Absolute Vorticity

Link is time sensitive but that's a nice dig and you can see the shortwave over AZ into NM. Moisture flow from the STJ looks great!


https://www.meteo.psu.edu/ewall/SAT_US/animwv.html

The Euro looks pretty good. This definitely has potential in a narrow area. Les, you talk about threading the needle quite a bit. Here's one of those storms. Someone in AV land is going to be in the eye of the needle!

dce wrote: ↑Sat Feb 10, 2024 2:06 pm The Euro looks pretty good. This definitely has potential in a narrow area. Les, you talk about threading the needle quite a bit. Here's one of those storms. Someone in AV land is going to be in the eye of the needle!

There could be a 4-6" narrow weenie band of snow outside of the 2-4" main band of snow. We'll have to wait and see tonight and tomorrow if the shorter term models start picking up on more enhanced QPF.

I might be wrong but, I believe the Euro had this from the beginning about 6 days ago??? Lost it and then came back. Snowfall rates will be interesting with this if it does pan out.

young pup wrote: ↑Sat Feb 10, 2024 2:08 pm I might be wrong but, I believe the Euro had this from the beginning about 6 days ago??? Lost it and then came back. Snowfall rates will be interesting with this if it does pan out.

GFS has been rock solid for days. Euro only recently came around to the stronger GFS solution about 1 or 2 days ago.

12Z EPS Mean looks good.

tron777 wrote: ↑Sat Feb 10, 2024 2:10 pm

young pup wrote: ↑Sat Feb 10, 2024 2:08 pm I might be wrong but, I believe the Euro had this from the beginning about 6 days ago??? Lost it and then came back. Snowfall rates will be interesting with this if it does pan out.

GFS has been rock solid for days. Euro only recently came around to the stronger GFS solution about 1 or 2 days ago.

Yes, the gfs has been solid that is for sure. I posted this of the euro in our snowplow group a few days ago. Told them we need to keep an eye on it.

Trentonwx06 wrote: ↑Sat Feb 10, 2024 2:12 pm 12Z EPS Mean looks good.

Strength and track looks good!

All right Happy Hour model run time!

18Z NAM is a bit stronger with a 1002 MB low in Nashville TN at 48 hours.

Deform band starts developing over S ILL Monday afternoon. Spreads into SC IN during the late afternoon and evening hours. Light rain coming for us at the beginning for all AV posters.

Low deepens over far SE KY and into WVA by Mon evening with snow over SC IN and our I-70 Crew. Light rain Tri-state on south, All changeover in that 10pm to 1am window from NW to SE as night evening wears on.

Then the transfer takes place so this is still a much weaker outcome and the deform band weakens for us.

Wow.. precip is less then 0.25" as a result of the earlier transfer. Let us hope this scenario is wrong.

The boys are throwing out some early numbers.

Period begins with potent low pressure tracking from the southwest.
Carrying a large swath of deep moisture on the warm conveyor belt
ahead of the low, this system will produce widespread precipitation,
starting as rain during Monday. Precip changes to snow from
northwest to southeast Monday night, with accumulating snow
likely, especially under the band of heaviest snow where snowfall
rates may overcome marginally cold surface temperatures. 2 to 3
inches of accumulation with locally higher amounts is the snowfall
estimate at this point, mainly around I-71 from Wilmington to
Columbus. Model variability adds to the uncertainty with respect to
this event regarding location, snowfall amounts and impacts.

Drier weather follows for Tuesday and Wednesday as the system
departs quickly east to be replaced by high pressure. Next low
pressure moving to the Great Lakes will provide a chance of rain on
Thursday, with snow mixing in Thursday night and Friday as the
system travels east. Low chance for rain and snow continues Saturday
along a lingering boundary behind the low.

Temperatures remain relatively mild through the period, with highs
mainly in the 40s, while overnight lows in the 20s and 30s allow
snow during nighttime hours

The 18z GFS is up to it's antics again. No way this happens. It's been consistent on placement, however. It does reflect the possibility of a really good deform band setting up somewhere across AV land. We will see if the short range models start to pick up on the deform band as we get closer.

