griteater

Precip on the 18z EPS Mean bumped north. It seems to keep wobbling back and forth each run (north/south)

OK I failed on that one. Precip is light on the GFS - stayed more suppressed than I thought it would

Happy hour GFS looks like it’s setting up to be a good run with how it looks out west

...Developing positive tilt Western trof with winter precip in Southern High Plains Wed.. ---Prior Discussion--- Further west, as the tail end of the initial shortwave swings out of the Rockies into the Great Lakes on Tuesday; reinforcing shortwave energy over-tops the amplifying Pacific Ridge dropping into the developing larger scale trof over the West by Wed. This wave, in combination with emerging shortwave energy out of the east-central Pacific (under the Pacific ridge, as well as lingering frontal zone across TX into the Southern High Plains will set up the next system with the potential for wintry problems by late Wed into Thursday. Here, there is much more substantial spread, keying on the timing of the the central Pacific shortwave/moisture transport through the Desert Southwest into the area of concern. Here the ECMWF shows the greatest timing differences being quite slow with the wave, mainly as it lost some energy to the northern stream along the western side of the developing Pacific ridge, which delays the energy advancing as well as dropping the focus further south. So as the shortwave from the northern stream drops, it does not phase/amplify delaying its ejection into the Plains. The 12z GFS and 00z CMC are much faster with this shortwave capture and start to break out increased QPF across the southern High Plains/TX by 00z Thursday. Even though it is typical of the GFS to have a fast bias, the similarity in timing presented by the 00z CMC and UKMET suggest less or no influence of the ECMWF in a preferred blend at this time. While not favored due to typical deeper/over-amplified solution through the West; the 12z NAM is also faster like the GFS/CMC with this energy, providing some confidence, as a stronger more amplified system should be slower. Confidence in average in a 12z GFS and 00z CMC/UKMET blend for this feature. 19z update: The 12z UKMET is very strong rotating the Pacific shortwave under the northern stream positive tilt trof across the Southwest late Wed, this is likely too strong/too fast. The CMC remains on par with the prior run and the initial preference. The 12z ECMWF while still weak, shows better timing of the weaker wave through the Southwest. So will still favor the 12z GFS/CMC but will have some ECMWF inclusion in the preference.

Ha, WPC is mostly favoring a GFS/CMC blend at the moment

Pivotal has the Euro - https://www.pivotalweather.com/model.php?m=ecmwf_full&p=prateptype_cat_ecmwf&rh=2020021612&fh=loop&r=conus&dpdt=&mc=

With respect to precip, this one is tough to figure out. Some of the modeling is bumping north, which happens, say, 8 out of 10 times regardless of the specifics of the setup. Yet, the two models generally regarded as the best at 500mb (Euro and UKMet) want to dive the northern stream energy too far east preventing moisture from surging into the region

The joys of extrapolation ha. It looked great with the storm and slower to gather out west which is good like you mentioned...but it looked like the southward push of cold air was about maxed out based on the height pattern over the southeast

So much that it has a mid-atlantic hit look to it

It bumped NW with overall QPF though. Good move tonight with precip on GFS and GEFS UKMet and CMC were both suppressed to the south

I'm torn on temperatures for the folks in South Carolina and southern North Carolina. While we don't have classic cold air damming, the surface high is a monster with northeast winds at the surface as the potential precip approaches, originating from a source region that is very cold (-12 to -28 C at 850mb). It's an excellent setup. Problem is, the 588 height line is in central Florida with 591 in the western Caribbean (strong subtropical ridge). Also, the cold air doesn't move in boldly behind the early week cold front like it did behind the pre-storm cold front for the recent snow in GA/SC. Having said all of that, I suspect that when the NAM comes into range, it will be a bit colder than the globals, with a better ability to resolve the low level arctic sourced air.

