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nrgjeff

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  1. nrgjeff
    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.
  2. nrgjeff
    Northwest Tennessee, Kentucky, Tri Cities Tenn, and southwest Virginia have a decent chance of snow. Nashville, Clarksvile and Knoxville need a miracle. I'd take MEM-HSV-CHA off the table. Middle Kentucky has the trickiest path with the warm nose. West Kentucky and northwest Tennessee benefit on the northwest side. East Kentucky is at a higher elevation. Tri Cities into Virginia are closer to the coldest air from the north, but the warm nose will make a run up the Valley. High pressure HP is strong but lacks very cold air. Unfortunately for points south, HP is strongest east of the Apps. Needed strongest HP west of Apps. Also 500/700 mb lows are at/north of US-72 which takes it out of snow consideration. Areas that receive snow will likely start as rain. TROWAL feature on some models may help snow on back side (north/favored only). TROWAL is basically a good comma head. Precip is enhanced by WAA from the warm nose into colder core on the back side. TROWAL would only benefit north/favored side of Region. TROWAL post coming in Education thread.. Northern third of our Region still has many challenges; however, it remains in the game for snow. I'm thinking northwest Tenn, Kentucky, TRI, Virginia.
  3. nrgjeff
    Agree the northern Stream will probably determine the outcome. Southern stream with surface low south looks good. Exact track of PVA is still up in the air, and that 75-100 miles is crucial. Northern stream will influence both the PVA and the cold air. Sure the southern stream will influence PVA too; but, I think the northern stream will be most crucial here. European weeklies are cold. Mid-December warm period now looks only about 5 days long vs 7-10. Week of Dec. 17 is now shown slightly cool here. I figure it will take a couple cold fronts to fully cool off though. The big GOA trough responsible for the mild 5 days will also scour the cold supply. However by Dec. 24 the new AK ridge will have been in place several days, replenishing cold air supply. So I like the gradual step slightly BN temps Dec. 17 week (perhaps still near normal). Then go more solidly BN temps Dec. 24 week. January starts pretty cold too. If week 5-6 is right, then things could finally get interesting here in January.
  4. nrgjeff
    Welcome to our Region @Drummer230 hope you like Tennessee! Clarksville is full of Southern Discomfort (snow heart break). Still it is on the better side of our Region. Mid South mauler might drag a warm nose into BNA; however, Clarksville could still eek out snow. If northwest Tennessee and western Kentucky are in a snow band, it can clip Clarksville. Good luck!
  5. nrgjeff
    The question is age old in the South. True that textbook HP is fair weather. However we do need a supply of low level CAA for snow. At the same time we need WAA aloft to create the precip. It is a delicate dance anywhere. In the South it's a delicate dance on a tight rope that often results in a fall, lol! Sometimes 500 mb offers the answer. PVA just south, with surface low farther south (a good tilt) and cold air in place, usually good. PVA at latitude / overhead, risk of ice if cold air in place. PVA north, probably rain. EDIT for below: I did not realize Knoxville climo has shifted so much. Yuck!
  6. nrgjeff
    12Z Monday runs have trended toward climo. I-40 north including Kentucky is reasonable this time of year. No sugar coating it for HSV-CHA. It is like watching prevent defense give up 300 yards. Still Day 6 so it could change. However the US-72 corridor needs a much colder solution in the next 24-36 hours. Day 5 in models will start moving less. Like Carvers said (page 9) it remains something to watch even if it looks more local than regional. Still days out too. If this one fails it is not a biggie so early in the season. I'd rather lose in December than in February, whether we are talking snow or college basketball. Heck even in Kansas I did not expect real snow until January. Yes I checked CAPE on a couple 12Z products. Gulf Coast MCS closes that door too. Weeklies come out in a few hours.
  7. nrgjeff
    Great post Flash! If the storm fails, either the pool option or drive a nice car off a cliff, LOL! Oh the ICON, make that a German luxury car. Flash is being straight forward, frank, and brutally honest here. Great analysis. Temp profile has problems. Main cause is lack of really cold air north. I do think if the 500 low really goes south it will be at least a little colder here. Note the GFS Para/FV3 has been colder than the Op. However the 500 mb rule still must be met. ECMWF has made perfect sense, regardless of track; temp profile and 500 mb track line up. Even the better models runs start as rain. Cold air comes in as winds back to the north and with the comma head. Agree that method risks failure in the South. Nashville suffers from what I believe is under-rated downslope off the Plateau. Many on this sub-forum will attest to it. Chattanooga definitely has a downslope issue off the Apps. We simply must have cold air well anchored with continued low-level CAA.
