Absolute Vorticity

12Z GFS had the clipper coming from Canada at 1009 MB at 42 hours. 18Z has it at 1006. Might be a nice run here.

The clipper still weakens as it drops in, don't think we are going to avoid that aspect of the storm, so the stronger it comes in to the CONUS the better.

18Z GFS 0.18" for CVG

18Z Euro is still the weakest model this evening with 0.08" of QPF at CVG. If the Euro is right, an inch or two. If the US models and CMC are right, the shot at getting 3" to iso 4" is there. That's where we stand right now.

Good Morning what about the clipper system on Monday. I am looking at a light event here locally and 1 inch is probably the most I see at this point. Clippers become stronger when you have a big temp difference in a short distance. I just believe the timing of this system is too fast and areas from say Iowa into the Ohio Valley will be on the 1-2 inch range for most but the system even weakens more once it gets into the Ohio Valley and why 1 inch is the most we will see and that is because ratios are higher than normal. The only way imo that we get higher totals is the system is delayed 12-24 hours and then you can get a surge of warmer air from the southern plains into the system but at the moment the flow is still rather fast so that is unlikely. The good thing is every flake will stick. Then we start the slow warm up Tuesday and Wednesday before we really kick it in gear Thursday.

Overnight guidance is still in the 0.10-0.20" range. My prelim 1-3" call is till on track. I've talked about the things we need to watch for and the things going against this system from being a bigger deal. This should be your typical light event that most clippers usually bring.

What seems to be the timing on this?

Browneyedgirl wrote: ↑Sat Dec 24, 2022 9:34 am What seems to be the timing on this?

This one is moving fast so probably a 6a-12pm on Monday kind of timing. Will watch to make sure it stays rather weak and if somehow it got a little stronger then timing would probably be a few hours later and last maybe an extra hour or two

Browneyedgirl wrote: ↑Sat Dec 24, 2022 9:34 am What seems to be the timing on this?

Timing is tough on these and you usually want to go a little faster then models indicate. I'm hoping it holds off until after the AM Commute but it'll be close. Should pull out by late afternoon or evening.

Watching the gfs come in concerning the clipper and so far much stronger in southern Canada. Is this a trend and will it hold its strength as it moves southeast?

Over the past 12 hours and this will continue for probably another 24 hours is there are several pieces of energy in the Alaskan Panhandle. These are the ones that are becoming the clippers. We know about the first one and there is a second one a few days later that is stronger but that looks to head towards southeast Canada and New England. So far though the 1st run is stronger in southern Canada it still looks to weaken heading this way. The second one I talked about is getting stronger and the reason is a strong push of southerly winds into the system. That is what we really needed for the first clipper but the timing is just too quick.

tpweather wrote: ↑Sat Dec 24, 2022 10:40 am Watching the gfs come in concerning the clipper and so far much stronger in southern Canada. Is this a trend and will it hold its strength as it moves southeast?

12Z NAM was around 0.10" of QPF. 12Z GFS still closer to 0.20" That's been the trends in most models to be within that range for available moisture.

If your someone that uses Kuchera method, a clipper event such as this one is probably going to be about the only wintry event around these parts that will work for you

Merry Christmas everyone! We are heading to Maryland Monday morning, are you seeing this as being a problem driving if we leave here around 9am?

Merry Christmas to everyone and your family. The clipper is heading this way but I am still not seeing much in the way of snow locally. I am guessing about 1 inch will be a common total. The piece of energy is rather strong but it looks to weaken quickly in the fast flow and that is why the lower end of what the models may be showing.

Good morning all! Based on the majority of models that I have just looked at, most are offering up 0.10" of QPF. I just don't see how 3" is going to occur with this one. The clipper is just going to be weakening too fast. If it weren't for that, this would have been a nice system! But that's not going to be the case. So going to lower my range to match Tim's. 1" to locally 2" should do it for the majority of the area.

