Pittsburgh/Western PA WINTER ‘25/‘26

[MikeB_01]

5 minutes ago, colonel717 said:

am I mis seeing it? Are those all good?

[southpark]

2 minutes ago, MikeB_01 said:

am I mis seeing it? Are those all good?

Looks that way to me. Looks like we can't go wrong with any of them.

[Burghblizz]

7 minutes ago, colonel717 said:

I was deducting the 5 hours like I do from models thinking it was 10pm. I guess this is actual time which stinks and means I have to stay up.

You are right about that - it’s actually 10 PM Sunday. Same idea though - would be nice to get that kind of icing on the cake late in the storm. 

[colonel717]

33 minutes ago, MikeB_01 said:

am I mis seeing it? Are those all good?

50 for 50... All good. Been consistently that way for couple days.

[Mailman]

.DISCUSSION...
KEY MESSAGE 1...
The Winter Storm Warning continues. Significant snow
accumulations are still forecast, but sleet and freezing rain
chances have increased in the ridges, particularly in northern
West Virginia.

The large-scale pattern as advertised by the model suite has 
not changed significantly with the upcoming winter storm. An 
Arctic cold front currently dropping across the region with a 
thin band of snow showers will have the main impact of 
introducing a very cold air mass back to the region. Upstream, 
shortwaves originating over the northern Plains and southern 
Rockies will begin to phase as they approach the Mississippi 
River Valley Sunday/Sunday night. Surface low pressure develops 
along the Gulf Coast Saturday night and lifts northeastward on 
Sunday, eventually handing off to a developing Atlantic Coast 
low by Monday morning. Inverted troughing pokes northward into
the Middle and Upper Ohio Valley Saturday night and Sunday. On
the eastern side of this, southeast flow and a decent southerly
850mb jet will support warming aloft mainly to the south and
east of Pittsburgh on Sunday. With increased confidence in this,
greater coverage and amounts of freezing rain and sleet have
been introduced. This is particularly true in the higher 
terrain of northern West Virginia, where one to two tenths of
ice accretion may occur, along with a period of sleet. This has
cut down the snow accumulations in this region. 

Overall, moisture and lift remain impressive overall with this
system. We still expect a coupled upper jet structure, layered
frontogenesis, and the inverted trough to support strong lift.
Precipitable water is forecast to reach around the 90th
percentile level as compared to late January climatology as
well. So, overall liquid equivalent totals of 1 to 2 inches are
still a good bet. With the further northward extent of warm air
aloft, snow-to-liquid ratios have trended down slightly, which
was the main factor in lowering storm total snowfall amounts.
Nevertheless, a widespread significant snowfall is still
forecast across the region with high confidence.

Here are the latest 48-hour ensemble-based probabilities for
48-hour snow totals through 7 AM Monday. They are similar to
previous model runs overall, but probabilities for the higher-
end accumulations have decreased slightly:

15":10-50% 
12":50-80% 
8": 75-95%
6": 85-100% 
4": 95-100% 

Given the lower expected SLRs, there remains a decent chance of
a heavier, wetter snow, especially near and south of Pittsburgh.
Also, given low SLRs and increased chances for freezing rain,
the chance of power outage impacts is increasing in the higher
elevations, particularly in northern West Virginia. We will 
need to continue to monitor precipitation-type trends and 
adjust accordingly. However, there is high confidence in Winter
Storm Warning-level impacts in any case. The timing of the
heaviest snow still appears to be during Sunday morning south of
I-70, and late morning Sunday through Sunday evening north of
I-70. Cold northwesterly flow and the crossing parent upper 
trough could result in lingering snow into Monday.

Continue to monitor the latest forecasts as this system
approaches, as widespread impacts to travel and daily life are
highly likely Sunday into Monday.

[colonel717]

[TheClimateChanger]

53 minutes ago, Burghblizz said:

What’s interesting is that is actually early Monday morning. Doubt that exact thing happens - but directionally the GFS is saying that if we get the prolonged back end, there could be some high ratio snows. 

3Z Monday is 10 pm Sunday [5 hours ahead], so that would be between 9 & 10 pm on Sunday.

[TheClimateChanger]

What time is the snow supposed to start? Looks like maybe some areas of light snow by 8 or 9 pm, but heavier and steadier snow holding off more towards 1 or 2 am?

[Burghblizz]

8 minutes ago, TheClimateChanger said:

3Z Monday is 10 pm Sunday [5 hours ahead], so that would be between 9 & 10 pm on Sunday.

Yeah I said that in a follow up. It’s Z

[Mailman]

18z HRRR looks real promising.