  8. nrgjeff

    ENSO

    nrgjeff replied to jaxjagman's topic in Tennessee Valley

    I remain bullish, slightly cold, for winter. Current El Nino is moderate, but it's only a snapshot. Two of the last three weak/mdt El Ninos briefly spiked strong before trailing off. Those were 2002-03 and 2009-10 both cold winters. Most recent weak-mdt El Nino 2014-15 stayed below moderate; it was also a cold winter. November verified cold eastern half to 2/3 of USA. It looks similar to 2014, but that year was colder to the East Coast. This year remember the cutter systems? Snow fans of course want that to end. Anyway 2014-15 was the last snow thump in Chattanooga. I'm quite comfortable with ENSO at the moment.
  9. nrgjeff
    Looking for a couple things this morning, still 6 days out. Need vort max to track south of here. Need high press (HP) north anchored and still spilling in somewhat. I am less worried about the surface low which looks good. First the 500 mb vort max should track to our south for snow. Right overhead is not good enough, especially this case. If HP is very strong, anchoring cold, and the vort max goes overhead, WAA may cause ice. That's like in Ferris Bueller where faking a fever lands you in the doctor's office. Wrong outcome, lol! Next HP has to be firmly anchored in the right place, and even still building in. Agree 100% with John's snapshot above. Also I'm looking for HP/cold to keep spilling in from the Plains and Midwest. Down the East Coast won't work here, though the Carolinas love it. You can almost feel the right pattern on the good model runs; isobars and thickness lines are packed tight - all wound up and energetic. Reverse is true on bad model runs with HP already starting to retreat with loose isobars/thickness lines. HP must anchor very firmly, especially this case. Midwest / OV air is not particularly cold or dry, so evaporative cooling will only be a slight help. Again HP/cold still spilling in (not retreating) would make it all work out. I mention the surface low pressure (LP) looks good. LP has been shown well south consistently across model runs (NWP). I would call it safely south, from a pro-snow perspective. In conclusion, the concern is the temperature profile. Gee, what's new down South? 500 mb vort max should be south to take care of the mid-levels. HP should firmly hold, and continue to supply low level cold. Both will depend on confluence (of the jet branches) location and timing, per previous page. Quick check: 500 mb vort max and surface HP look & feel. Finally, I think somebody in the sub-forum Region will get it. Odds are best I-40 north IMO. Perhaps even Kentucky, but NWP verbatim is I-40. Most of my pessimism / nit-picking is to get it into MSL-HSV-CHA, always a huge chore.
  10. nrgjeff
    I agree. December name change to Pattern Discussion or even Forecast thread would ease confusion with the other Speculation title thread. Original Winter Speculation from July could either be closed, or continued as Long-Range. I'm thinking Jan/Feb (now) or months 2-3 at any time, based on a current month Forecast thread going. Winter Spec is already rightfully evolving that direction. Finally, my Sunday post with points 1-4 I forgot 5: Thunder now, snow next week. In Illinois and Kansas* it is tornadoes now, snow next week. *Kansas did not have tornadoes this time, but OK did. I can remember past years tornado, snow in KS though.
  11. nrgjeff
    Monday edits in bold. Few quick thoughts in case work load shuts me out of the Board Monday. This is a rare Sunday post. Here is my take on 12Z data. 1. GFS Para (FV3) is closer to that ECMWF run which slams MEM to CHA. Watching vort max track south and high press staying very firm north. No wavering! 2. ICON I infer is warmer most areas, less favorable esp south. Just one model and this is way out at its end at 180 hr. 3. Still a week out. I expect more shifts south; then, shifts back north. No idea where that ends up. 4. I have no reason to get hopes up yet this far south (CHA) but I'm interested and watching. I-40 still has better odds based on climo. 5. Yes the thunder then snow rule might verify. We laugh, but it has some meteorological reasoning. Both require amplified long-wave troughs, meridonal vs zonal flow. Discussion in this thread is exemplary. Hopefully this builds up into a real event for most of us!
  12. nrgjeff
    Warm one-eyed pig continues to be delayed. Confidence is high it will happen; but, it is looking less like the monster it did before. I'll give it 7-10 days in mid-December. @Carvers Gap analog post is reasonable. Dateline convection is already trying to regenerate (cold signal), which would start to battle with the (warmer signal) convection farther east. MJO forecast is a mess, because the actual convection is in two clusters. Also, the AK ridge has been stubborn. AK troughs have tended to be transient. More broadly, even when it is not Alaska, other areas of blocking remain forecast in the Arctic and near Arctic. Finally, surface press is AN in much of the Arctic. My gut thinks the atmosphere is just cold for parts of the US this year. My only hard spot is little interest in storm tracking in the immediate future. During cold/stormy periods, NWP does not show cold air in place at the right times. However that could change esp a week out. Then the warm period comes through. After that it will be the heart of winter. Hopefully around the Holidays or shortly after things will get interesting. Wishing for snow.
