nrgjeff
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If any science is behind it, I submit the amplified weather pattern in general. Also could get the warm sector storms followed by cold sector snow. If separated by a week. probably two separate troughs in an amped up pattern. Makes some sense. Plains versions is tornadoes and snow, lol!
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December 2018 Pattern And Forecast Discussion
nrgjeff replied to AMZ8990's topic in Tennessee Valley
First I enjoy reading the Obs thread for the past weekend storm. Thanks for letting us who were blanked live vicariously, lol! This weekend (Dec 15 ish) looks elevation only. Models blank the Plateau, but Upper Plateau snow is possible back side. Models have snow in the Mountains based on both the ULL and upslope behind. System looks like a loser at lower elevations. It is stacked and getting barotropic. Prefer baroclinic with a deepening surface low, which is not shown. This will be my last post about Dec 15 if nothing changes. Meanwhile it looks like a colder pattern will try to rebuild starting around Christmas; however, surface effects may be after Christmas. Could be a cold New Year. For now the warm period looks a little longer than I'd thought, 10-14 days vs 5-7 days. Does not seem like a deal killer for more cold later. MJO is just in a warm phase, which will pass. Models have more signs of Alaska ridging and other blocking by Christmas. Again it might take until the New Year reflect on the surface in the Southeast. While I may sound pretty meh about upcoming storms, I am still optimistic about January. Cold pattern on top of cold climo is friendly if one likes snow. -
Winter 'Tis the Season Banter Thread 2018-2019
nrgjeff replied to Carvers Gap's topic in Tennessee Valley
The simple take on the downsloping: it matters most when temps are borderline. Downsloping can kill the deal at 35. At 28 it will not matter. At 32 the forecasting gets challenging. Blunderstorm post just above (packed with science) might fit in the Storm Discussion thread. Always good to keep discussing the storm. Congratulations Tennessee defeating Gonzaga on a neutral court! Sure Kansas is happy about it, should be #1 - unless we get penalized for close games. I just love a good game and I cheer for the Vols. Very fun watching Tennessee hit clutch 3s when it matters! -
Bye bye severe wx season.
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December 2018 Pattern And Forecast Discussion
nrgjeff replied to AMZ8990's topic in Tennessee Valley
Low press is a beast all levels. @Carvers Gap maybe stacked low? Anyway it does look like something from the Plains, or a Nor'easter. We'll see how it goes in the Ohio Valley. -
December 2018 Pattern And Forecast Discussion
nrgjeff replied to AMZ8990's topic in Tennessee Valley
Yes that Dec. 14-15 storm looks quite elevation dependent now. Probably too warm Valleys, maybe warmer than this weekend. Are you looking for TROWAL, comma head, or another one? I got plenty of names for it in Chattanooga, but I should not write them on the forum, lol! Seriously, about the path to higher elevation snow, yes dynamic cooling method works better Plateau/Mountains. Fails Valleys if surface temps mid-30s. Anyway the current event looked better a week out than the 14/15 event looks now. Current event still looks better (north of course) so good luck to all! -
The ECMWF, ICON, and GFS-Para all halted the poor overnight trends. Preliminary only: I'm going 1-3 inches from northwest TN, across KY/TN border and 1-2 counties each side. Upper Plateau (Tenn) Southeast KY into TRI could get 2-6 inches but the temp profile still, could be less could be much more. Southwest VA 4-8 inches seems reasonable. Of course the mountains will be hammered; 10-15 seems reasonable, esp NC side. It really is about elevation, as usual before Dec. 15. Likely be a little ice during transition(s) to snow. Some risk of wet snow on top of ice. However it does not look awful, nor like a snow show stopper (where it snows). This is my last forecast post of the event, with a busy weekend at home, but I will keep reading. Good luck to All! I really think it'll turn out OK despite the NAM and GFS-Op.
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Ditto Friday morning in East Brainerd @Chattownsnow and @Jed33 a few pings of sleet on car; otherwise, light rain. Morning @Holston_River_Rambler thanks for the 2014 and 2015 memories! OK the forecast. Tough to sugar coat the ECMWF and ICON overnight. Oh but they do still have powdered sugar, snow at/north of I-40. Lower QPF is one problem which impacts another problem, less cooling of the column. Silver lining is a little farther south vort max. Only in the South could that improvement actually hurt the low levels. As others have written, it could still work out. Precip shield could verify north of progged. I am not as concerned about ice as some. Low levels are a bit warm. In some areas (West KY, Northwest Tenn) 850/925 mb drops below freezing before the surface, no ice. Many areas they are close, which is only a little ice. Global NWP shows some 0 surface,+2 aloft, ice northeast Tenn. However short-term high-res NWP has 850/925 colder faster; so, maybe not much ice. Still early to bank on high-res at 36 hr but my gut does not feel so much ice. Added: Now just a few inches of wet snow on top of .10" ice would be an issue. Normally I do not get concerned below .25" ice, but wet snow is forecast too. Thinking out loud, while I'm not expecting much ice to ruin the snow show where it snows, trees might be a little stressed. Southwest Virginia very likely will get snow. One can relax a bit up there regardless of models. Could be my last quality post, but we will see what 12Z data brings. Hvward is too high Tenn. Hvward is usually money in NC though, very good forecaster. I might take a stab at amounts later. If chasing snow, I'd try to get into a NC ski area. Not sure if they are opening but it'll be pretty!
