Pittsburgh, PA/Western PA Fall/Winter Discussion 2022-23

[TheClimateChanger]

14 minutes ago, Ahoff said:

Could be worse.  At least a small shift down and we're in, and if not it might not be heavy snow, but it should still be snow.

Well, this seems a little bit optimistic, no? I don't think anywhere near us is actually going to see "heavy snow" except up by the Lake Erie shoreline.

[TheClimateChanger]

Well... I guess the 18z GFS sees the possibility of up to 24" in northwest Butler County, at least on these inflated Kuchera maps. Although I have no idea how the model is coming up with that amount. The whole map looks bizarre and splotchy.

[TheClimateChanger]

On the Kuchera maps at hour 63, it hasn't even started snowing anywhere near Grove City. Three hours later, it shows 10 inches. Yeah, I don't think that's going to happen. 

[RitualOfTheTrout]

21 minutes ago, TheClimateChanger said:

On the Kuchera maps at hour 63, it hasn't even started snowing anywhere near Grove City. Three hours later, it shows 10 inches. Yeah, I don't think that's going to happen. 

I'd probably just use 10:1 maps from a 24 hour period 12z Friday - 12z Saturday and see what that looks like. That's our most likely period to see accumulating snow I'd say. 

[north pgh]

I still think we are looking at a solid 1-3 and like Trout said it will be blown around so much that there will be grassy areas uncovered but some drifting in spots. At least the ground will be white for Christmas eve with temps in the single digits.

As far as the snow goes it will be a minor event the will all come down early Friday morning and then light snow showers blowing around the rest of the day.

What I am looking forward to is the extreme change and temps when the front comes thru.  I am old enough to remember a front in the mid to late 70's when I was in high school where we had white out conditions for an hour or so and the temp dropped from the 40's to single digits in several hours. I remember it was hard to look out our kitchen windows because the wet spots froze up with the quick temp change. 

I say make sure you are up Friday morning and watch the front come thru. Who knows, you might even hear a clap of thunder. 

 

[olafminesaw]

13 minutes ago, RitualOfTheTrout said:

I'd probably just use 10:1 maps from a 24 hour period 12z Friday - 12z Saturday and see what that looks like. That's our most likely period to see accumulating snow I'd say. 

I agree. People knock 10:1 maps, but it's really much better for comparing run to run differences. Even so it probably will have some changeover timing issues, with how quick the front is moving through.

[Ahoff]

1 hour ago, TheClimateChanger said:

Well, this seems a little bit optimistic, no? I don't think anywhere near us is actually going to see "heavy snow" except up by the Lake Erie shoreline.

Well, the risk of heavy snow is not far away, and it doesn't discount the possibility of a brief period of heavy snow as the cold air collapses in.  I don't think anyone is expecting a foot of heavy snow.  It's just saying the risk is there.  We'll still likely see some snow, let's just enjoy that possibility.

[Ahoff]

1 hour ago, Rd9108 said:

I'd take this although probably a little over done

Realistically do we want this to trend to be stronger or what's our best case here lol.

If the secondary trends stronger, wouldn't it cause the upper atmosphere to cool quicker for us and allow temps to drop even before the front moves in?

[RitualOfTheTrout]

30 minutes ago, olafminesaw said:

I agree. People knock 10:1 maps, but it's really much better for comparing run to run differences. Even so it probably will have some changeover timing issues, with how quick the front is moving through.

I usually just look at total qpf after sounding supports snow. When we get closer in time sometimes bufkit / Cobb data etc. Skew-ts are a great visual of the column and lift in the dgz. All the snow algorithms have their issues and work best under a certain situations. Throw in temporal resolution issues in change over situations (think a model sounding supports snow at hour 3 and so assumes everything that falls between hour 3 and 6 is snow when in reality a warm nose punches through at hour 4) and you have a recipe for disappointment.

Don't get me wrong, I love to look at those maps when they show a big hit and if I'm in a hurry they are a good summary of what the model shows but especially in marginal temperatures and change over situations need a few grains of salt.

[Rd9108]

Ehh going to bed now since I gotta be up at 2 but my guess is 1-2 with one more likely. Who knows once the front comes through if we get any Lake effect or a sneaky wave but the storm itself looks like it gets going too late which cuts back the backend snow. Unless this changes I don't see us getting anything more than maybe a coating-inch.

[TimB]

The other shoe has finally dropped. GFS is coming in line with other models on our lack of snow potential. Ceiling can’t be more than an inch and a half.

[Rd9108]

I'd take this and run 

 

[olafminesaw]

TBH, we may not really know how much will fall until about 8-12 hours before the event. Mesoscale models will be key. It does seem that the door has been closed on more than 3" though 

[olafminesaw]

This is a weenie model, but it shows the potential that exists for some really heavy snow at the backend of the front. Even if it's short lived, it could get us to 2" in short order. I do suspect that moisture will be cut off quickly, once any dynamic lift shuts off.

[Rd9108]

Maybe it back builds somehow lol. That's usually how we overperform. 

[Ahoff]

That NAM total looked decent.  Still "long range" NAM, but not 84 hours at least.

[Gordo74]

I'll go back to my original comment. White Christmas with an inch or two on the ground, anything after that is gravy.

