John1122 Posted December 16, 2022 Share Posted December 16, 2022 I love looking back on these threads to see what went right or wrong. So I'm glad it's here. I feel like it'll be Tuesday before we have the right idea or something close, on this one. I will say this, I was reading the CPC talking about model biases and model verification. It noted that the GFS scored much better in what they called "extreme events" and I believe this qualifies. It also noted that all models had a North precip shield being to dry bias West of the Appalachians. Something we've discussed on here for years. 5 Link to comment Share on other sites More sharing options...
Silas Lang Posted December 17, 2022 Share Posted December 17, 2022 1 hour ago, John1122 said: I love looking back on these threads to see what went right or wrong. So I'm glad it's here. I feel like it'll be Tuesday before we have the right idea or something close, on this one. I will say this, I was reading the CPC talking about model biases and model verification. It noted that the GFS scored much better in what they called "extreme events" and I believe this qualifies. It also noted that all models had a North precip shield being to dry bias West of the Appalachians. Something we've discussed on here for years. Agreed on having the thread. Boom or bust, it is nice to have to reference. Besides, not like we get many shots some years. May as well enjoy what we get...or don't get! 4 Link to comment Share on other sites More sharing options...
PowellVolz Posted December 17, 2022 Share Posted December 17, 2022 I just read a post, maybe even by you, from the March storm as it approached, that the Euro had just completely caved to the GFS. That said, this one is still early in the game regarding the storm. Extreme cold seems nearly unavoidable but it would be tempered with snow vs without snow. There's still very often major model disagreement inside 90 hours over the last few years.I mentioned something about that earlier today from March. I also remember the GFS was really close in the 7-10 day range, kinda lost it or started jumping around for 48 hours and then it settled back in with what it was showing in the 7-10 day frame. I don’t remember much about the CMC but the Euro was pretty wild until about 4 days out when it came to the GFS. Both mods made minor adjustments inside d5 but they pretty well settled in enough that we knew a storm in the south was likely. . 2 Link to comment Share on other sites More sharing options...
fountainguy97 Posted December 17, 2022 Share Posted December 17, 2022 Icon with a big shift to GFS. Single digits and heavy NW flow for most of TN. Meanwhile GFS making a tick toward euro at 500mb so far. We may end up with one of these weird in between systems after all 2 Link to comment Share on other sites More sharing options...
John1122 Posted December 17, 2022 Share Posted December 17, 2022 Beautiful pass by the GFS. ICON trended towards it as well. Still 72 hours before we can get a better idea what might happen. 1 Link to comment Share on other sites More sharing options...
Silas Lang Posted December 17, 2022 Share Posted December 17, 2022 Less cutting and more coastal this go around 2 Link to comment Share on other sites More sharing options...
Wurbus Posted December 17, 2022 Author Share Posted December 17, 2022 Canadian doesn't have the snow, but the cold is insane. At 144 Knoxville is sitting at 55 and at 150 we are down to 14! Not to mention -10 to -15 wind chills. Link to comment Share on other sites More sharing options...
Daniel Boone Posted December 17, 2022 Share Posted December 17, 2022 2 minutes ago, Wurbus said: Canadian doesn't have the snow, but the cold is insane. At 144 Knoxville is sitting at 55 and at 150 we are down to 14! Not to mention -10 to -15 wind chills. Yeah, it continues the cutter idea. Hopefully it's wrong. Link to comment Share on other sites More sharing options...
Daniel Boone Posted December 17, 2022 Share Posted December 17, 2022 11 minutes ago, John1122 said: Beautiful pass by the GFS. ICON trended towards it as well. Still 72 hours before we can get a better idea what might happen. Yeah, kind of puts you in mind of a couple of the systems in the winter of 95-96. Link to comment Share on other sites More sharing options...
John1122 Posted December 17, 2022 Share Posted December 17, 2022 The Canadian would be an extremely rare storm. Models show that look of a low retrograding to the WNW on occasion but it almost never happened. I've seen it modeled several times over the years and none of them verified. The Great Appalachian Storm of 1950 did that. And maybe one of the 70s blizzards. They are extremely rare. 3 Link to comment Share on other sites More sharing options...