  13. nrgjeff
    GOES-16 eye candy never gets old! Yes @Holston_River_Rambler cold hanged in the Valley. I might call it more cold air drainage from SW Virginia. Sometimes light winds will let it drain without warming on the way down. Happens going into Portland, OR (and other Pac NW) sometimes with high press anchoring the cold. We had a high press anchor Wednesday night here. In other cases the Plateau can act like a (micro-scale) cold air dam. Precipitation event a few years back (and others) the west side of the Great Valley was below freezing while temps on the east side got above freezing. One could almost call that in-situ, as HP was nowhere to be found in another cold rain day for Chattanooga. Still the Carolinas are the king of CAD on the meso-scale, bigger than our micro. They can have it. Much as I complain about cold rain, I'll take it over ice 1,000 times. If it's not a snow temp profile, punt.
  14. nrgjeff
    Saturday afternoon events Middle Tennessee and points west might luck out if rain can get out before events start. John I hope the Christmas parade works out. I've lost interest in thunderstorms; so, I will hope for fair weather. Appears severe starts Friday in the Ozarks; even more LOL with early sunset. Saturday dynamics seem to drift north of instability; so, rain here should be fairly benign. Rain timing should be in the morning many areas, including Mid-Tenn. Might still be afternoon showers in East Tenn. GFS is slower (wetter for Mid-Tenn) but ECMWF and NAM both push out the rain in time.
  15. nrgjeff
    Yes I presume it is Bays Mountain. Effect might be more concentrated with a more westerly component, narrow more intense band. NW wind spreads it out and it is lighter. The more westerly the wind, less perpendicular to the mountain, the more it can line up and converge well at the end of the mountain. If it were ever cold enough on southwest winds (unlikely with WAA) an intense band would set up flowing to the northeast. Again, it is just a hypothetical. Meteorology around here rarely if ever would support the scenario. IDK, anyone in Kingsport see something like that? I find Kingsport vs JC quite interesting in a wide range of cases, from these micro-scale events to the synoptic scale. Kingsport and JC behave differently on the front and back side of synoptic systems. I'm not sure which would mess with my head more, Kingsport gets the early start, but risks early shut-off. JC has to wait, nerve racking, but usually gets it eventually. Chattanooga is easy. Just forecast rain, lol!
  16. nrgjeff
    Keep calm, and listen to that chain as the roller coaster takes the cars up the hill. Guess that is not really a calming sound, lol! Anyway I'm going roller coaster December. I do not believe 4 weeks of torch. First it looks warm this weekend. Next week cold should verify. Transition timing is up in the air even more after 12Z runs, but it'll get cold next week. Fewer Deep South lows are shown, little disappointing, but we have discussed December is generally not our month for snow anyway. Middle of December looks warm for a couple reasons. Cold dropping into the West is a SER signal. We have a Kelvin wave trying to come out into a warm zone. Ensembles and weeklies pick up on the warm signal. Now I doubt the warm will last as long as weeklies predict. Yet another dateline flare-up is starting; and, it could be a cool signal. If it becomes another tropical storm or typhoon, it would strengthen the cold signal here. This late in the season the tropical cyclone does not need to be strong. Just needs to merge up with the jet stream off Asia. Two have done so ahead of and during current cold. Back to the weeklies, though majority warm, they have cold clusters starting as early as before Christmas. Cold clusters increase (still minority) Christmas week. I would not be surprised if the cold clusters become majority Christmas week. Then, the trend would be a friend. Will December overall verify AN or BN temps? Looks variable averaging near normal first 3 full weeks. That last week starting around Christmas may determine the outcome. Regardless, plenty of cold Oct/Novie and warm December have been cold Jan/Feb. This snow lover has no concerns attm. UPDATE: Forgot to mention, I love the one-eyed pig. Huge LOL!
  17. nrgjeff
    Wake convergence appears to be the driver. Drag of the mountain causes low level winds to slow next to it; keep ambient wind speed farther off to the sides. So the winds try to curve around the mountain and meet up in the wake. The meeting causes low level convergence. Viola! Snow. Bernoulli Effect could add to the curve around, with the speed-up phenomenon occurring just outside the friction zone. At any rate, I also remember seeing this last year. Enjoy!
  18. nrgjeff
    It is that time of year! Using my Kansas City, Country Club Plaza, Christmas Lights picture! Took my daughter to see them for her very first time this Thanksgiving. We also saw the Mayor's Christmas Tree lighting at Crown Center, which is close to the Plaza. The said area of KCMO is like Buckhead, Lennox, Phipps in Atlanta. I can't afford to shop there but I love the lights! We also saw Union Station KCMO which was my first time too! Major revitalization was about 10 years ago when I was down in Texas. The Plaza is my favorite though because it is my childhood now shared with my own daughter. She liked the tree lighting at Crown Center. After the long drive both felt like 2 cyclical tornadoes in May. Well, it is kind of apples and oranges, lol! Agree with others the UT/KU game the Refs were too involved. Seeing Williams and Azubuike (Doke nickname) finish OT would have been special. On the other hand, despite his excellent FG%, Doke can't shoot free-throws so we might have sat him at the end anyway. KU is lucky to have back-up not recovering from injury in Lawson. @Greyhound those seats are amazing! Kansas will and should be number one thanks to a more robust schedule to-date compared to Gonzaga. The Zags are for real this year, but Kansas has the resume to-date. Chattanooga has Rock City and Kansas City has the Plaza. Frankly I think both beat Buckhead in ATL.
