TellicoWx

Maury Co on Hwy 43

Even the GFS upgrade says the old system is lost

Either GFS/UKIE are going to pull the ultimate coup, or they are completely lost...rest modeling world has generally same are from southern middle TN, running up the plateau, and points east

Euro not backing down

Compton, AR (NW AR) reporting 4.3" now..only model that got that right...3k NAM. Time to watch the actual vs ops out west.

I've kept my hopes muted with this one lol. Big boom or bust potential with this one for me..1°-2° will be a world of difference. We will find out around midnight if the changeover begins to occur..0"-6" here we come lol

Yeah noticed that too..wonder if it's just due to the snapshot at that particular hour and the dendrite zone is beginning to dry out.

I can't figure the GFS out...has almost the same RH/PWAT/UVV as the RGEM/NAM...just never produces the precip

0z RGEM,...columns moist/ no dry air issue. Difference with the surface temp is the precip rate isn't as high on the RGEM vs NAM (central/southern valley)

Yeah, looking at the sounding for here..looks like it has the moisture like the NAM..but it doesn't generate quite the same dynamic cooling right at the valley floor..that 1-2° makes the world of difference for the central/southern valley.

If the dry air is right at the surface then yes..but on 18z, the bigger separation is in the mid levels..if this was more woundup surface low vs ULL then the available moisture would be more plentiful. Since it's an ULL..we need the mid levels to be as moist as possible at the start. There has been hints at modeling on a slight downslope component as well..that would be another issue the ULL would have to fight off..but that's more track dependent and angle the winds are coming across the mtns from NC side.

Green line is the DP...Red line is the temp...as the line moves up the chart, it's like a weather balloon rising...shows how each layer is responding. Chart on top is 18z...as you follow the green/red line up, they separate (shows the dry air just off the ground). 0z the entire column is moist (green/red line together). The temp at the start of the lines when comparing the two, shows how if we can get the moisture feed right...dynamic cooling (snow melting as it falls, cooling the lower atmosphere near the ground) helping the lower elevation be 4° colder. The 0 line is the dark blue faint line running up the chart at an angle...if the temp line stays below or right at that line on its entire path, then you get snow...if it goes to the right of the 0 line (warmer temps) then you get mix or rain.

Difference the moisture feed makes...18z vs 0z (south/central valley). The dry air out in front was significantly less when the ULL pivoted east near AR on the 0z.

0z NAM

Still snowing across NE TN at 66..already closing in on 12" at MRX

Good run for the entire eastern valley

Chatt gets NAM'd again lol

Moisture feed looks better on 0z NAM compared to 18z

18z NAM coming in way weaker on the northern side precip shield

Euro cut way down of QPF vs 0z = warmer solution/ no dynamic cooling

More of a problem with using globals with this type of system..it will be very dymaic cooling driven, and it's hard for globals using 6hr windows to "see" exactly what's going on. Take McMinn Co as an example..12z actually looks better on the sounding and qpf increased from 6z, but snow accu didn't...it's hard for the model to interpret what exactly happened during the window of heaviest precip (add in this is very marginal..not much separating from light rain and big wet snowflakes). Hourly meso models may have a better feel for what happens in this setup.

RGEM was close to a decent event (2" per hr rates along spine of the mountains). NAM took the heavier rates along TN/GA border...if the rates keep trending better/shield expands..a lot more of the forum could be in buisness

Could the 18z GFS be a sign it's starting to step toward the Euro? Looks much better for east of Knox on that run...(1st system). Not sure it has been handling the precip rate well (dynamic cooling is going to play a big factor).

Quite a few outages for FLEC here as well