Absolute Vorticity

tron777 wrote: ↑Thu Jan 04, 2024 8:43 am 9Z SREF plume for CVG shows 0-2" for the majority of the members. The mean is 0.72" So we lost those silly weenie members from yesterday in other words which makes sense. Mean QPF is 0.51" You might be thinking, why the low snow amounts then? It's the temps... 33 to 35 degrees is where the majority of members are so "white rain" in other words is what the model is showing.

tpweather wrote: ↑Thu Jan 04, 2024 9:24 am

tron777 wrote: ↑Thu Jan 04, 2024 8:43 am 9Z SREF plume for CVG shows 0-2" for the majority of the members. The mean is 0.72" So we lost those silly weenie members from yesterday in other words which makes sense. Mean QPF is 0.51" You might be thinking, why the low snow amounts then? It's the temps... 33 to 35 degrees is where the majority of members are so "white rain" in other words is what the model is showing.

Hey Les and this has been showing up for awhile and the amounts in Indy have been going up while we are heading downward. I still believe its how hard does the precip fall to get a decent snow. Give me 4 hours of a moderate snow and I will be happy. I agree about the temp being the problem but not sure models take into account a heavier burst of precip can of course give us snow but also lower the temps early Saturday morning. Still a work in progress my guess this may be the case even on Friday.

Trevor wrote: ↑Thu Jan 04, 2024 10:49 am GFS keeps the 1-3" bullseye right over the tri-state.

tron777 wrote: ↑Thu Jan 04, 2024 10:53 am QPF of 0.17" from the GFS for CVG on Sat

EDIT: IMO the bulk of it falls early in the morning so that should help with grassy accum.

Trevor wrote: ↑Thu Jan 04, 2024 11:45 am Adjusted the 1-3" band further to the north and narrowed it. Removed measurable snow from the far south/southeast. For transparency, I have attached all maps through my forecast process to show changes.

tron777 wrote: ↑Thu Jan 04, 2024 4:34 pm 18Z RGEM looks good for the Tristate. 0.25" of QPF to work with. 18Z NAM only about 0.12" for Sat and 0.11" on Sun. (That is for CVG).

tron777 wrote: ↑Thu Jan 04, 2024 6:44 pm Looking at the current picture going into the weekend and we have a broad area of low pressure over New Mexico this evening providing mountain snows and valley rains over NM, the TX Panhandle and getting into SE Colorado as well. This is just one of the pieces of energy. We have a northern piece associated with the polar jet in West Central Canada dropping to the SE. If you look at the water vapor loop, you can see what I am talking about here. Link is time sensitive: https://www.iweathernet.com/satellite-images-and-loops

Latest pressure falls indicate that the southern piece will organize a new low over S Texas tonight and the northern piece should be dropping SE from Canada into N MN. We should begin to see (tonight and tomorrow) SE flow from the Gulf at the 925-850 MB levels into Texas increasing the moisture down there in that area. Meanwhile, once we see the southern low become the primary low, it should develop and track NE into the TN Valley Sat morning bringing with it, the wave of accumulating snow to the OV. That low will weaken and give way to the EC Low during the day on Saturday. A secondary piece of energy will drop into the trough to being us rain / snow showers on Sunday as well.

This is kind of how I see this system playing out. I still think an inch or two of slushy snow is possible for us. If you can get to the 3" mark, I'd consider yourself lucky. If there will be any road issues, they will be late Fri night into early Sat morning as that is when the heaviest precip will move thru and temps will be at their coldest point... 32-36 degree range depending on the rate of precip that falls. The heavier the better. Once things lighten up, we will see light rain / drizzle Sat afternoon and everything will be just fine for traveling. I'm not expecting any issues for Sunday at this point since the precip will be much lighter and temps will be marginal as well so roads should be just wet.