Carvers Gap

True! We were past due for some duds. I think the forum area hit on three out of four (maybe five) storms straight. How do you feel about the pattern after the cutter?

Ditto. Cutters, if cold is available in plentiful quantities (which it is), will often press the cold eastward. Looks to me like the cutter creates a gradient pattern in its wake which the next storm will slide along and then turn northward at some point in its journey across the SE.

12z Euro pushing that next front even further into the forum area. Nice look at 210.

Wow. I missed that. Deep snow pack and cold to the north. -22F real temps. Those would be all-time record lows. There is a reason it is in banter, but 84-85 right there @John1122.

The reason I ask....I usually put a "clock" on weather patterns. Rare to get a pattern to last past 6 weeks. That said, just because the pattern changes does not mean it goes to a pattern which is worse(I am kind of conditioned to that line of thinking though, meaning it gets worse!). Initially, it looked like a flip on LR modeling. Then, it kind of looked like new pattern. However, what the GFS just produced was almost identical to what we say it advertising for the Jan 20-30th time frame - centered slightly west of where it is now. That would bring the storm track onto the eastern seaboard and park it there verbatim. Storm tracks look something like 2/3 cuts west of the Apps, but 1/3 take the low road. That is a very traditional storm track or La Ninas IMHO. So, just trying to figure out if we are stealing a couple of more weeks with the same pattern or is this a new look. I can't honestly tell. There are aspects, as you note, which are slightly different. @John1122, sure looks like the "cold November" correlation may verify this year....

Yeah, details at this range will be scarce. I tagged you int he post above. I thought it interesting to see MRX make a note of that active pattern in their morning discussion. Originally, I really felt like the system after the Nor'Easter would cut west of the entire forum area. I think modeling is adjusting to the idea that maybe trough in the west could be quite temporary and the cold front may push eastward more than LR modeling had to begin with...I think a large scale overrunning event looks plausible for folks to my west, but huge cone of probability at this point.

Stellar write-up by MRX. I am going to post all of it. Great discussion about the short and medium range. Of note, read the last two sentences of the last paragraph @Weathertree2. Key Messages: 1. A mix of rain, snow, and possibly sleet on Friday will changeover to light snow Friday evening with heavier rates in the highest elevations. Accumulations are most likely in the mountains, northern Plateau, southwest Virginia, and possibly portions of northeast Tennessee. 2. Well-below normal temperatures are expected Friday night through Saturday night with wind chills possibly near or below 0 in the higher elevations. A gradual warmup will follow. Thursday through Saturday At the start of the period, a shortwave will be moving out of the Rockies with surface high pressure centered over New England. This approaching shortwave will be the focus for much of the extended period with the initial setup yielding more seasonal and dry conditions locally. Heading into Friday, the aforementioned shortwave will dig significantly with cyclogenesis expected in the western Atlantic ahead of the developing nor`easter. This will result in significant height falls and increasing low-level convergence. Cross sections from the latest NAM/GFS show notable ageostrophic upward motion, well above the dendritic growth zone for much of the area. However, the column does look to be fairly dry in the lower levels at the onset of precipitation in the first half of the day. This will likely inhibit precipitation reaching the ground initially, but the later timing of precipitation suggested by the latest model runs has raised potential for more of it to fall as light snowfall, even outside the mountains. In any case during the overnight period, focus will be on the mountains for more notable accumulation potential as 25+ kts of N/NW flow is expected to persist at the 850mb with continued low-level saturation. With all of these factors in mind and more aggressive snowfall accumulation indications from the NAM and many GEFS members, confidence is high enough for inclusion of wording in the HWO. The focus for better accumulation potential will be in northeastern portions of the area where there is better overall moisture, in addition to the higher elevations of the Plateau, mountains, and southwest Virginia. Then, heading into Saturday, the focus will be notably cold temperatures following significant CAA and far below normal 500mb heights. For places that do see accumulating snowfall, overnight temperatures may fall to the single-digits as surface high pressure will promote subsidence/radiational cooling on Saturday night. With all of these factors in mind, much of the area is likely to remain below freezing from Friday evening until mid-day on Sunday, perhaps longer in some locations. Additionally, synoptically-driven winds early on Saturday when the MSLP gradient increases could produce wind chills in the teens to near 0 degrees, especially in the higher elevations. Below 0 wind chills are looking increasingly likely in the mountains. Sunday through Tuesday By Sunday, the mid/upper trough will have moved to our east with height rises expected into early next week. This will promote a gradual return to near normal temperatures with drier weather also expected during this timeframe. At the very end of the period, deterministic and ensemble models suggest notable troughing in the central U.S. to begin ejecting eastward. This will likely allow for a return of a more active pattern at the end of period and beyond. BW

