Central PA Winter 2022/2023

[Blizzard of 93]

The 18z Euro joined the rest of the 18z models with a similar snow line showing.

[Blizzard of 93]

3 minutes ago, Blizzard of 93 said:

The 18z Euro joined the rest of the 18z models with a similar snow line showing.

 

[Blizzard of 93]

The 18z Euro shows a little potential for a light coating of snow on the back end post front.

[Blizzard of 93]

I think it’s just a matter of time until more counties are added to the CTP Advisory.

[GrandmasterB]

I’d pay for the HRRR to be right.  Gets 1” pretty far south and east.  We’ll see how accurate that is.

[Blizzard of 93]

Great start to the 0z runs with the HRRR.

It keeps snow going in the Harrisburg area well into the afternoon.

[Bubbler86]

29 minutes ago, GrandmasterB said:

I’d pay for the HRRR to be right.  Gets 1” pretty far south and east.  We’ll see how accurate that is.

The 3K has been spitting out some nice eastern snow/frozen as well prior to 0Z.  0Z is a bit of a pull back.  For after the snow, the Nam is a small stream and road flash flood flood threat for the MA and LSV.  2-3" across a very large area (including the snow that melts.) 

[canderson]

It went from 42 to 5 within one hour at Denver today. 

[paweather]

Battin down the hatches for a couple of days! 

[GrandmasterB]

HRRR not backing down. Noted

[paweather]

5 minutes ago, GrandmasterB said:

HRRR not backing down. Noted

Good deal look forward to before and after snow 

[GrandmasterB]

4 minutes ago, paweather said:

Good deal look forward to before and after snow 

Looks like it will be another battle of short range mesos vs. globals. Hopefully mesos win out again!

[Blizzard of 93]

56 minutes ago, GrandmasterB said:

HRRR not backing down. Noted

Latest 2z HRRR is getting even better for all of the LSV.

[paweather]

No front end on the GFS but back end produces a trace or so. 

[paweather]

1 minute ago, Blizzard of 93 said:

Latest 2z HRRR is getting even better for all of the LSV.

Let’s hope Blizz! GFS wasn’t to impressive.

[Blizzard of 93]

The 0z GFS looks good for front end snow tomorrow for Harrisburg & York to the north & west.

[paweather]

2 minutes ago, Blizzard of 93 said:

The 0z GFS looks good for front end snow tomorrow for Harrisburg & York to the north & west.

Gotta hope! 

[Blizzard of 93]

2 minutes ago, paweather said:

Let’s hope Blizz! GFS wasn’t to impressive.

Lol, I have no idea what you are looking at for the 0z GFS.

See the maps that I just posted.

This is the best GFS run yet for the front end potential tomorrow.

[Blizzard of 93]

3 minutes ago, Blizzard of 93 said:

The 0z GFS looks good for front end snow tomorrow for Harrisburg & York to the north & west.

Best GFS run yet for Harrisburg & York for the front end.

[Blizzard of 93]

0z Canadian looks very similar to the GFS

[CarlislePaWx]

6 minutes ago, Blizzard of 93 said:

0z Canadian looks very similar to the GFS

I think LSV criteria for WWA for snow is 2-4" range.  5"+ is WSW criteria.  Temp has been hovering just below and above 26 degrees with 26.4 right now.

[Newman]

This 3z HRRR run coming in now is gonna be very very solid for the area

[Newman]

We'll see if this cooling trend continues on the HRRR, or even verifies, but it's definitely not a bad thing to see. 

[Blizzard of 93]

3 minutes ago, Newman said:

We'll see if this cooling trend continues on the HRRR, or even verifies, but it's definitely not a bad thing to see. 

I think rates as always will help the areas that see the best accumulations.

[paweather]

27 minutes ago, Blizzard of 93 said:

Lol, I have no idea what you are looking at for the 0z GFS.

See the maps that I just posted.

This is the best GFS run yet for the front end potential tomorrow.

Yeah gotta hope our area gets some. You’re west than I am. Hope we can get something. 