Daniel Boone Posted December 17, 2022 Share Posted December 17, 2022 Just now, John1122 said: The Canadian would be an extremely rare storm. Models show that look of a low retrograding to the WNW on occasion but it almost never happened. I've seen it modeled several times over the years and none of them verified. The Great Appalachian Storm of 1950 did that. And maybe one of the 70s blizzards. They are extremely rare. Exactly Odds are against that for sure. 1 Link to comment Share on other sites More sharing options...
John1122 Posted December 17, 2022 Share Posted December 17, 2022 The Canadian was more snowy than its 12z run across the area. But because of it's crazy evolution it shows Lake Effect from every direction on every lake at some point and you get lots of 2-4 foot totals around them all. 1 Link to comment Share on other sites More sharing options...
Daniel Boone Posted December 17, 2022 Share Posted December 17, 2022 3 minutes ago, John1122 said: The Canadian was more snowy than its 12z run across the area. But because of it's crazy evolution it shows Lake Effect from every direction on every lake at some point and you get lots of 2-4 foot totals around them all. Yeah, it's confused, lol 2 1 Link to comment Share on other sites More sharing options...
John1122 Posted December 17, 2022 Share Posted December 17, 2022 GEFS basically in line with its OP. Nice snow mean across the area. 1.5 to 4ish at 10:1. Would be slightly higher with a ratio map. 3 Link to comment Share on other sites More sharing options...
John1122 Posted December 17, 2022 Share Posted December 17, 2022 Euro is a no go again. Extreme cold front with virtually no moisture behind it, nothing more. Something will give one way or another over the next few days. The GFS is locked in, the Icon moved toward it. The Canadian is locked in and the Euro now is two runs in a row. Eventually it'll all come to a head. The energy for this storm has been over Siberia and is now probably in the northern Pacific. 1 Link to comment Share on other sites More sharing options...
John1122 Posted December 17, 2022 Share Posted December 17, 2022 No idea if it will mean anything for this event, but the Euro was completely lost on the December 2020 Christmas even snow event as little as 36-48 hours out. The GEFS was rock steady except for maybe one off run in the 36 hours out time frame, the GFS spotted the event first at hour 228 and was steady until it waffled some inside 48 hours. The Euro was all over the place, showed almost every possible outcome. The UKIE kept missing the area completely. The NAM suite was all over the place and the RGEM was steady and eventually very close to correct as well. The RGEM was initially who correctly modeled the snow showers that lasted into Christmas day that added 1-2 inches for many in the area. 24 hours out the Euro finally got close to the actual final solution and the GFS returned from it's 24 hours MIA. I'll also note that in the thread about the December 20202 event I noted the prior year the Euro had also been led by the GFS on a potent cold front/anafrontal snow situation. None of that may apply here but it shows you how much modeling chaos there potentially is remaining in this event at this distance. 2 Link to comment Share on other sites More sharing options...
Carvers Gap Posted December 17, 2022 Share Posted December 17, 2022 Having the ICON climb on board gets me back to 55/45 it is going to happen as the GFS has it. I think the Euro is playing into some old biases. @Holston_River_Rambler, what are you doing up so early? As for me, we had a carbon monoxide detector battery go bad. The periodic beep was driving us crazy. LOL. We have been wondering through the house for about fifteen minutes trying to find which detector was bad. As any good wx hobby person would do, I sat down and looked at modeling instead of going back to bed. 3 1 Link to comment Share on other sites More sharing options...
Carvers Gap Posted December 17, 2022 Share Posted December 17, 2022 Something to consider, the 0z EPS is much different over the Aleutians d10-15. It is much warmer than other modeling in the LR. Its 500mb pattern over the continental US/Canada looks similar to other modeling, but the strength of that low is causing very warm temp anomalies. I can't find that on other models, especially over the eastern US. It makes me wonder if there is an issue w/ the model in the northwest Pacific. It seems like it is stalling systems in error. Link to comment Share on other sites More sharing options...
Holston_River_Rambler Posted December 17, 2022 Share Posted December 17, 2022 @Carvers Gap trying to go back to sleep on a friend’s couch in Boone lol. But it was 445 and of course I had to see how the Euro went down after everyone was saying the Icon made a move towards the GFS. 1 Link to comment Share on other sites More sharing options...
