April 2-3 Severe Weather Threat

Our first organized severe-weather threat of the season is shaping up later this week, particularly Friday.  You want details?  Here they are!

I’ll emphasize in print what I said in the video…we’re still more than 48 hours from the greatest severe potential around here.  Plenty of time for things to change!  We’ll keep you posted on-air, online, and on social media (yes, I know that social media is online as well, but the sentence flows better when the “rule of three” is observed).

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Social media links

Twitter: @WSMVweather, @PaulHeggenWSMV, @WSMVLisaSpencer, @WSMVDanThomas, @WSMVNancyVanC, @NWSNashville

Facebook: 4WARN Weather, Paul Heggen WSMV, Lisa Spencer, Dan Thomas WSMV, Nancy Van Camp WSMV, NWS Nashville

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UPDATE: March 4-5 Winter Storm

Some new info for you…and hopefully some clearer explanations.

3:45pm UPDATE: NWS-Nashville has slightly altered their changeover-time graphic, to the point where there’s now no appreciable difference between this and what I said in the video:
image_full16

Also, the latest model data has been trending in a more snow-y and less sleet-y direction, especially for Nashville and the surrounding counties.  I have a strong suspicion that this is a computer-model trend and not a reality trend, but let’s hope for the best.  (Snow is better than sleet.)  The latest SREF and RPM model output shows the same pattern outlined by in the video, but with a slight southeastward shift:
SREF_Mar4
RPM_Mar4

Anyway, my overall thinking remains unchanged: this looks like a sleet machine, with more snow to the northwest of Nashville.  The best possible way for this to change (at this point) is for the models to be right and for snow to take over quickly.  If I’m wrong, I’d LOVE to be wrong in this manner.  (Except for the fact that I would owe Dan Thomas an apology, which would be more humbling than a public perp walk.)

Any more big(-ish) changes, I’ll post an update on Twitter or Facebook.  I will, at some point, sleep as well.  I hope.  Of course we’ll have you covered on TV as well — on our regularly-scheduled newscasts this evening, and I’ll be back on TV tomorrow morning beginning an hour early at 3am…it will still be sleeting and snowing across most of the Midstate at that point.

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Social media links

Twitter: @WSMVweather, @PaulHeggenWSMV, @WSMVLisaSpencer, @WSMVDanThomas, @WSMVNancyVanC, @NWSNashville

Facebook: 4WARN Weather, Paul Heggen WSMV, Lisa Spencer, Dan Thomas WSMV, Nancy Van Camp WSMV, NWS Nashville

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Rain then Sleet then Snow — March 4-5

A couple of “hey, I should have said [whatever]” additions to the video below:

1) The ranges of potential sleet and snow I outline in the ice/snow forecast accumulation graphic within the video (helpfully titled “SNOW & ICE FORECAST”) don’t represent our best-case/worst-case scenarios…rather, they’re the range of likeliest outcomes.  Basically, it’s the middle slice of the bell curve representing how this storm will evolve.  There are better-case scenarios than what I talk about, and believe it or not, there are worse-case scenarios.  But what I’ve outlined is bad enough.

2) Just to make sure everyone is clear on the distinction between sleet and freezing rain: freezing rain is the ice that develops on elevated surfaces (like trees and power lines).  Sleet is frozen raindrops — the ice pellets that accumulate on the ground.  Freezing rain causes power outages, sleet causes travel problems.  1″ of sleet is about as unpleasant to drive through as 4″ of snow, if you’re looking for a rule of thumb.

Anyway.  Video time!

11:30am UPDATE: Naturally, as soon as I posted the video, NWS-Nashville adjusted their timing slightly (closer to what I outlined in the video)…
Mar4_transition

…and they issued a graphic highlighting the potential for freezing rain accumulations in southern Middle Tennessee.  0.25″ isn’t enough for major problems, but it bears watching.
Mar4_advisory

Our accumulation forecasts are really very similar — the one difference is that they combine the sleet and snow accumulations into one forecast number.  We haven’t done that, because sleet is a different thing…especially when you’re shoveling it.

