Holston_River_Rambler

Vivid lightning and thunder up here on the plateau. TIMS model is hopefully holding steady here at 1z.

18z Euro: as usual, the precip type maps are late, but here is the qpf:

Sadly you have tapped out my knowledge at my post above. I would go over to southern and ask Webb about what exactly the VPs mean. Divergent winds and jet modulation is sadly about as far as I have gotten so far.

As I understand it @Mr. Kevin, convection in the tropics modulates Hadley cells, which in turn modulate the jets. Here are a couple of images: source: https://www.researchgate.net/figure/Schematic-of-the-Hadley-circulation-Abbreviations-TTL-Tropical-tropopause-layer_fig1_322886947 Source: https://www.saltworkconsultants.com/hadley-cells-and-deserts/ As to why we want it over the central Pac, I think that helps strengthen the Sub tropical jet (thus El Nino years are usually wetter than average in the southeast) but it could also be that anywhere is better than the 4/5/6 areas, when it comes to modulating the pattern for folks in the eastern US. Also keep in mind that which phase is good for us can change depending on the season and situation. So a VP plot shows where there are divergent winds aloft, modulating the Hadley cells as seen in the above image Example: Green colors indicate divergent winds aloft created by convection, while orange colors indicate convergent winds aloft. I can't find a current image, but Michael Ventrice has created some plots that show how the divergent winds modulate the jet (sorry the colors are different) TBH, I don't really know how all this correlates to the RMMs, but they were created by Wheeler and Hendon to help monitor the MJO and they use several variables to plot the circulation, in addition to VP anomalies. Here is info regarding the MJO calculation: https://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/MJO_summary.pdf (see section III) There are other details to consider, but for my hobby purposes, I usually start by looking at the RMMs in the morning, then the satellite of the Western Pac using the Himawari 8 found below, to try and see how tropical convection looks https://rammb-slider.cira.colostate.edu/?sat=goes-16&sec=full_disk&x=10848&y=10848&z=0&angle=0&im=12&ts=1&st=0&et=0&speed=130&motion=loop&maps[borders]=white&lat=0&p[0]=geocolor&opacity[0]=1&pause=0&slider=-1&hide_controls=0&mouse_draw=0&follow_feature=0&follow_hide=0&s=rammb-slider&draw_color=FFD700&draw_width=6

Here it is:

@Mr. Kevin Sorry I saw that you asked about the MJO earlier, but I've hyperventilating about the current system. This is probably the best I've seen convection look in the central Pac in a while: It is south of the equator, so not sure exactly how that squares with the MJO. Ventrice's VP plots to have an interesting evolution: Roundy's analogue page does show what seems to me like a sensible progression through the 3rd week of January: SOI also dropped to 3.82 today.

Wow at the RAP.

In regard to soil temps, I will say that they seem to be able to crash back down pretty quickly (12/18 - 12/20)

Do any of y'all remember the "Dandridge Dollop" storm? This one just dolloped me here in Morgan county in the same way, lol:

Happy hour requires the COD webpage color scheme:

Looks like the 18z GFS just NAMed eastern areas

Stout short wave. Nice STJ connection.

I managed to catch 80+ on a weather station earlier: Euro sees the second system later next week:

Here is the evolution wrt precip:

Euro was more amped with the energy at 12z too.

Some batch of bugs just hatched and is flying around up here. I guess its time to head to Clinch to trout fish. Low 70s even on the plateau. Do we think someone in the foothills sees 80 today? Sevierville is up from even the earlier post:

I love the RGEM. It's such a happy little model.

Happy New year to all too! 6z GFS gives us a present. It's not been prefect by any means, but I feel like the GFS has been a little steadier with the medium range with out current system and as other have mentioned it has had this one its radar for a while too, so made it's on to something: Euro has the system too, but further north:

6z GFS kind followed the 6z NAMs in that it resolved the energy as a little bit better, but still not as good as some of the runs yesterday. The last few runs:

No precip type maps yet, but the qpf does seem a little south IMO:

18z Euro a little deeper and little slower with the energy. Gif with the 12z run and the 18z run:

#Imchasingthedeckpic

I'm sure some of you already ready MRX's disco, but I thought I'd post it here for posterity due to the topic points: 1) Severe. Very warm day is expected with a strong low level jet out of the southwest to the south of the frontal boundary. This will help to pump in warm, unstable air, along with good speed shear. Directional shear component is not as impressive, but with these strong winds helping to increase low level shear of 30+ knots in the eastern TN Valley, the chance for a possible tornado is present. Biggest question looks like it will be how much instability is available for storms to tap into. As usual the NAM is the most bullish with MLCAPE while most other forecast soundings showing a more moderate 300-500 J/kg, but all of these are pretty high for New Years Day. Think the biggest threat with possible severe weather will be strong straight line winds as this fast moving system makes it`s way through, but a quick isolated spin up of a tornado can`t be ruled out along the QLCS line. Think the main line will move onto the Cumberland Plateau around 00z, and quickly push east of the mountains by around 06/07z. 2) Flooding. This system will also have a good amount of moisture to work with as the jet helps to pull in Gulf moisture, and PWAT values rise above 1 inch in the Valley. This will help produce heavy showers and thunderstorms that could quickly dump a moderate amount of rain ahead of the line with isolated storms, and as the main line moves thorugh. High resolution models and Plumes indicate that 0.5-1.5 inches of rain are expected on Saturday which could lead to flooding of low lying and poor drainage areas by Saturday evening into early Sunday. But hopefully with this system quickly moving through the QPF amounts and flooding will be somewhat mitigated. 3) Snow. By Sunday we should get a brief break in precipitation chances as the line is to the east of the mountains, and the surface low begins to move through the Tennessee Valley. This will bring with it a strong shot of cold air Sunday night into Monday morning quickly dropping temperatures below freezing. With the 12z model runs some of the operational models are now indicating that the system will be stronger and slower than previous model runs. If this verifies it would mean that colder air and higher QPF amounts would be likely leading to more snow in the southern Appalachians and eastern TN Valley. Operational GFS has gone MUCH higher on snowfall amounts overnight, and in general most models have increased snowfall amounts overnight. Have bumped up official snow amounts in the Valley, but have been much more tame with amounts ranging from a dusting to quarter inch around Chattanooga, up to around an inch or more in the Tri-Cities... Higher amounts closer to 2+ inches can be expected in the higher elevations of the southern Appalachians and northern Cumberland Plateau. Have stayed closer to GEFS plumes which show a much lower amount compared to the operational models. Think that snowfall totals may need to be bumped up if models continue the trend of slower and stronger with the low, but would like to see multiple runs of the stronger/slower solution, and would also like to see ensemble members in better agreement with the slightly higher snow amounts. Have also undercut some guidance because ground temperatures are still going to be very warm (highs in the 70s/60s the days before) so snow will hit the ground quickly melt... Snow totals on the snow board will be much higher than what people actually see on the ground and on the roads (which is what most people actually care about). Weather quiets down by Monday afternoon and we get into a more mild and seasonable pattern thorugh the middle of the work week. Another trough will begin to swing through the eastern half of the US by the end of the work week... Temperatures are expected to be warm enough that most of the precipitation that falls Thursday into Friday will be all liquid, but in the overnight hours we could switch over to light snow in the Valley... But this is still a ways off and confidence will likely increase after we past this weekend system.

Beat me to the punch! The vort pass made me breathe heavily:

Yeah, the NAM looks better than 12z for sure: Still not as good as 12z GFS, but better than it was.