RCNYILWX

I've been thinking the same thing and suspect there will be at least some correction colder. Sent from my SM-G965U using Tapatalk

If you loop tmdw long range reflectivity, can see things filling in down to close to I-80 near JOT latitude now. So that'll stop the northward advance of the snow line that had been occurring. Sent from my SM-G965U using Tapatalk

SN here in southeast Naperville, already covered my driveway. Thinking somewhere in 4-6" range here, hopefully sneak in over 6". A bit uncomfortably close to where the gradient is setting up, but I think we'll be okay in this area. Sent from my SM-G965U using Tapatalk

Unfortunately, with the wind field slackening, almost impossible to tell where the low level wind convergence will ultimately set up. The NAM favors long duration IL side, GFS drifts fairly quickly into NW IN, FV3 and GEM kind of split the difference a bit. With that said, from a low level convergence and omega perspective, it looks good to overcome the less than ideal inversion heights. I think 6"+ amounts are a distinct possibility if evolution of convergence allows for a stall scenario. I'm working today but not sure yet how it will be handled by forecast desk, could see us holding off and midnight shift issuing a watch or advisory, or we go with a low confidence watch. From what I've looked at, I'd consider Cook, Lake IN and Porter for a watch and would feel best but still low confidence about Cook and Lake IN. Sent from my SM-G965U using Tapatalk

We were rerunning the expected snow graphic and probs this afternoon and wanted to only include the system snow but we're having issues with it including the LES as well. That's why there's a disconnect with the other probabilistic stuff and 10th and 90th percentiles. Sent from my SM-G965U using Tapatalk

We preferred not to do a watch south but for collaboration purposes went along with it. Sent from my SM-G965U using Tapatalk

I'm starting to think that there's something going on with the warm sector convection with this system that some of the globals aren't handling that the meso models are. There's a good reason to be a bit uneasy when the Euro is much more paltry and you'd like to see some even minor positive trends today. On the other hand, we're in the non clown range of the meso models, sampling of the Pac wave has begun, and the meso models aren't backing down. Also, to second what's been said, fgen will absolutely be handled better by the meso models than the globals. Sent from my SM-G965U using Tapatalk

Was clicking around weather.us and found out that you can view a bunch of the parameters for the individual Euro ensemble members, including at the all important 500 mb level. A nice way to check out what's needed to get to the more amped solution some of us are hoping for is by looking at the h5 evolution of the more amped members. Sent from my SM-G965U using Tapatalk

The Euro shows pwats of upward of 1.5" (spots pushing 2"!) in the warm sector available to wrap back into the cold air, with a large area of 0.6"+ in the cold sector. I totally buy the potential for extreme cold sector qpf and snow amounts unless the system ends up a sheared out pos. Orientation W-E vs SW to NE matters less than available moisture. With this system, should it come close to what's modeled on Euro or further maxes out will likely have, in addition to antecedent Pac moisture, additional deep layer tropical Pac moisture drawn northward as it matures, which was easily seen on w/v with just this past system and GHDII as recent examples. In addition, once it emerges into the Plains you'll ramp up low level moisture advection from the Gulf.

The ensemble members have the same background model physics but are run at a lower resolution than the OP so the operational model is certainly better in that aspect. The big thing is that the small changes in initial conditions in the ensembles show you the range of possible outcomes and give you a sense of confidence or lack thereof in a certain solution (uncertainty interval). One of the members could certainly end up being close to what verifies, but if there's a ton of spread at a certain lead time that individual member is not really useful. The EPS itself is considered a very useful ensemble suite because it has 51 members and does a better job than the GEFS in showing that pdf (probability density function) of the projected future state of the atmosphere. Sent from my SM-G965U using Tapatalk

Yep, a pleasant surprise. An encouraging sign considering that known tendency with ensembles vs. the OP model. Despite what I posted earlier about the GEFS in particular, this is a good reason to lean more heavily toward the ensembles at this range. The op models are not useless, they shouldn't be taken verbatim but they can be instructive on the positives and negatives with a particular setup.

I fully expect the GEFS to shift south because it's well known as being too non-dispersive with the operational GFS. Edit: Obviously if the negative trends on 12z runs thus far continue as we get closer, then we get concerned. Just for point of comparison, both GHD events had a few model cycles that drifted south until correcting way north. The synoptic setup has too much potential to give up on it yet. Edit 2: Never mind on the GEFS [emoji23] Good sign there.