  19. nrgjeff
    ECMWF remains consistent with a chance of severe weather Friday night and Saturday from the Mid-South to the eastern Tennessee Valley. Many details need to work out from instability to short-wave timing. Looks like multiple waves, which can giveth or taketh away. I infer from the text SPC really wants to outlook Saturday, but I agree it would be hard to place the 15%. Too early to worry for those who dislike severe. Just those of us who like it, we want to track it. Honestly, at Day 6, it is not any more likely than snow in Dixie, lol! PS.. I will comment on December after the ECMWF weeklies update. Maybe I should have stayed with Carver for Dec. Did I go cold too fast?
  20. nrgjeff
    I was in KCMO for Thanksgiving and enjoyed tracking the storm. Interesting that at 30 hours the ECMWF just schooled the NAM. I joke about the latter choking 36-48 hours out, but it should beat the Euro and GFS inside 36 hours. NAM finally caught on farther south by 24 hours out. Euro was first to sniff out the vort max keeping south. NWS did a great job going Blizzard Warning. Plains pattern recognition promotes doing so with a tight vigorous vort max and deepening surface low press. Then, how about some thunder snow? Little busy with family to post or look deeply, but I was following it. For safety we departed Saturday evening before it started, so I missed the real fun. Wish the blizzard had been a day earlier.
  21. nrgjeff
    Kansas gave me a little scare; actually, Marquette gave us a little scare. Second half KU took care of business. Tennessee game was good too, a little more defense. Auburn played Duke well, held up better than Kentucky. Then Gonzaga took down Duke? Really! Anyway Tennessee and Kansas meet on Friday. It's happening! If the cold pattern survives the long weekend I will have much more to say on the weather threads. Enjoy all the long- weekend sports! Happy Thanksgiving everybody! Safe travels if you do so.
  22. nrgjeff
    ECMWF Euro weeklies remain cold most weeks. CFS is gradually succumbing. Resistance is futile. Let the power of the dark cold side flow through. Happy for a Thanksgiving mild break, especially for Chattanooga's Holiday Cheer at the Pier Friday, much better and far more rewarding than shopping! Otherwise looks cold through early December. Mid-December the Euro weeklies show a mild break, which lines up with the EPS MJO forecast (at Day 14) so FWIW. Euro weeklies are cold again by week 6 (week 5 EIA Fri-Thu weeks) or about December 20. The mild mid-Dec and cold end matches that 1969 analog. Parts of the region had a white Christmas in 1969, but I don't want to get too carried away. Still fun enough that I've mentioned it in two threads now, lol! November is starting to remind me of cold years where the blocking just kept on giving more cold. We'll see, but this is a statistically favorable pattern to be in early if one likes winter.
  23. nrgjeff
    In a nutshell, Anthony is cold. Some of the threads are confusing, because he addresses multiple issues. His secondary line is that this is not SSW and is driven by the Troposphere. However that does not take away from his cold forecast. Sometimes I wonder if he is vague on purpose. It's a fire hose even for another Met, lol! He is sharp as they get though.
  24. nrgjeff
    Coworker used to have a Les Miles quotes calendar. I need to find one for 2019. Chiefs and Rams had a high scoring college type game. Regrettably the Chiefs could not beat both the Rams and the Refs at the same time. Tough assignment, but Mahomes almost prevailed! Finally good luck to both Tennessee and Kansas in the NIT Tip Off. Hope we meet!
  25. nrgjeff
    In addition to 500 mb blocking I like to look at surface pressure anomalies in the Northern Hemisphere. Started in a buffet line of bashing the SSAI which I still think is a bad tool all by itself. However the SSAI keeps coming back like Cousin Eddie. I believe a holistic (whole) look helps. Is Siberian snow due to a zonal active storm track (mild) or associated with cold air in place early and often (cold)? Note I do not claim any causation, but correlation can be useful. Forum has hit the 500 mb blocking pretty well. In addition surface press has been AN in much of the high latitudes. For cold I would also look for more BN surface press in China and the Lower 48 USA. However, the high latitude signal is there. Gin up some storms in China and the USA, and the surface press means may work out. In other news I have heard 1969 come up as an analog. I have no opinion there, but it was a white Christmas in parts of Tenn.
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