Holston_River_Rambler

https://ams.confex.com/ams/WAFNWP34BC/techprogram/paper_94815.htm

No sleet for me in Knoxville, but huge, fat rain drops with the leading edge. Some culvert near a local market already gushing water after maybe 20 minutes of this. Hoping for a clap or two of thunder tonight.

Euro a little more optimistic for East TN this morning with a widespread 3 - 4" over the next 10 days. 5 - 7" (isolated 8) for areas west of the Cumberland plateau, so still not so good for the overall watershed. Fortunately 10"+ amounts no longer showing up, but I guess some of that from several days ago has already fallen.

I feel like the RGEM did pretty well with the last slug of moisture and it looks quite a bit more widespread that the NAM this AM. Interestingly though, if it is right with the precip maximum, that would be a better place for it since there is a mini divide there. All water does go to the Gulf, but there it flows straight in from AL, instead of going through the TN to the Mississippi.

Always wondered what Rossby waves looked like; Kind of glad those suckers formed since it looks like they may be sucking up some of the moisture that may have been aimed at us otherwise.

Their graphic is still pretty aggressive though. I guess they are still factoring in later storms, but lowering the totals for the upcoming one.

Some additional thoughts about AAM from Isotherm (this isn't really a description, but the way he is using the features at least is helping me to try to understand it better): "I'd say it's fairly incontrovertible that the Pacific structure will be ameliorating, finally, as a function of the ewd propagation tropical convection and realignment of W/C forcing in more canonical orientation. Phase 8/1 entrance in a few days + 7-8 day lag, should elicit vicissitudes in the PNA domain by the end of February. The more intriguing and challenging inquiry for me, is can we get the NAO to play ball, at all? We have discussed this heretofore, and it's something @Snowy Hibbo noted I believe; namely, that much of the positive angular momentum has been concentrated in the southern hemisphere. Further, I noted that the equator-pole distribution of the angular momentum has been "wrong" and antithetical to the genesis of sub-tropical troughs, which accelerate jet flow and tend to initiate decelerating polar jets immediately to the north. Those conditions remain unpropitious through the next 7-10 days; however, if the CFS is correct, there may be a window within which a legitimate NAO *could* develop and actually retrograde a bit toward Greenland. This window of opportunity is approximately March 1/2-March 10th +/- a couple days. Besides the phase 1 lagged effects, forecasted equator-pole zonal winds are suggestive of an alteration from this winter's base state in the March 1-10th period by the CFS. Now, we continue to have persistence and descending wly QBO modulation countervailing, but if other variables rearrange, that shouldn't totally obviate the chance for at least a transient blocking feature. We'll have to monitor it, but I like what I see on the CFS zonal wind proggs in the first 10 days of March. Momentum diminutions in the SHEM, and reorientation of +AAM in more conducive places. We'll see. But, the Pacific alone will make things colder for the first half of March. The question is, are we talking about a decent pattern (which would be much better than what we've had = ghastly, hideous, and diabolically impudent), or, could it be "better" than decent? That's contingent upon whether we can induce a transient blocking period. As said, there's a chance. But it also may not happen. Right, James. The tropical forcing and extratropical progression, i.e., MJO, GWO, etc., would certainly augment the argument for a retrogressive HLB feature. But the -AAM in the sub-tropics needs to decrease to permit it."

Already a rockslide between Walland and Townsend has 321 shut down, both directions.

Definitely did so yesterday. When I can back from my hike and looked at the radar, I thought hmmm, that was a little more robust than modeled.

Sounds like some good news!

Not the obs thread, but seemed like it might fit better here. Took a group on a hike up to White Rocks near Ewing, VA. This would be the headwaters of the Powell. Water is already spewing out the side of the mountain, literally. Springs on the hillside are shooting water out. Creeks I've never seen as more than a trickle or completely dry are filling very old creek beds. The valley bottom already had creeks running out of their banks, without the additional water from the mountainside having made it there yet. All this after only round one. Creek I've never seen with any water: Waterfall at Sand Cave; Dry spring turned creek: https://imgur.com/a/DXbm4PA

Big blocks being advertised by the Euro to develop across the N. Hemisphere. Hopefully if that happens they can effect some change in the pattern. But, as with all things this winter, 8 - 10 days. Looks like it might be snowy in N. Africa though.

Yeah the bad part about this is that out current forecast period ends when a pattern like this is starting to become climatologically (at least in my experience) favored for this area.