Carvers Gap Posted December 17, 2022 Share Posted December 17, 2022 At 135, the GFS has a slp in the eastern Panhandle. Got think that is gonna make some sparks here in a few. 1 Link to comment Share on other sites More sharing options...
Carvers Gap Posted December 17, 2022 Share Posted December 17, 2022 The 6z GFS still goes w/ a powerful Noreaster. It does pop a low over Erie, so it does see the potential for a more westward solution. At one point it has a low was of Detroit, one over maybe PA, and one off the SE coast. There is more snow in Ohio on that run which tells me more energy was held back west of the Apps. I think that is a reasonable run as wonky as it was. The Euro seems too wound up. It makes sense to pop a coastal or a slp in the GOM(which this GFS run has) due to the strength of the front. The 500vort map definitely had a more shallow run over the TN Valley. Link to comment Share on other sites More sharing options...
Carvers Gap Posted December 17, 2022 Share Posted December 17, 2022 The 6z GFS, as did the CMC about a day later, has a slider which would give light snow to nearly everyone in the forum area after the 23rd/24th system. I have the discussion for it in the pattern thread so as to keep the two systems separate for now. We can slide it over here when needed. Hopefully, that means that the northern stream is going to be active similar to 14-15. 1 Link to comment Share on other sites More sharing options...
Kasper Posted December 17, 2022 Share Posted December 17, 2022 Well, well, well what do we have here! Nothing to see here folks, just Kasper taking a peek in your window 1 Link to comment Share on other sites More sharing options...
fountainguy97 Posted December 17, 2022 Share Posted December 17, 2022 Yet another event we have to kick the can down the road for. Been doing it since thanksgiving. EURO obviously going to win this match. Link to comment Share on other sites More sharing options...
jaxjagman Posted December 17, 2022 Share Posted December 17, 2022 National Weather Service Nashville TN 518 AM CST Sat Dec 17 2022 ...New AVIATION... .SHORT TERM... (Today through Sunday night) Issued at 201 AM CST Sat Dec 17 2022 Satellite imagery this morning shows some scattered low clouds across our east but shrinking in coverage with time, and most of the area is now clear with temps in the 30s. Clouds clearing out along with dewpoints in the 20s should allow lows to drop into the upper 20s by sunrise. Even colder weather is expected this weekend with highs only in the 30s/40s and lows in the low to mid 20s later today through Sunday night. && .LONG TERM... (Monday through next Saturday) Issued at 201 AM CST Sat Dec 17 2022 Warming trend begins on Monday as flow aloft becomes more southwesterly. Light rain will spread across MS/AL/GA just to our south from Monday into Tuesday as a shortwave trough travels eastward along the Gulf Coast. Have kept our forecast dry, but some sprinkles are possible in our far southern counties. Forecast from Wednesday onward continues to be difficult due to significant differences amongst the main global models, and how far southeast an initial surge of Arctic air will make it on Wednesday. Overall, 00Z guidance shows a large and very intense upper trough digging southward into the Gulf Coast states from Wednesday into Thursday, with strengthening WAA ahead of the trough causing light rain to develop areawide Wednesday night into Thursday. As the Arctic cold front races through the area Thursday afternoon/evening, rain rapidly changes to light snow from west to east, with snow continuing into early Friday before ending. Although models generally agree with this scenario, 00Z GFS continues to show some of next week`s Arctic airmass oozing down into our northwest counties as early as Wednesday morning, with the Arctic air remaining in place into Thursday as the main surge pushes through. This would cause precip to be ice/snow much longer than than the considerably warmer ECMWF, which keeps the Arctic air well off to our northwest until Thursday afternoon/evening. Regardless, both models and NBM have trended wetter so have bumped up pops and snow accums accordingly for the Thursday/Thursday night timeframe. Even if the current forecast snow amounts are too high, any ice or snow accumulation combined with the expected cold temperatures would create hazardous travel conditions. Bitterly cold and dry conditions are expected to continue through the holiday weekend, with lows in the single digits and teens and highs only in the 20s through at least Christmas Day. Temperatures could be even colder than currently shown if we get substantial snow cover. Wind chills will also fall as low as 10 below zero at times, which would be well into our wind chill advisory criteria if it pans out. 1 Link to comment Share on other sites More sharing options...
