It's Friday! An all important weekend of outdoor fun awaits.
Whether it's the Ceredo-Kenova Autumnfest, Halloweast in Charleston, Harvest Fest at Fort Randolph, the Marshall home game, etc.-- there's a lot of outdoor activities where everyone wants the summer-like weather we've been having to continue right on through. Well, it isn't.
There is good news about this weekend though, because our big-deal storm set-up is not until later. We are still going to get colder temperatures and scattered showers, but it will be manageable.
|NHC - Surface Map - Saturday AM|
Though the front itself approaches the Ohio River by sunset on Friday, the showers are mostly behind the front, and not out ahead of it. This is a testament to how the dropping temperatures will be the main force squeezing moisture out of the air, rather than the front itself. By the same token, the actual coverage and intensity of the showers will only be scattered-- making the cooling weather the important thing to plan ahead for.
|NAM - Friday PM||NAM - Saturday PM|
The showers are fractured during the day, and the best juice misses us to the north. Eventually, the front just stalls out anyway, because cold air push doesn't get along with Sandy's movement through the Bermuda Triangle. Here's how it looks for temperatures in the region:
|GFS - Max Temps - Friday||GFS - Max Temps - Saturday||GFS - Max Temps - Sunday|
The 50s make it quickly to the mountains, creating a greater than 20-degree drop in temperature from Friday to Saturday. But they can't get over the hump, and places east of the Appalachians start to be influenced more by Sandy than this front. Scattered light showers will also hang around into Sunday as well because of the stalling.
Turning our attention to the new "Perfect Storm"
In the last 24 hours, the computer models have converged on a relatively consistent solution and held it. Amazingly enough, this particular solution is closer to the rare "perfect storm" kind of thing-- with a side-order of the 1950 Thanksgiving storm. Feel free to review the blog post from yesterday to see how the options were playing out.
Here's the recent model runs demonstrating the relative consensus, with a few deviations in time and placement:
|GFS - Wednesday PM||CMC - Tuesday AM||Euro - Tuesday AM|
Yes, there are differences, but in the day 4-5 range this is the sort of accuracy we're looking for. NOT the exact placement of the low, NOT how much snow we'll be seeing, but rather the flavor of how it's going to go-- removing other drastically different meteorological scenarios. Hopefully this is the one we'll stick with, because it takes a long time to cut into deeper layers of the onion, and it's nice to just have one storm scenario to look at. No one wants to see a "Day 5" forecast of "Chance of rain/snow/sleet/hail/sunshine with highs anywhere between 30-70" :-)
There are a number of very interesting and significant aspects to this forecast, and since we've got several blog posts between now and the main event, I'll try to break it up into various parts and save you the hassle of trying to read it all in one huge post. However, if you have any questions/comments, please let me know.
The most important part of this forecast for our area that will determine snowfall prospects is also the crazies: Whatever we do, we need to be on the south side of the system. That's not normal-- but it's true in rare circumstances. When you have an extremely strong system (like as depicted in the models above), the wrap-around windflow is so persistent that it can take cold air from the north, and curl it all the way around and underneath the low-- and even bring it right back up the east side of the system. At the same time, the warm air, instead of just hanging around the south side, gets pulled up around the east.
|Normal Storm System||Crazy Storm System|
This is how it's possible to get the coldest air arriving on southerly winds, and the warmest air coming in on northerly winds. It's exactly backwards, but it makes sense when you're talking about a giant rarity like this set-up. In the Thanksgiving Day Blizzard of 1950, temperatures in Charleston were in the single digits with blinding snow, but in Buffalo, NY they had 50 degree temperatures (and 50-mph winds). We're not talking about that magnitude with this storm, but we are talking about a scenario in which the air will be colder in the Tri-State than it will be in the ski-country mountains of northern New England, Canada, and all the rest.
Current Snowfall Prospects...