12z Euro has that system as well, but further to the west. I am guessing that is going to be a cutter for the Plains, but it has trended better for middle and western areas of the state. If it comes to pass, the GFS nailed this from d16. I think there is a pic of it in the banter thread. Regardless of that storm, the pattern that comes after that looks really good. That 6z GFS run looked a lot like last winter's overrunning event. The GFS has some DGEX DNA in it. It has been over-amping stuff this year in crazy ways, but generally getting the placement of the features reasonably correct on a large scale. It seems to have feedback issues when a slp turns to the NE or when it phases. It has done that all winter. I will say this though as a counterbalance to that last opinion, February systems tend to over-perform in my book. Modeling often overestimates how far south those storms will be suppressed and underestimates the strength and precip. In the LR, modeling(ensembles and operationals) look really good. What looked to be a pattern change, now looks like an EPO ridge which has ideal placement. I am a little wary of this flip back to a colder look(after several days of a flip to warm after Feb2). If you remember back during late December when we flipped cold, for a time modeling only had the monster cold front on Jan3rd, and then turned warm after the front. In reality, that was a pattern change. We had a slight warm-up after that front, and then the hammer dropped for good. Right now we have a similar (but opposite) look where a strong cold from drops into the West during early February. At first, modeling had that as the pivot to a warmer pattern over the East. For the past 3-4 days, modeling has trended much colder for the East as it rolls that trough out of the west right back into the East, and then locks it into place. The 6z GEFS is now a complete flip to a very cold look, and its look is one that could deliver a very cold air mass into the US. The 0z CMC has something similar. The EPS has been a few days behind @Mr. Kevin, but it is almost there. The EPS has been less than consistent in the LR. Again, GREAT looking pattern. And again, I am wary of modeling perpetuating the current pattern. For you LR model watchers, does that pattern after the cutter look like a return of the current pattern or is it a new pattern? It looks to me like a variation of the same family of EPO ridges, but the center of the ridge looks further south than the previous pattern. The reason I ask, the current pattern is due to break 4-6 weeks after Jan 3. That would mean that look in the LR is very temporary. If it is a new-is pattern, we may see much of February get cold.

Truly one of the more impressive runs of the NAM(even for the NAM!) that I have seen. It brings snow howling all of the way to the Florida/Georiga border. I have my doubts that it can get the Atlantic feed back this far, but a historic blizzard on the EC certainly seems plausible.

The 18z GFS is loaded for bear after the cutter. Gradient pattern with a cold and an active pattern.

It has more to do with the parabola of a the track. Need that entire parabola to slide a bit west. I honestly don't think it has room at this point, but let's see what happens when the get recon over that energy. I suspect we see one big shift(not idea which way) once models ingest that data. What we really need to hope for in E TN, is for that storm to just amp big time. If that storm is a monster which it could be...If we can get it just barely inside Hatteras with a deeper solution, that snow band might form one of the outer deformation bands as it comes through. Then, we just need that band so set up shop and hold there as the storm wraps up. FWIW, I really like the pattern right after that cutter. Have I said that yet today? LOL

Agree. I am not sure it can work that far back, but was just swinging by to say that. Looks to me like models have a track and are now figuring out the slp is going to be a brute.

Be ready for some changes in modeling when that occurs.

We have definitely run out of the TIM model mojo. Time to put some deposits back in the account. Just thunder...nothing dangerous.

No idea if it is even close to being right, but the 12z Euro ends with the coldest setup of the season IMHO.

February 2015 and comparison to the d10-15 means of the 12z GEPS and GEFS. Not saying that happens, but that is a bit uncanny.

Looks to me like modeling was possibly too quick in breaking down the pattern....OR the new pattern is just a reset of the current Pac pattern which we are in. That is splitting hairs slightly. So, if modeling is correct and is not erroneously perpetuating cold(that has happened before), looks like a warm-up for the first few days of February as cold pulls back into the West....and then the trough quickly gets pushed back eastward. That look late in the runs of the 12z GEFS/GEPS could deliver extreme cold if the look is real.

Kind of raising our eyes past the weekend storm's horizon...Don't look now, but the GEFS now has a full fledged AK block late in its run. That forces the cold eastward. I had at one point though the clock might run out on winter around Feb 2. I think It plausible that we get to at least the 10th... The 12z GEPS has a monster EPO(kind of PNA) block as well. That trough which is going to go out West...it is modeled to roll right back into the East. Good changes/trends from the past couple of days. That may very well be the new pattern...If it is, we may get a couple of bonus weeks of tracking during February. That is a month which is known for frequent storms and changing wavelengths. IF IF that is real, that is a 14-15 type of set-up to me, ie cold an e plentiful precip. If that AK block is real, it might be tough to move.

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.

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.

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....

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.

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.

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).

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.