[RitualOfTheTrout]

1 hour ago, olafminesaw said:

TBH, we may not really know how much will fall until about 8-12 hours before the event. Mesoscale models will be key. It does seem that the door has been closed on more than 3" though 

I agree, other than a quick cursory check its not worth over analyzing anything until tomorrow afternoon / evening. 

[Ahoff]

Storm aside, very sad day for Pittsburgh.  RIP to Franco Harris.  Will be a much different event at the game on Christmas Eve.

[MikeB_01]

I always like the check the SREFs. Not the most reliable, but still fun to look at.

 

Hovering right around 1" of snow.  All falling with the passage of the front. The temps will be brutal by midday and not much change for 48 hours. Very impressive for December.

[TimB]

Looks like the NWS got their excuse not to put up Friday snowfall maps yet, with the small amount of front end ice in the higher elevations tomorrow being the threat their maps address. Typical.

[jwilson]

Should have relocated to Buffalo this year.  Some places are going to have upwards of 200" and it's not even January.

[jwilson]

As for this storm, GFS ensemble plumes suggest a quick inch of snow of the anafront variety.  Maybe a little more additional (0.5") from lingering snow showers.  That's more or less inline with the OP.

It's going to come down to nowcasting because of potential resolution issues on the models, and I imagine the temp change / gusting winds will limit dendrite growth somewhat.  That's a -40F temp departure and winds of up to 20 kts.

[Ahoff]

NWS won't even give us a wind chill advisory, lol.  We'll have 0 degree temps and 50 mph winds, but no advisory, crazy.

[TimB]

3 minutes ago, Ahoff said:

NWS won't even give us a wind chill advisory, lol.  We'll have 0 degree temps and 50 mph winds, but no advisory, crazy.

NWS will give us a wind chill advisory. I give that a 99% chance. Wind chill is progged to be below the -10 threshold for like 24 hours straight at PIT.

[olafminesaw]

47 minutes ago, Ahoff said:

NWS won't even give us a wind chill advisory, lol.  We'll have 0 degree temps and 50 mph winds, but no advisory, crazy.

At minimum it's 36 hours lead time. So probably they will go up this evening or tommorow morning 

Edit: at maximum 36 hours

[TimB]

Just now, olafminesaw said:

At minimum it's 36 hours lead time. So probably they will go up this evening or tommorow morning 

CTP hoisted a wind chill watch this afternoon so I anticipate PBZ could possibly do the same for continuity.

[TimB]

Looking a little longer range, there’s a solid chance the final day of the year will get above 50 for the 8th(!) time this century. Almost coin flip territory these days.

[MikeB_01]

1 hour ago, TimB said:

NWS will give us a wind chill advisory. I give that a 99% chance. Wind chill is progged to be below the -10 threshold for like 24 hours straight at PIT.

Wind chill watch was just issued.

[MikeB_01]

1 minute ago, MikeB_01 said:

Wind chill watch was just issued.

URGENT - WINTER WEATHER MESSAGE
National Weather Service Pittsburgh PA
235 PM EST Wed Dec 21 2022

...A STRONG WINTER STORM WILL CREATE MULTIPLE HAZARDS ACROSS THE 
REGION...

PAZ007>009-013>016-020>022-029-031-073-075-WVZ001>004-012-021-509-
220345-
/O.NEW.KPBZ.WC.A.0001.221223T1100Z-221224T1800Z/
Mercer-Venango-Forest-Lawrence-Butler-Clarion-Jefferson PA-Beaver-
Allegheny-Armstrong-Washington-Greene-Westmoreland-Fayette-
Hancock-Brooke-Ohio-Marshall-Wetzel-Marion-Monongalia-
Including the cities of Grove City, Latrobe, Weirton, Kittanning,
Murrysville, Punxsutawney, New Castle, Canonsburg, Fairmont,
Ambridge, Franklin, Sharon, Ford City, Butler, Lower Burrell,
Morgantown, Tionesta, Washington, Monessen, Monaca, Wellsburg,
Brookville, Waynesburg, Wheeling, Oil City, Hermitage, Clarion,
New Martinsville, Aliquippa, Moundsville, Greensburg, Uniontown,
Pittsburgh Metro Area, Ellwood City, Beaver Falls, Follansbee,
and New Kensington
235 PM EST Wed Dec 21 2022

...WIND CHILL WATCH IN EFFECT FROM FRIDAY MORNING THROUGH SATURDAY 
AFTERNOON...

* WHAT...Dangerously cold wind chills possible. Wind chills as low 
  as 20 below zero. Wind gusts of 40 to 50 mph are expected Friday 
  through Saturday afternoon.

* WHERE...Portions of northwest, southwest, and western 
  Pennsylvania. Portions of northern and the northern panhandle of 
  West Virginia.

* WHEN...From Friday morning through Saturday afternoon.

* IMPACTS...The dangerously cold wind chills could cause frostbite 
  on exposed skin in as little as 30 minutes. Strong winds could 
  produce damage to trees and power lines, resulting in scattered 
  power outages.

Winds may gust over 40 mph Friday afternoon through Saturday evening.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Monitor the latest forecasts and warnings for updates on this 
situation.