0z Euro still with widespread 6 - 7.5" through TN and Ohio watersheds. Some areas 8+. WPC basically sums it up. And that discussion above as well. Just amazing how wide the 7 - 10 inch field is. Weathertree I think janetjanet mentioned that a run of the GFS yesterday broke the pattern down, but (janetjanet can correct me if wrong) I took that as just a hopeful mention of what that model depicted as a way out of this awful pattern. 6z GFS is back to this; Basically GFS think we are one of the most soaked places on earth over the next 15 days. Good news is that it's just one run of the GFS. That being said, the 0z Euro really flattens the jet after day 7-8 and that would help a lot. Maybe not totally shut off precip, but at least stop this training mess. The Euro control (Euro itself run at slightly lower resolution), keeps it coming though, but with a slightly more suppressed flow.

EPS with aims the highest QPF mean into N. Alabama as of 12z today. 8-9 inch mean into N. Alabama and 7 - 8 inch mean into N. GA.

@AMZ8990 Sorry for taking a while to get back to you. I'm putting this response in here because I'm still trying to learn about this stuff too and welcome any thoughts. As I understand it, AAM (Atmospheric angular momentum) is a measure of the momentum of the atmosphere across the globe at all latitudes at a given time. Sort of like where the most umph is and where it is aimed in latitude and whether or not it is westerly (+), or easterly (-) (yellows and oranges/ blues and greens respectively in the image attached). The earth is a solid object, surrounded by a fluid (atmosphere). That fluid rotates with the earth, but the sloping surfaces and mountains and just plain old fluxes and ebbs embedded in it can change over time and impact the state of flow in the atmosphere (its momentum) and importantly for us, high latitude blocking. For example. this year, from Dec - Feb the + momentum was aimed from the equator toward the pole in the N. hemisphere (orange arrows in the image, latitude markers circled in black on the left). More momentum aimed that way, at least as I think I understand it, would lead to less chances to block things up at high latitudes. It looked like that was changing, but it is now back. There are also two ways to measure it: relative and total. Notice the total in this image is currently off the charts. Also notice that total was relatively low back when we got our Dec storm. I don't understand it much more than that and used it in my speculation earlier only in the sense that it was aimed back toward the equator at that time. Its certainly just on piece of the puzzle and I really don't understand how to use it right now more than to say "oh look, it's changing and "X" expert said that's good" so still a ways to go for me. Here is a nice .pdf I found, but the mathematical side is currently over my head. But then again I've never seen anyone show their work, so to speak, when using AAM charts to make a pattern point, so I suspect there is just more meteorological depth to using these charts than I currently understand. https://uol.de/fileadmin/user_upload/icbm/ag/physoz/download/cl_dyn/ang_mom.pdf

always wondered what these were called:

Alright severe people, I'm coming over to play for a week or two. I have access to all these fancy maps and nothing to use them on for now. What would you like to see? I really don't know what to look for in terms of severe weather, so let me know. But if I'm going to post Kuchera snow maps for winter folks, may as well most CAPE/ shear/ K index (whatever that is, but think has something to do with severe) maps too. Euro Surface CAPE: Euro Deep Layer Shear: Euro K Index: Here are other Euro products I have access to, but don't know what half of them mean:

The following image is from the paper “Wind Regimes in Complex Terrain of The Great Valley of East Tennessee“(Birdwell). The research used surface wind data from several locations to examine how the area’s complex terrain alters the regional wind flow. The graphic labels a convergence zone resulting from the features you identified earlier today. Near surface winds through the gap (during WNW-NW flow) have more of a westerly component, while winds around the northern part of the barrier have a more northwesterly direction. This convergence on the lee side of the mountain range triggers vertical motion in the valley and could have aided in the formation of the snow band from earlier today. As you also mentioned, this band is likely enhanced east of Knoxville due to lift from the WNW flow interacting with the terrain in the eastern part of the valley I've noticed that band several times over the years. It's nice to have a plausible explanation for it. That's an awesome dissertation. Thank you for that. I didn't realize someone had put so much time into the wind regimes of the Great Valley. Based on what you said above, I think I have a speculative explanation for the Bays Mountain band. Forced low level flow funneled between the Smokies and Bays Mt/ Chimney top in Greene county (you can see that on the satellite image), meets NW flow less inhibited coming around the NE flank of Bays Mt. Lift provided by the up valley flow, convergence, and overall trajectory of everything towards the higher mountains to the SE. You might also be able to argue some of that flow continues on to Boone, through relative gaps between Buffalo and Holston Mountains, the NE flank of Roan, and ends up aimed at the ski resort areas there and Boone.

Yes, I have summoned you! But in all honesty, would it be any worse than Flora or Heath or Jimbly-bob, or whatever the Weather Channel goes with? Maybe Old Gregg?

#Grumpycat

Have a buddy in Wetumpka, AL. Tornado hit 3 blocks from his house.

Potential Vorticity and water vapor imagery http://rammb.cira.colostate.edu/wmovl/vrl/tutorials/satmanu-eumetsat/SatManu/Basic/Parameters/PV.htm