With regard to precip, as others have alluded to, we need the northern stream shortwave to drop down farther to the west. We need it to drop from Montana down thru the spine of the Rockies as opposed to dropping down east of the Rockies. This improves the flow over the southeast for moisture return...specifically, it opens the door for more interaction with subtle subtropical waves that can inject moisture from Baja>Texas>Carolinas and VA. Here's the shift west with the wave shown in this loop of the last 2 runs of the Euro Control.

Think he meant the snowfall from the mean

18z Euro Ens Members Snowfall below...the mean snowfall is light - 0.1 to 1.5 inches from Northern SC thru VA

Trend on last 3 runs of the Euro Ensemble Mean for Thursday aftn. More precip to the north and warmer

So the 18z Euro only goes out to hr90, but the 18z Euro Ensemble goes out to hr144. The control run is part of the ensemble, so it goes out to hr144. Here's the snow map

GFS and UKMet also moved to the suppressed camp with the wave diving down too far to the east....Euro takes the lead in the clubhouse for now

Yeah I counted (18z GEFS): 11 - SE Forum hit (somewhere) 7 - No Storm / Suppressed into the Gulf / Miss 2 - Hit to our north Previous run (12z GEFS): 11 - SE Forum hit (somewhere) 9 - No Storm / Suppressed into the Gulf / Miss 0 - Hit to our north

18z GFS says I’m in! Beautiful setup

Appreciate that Niner. A few things to supplement the other comments on this topic: 1. Although our winter has been warm, it's been cold in Canada, and the surface high drops out of the Yukon Territories, an ideal source region for cold. 2. As currently modeled, the surface high is big and sprawling, with northeast winds at the surface. It's a good setup for getting a good supply of cold into our region. 3. Having the soundings show a shallow warm layer at the surface is much better than dealing with a warm layer moving in aloft (warm nose). 4. Assuming a cold front passage Tues night, the timing window for wintry precip would be Wed night to Friday night...gotta have the precip in that window.

The modeling today actually looks surprisingly similar IMO. Dual shortwaves drop into WA state and Montana next Tues. The WA state wave pinches off / closes off over the Great Basin and the Montana wave works toward NE Colorado. The UKMet keeps the two waves together, with a stout wave closing off over Utah. The UKMet and CMC are the most aggressive with getting the subtropical jet stream moisture involved (streaming northeast out of Baja), with the GFS next in line. The Euro and ICON are the least aggressive with getting the Montana wave to dig far enough to the southwest to ignite precip from Texas to the Carolinas. All things considered, I thought the 12z suite was a step in the right direction. We haven't lost our cold high dropping down, and the path to victory with the southern slider overrunning precip is more than just a pipe dream. Here's the aggressive look with Baja moisture streaming in on the UKMet...

Here's the 12z GFS. There are two key shortwaves in the northern stream (top left panel). The first is in the eastern Great Lakes at the start of the loop. That's the table setter with the cold high pressure coming in behind it (behind the eastern U.S. cold front). The next one drops down from Montana into NE Colorado - this works to keep the flow more southwesterly across the south. I've noticed a trend in recent model runs to have this shortwave drop a bit farther to the southwest, which is what is needed to get the overrunning precip going. Having that wave drop into the southwest and then hope it spins and comes out at just the right time is a riskier play (as ILMROSS referenced earlier). That wave also links up with waviness in the subtropical jetstream. Note on the bottom left panel how the moisture blows up in Texas before heading east. The ICON had a very similar look to the GFS, but it was a close miss with the storm over the SE. This GFS run though no doubt has some good qualities to it.

No worries on the question, but the reality is that it wouldn't be a fruitful exercise to ponder on that type of detail this far in advance. The most important thing IMO is for us to see a big, sprawling high pressure drop down out of Canada, delivering cold air. Most likely, the high isn't going to stick around very long, but the bigger/stronger it is, the slower it will be to exit. If we can get the good high pressure in place, then we look down south to see if we can time some SW flow and/or a wave in the southern stream to deliver moisture into the cold air

Not as much on the EPS Mean this run, but some hits on that second image