I’ll post any updates, changes, additional NWS graphics, or random thoughts in this space as we head through the afternoon.  And of course we’ll have you covered on TV as well — our regularly-scheduled newscasts at noon and this evening, plus an extra hour starting at 3pm.  And I’ll be back on TV tomorrow morning…it will still be sleeting and snowing across most of the area at that point.

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Social media links

Twitter: @WSMVweather, @PaulHeggenWSMV, @WSMVLisaSpencer, @WSMVDanThomas, @WSMVNancyVanC, @NWSNashville

Facebook: 4WARN Weather, Paul Heggen WSMV, Lisa Spencer, Dan Thomas WSMV, Nancy Van Camp WSMV, NWS Nashville

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March 4-5 Winter Storm

As anticipated, there have been some changes to the forecast since yesterday…unfortunately, those changes don’t change the bottom line a whole lot: Wednesday night and Thursday morning are looking very messy in Middle Tennessee and southern Kentucky.  The exact nature and timing of that messiness are still subject to change…and yes, there’s still time for the forecast to change for the better.  As I say in the video, I’d LOVE to be wrong about this one.  Enjoy…

2:30pm UPDATE: Late this morning, NWS-Nashville trimmed the southernmost counties from the Flood Watch, so that map now looks like this:
Mar4_flood

The NWS is forecasting a faster transition (by a couple of hours, which is a fairly small but important difference considering the complexity of this system) from rain to sleet compared to what I outlined in the video.  For what it’s worth, having seen the early-afternoon model data, I stand by what I said in the video.  Regardless, here’s the National Weather Service’s version of transition times:
Mar4_transition

5:30pm UPDATE: The NWS has upgraded our Winter Storm Watch to a Winter Storm Warning for the northern half of the Midstate…
image_full9…and a Winter Weather Advisory for the south.
image_full7

Southern Kentucky and West Tennessee, you’re under a Winter Storm Warning as well.  Lincoln, Moore and Franklin counties are still under a Winter Storm Watch.  (Why those three counties?  No meteorological reason — it’s just because NWS-Huntsville issues the advisories there.)
ALL

The snow/sleet accumulation numbers from NWS-Nashville are roughly similar to what I’ve outlined in the video — a little higher in spots, but we’re much closer in our thinking than we were earlier today.  (Please note, these are combined snow and sleet accumulations.)
image_full3

Overall, things are coming into clearer focus compared to 24 hours ago…or even 12 hours ago.  This is looking like a major travel headache beginning already Wednesday evening and continuing through Thursday and even into Friday (temperatures will remain COLD, which will limit how much melting we can do).  I’ll emphasize it one more time: the later arrival time for the rain-to-sleet changeover gives us more time tomorrow to further narrow things down regarding timing and accumulations…but there’s also more time for the atmosphere to change its mind and do something completely off-the-wall.  Stay tuned!

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Social media links

Twitter: @WSMVweather, @PaulHeggenWSMV, @WSMVLisaSpencer, @WSMVDanThomas, @WSMVNancyVanC, @NWSNashville

Facebook: 4WARN Weather, Paul Heggen WSMV, Lisa Spencer, Dan Thomas WSMV, Nancy Van Camp WSMV, NWS Nashville

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March 4 Winter Storm

The bottom line at this point is that Wednesday and Wednesday night are looking very messy across Middle Tennessee and southern Kentucky…but there are still a lot of different ways for that messiness to unfold…and even a couple of ways for it to NOT be messy at all!  I outline some of those ways in the video, but keep in mind — we’re still about 48 hours away from the first changeover from rain to ice, so there WILL be forecast revisions.  We’ll keep you posted!

