Potential Weekend Snow Jan 7-8th, 2023

[tron777]

We have the potential to see some snow this weekend over the forum area. A wintry mix and rain are also possible. Guidance supports the I-70 Crew as having the best chance to remain as snow versus a wintry mix or even mostly rain as one goes south of the river. The strength of the low, low track, and amount of WAA are all coming into play with this set up. Discuss!

[tpweather]

Great Job Les and just read the info from the Indy and Louisville NWS and both talk about this weekend and I still believe trying to figure which piece of energy is finally the winner will determine when,where and what kind of precip happens. I do believe there will be a system but these smaller ones much harder to grasp this far away.

[tron777]

Great Job Les and just read the info from the Indy and Louisville NWS and both talk about this weekend and I still believe trying to figure which piece of energy is finally the winner will determine when,where and what kind of precip happens. I do believe there will be a system but these smaller ones much harder to grasp this far away.

Great post Tim! I think you're absolutely right with this line of thinking. We can clearly see two pieces of energy at play. Do we get two little pieces or a phase and a much stronger, longer duration system as a result? We should be able to pin point this much better in the next couple of days.

[tpweather]

Just a little update on temps in Siberia and Canada. The lowest in Siberia is -63 but in Canada though its cold in the north central part of the country as usual its in Saint Germain Quebec at nearly -50. This is important as the cold is building in northeast Canada. They tend to be much colder later in the winter season compared to the central and western areas. Getting a stronger high pressure to build and build back somewhat to the south and west will help with the weekend system or systems. The jet is still rather strong this weekend but no such much that it brings up a ton of warm air. Still to early for any kind of forecast but like seeing the players on the field early on

[tron777]

The boys had this to say... about the same as our early thinking is on here:

The next low pressure system is expected to affect the Ohio Valley
Saturday into Sunday. There continues to be phasing issues with
associated upper level energy and therefore surface low placement,
strength, and timing issues. This will have an affect on where the
rain/snow line will set up. Right now, the operational GFS is the
most favorable with the low track for more snow to occur north of
the Ohio River. However, it doesn`t have support from the CMC/ECMWF
which are slower with the low and farther north (a warmer solution).
At this point, have increased PoPs, but do not have confidence in
snow accumulation amounts, so the HWO product will continue with a
low hazard threat. Highs will be in the 30s and 40s over the
weekend with lows mainly in the 30s.

[tpweather]

Will be back to discuss the possible weekend system

[tron777]

18Z GFS is fairly similar to what the 12Z run showed. Maybe a hair farther to the south with the snow since the model came in a hair weaker with the strength of this system. Overall, it's still the GFS being the most aggressive with this system right now.

[tron777]

Good morning all! Overnight models all pretty much showed that we get two pieces of energy this weekend. The first comes on Sat with a warm front coming thru. A brief shot of snow all areas that quickly changes to rain before ending. Then, the second pieces Sat night and Sunday is much stronger so a bigger push of warm air and mainly rain for most folks ending as a few flakes. that big high we were seeing over Eastern Canada is weaker and it gets pushed out quicker as a result. So those are the issues that I saw with the overnight guidance. We are still early, plus are being impacted by the current system (still waiting on cold front to come thru today) so we'll look at a couple more days worth - today and tomorrow - is wise before issuing any final rain or snow calls in my mind.

[tron777]

Both the 6Z GEFS and EPS low clusters are bringing the low into S ILL and then up the river thru our area then off to the NE over Central Ohio. That is the mean. There is still some spread though of low tracks. A handful NW and SE of that line.

[tron777]

SnowTalk!

[tron777]

12z NAM is so weak, the system moves in, peters out and any precip remains to our south.

[Bgoney]

The flow is to flat and weak getting past the rockies and no temp contrasts , so it remains very weak

[tron777]

12Z RGEM is decent on Saturday for the Metro and points north for a band of snow associated with the warm front. RGEM is weak but just enough frontogenic forcing to produce the snow band over the Tri-state. There really isn't a surface reflection in terms of a low pressure system on this run, so it's just an upper level disturbance basically and some overrunning taking place. This type of scenario as modeled would produce a 1-3" band of snow (lighter amounts for Cincy and NKY and again N of I-70) with the heavier amounts N Cincy Burbs to S of I-70 posters.

[tron777]

12Z GFS is slower with a stronger looking system on this run. We have an actual surface low that tracks over N MO that weakens N of STL over Central ILL. A weakening band of rain moving in is the end result. The upper low closes off over Iowa for a little bit before opening back up and moving into Northern ILL. The southern piece down in Texas draws up some rain along the frontal boundary from Texas into the Apps. This system remains disjointed overall and no phasing really takes place until it gets into Interior New England.

The best case scenario for us is something like what the RGEM shows. Keep it weak, more southerly, and have it be an overrunning event with a nice band of WAA snowfall to whiten the ground up before the warm air wins out and melts it. I will say that the outcome on this system is far from over. A weak cutter like solution as the GFS shows to a more WAA snow like the RGEM shows (and everything in between) is still on the table in my mind.