12Z GFS supports the call. RGEM and CMC match up fairly nicely also. I think we can pretty much lock it in.

Euro continues to have the lowest QPF of all. 0.05" as it weakens the clipper faster.

Latest thinking from the boys...

An Alberta clipper will be weakening as it approaches the area
tomorrow with the remnants of the system crossing the region
tomorrow night. However, there is a short wave, currently in
Wyoming, that is tracking just ahead of the clipper. This will
induce a period of moderate low level warm advection leading to
reasonable upward motion as it passes across the area on Monday.
Low levels will be dry initially, but then moisten. So a period
of light snow is expected to move through the area starting just
after daybreak and ending in early afternoon. This will
result in some light accumulation, with slightly more in western
counties and lower amounts in the east. It is not out of the
question that there could be some additional spotty light snow
Monday afternoon and evening and the clipper remnants move
through, but there is much less confidence that there will be
sufficient lift to result in much.

Temperatures will be able to warm into the 20s on Monday and
only drop back into the mid to upper teens Monday night.

Our boys are covering the event with an SPS:

...LIGHT SNOW EXPECTED MONDAY...

A fast-moving system will cross the area on Monday bringing a
period of light snow from the morning into the early afternoon.
Accumulations are forecast to range from one half inch to one and
one half inches. This may result in slick road conditions.

Motorists are advised to check the latest weather and road
conditions before heading out on Monday.

Meanwhile, LOU has an advisory out for their Western CWA including Louisville and Madison, IN for up to 2" of snow.

I really have no changes this evening. 1" for most, isolated 2" if you're lucky especially West and NW. Radar has a band of snow over Iowa and Missouri. Currently our clipper is a 1012 MB low (it has already weakened, was 1009 this morning) over SD diving to the SE. Track is great. That isn't the issue. Low is weakening so QPF / radar presentation will be looking less and less impressive as time goes on. So we have to keep things lower then you'd otherwise expect. Ratios are good. Temps are great. Lack of QPF since it is weakening is the only issue we have with this system.

tron777 wrote: ↑Sun Dec 25, 2022 6:47 pm I really have no changes this evening. 1" for most, isolated 2" if you're lucky especially West and NW. Radar has a band of snow over Iowa and Missouri. Currently our clipper is a 1012 MB low (it has already weakened, was 1009 this morning) over SD diving to the SE. Track is great. That isn't the issue. Low is weakening so QPF / radar presentation will be looking less and less impressive as time goes on. So we have to keep things lower then you'd otherwise expect. Ratios are good. Temps are great. Lack of QPF since it is weakening is the only issue we have with this system.

I agree Les and timing was also key and wish it was 12-24 hours later as we would had more of a temp gradient as the central plains would have warmed up a tad more since there is not much snow on the ground there. Again not everyone will probably even get an inch and like you mentioned to the southwest you could see a tad more.

Good morning all! 16 degrees imby. Have received a new dusting of snow but that's been it. The "meat and potatoes" of the event is moving in from the West now so grab your coffee and start staring out the window! Look for slick spots on roads esp this morning. Not much else to say right now.

17 / 7 here... dry air aloft is eating away at the clipper snow it appears. We should moisten up eventually for some light action but we probably aren't going to hit that 1" mark. Oh well, can't win them all. I would much rather bust on this then on a bigger event (like the last one lol)

tron777 wrote: ↑Mon Dec 26, 2022 8:48 am 17 / 7 here... dry air aloft is eating away at the clipper snow it appears. We should moisten up eventually for some light action but we probably aren't going to hit that 1" mark. Oh well, can't win them all. I would much rather bust on this then on a bigger event (like the last one lol)

I agree Les and I watched these pieces of energy on Saturday and the trend was they were weaker than models showed. I put that in my equation plus the speed was to quick to add any warmth from the southwest of us which is a key factor to get a nice clipper. So far I have not seen one flake from the system and the radar is a little deceiving.