5pm UPDATE: Well, the computer model data is still all over the place.  One model gives us almost an inch of sleet and then several inches of snow, one model keeps most of the wintry stuff away from us almost completely.  Right now, I’d bet that the forecast trends in the “not-as-scary” direction, but the National Weather Service has already issued a Winter Storm Watch.
image_full8

Please note: while I’m passing along the information contained in their advisories, at this point I’m thinking we will get less than what the NWS is outlining.   By the time I’m on the air at 4am tomorrow, a couple of new batches of model data will be processed, and hopefully we’ll be building toward some kind of consensus.  For right now, I’d still view Wednesday as potentially a very messy day, especially in the evening and overnight.  But I’m more optimistic than I was this morning regarding our chances of seeing a lower-impact winter storm.  Like I said above the video, there WILL be forecast revisions…it’s inevitable with a complex setup like this.

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Social media links

Twitter: @WSMVweather, @PaulHeggenWSMV, @WSMVLisaSpencer, @WSMVDanThomas, @WSMVNancyVanC, @NWSNashville

Facebook: 4WARN Weather, Paul Heggen WSMV, Lisa Spencer, Dan Thomas WSMV, Nancy Van Camp WSMV, NWS Nashville

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February 25 Snow Update

As I said on Twitter this morning, this has been my inner monologue every time new forecast model data comes in:
direwolf

followed by:
bartletheadsmackgif.gif~c200

To say the least, it’s been a frustrating experience to try to pin down the details of what/where/when with this system.  Here’s my best effort…

12:30pm UPDATE: dry air over the Midstate is definitely eating away at the snow’s northward progress.  I’d bet on the later end of the arrival times outlined in the video.

3:30pm update: Even the “later” times in the arrival windows were too optimistic.  Monitoring the radar trends, NWS-Nashville has issued this graphic to outline the expected snow-start times…
Feb25_NWS-timing

Their updated snowfall estimate:
Feb25_NWS-snow
I still think those numbers are too high for Metro Nashville — I stand by the pattern I outlined in the video, with a sharper gradient between “a lot” (along the TN/AL line) and “nothing” in northwest Middle Tennessee and the western half of southern Kentucky.  As I’ve said in previous blog posts, I point out the difference between my forecast and NWS-Nashville not as a criticism of their work (we coordinate with and just genuinely LIKE the folks at NWS!) but as an example of how experienced forecasters can interpret the data in slightly different ways.

As I mentioned in the video, I’ll post any other updated NWS graphics in this space.  Stay tuned for more updates during our normal newscasts this evening.  I’ll be posting updates on social media as well until I go to bed (don’t even ask how early that is)…and then I’ll see you dark and early Thursday morning!

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Social media links

Twitter: @WSMVweather, @PaulHeggenWSMV, @WSMVLisaSpencer, @WSMVDanThomas, @WSMVNancyVanC, @NWSNashville

Facebook: 4WARN Weather, Paul Heggen WSMV, Lisa Spencer, Dan Thomas WSMV, Nancy Van Camp WSMV, NWS Nashville

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February 25 Snow Potential

Yes, we could see more snow tomorrow.  No, it’s not a guarantee.  You know the drill.  Things are trending in a snowier direction, but the #SnowDome has been rebuffing all challenges for four-plus years in Nashville.  Stay tuned for updates…

For what it’s worth, the European forecast model puts Metro Nashville right on the edge of the 1″ snowfall line…but it’s been trending northward with every new batch of data.  Since I recorded the video, a new version of the SREF model basically held serve, maintaining roughly the pattern and amounts I showed in the video.

UPDATE: NWS-Nashville has now issued a Winter Weather Advisory (for 1″+ of snow) and Winter Storm Warnings (for 3″+ of snow) for many counties in the Midstate…
image_full3

As always, some subtle differences between the NWS accumulation forecast and the one I included in the video, but they’re quite similar…
image_full8

Stay tuned for more updates during our normal newscasts this evening and tomorrow morning, and I’ll have an updated blog post posted by 10am (or thereabouts).  I’ll be posting a few updates on social media as well, as data trickles in…

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Social media links

Twitter: @WSMVweather, @PaulHeggenWSMV, @WSMVLisaSpencer, @WSMVDanThomas, @WSMVNancyVanC, @NWSNashville

Facebook: 4WARN Weather, Paul Heggen WSMV, Lisa Spencer, Dan Thomas WSMV, Nancy Van Camp WSMV, NWS Nashville

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