[tron777]

12Z CMC is pretty much like the RGEM on Sat with the WAA induced snow band then we all get rain for the most part with the second wave on Sunday. Maybe some flake action N of I-70 on this run for Sunday.

[tron777]

12Z GEFS is supporting the OP GFS's solution today for this system.

[tron777]

The 0Z UKMET looked dead on like today's 12Z OP GFS run. The new 12Z run that just came in shows the high's axis providing the stale cold air over MN into Southern Ontario Canada. The 0Z run had that high from Michigan thru the Ohio Valley already (meaning it was already about to move away and thus the weak cutter solution). If that high pressure placement is correct then the system will be weaker and forced more southward for that potential WAA snowfall to potentially occur. Indeed that is what happens on the new 12z run. The low goes from S MO into Western KY then tracks east over SKY. That is usually not a bad track for us.

[tron777]

12Z Euro is coming in stronger and slower on today's run and keeps us dry on Sat. Then we warm up and see light rain on Sat night into Sunday down south with snow / wintry mix possible for those to the north. Low track starts off okay over S MO into West Ky. but instead of the low staying weak and tracking over SKY, the low is a bit stronger and moves NE right up the river to Cincy. We know that isn't a good track for many on here.

[tpweather]

Good Afternoon and it looks like the models believe something is going to happen this weekend but the where,when and to what extent is still not set in stone. I always believed these smaller systems that are not some form of a clipper can be much harder to predict until about 36-48 hours in advance and sometimes that is too quick. The good thing is we are at least getting away from the milder air and into the more seasonal air which at least gives us a shot at some winter weather nearby. More to come this afternoon and want to look at a few more items and though these items may be small they can change the outcome of a small system like this weekend. I still want to see there is more than 1 piece of energy as well.

[tron777]

Good Afternoon and it looks like the models believe something is going to happen this weekend but the where,when and to what extent is still not set in stone. I always believed these smaller systems that are not some form of a clipper can be much harder to predict until about 36-48 hours in advance and sometimes that is too quick. The good thing is we are at least getting away from the milder air and into the more seasonal air which at least gives us a shot at some winter weather nearby. More to come this afternoon and want to look at a few more items and though these items may be small they can change the outcome of a small system like this weekend. I still want to see there is more than 1 piece of energy as well.

Exactly Tim! We have two solutions right now showing up. WAA snow on Sat with the first piece then rain on Sun with the second one. Or are we dry on Sat and get just 1 bigger piece Sunday which would be rain for probably 3/4's of the forum area.

[tron777]

12Z EPS Mean showing the weaker / southern route with the low going thru extreme SMO and into Western KY then weakens thru SKY and dissipates over the S Apps. Freebie precip maps aren't out yet so just going by 500 MB and SLP clustering maps for this post. It looks decent from my vantage point.

[tpweather]

The latest Nam gives us what I have always called a river runner. This is usually a small system and weaker system that gives a decent 1-4 inches 50-75 miles either side of the river. Back in the day these kind of systems would bring out the old winter warning Travelers Advisory which was usually for 1-3 inches of snow and once you were expected to get over 4 inches we used the Heavy Snow Warning.

Normally I don't pay much attention to the run to run by the models but with these smaller systems I pay a little more attention because once we start to get into the 36-48 hour range and once the models lock in on the strength and path it seems to me the major models will be very close in their outcome.

[tron777]

18Z NAM is in the WAA snow camp and the solution we need for snow due to the pattern we are getting into. If the run went out further, we'd probably see rain on Sun with that second piece. Surface temps stink but we know that going in. Still, the model gives us 0.20" of WAA snow on Saturday so if correct, we will at least be watching it snow for a while on Saturday with some grassy accum as well. Roads not an issue due to surface temps staying in the mid 30s. The only way that would become an issue is if the snowfall rate is very intense. Way too early in the game to be trying to pin point frontogenic forcing and all of that.

[tron777]

18Z RGEM backs up the 12Z run which is nice to see again with the WAA snows on Sat.

[tron777]

The boys are favoring the slower / one piece / more northern solution by their below AFD. I am not favoring either solution personally. Both are possible in my opinion.

A mid level trough traversing from the west into the central Plains
has slowed some for the upcoming weekend. As a result, associated
surface low pressure and isentropic lift has slowed as well. For
Friday night into Saturday, chances for rain/snow have been lowered
significantly due to the delay in the previous forecast
precipitation shield.

As the mid level trough pushes east across the Great Lakes and Ohio
Valley between Saturday night into Sunday night, aforementioned
surface low pressure will rotate northeast across our area. The
current forecast track should change any rain/snow mix over to rain
on Sunday due to WAA. Highs will warm into the lower 40s north to
near 50 far south. By Sunday night, the system begins to exit and
the pcpn threat will taper off.