Carvers Gap
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Everything posted by Carvers Gap
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True. I would gladly take 1-2" of snow with the cold that will follow. Also, with 70-80 hours to go on this thing, I expect one more big jump in modeling as it gets closer to NA and gets sampled well.
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Last comment until the Euro rolls. The 12z GFS has a cutter (after the coastal this weekend) which drives the boundary southwestward. It is the storm after that which interests me.
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It appears the 12z CMC will be rolling on time. I will place all comments about that run within this single post. Out to 54, the RGEM appears to be a close copy of the RGEM at 12z. Substantial trend westward on the CMC. Not quite good enough to help yet, but one more trend like that....
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With the 12z RGEM also with a coastal storm, I am of the opinion we are now looking at a Nor'Easter. Not sure we can get into the mix as we are on the far, far western cone. However, enhanced upslope snowfall by the coastal low is plausible or even likely for the upper 2/3 of E TN. Not sure highs get out of the mid 20s in E TN for Saturday afternoon to echo John's comments earlier. For now, we want to a strong storm which deepens and forms a bit earlier. With modeling correcting in the southwest, it will be interesting to see where the final correction ends-up.
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12z GFS is rolling. I will keep all posts pertaining to this particular run within this one post. I will update this post as it rolls. -Through hour 12...the western ridge is taller and a smidge more eastward. This may prevent the energy from digging into the SW by a fraction -At 42, we are approaching the point where it sheered out during the last two runs. Let's see where it goes. -At 54, there is slightly less digging...this might make a run for it. -At 60, it would appear this trough will try to go neutral slightly earlier in the run. We will see. All thoughts are my own, and those of a person who does this as a hobby. LOL. -At 66 you can toggle back in time with the 500vort maps, and see the correction during the last several runs, ie less erroneous digging into the southwest. -By 78, the slp along the SE coast is tucked-in right along the coast...that is a change. -Trailing energy is not as strung out and should allow for the trailing energy to be inputed into the developing coastal storm. -By 90, the GFS has the storm closer to the EC. Not sure this run would help us a ton, but there is a noticeable trend at 66 to correct the over amplification in the southwest. That in turn is causing the slp just off the EC to track more westward. -By 96, the storm definitely has received input from the system in the southwest and is neutral to slight neg tilt over the Carolinas. This looks much more like the system modeled at 12z yesterday but slightly east of that run. Not sure it can get back this far west during future runs, but that is an improvement. Over and out.
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An interesting move by the 0z EPS last night. It has some support from the GEPS regarding the EPO ridge. This is the last 5 days of the run. All three global ensembles are BN or temps in the East. There is one trough amplification in the West around 180, and then the EPS firmly entrenches the trough in the East again. If you go look at the historical thread, take a look at the 0z EPS and compare. The GEFS holds the trough centered mid-section/west. It has done better with transitions, but seems to have been left to its solutions...both the EPS and GEFS had similar looks. The overnight and 12z(yesterday)EPS run is substantially different than its Weeklies. The EPS made a move at 12z yesterday in the LR. Weeklies were derived from 0z. The 0z run continued that trend. That pattern on the left would be quite cold here w/ some hints of split flow(see the low underneath).
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Morning disco from MRX. Good write-up and similar to discussions here: With the approaching trough, significant 12-hour height falls of 200+ meters are expected, which will provide synoptic-scale ascent on Friday, more notably to our southeast closer to the surface low that eventually becomes a nor`easter. With the increased NW flow in the lower levels, the focus for increased PoPs and longer precipitation windows will be in the higher terrain. While there does remain much uncertainty, current indications of the vertical atmospheric profile suggest mainly a rain/snow mix with 850mb temperatures to stay below freezing. This also could be accompanied by sleet, depending on the depth of the saturated layer. Based on the latest model guidance, it still appears that the best potential of accumulating snowfall remains in the higher terrain. This is given the continued uncertainty for residence time of moisture in the region, dynamic cooling efficiency, and the overall timing in general. It is also noted that the latest ECMWF and many ensemble members are more aggressive on widespread light snowfall accumulations due to a later exit of moisture and better forcing. In any case, the overall message remains the same with potential for widespread impacts remaining fairly low. By Friday night, strong low- level CAA will be in place with the trough having moved just east of the region. Saturday through Monday The main story for Saturday continues to be the likelihood of far below normal temperatures, potentially colder than any seen so far this season. The ensemble and deterministic consensus is for 850mb temperatures to fall into the negative teens (C) after 500mb heights fall to 5300-5400 meters, normal January values in the upper Midwest/Great Lakes. This could mean much of the area will stay below freezing for 48 hours or more, not to mention subsidence from the surface high likely allowing for significantly cold overnight lows Friday and Saturday nights. Depending on the strength of low- level winds early in the weekend, wind chills could drop to the single-digits area-wide to below zero in the higher elevations. The remainder of the period will likely experience a warming trend as height rises are indicated.
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Indeed the 6z off-run Euro would be a widespread light snow event for E TN. Turns neutral tilt right on time - northern stream dominated event.
