in it like Doppler Carol and HokieTrax but wouldn’t want a repeat of last year when I think the absence of a “normal” seasonal rhythm was disruptive for nature. Lost more than half of our hives late last year and I think the weird weather pattern was partly to blame especially the early snow and cold temps last fall. My asparagus came up really early so that was really nice but I remember noticing a unusually high number of insects/bugs last spring and my cool weather crops took the hit especially the spinach. I still have some key transplanting to do and need some cold March weather in the mix so I am with Nate on this. Looking forward to a timely annual burst of color from the forsythias to start it all off and the warm weather.
Nick, I will reply to your Q on this thread, rather than using up a comment on the current one. March 2008 was warmer than normal for both Bburg and ROA. 2.6 degrees warmer than normal in Bbg, +2.2 in ROA. It was a month with some quick turnarounds in temps. In Hokieburg, for example, it was 11 degrees wtn (“warmer than normal”) on the 19th, a +8 on the 22nd, but 6, 9, and 8 degrees ctn on the next 3 days. Then 9, 9, and 10 degrees wtn on the 26th – 28th!! Ten different dates, but 8 of them were at least 6 degrees “variant” from normal. One day folks have got only a sweater on, then the cold weather gear, then back to the sweaters only.
BTW, Nicko, guess who also predicted that March 2012 was going to be colder than normal, because the NAO was overdue to become negative?? Easily my WORST PREDICTION ever. Probably the worst prediction ever on this blog by anyone. ……. that takes skill …… :>) :>) :>) :>)
I cant believe WSLS just put a forecast up showing sun for the next few days not showing anything about the ICE