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December 2018 Pattern And Forecast Discussion
nrgjeff replied to AMZ8990's topic in Tennessee Valley
Overnight NWP wants to kick the Dec 14 system north. Yup it does wrap around a comma head west half to 2/3 of sub-forum region, plus higher elevations (Plateau and Mountains). Easy all rain forecast for Chattanooga though. Still a week out, but verbatim looks like the Midwest/OV benefits from some sort of phase. Again this is the December 14th event. -
ECMWF has been a little south of American guidance (NAM/GFS Para) for a few runs. This happened in KCMO right after Thanksgiving. While I trust the Euro more 36+ hours out, at 30 hours they were still pretty different and I was leaning NAM. Finally at 24 hours the NAM caved to the Euro. ECMWF scored what I'd say was a significant coup. I'm not saying it'll happen again, but I do like the discussion about the models. In fact this is likely the one of the best all-time threads. Lots of real-time data discussion has entered the mix which sweetens the deal even more. I'm still optimistic for northwest Tennessee, southern Kentucky, and northeast Tenn. Higher elevations look best. TRI looks better for snow than it did 24 hours ago.
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Winter 'Tis the Season Banter Thread 2018-2019
nrgjeff replied to Carvers Gap's topic in Tennessee Valley
University of Kansas snags another SEC coach. Les Miles hires Chip Lindsey from Auburn. Miles received a very warm welcome at a home basketball game. KU is excited about football too! In other news I'm way behind on the Dec. 8-10 storm thread. My thoughts have not changed and line up well with NWS offices along the route. I will read and post in the next 24 hours. Cheers! -
ECMWF Euro monthlies came out with a cold 500 mb pattern. Monthlies released on Wednesday. Jan. Feb. March all look similar with AN heights over Western Canada and at times Central Canada. The latter scours out some source region with Chinook wind. However they all show BN heights over the Southeast US. Main question is cold air connection. Can the Southeast get really cold? Clusters break down mainly into three camps each month. Typically one cluster is classic cold. One is the orange Canada blob; unsettled and cool here, but not particularly cold. Please, just say no to cold rain! Third cluster has AN heights over Bermuda skimming the US East Coast, but not SER hard-core. Cold solutions are out there. I believe some weeks will be classic cold. Then we have the El Nino blah weeks, and of course a few mild weeks. With the El Nino CAVEATs and questions, such as cold air in place and mild interludes, I still like a slightly colder than normal winter. Psychology of the mid-December warm-spell can discourage, at least until Day 15 starts looking colder. However the background state and trends have been cold.
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December 2018 Pattern And Forecast Discussion
nrgjeff replied to AMZ8990's topic in Tennessee Valley
ECMWF has the second storm around Dec 14. No high press north; but, Euro dynamically cools the column. Euro shows a more vigorous 500 mb trough and deeper surface low. I would not trust any of that past day 7; but, FWIW the GFS concurs. -
First two weeks of January show up on the European weekly charts. Looks cold. Here are some thoughts. 1. Blocking signal is strong for weeks 5-6. Normally one expects 50 ensemble members to scatter. This issue the clusters are similar and with lots of blocking. Does not guarantee verification, and short mild interludes are quite possible. However it interests me. 2. AN precip is limited to the Deep South / Gulf Coast. It may be wrong in the moist pattern to-date, but I hope it is right. Snow holds much lower moisture; so, BN precip is OK for snow. Do not want dry NW flow BN. However with rain Deep South, one can infer snow Mid South. Speculation only as the thread title shows, lol!
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Education and Questions/Discussion Regarding Weather Features
nrgjeff replied to EastKnox's topic in Tennessee Valley
I promised some TROWAL explanation on the Dec 8-10 storm thread. Trough of Warm air Aloft stands for TROWAL. It often happens behind an occluded front/system. One can easily find cross section diagrams of an occlusion with a web search. However these two images show what I'm looking for when forecasting. Here it is on satellite, an old storm over the Great Plains. Bring it baby! On an 850 mb chart (also 925/700) one can see WAA from the north, vs usual southeast. Average comma head is associated with the cold conveyor belt, and some split off the warm conveyor belt. Usually the better precip is off the more robust warm conveyor belt. (Conveyor belts are also an easy web search.) TROWAL feature is interesting because it can amp up the normally secondary comma head. WAA is notable into the comma head. Example below is ECMWF forecast valid Monday. Most of the snow has fallen, but the 850 mb chart shows it better at the end of the event. Note WAA from north to south. Favors I-40 north. CAA south of I-40 shuts off precip.