As it stands right now (and trust me, things can still change markedly, so don't go Gospel on this)...The first hints of a change-over to snow will occur in the eastern WV mountains as early as Monday morning...
|NCEP - Precipitation Type - Early Monday|
This is because the cold air inflow behind the front-- the culprit responsible for our scattered light showers Saturday and Sunday, will simply continue to work. Eventually we'll get to flakes in the higher elevations. This is not heavy stuff-- but quite a novelty at any rate. It's worth pointing out that nowhere else in the eastern US will be seeing flakes at this time.
|NCEP - Precipitation Type - Tuesday Afternoon
As the stalled-out weakened front continues to be hung up in the Appalachians, the higher elevations will keep on getting those misty flakes, scattered about during the day Monday and even into Tuesday. By Tuesday afternoon however, we'll start to work in the new arrival of deeper moisture courtesy of "Sandy", which by then will have transitioned into a mean "post-tropical" system and made a turn toward the Mid-Atlantic/New England coasts. The combination of the ambient northerly airflow supplied by the first system, and the new shot-in-the-arm from Sandy's circulation, will generate even colder air over the WV mountains, bringing temperatures at the 850mb level below -2°C (here, and nowhere else). This is the magic number for accumulating snows in winter time, but I usually like something higher in the fall (like -5°C) because you still have to overcome the warm ground temperatures. The mountains will not suffer as much for this, so if snowfall hasn't started sticking in the high-country by then, it should start Tuesday afternoon. Late Tuesday would also represent the first opportunity for folks off the mountains (like the I-79 corridor) to see flakes fly.
|NCEP - Precipitation Type - Wednesday Afternoon|
By Wednesday, the remnants of "Sandy" should be fully merged into one "Frankenstorm" (as they're starting to call it) of a system, and will be nearly stationary somewhere between the Mid-Atlantic States and New England. This puts us squarely underneath the storm, and also as the beneficiary of the continued influx of cold arctic air wrapping into it. Even though the temperatures at the 850mb level are more marginal at this time, the extra influence of wind-chill may well get some flakes to mix in as far west as the River Cities area. As far as accumulations go, it still looks like the mountains are the best target for this (and naturally so).
It is not time to be talking about anticipated accumulations for our region-- we still have a lot of time for this. It's important to describe the long-evolving nature of the storm, the fact that it's going to be around for a while, and its ability to drastically drop our temperatures. This has the makings of the first sightings of snowflakes for many (not all) of us. Overall, it still looks to be a light event, with the novelty of flakes being the main 'winter' experience we're shooting for. However, in the mountains east of Charleston (and especially up by Canaan Valley), it is completely within reason to expect the shovels to come out!
Please feel free to comment and/or ask questions below. This is a complex storm system, and one that still has days to go before it materializes. Keep that in mind as we go forward-- and enjoy this last day in the 70s :-)
Update (4:00pm) - In another amazing turn, the National Weather Service has issued a "Winter Storm Watch" for Pocahontas, Webster, and Randolph counties in the West Virginia Mountains, for this upcoming storm. The first flakes won't even fly until late Sunday night (as in the above map), but I guess all the chatter about "Frankenstorm" is too juicy to not get caught up in it. Nevertheless, I think that the potential does exist for such accumulations (they're citing the possibilities of 8"- 10" of accumulation out that way between then and Tuesday night) in a range of scenarios and storm tracks. I wouldn't stop there though, I would also be issuing a Watch for Preston and Tucker counties, and to a lesser extent Nicholas county. The threat is indeed there for accumulations closer to a foot(!) of snow near Canaan Valley-- but, it's simply not "good form", in my opinion, to go there until we get a little closer and a little clearer. There are still a wide range of what could happen with this thing. One thing that just keeps jumping out at me is that our WV mountains appear to lead the way in snowfall US-wide in nearly every current storm track scenario.
Update (6:00pm) - The front has now crossed the River Cities area on its way to the east. From here on out, the temperatures will keep dropping, and those 70s and 80s will drift out of sight, perhaps the 80s not to return until next spring. You should notice the breezes (it'll look like it's "raining leaves"). They may not stop until Thursday... As temperatures continue to cool, we'll then get the showers, as that particular feature is driven by the cold blast of air wringing out the clouds overhead, a little bit at a time with each falling degree.
|Regional Radar/Satellite with Warnings Tracking||
From the Storm Prediction Center (below): Click For a Larger Image
|Activity Overview||Storm Outlook||Watches||Potential Watches||Storm Reports|
|Temperatures||HD Doppler Radar||Estimated Rainfall||Active Warnings|
|Click For Larger||Click For Interactive Radar||Click For Larger||Click For Larger|
Have a great day everyone!