[Newman]

[Blizzard of 93]

2 minutes ago, Newman said:

Best HRRR run yet..lol, even @paweather will approve of this run!

[MAG5035]

Hard to argue with a pretty decent model consensus getting notable accumulating snow pretty far into the Sus Valley, although I’ve been working on trying to be more cautious with these type of situations there this season after learning the hard way the last couple seasons. I’m still leery southeast of I-81. Comparison of the high res short range guidance shows some differences. HRRR has a much colder column, allowing the widespread snowfall as far into the Sus Valley as it goes. The 3k NAM (not the coarser 12k NAM) definitely isn’t as enthused, and looks pretty close to what CTP has out for a snowmap right now, not showing much at all in the LSV . That particular model erodes 850mb much faster in the Sus Valley and keeps most accumulating snow even out of Harrisburg. Adding to that, here’s what the 0z run of SPC’s HREF has, which looks similar to the 3k NAM. 

So just keeping things in perspective a bit, showing there are some high res short range things that don’t show the explosion of snow in the Sus Valley. I tend to think reality lies somewhere in between, as there should be enough cold to start things as snow in a good portion of the Sus Valley especially if precip gets here in a timely fashion and there are good rates. Top end accums are another thing to get sorted out. A lot of the short range and global guidance have no problem getting high end advisory amounts, with some full blown WSW type amounts in the interior south central counties. Still trying to figure whether I would want to pull the trigger on believing that or not. I do think the current advisory counties should be bumped up from their 1-3” to at least 2-4” with some scattered 5”.. and perhaps getting the 1” line to I-83 with Harrisburg maybe 1-2”. That would be my “safe” call with this. My worry is the HRRR is too cold.. and some of the short range stuff was a couple degrees too cold with the last event. I’m also not completely ruling out the colder, snowier HRRR type solution either. 

[MAG5035]

Switching gears to the post front phase of this storm, really concerned about the combo of the cold and wind. I mentioned this earlier today but I’m going to illustrate. 

With the position of the very deep low, the westerly flow transports the arctic air from the north-central states underneath the lakes, meaning the unfrozen lakes aren’t going to modify the air via a NW flow like if this had been say.. a major coastal low lifting up the coast. It obviously does no good for much snow anywhere in C-PA once past whatever ends up right behind the actual front and maybe some lighter upslope type stuff in the Laurels. It sure will for western NY though, where BUF south probably sees x number of feet of snow again to go with their 40-60mph winds.

At any rate, I really don’t think this is a situation where the cold “modifies” as it gets closer to the time it arrives. On the contrary, I think this is a situation that may be underestimated a bit. I used the 3k NAM for illustration, which is plenty cold showing temps getting below zero in the Laurels/NW PA. That’s also not the coldest frame as by 12z Sat, KAOO and UNV are also below zero with MDT around 5 or so. That’s where the wind has to be considered. I’m still not sure LSV sees crazy winds from this but you combine those temps with even 35-45mph gusts and you easily have wind chill advisory criteria in the whole Sus Valley. 

Here’s the 3k’s wind chills at 12z Sat morning:

And since I mentioned about my worry that the HRRR might be too cold with the front end precip tomorrow, I might as well also mention that the last full HRRR run back at 0z was much colder than even this 3k NAM, having JST at -11ºF, -8 & -6 at AOO and UNV respectively and near 0 temps all the way to H-burg at the end of its range which is only 0z Sat. That is while having 50-60 mph wind gusts in the Laurels/immediately adjacent central with 35-40mph elsewhere at that point. So with all that, wind chills are practically off the charts for this region (nearly -40ºF in the Laurels) and -15 to -20ºF in MDT. I’d say thats probably a bit over the top, but either way I still believe the wind chill watch areas should go to warnings pretty easily, with the rest of the area seeing advisories. 

To put things simply, Friday night into the first half of Christmas Eve is going to be brutal until the wind starts settling down. 

[Wmsptwx]

Ugh