matt9697 Posted December 17, 2022 Share Posted December 17, 2022 35 minutes ago, jaxjagman said: National Weather Service Nashville TN 518 AM CST Sat Dec 17 2022 ...New AVIATION... .SHORT TERM... (Today through Sunday night) Issued at 201 AM CST Sat Dec 17 2022 Satellite imagery this morning shows some scattered low clouds across our east but shrinking in coverage with time, and most of the area is now clear with temps in the 30s. Clouds clearing out along with dewpoints in the 20s should allow lows to drop into the upper 20s by sunrise. Even colder weather is expected this weekend with highs only in the 30s/40s and lows in the low to mid 20s later today through Sunday night. && .LONG TERM... (Monday through next Saturday) Issued at 201 AM CST Sat Dec 17 2022 Warming trend begins on Monday as flow aloft becomes more southwesterly. Light rain will spread across MS/AL/GA just to our south from Monday into Tuesday as a shortwave trough travels eastward along the Gulf Coast. Have kept our forecast dry, but some sprinkles are possible in our far southern counties. Forecast from Wednesday onward continues to be difficult due to significant differences amongst the main global models, and how far southeast an initial surge of Arctic air will make it on Wednesday. Overall, 00Z guidance shows a large and very intense upper trough digging southward into the Gulf Coast states from Wednesday into Thursday, with strengthening WAA ahead of the trough causing light rain to develop areawide Wednesday night into Thursday. As the Arctic cold front races through the area Thursday afternoon/evening, rain rapidly changes to light snow from west to east, with snow continuing into early Friday before ending. Although models generally agree with this scenario, 00Z GFS continues to show some of next week`s Arctic airmass oozing down into our northwest counties as early as Wednesday morning, with the Arctic air remaining in place into Thursday as the main surge pushes through. This would cause precip to be ice/snow much longer than than the considerably warmer ECMWF, which keeps the Arctic air well off to our northwest until Thursday afternoon/evening. Regardless, both models and NBM have trended wetter so have bumped up pops and snow accums accordingly for the Thursday/Thursday night timeframe. Even if the current forecast snow amounts are too high, any ice or snow accumulation combined with the expected cold temperatures would create hazardous travel conditions. Bitterly cold and dry conditions are expected to continue through the holiday weekend, with lows in the single digits and teens and highs only in the 20s through at least Christmas Day. Temperatures could be even colder than currently shown if we get substantial snow cover. Wind chills will also fall as low as 10 below zero at times, which would be well into our wind chill advisory criteria if it pans out. Interesting to see such transparency in the morning discussion. 1 Link to comment Share on other sites More sharing options...
tnweathernut Posted December 17, 2022 Share Posted December 17, 2022 1 hour ago, matt9697 said: Interesting to see such transparency in the morning discussion. Agree. Here in east TN, the Morristown NWS office at times has to see the snow falling before making the type of statement Nashville made. lol Complicated evolution coming up. Northern stream systems are notorious to throw wrenches in things, especially when there’s the potential of a phase and especially when there is a handoff of energy to occur. Probably wise for Nashville to at least mention it. As they say, the coming cold will be so sudden, even a small amount of snow/ice could prove to be a problem in such a populated area as Nashville. There have been SO many move to that area, it wouldn’t surprise me if that factored in to the decision to make the statement. 2 Link to comment Share on other sites More sharing options...
Reb Posted December 17, 2022 Share Posted December 17, 2022 GFS caving this run to the dreaded cutter it appears Link to comment Share on other sites More sharing options...
Daniel Boone Posted December 17, 2022 Share Posted December 17, 2022 2 minutes ago, Reb said: GFS caving this run to the dreaded cutter it appears Not surprising, unfortunately. Hopefully, the cold will crash and still produce a measurable snowfall on backside. Link to comment Share on other sites More sharing options...
PowellVolz Posted December 17, 2022 Share Posted December 17, 2022 Going to be a lot of back and forth until we get to around Tuesday. Will be interesting to see what that first NAM run looks like also. . 1 Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now