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It is on an island right now, but the Euro (again at 6z) appears to get most of the energy clear of the southwest at hour 60. I can only see it in the front range right now, so we will see where it goes from there.
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The 0z Euro absorbs most of the energy from the southwest where it didn't during prior runs. The GFS leaves it behind over the southwest. It "appears"(my two cents and not the gospel) that when that energy actually moves eastward....the storm occurs close enough to the coast to have meaningful impacts in E TN. Maybe the 6z Euro will show some consistency. Maybe not. If the storm is going to occur two things have to happen: 1. The energy can't be left behind in the southwest. It can be strung-out some, but not completely sheered and left. 2. Phase has to occur early. The 0z Euro had both of those. Even still, it needed to phase a bit earlier. I wondered this yesterday, and still wonder today....are models erroneously leaving that energy back? I don't know the answer to that, but it is something to watch. We have seen that verify at times, and also be an error at times during the past decade.
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And then the Euro goes back to the old GFS runs. I have noticed this winter that the Euro seems(at times) about 24-48 hours behind the GFS this winter with trends. Seems like it is almost where the GFS was yesterday morning. Models leaning towards a clipper event for the weekend for northern areas with only the fair coastal cities having potential for significant snow. If things don't move by 0z, there is really little room or time for the system to work its way back west.
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Fall/Winter Banter - Football, Basketball, Snowball?
Carvers Gap replied to John1122's topic in Tennessee Valley
The 12z Euro wins the belt back today. But will it keep it? -
That is a 100% cave by the 18z GFS to the Euro. Both solutions still look wonky as all get out...and not sure I buy either. Euro is king today.
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On another note, the 6z GFS and 12z GFS are flirting with a multi-day, over-running event after the cutter which follows the potential weekend storm. Not even going to get into details, but that has been on modeling off-and-on for 5-6 days I think. It is still there.
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I picture these troughs like a pendulum swinging. We want it neutral over Alabama and not the Carolinas. Not sure that is going to get fixed. To continue what I said above, we just need that base of that northern stream trough to get hit with the STJ turbo boost as seen on the GFS. Without that, the storm fires later which equals a later turn/recurve. The formation of the slp earlier would likely allow/force the northern stream to buckle and pull back on the slp, thus lifting its almost due north. If that won't work, we want a strong northern feature in order to get some clipper snow. GFS/GEFS/GEPS vs Euro cage match. CMC is injured and in the locker room for evaluation.
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But honestly as weird as this might sound, that Euro run is an improvement since it finally depicts the northern jet being organized. It looked like hot garbage at 0z. Get that energy feeding into a more organized northern feature, and that is not a terrible look. We need some fire injected into the base of that trough to force it to go into beast mode earlier. I think the general progression/timing/location of the trough looks pretty well set - and that likely won't help us. We need that low to fire a bit earlier in the run. With no blocking over the top, a strong storm would back west IMHO. The more strung out it is...the more it waits to turn northward.
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One more note about 12z....The CMC has not run, but its ensemble has as Holston notes. Both the CMC and GEFS ensembles have that energy over the GC and SE. The Euro is the only one without it. If we take into account known biases, the 12z suite is a storm signal for the EC. Time will tell just how involved E TN can get.
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Here are the comparison maps of the 12z Euro and GFS. Just watch the energy in the southwest. Notice how it feeds into the base of the trough on the GFS at 114 vs being strung out on the Euro. Then, take a look at 123. That energy on the GFS turns that trough natural tilt. At the surface, there is almost nothing on the Euro over the SE. Look at the differences at the surface at 111 in terms of precip over the SE. The Euro holds back that energy and strings it out. It then consolidates along the front piece of energy while the second piece heads to the Yucatan.
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12z Euro has a more organized 500vort look. However, when it holds back that piece of energy(aka drags its feet), the STJ lacks the power to create anything at all until the storm begins to recurve into the the big cities of the NE. That is a legit option, but seems like (said this before) bias coming into play. On the vort map, you can easily see that energy from the 4 Corners get strung out. If that energy had come out into that nice northern stream trough there would have been fireworks. I think that likely an error.
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Euro is a bust...held too much energy back and got strung out. That is a major bias of that model. It could be right, but that is how it looks when that occurs. It held back too much energy in the southwest and washed out STJ vortices.
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Out to 90 on the surface map, the cold front is either slower or just didn't make it as far. That "should" give the system room to move west. I may be wrong.
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Through 84, looks like a more energy is being held back by the Euro than 0z. That could be a bias on its part. Four Corners energy is notorious for being slow to kick on the Euro. That said, this system could maybe benefit from exactly that.
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At 81, the base of the energy is now centered over the 4-corners. That has traditionally been a good spot for eastern storms.
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At 75, noticeable digging more into parts of Utah...nothing there at 0z. Not sure this makes much of a difference, but would almost think this pulls back along the coast a bit east of the GFS.
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Not sure we see any major changes to this run of the Euro. Looks super similar, and phase will likely be late...though it does dig a bit more. Just likely won't be enough. So will hold off on any updates unless this run changes. Looks like a carbon copy of 0z up to this point.