The placement differs but the GFS is not backing down in the slightest, 18Z GEFS Mean hammers the area! 3-6" heaviest I-70 and it tapers down north and south from there.

Good Evening and I believe a few things about the upcoming snow chance. I believe the models are having a hard time with the snow that actually falls and snow that accumulates. When it switches from rain to snow it may take 1-2 hours before we start seeing any accumulation because of the warm ground plus it will have rained before hand. I have a hard time going higher than 1-3 inches and even then I feel the low end is the better way to go. Further to the northeast probably northeast of Columbus maybe the higher end but not even sure that will work. No doubt the mid-Atlantic and parts of the northeast will get a nice storm out of this and I believe this is a start for them of several nice storms that really boost the snow amounts this winter.

So if the models show .5 while snow if falling I would probably cut that in half and then do a 7-1 ratio. We are still 2 days away but that is what I am seeing at this moment. The track is important as always but this system we need a huge increase in strength while its nearing to bring the colder air down quicker in the atmosphere and that imo is the only way get to the higher end of snow totals.

0z GFS says no go. Dayton still looks like the sweet spot. Amazing cutoff on this system if those snow maps are even remotely correct.

We got NAM'ed on the 6Z run. It's finally showing the strong solution. 6Z GFS looks good as does the Euro. No changes from my earlier call. 6Z HRRR and RAP also look good. 3Z SREF has almost 2" for CVG and 3" for DAY on the mean.

The latest thinking from the boys:

The start of Monday will be dry with quite a bit of sunshine,
especially in the morning. With quite a bit of insolation during
the daytime hours, highs will breach 40 degrees across the
entire CWA, topping off near 50 degrees in portions of northern
KY and southern OH. This will lead to pavement temps becoming
quite warm during the day, perhaps even into the 60s. This may
play a role later when snowfall potential increases. During the
afternoon hours, rain will begin to push in from the south as a
low pressure system tracks northeastward through the Tennessee
Valley. As we head into the evening hours, falling temperatures
will allow snow to begin mixing in across our northwestern
counties. One of the biggest uncertainties with this event is
forecasting how quickly thermal profiles cool to allow for a
complete transition to snowfall. Models continue to suggest the
formation of a deformation band, which creates a narrow band of
higher QPF. Dynamic cooling from the higher precip rates may
lead to a faster transition to all snowfall for a portion of our
CWA, but where exactly this occurs still varies quite a bit in
models. And while the warmer daytime pavement temps may
initially inhibit snowfall accums, the ripping rates may allow
for this to be quickly overcome.

For this event Monday night, have kept the higher snowfall axis
around the I-71 corridor, but increased snow totals NW of I-71.
With room to change, have a broad area of 1-3" of snowfall for
this area, trending below 1" as you get closer to the Ohio
River. Hi-res model guidance may help provide more insight on
the higher QPF/snowfall axis as locally higher amounts of 4" or
so isn`t out of the realm of possibilities, especially if
intense banding occurs.

Some lingering snow SE of I-71 is possible Tuesday morning
before the precip axis shifts eastward with the surface low.

Still over 36 hrs away, not much has changed for days with the axis of accumulations jiggling back and forth centering on 71 corridor. More jiggles to come from the not so good long ranges of the short range models . Don’t particularly like the trend of the low reaching west Tennessee/kentucky , would keep temps up a bit longer Monday evening. We’ll just have to follow the lows every move tomorrow afternoon and evening.

The NBM has the sweet spot right over the tri-state.

Good Morning and seems the Nam is showing a quick hit of snow. The good thing is timing at night so that always helps. Keeping the forecast the same. Still probably 30 hours away from the system starting to hit us with rain at first. Now cast will be very important along with surface reports and of course having folks on our forum report in but having it at night the amount of folks able is less

12Z HRRR has the best snow from I-71 and points SE. 12Z NAM and 9Z RAP also concur.9Z SREF has CVG now dead on at 2". 2.5" for HAO and 3" for MGY. 4" along and north of I-70 corridor.