I like to think of operational model solutions at this lead time as being like individual ensemble members. They fall into the range of possible outcomes like the ensembles themselves. It's a good way to assess what you need to see happen to get the event you want or what could go wrong. We're still at a point where the shifts you see in the model suites may or may not be meaningful to the eventual outcome. Sent from my SM-G965U using Tapatalk

The 12z GFS has the longest duration single snow event I've ever seen modeled here next week. Sent from my SM-G965U using Tapatalk

Not a good run vs very encouraging 00z last night. Good thing there's plenty of time to get the changes we need. GFS did a horrible job handling the h5 wave at closer leads with this past weekend's event, so there's that. Sent from my SM-G965U using Tapatalk

End of NAM caveats apply but nice look at h5 at 84 hours and surface low a good deal farther west compared to GFS and FV3 at that time. Sent from my SM-G965U using Tapatalk

I think our latitudes are in good shape, still would be enough confluence from PV to your north to act as a pseudo block from enabling a hard cut. We just want the more SW to NE trajectory you mentioned earlier. This run was a step toward getting that if we can get the further needed improvements. Sent from my SM-G965U using Tapatalk

Yep, really not far at all from the extreme totals being pulled farther north. Southern wave was much improved until final approach toward northern piece, going neutral tilt and closing off at h5 over the Plains. If we can keep that southern wave stronger for longer, it would argue for gaining more latitude before phase. Great trends overall on that run. I expect to see some explosive solutions on the EPS members. Sent from my SM-G965U using Tapatalk

Looks particularly good for west side of the lake LE/LES. And a huge run for northern IN-OH, solid for southern lower MI. Sent from my SM-G965U using Tapatalk

It appears that the long expected effects from the downwelling of the SSW will be coming, so the sort of output on the weeklies is not unexpected. From what I've read both last March and April were significantly affected by the Feb 2018 SSW. Can't expect the same sort of behavior this time, but perhaps Feb and part of March and then things break. I guess the hope would be that with everything shifted a month earlier, would give time to get back into a better pattern earlier, as opposed to last March and April both being toast and then quickly flipping to summer in May. I am with you on not wanting this to last deep into spring.

LES setup will certainly feature extreme lake induced instability with 850s plunging to -20C or colder over the lake by early Sunday. Forecast soundings indicate inversion heights between 850 and 700 mb lifting to closer to 700 mb during Sunday as cold air mass deepens. The inversion height is probably on the low side but when you consider that the DGZ is so low in such a cold air mass, it may be less of an issue than you'd otherwise think. Sent from my SM-G965U using Tapatalk

The new run of the Euro weeklies is basically like 2014, wire to wire and averaged out, the core of the coldest anomalies centered over the central and western sub. Sent from my SM-G965U using Tapatalk

Just as an aside, about the way PoPs are done in extended range at central region offices, we have a model blend called superblend that includes previous forecast, and certain percentages of raw model (which are themselves derived from model QPF) and MOS pops. Sometimes this can be fairly deterministic and be prone to fairly large shift to shift changes. However, it's by and large a huge time saver for us to do it this way. Superblend is the baseline starting point period 4 (12z 2 days from now) and onward on a day shift for all of our weather elements and we collaborate changes to these elements when needed (most often temps, pops and qpf). Eventually this year, probably delayed because of the shutdown, we'll he going to the National Blend as our starting point and I think that'll be done nationally. When there is categorical pops several days out, if surrounding offices don't feel they're warranted, we often lower them to likely or even cap them at chance (25-54%). Having worked today, there was no chatter about changing the Friday night 06z-12z pops given the overall very good agreement in the models and their ensembles in measurable qpf in that 6 hour period. Sent from my SM-G965U using Tapatalk

Also we can still get to a more northeast trajectory if we can get neutral or negative tilt to southern wave or earlier phasing with northern stream/PV lobe like last night's Ukie and the stronger ensemble members. Sent from my SM-G965U using Tapatalk

It's not on the list but this setup to me is pretty reminiscent of 1/4-5/14. I know you or someone else mentioned the similarities to that event as well. It had the initial fronto snows in northern IL that were more significant than earlier modeled and also the main wave and surface low trended northwest leading up to the event. Also the huge cold dump following closely on the heels of the synoptic snow. Outside of GHDI & II, that's one of my favorite events since I've lived here. Edit: in addition to the above, there was also a significant lake enhancement component to the totals in NW IN, with some localized ~18" amounts.