[southpark]

15 minutes ago, Mailman said:

.DISCUSSION...
KEY MESSAGE 1...
The Winter Storm Warning continues. Significant snow
accumulations are still forecast, but sleet and freezing rain
chances have increased in the ridges, particularly in northern
West Virginia.

The large-scale pattern as advertised by the model suite has 
not changed significantly with the upcoming winter storm. An 
Arctic cold front currently dropping across the region with a 
thin band of snow showers will have the main impact of 
introducing a very cold air mass back to the region. Upstream, 
shortwaves originating over the northern Plains and southern 
Rockies will begin to phase as they approach the Mississippi 
River Valley Sunday/Sunday night. Surface low pressure develops 
along the Gulf Coast Saturday night and lifts northeastward on 
Sunday, eventually handing off to a developing Atlantic Coast 
low by Monday morning. Inverted troughing pokes northward into
the Middle and Upper Ohio Valley Saturday night and Sunday. On
the eastern side of this, southeast flow and a decent southerly
850mb jet will support warming aloft mainly to the south and
east of Pittsburgh on Sunday. With increased confidence in this,
greater coverage and amounts of freezing rain and sleet have
been introduced. This is particularly true in the higher 
terrain of northern West Virginia, where one to two tenths of
ice accretion may occur, along with a period of sleet. This has
cut down the snow accumulations in this region. 

Overall, moisture and lift remain impressive overall with this
system. We still expect a coupled upper jet structure, layered
frontogenesis, and the inverted trough to support strong lift.
Precipitable water is forecast to reach around the 90th
percentile level as compared to late January climatology as
well. So, overall liquid equivalent totals of 1 to 2 inches are
still a good bet. With the further northward extent of warm air
aloft, snow-to-liquid ratios have trended down slightly, which
was the main factor in lowering storm total snowfall amounts.
Nevertheless, a widespread significant snowfall is still
forecast across the region with high confidence.

Here are the latest 48-hour ensemble-based probabilities for
48-hour snow totals through 7 AM Monday. They are similar to
previous model runs overall, but probabilities for the higher-
end accumulations have decreased slightly:

15":10-50% 
12":50-80% 
8": 75-95%
6": 85-100% 
4": 95-100% 

Given the lower expected SLRs, there remains a decent chance of
a heavier, wetter snow, especially near and south of Pittsburgh.
Also, given low SLRs and increased chances for freezing rain,
the chance of power outage impacts is increasing in the higher
elevations, particularly in northern West Virginia. We will 
need to continue to monitor precipitation-type trends and 
adjust accordingly. However, there is high confidence in Winter
Storm Warning-level impacts in any case. The timing of the
heaviest snow still appears to be during Sunday morning south of
I-70, and late morning Sunday through Sunday evening north of
I-70. Cold northwesterly flow and the crossing parent upper 
trough could result in lingering snow into Monday.

Continue to monitor the latest forecasts as this system
approaches, as widespread impacts to travel and daily life are
highly likely Sunday into Monday.

1 to 2 inches of QPF. Fantastic.

[colonel717]

NAM way south with mix over Tennessee a good 50-75 miles.  

[colonel717]

1 minute ago, southpark said:

1 to 2 inches of QPF. Fantastic.

QPF is the key so we are good even though totals might not be as much. Fluffy dry snow while easier to shovel settles in a day or two and we're pretty much where we'd be with lower ratios. Fluffy snow looks better for our totals, but lower ratio snow looks better for our base.

[colonel717]

[jwilson]

4 minutes ago, TheClimateChanger said:

What time is the snow supposed to start? Looks like maybe some areas of light snow by 8 or 9 pm, but heavier and steadier snow holding off more towards 1 or 2 am?

NAM says 10 PM give or take an hour, and logs an inch by 3 AM.

GFS holds back a bit more and says up to an inch at 5 AM.  Starts around the same time but then takes a two-hour break.

These according to Bufkit data.  I'd imagine the best rates are early Sunday and then maybe again overnight into Monday.  We'll get a better idea with the higher resolution models, as has been mentioned.

[Mailman]

[southpark]

7 minutes ago, jwilson said:

NAM says 10 PM give or take an hour, and logs an inch by 3 AM.

GFS holds back a bit more and says up to an inch at 5 AM.  Starts around the same time but then takes a two-hour break.

These according to Bufkit data.  I'd imagine the best rates are early Sunday and then maybe again overnight into Monday.  We'll get a better idea with the higher resolution models, as has been mentioned.

 

[ChalkHillSnowNut]

Hard to fathom how much cold air is gonna be around yet it’s gonna intrude 

[Mailman]

Geez.

 

[dj3]

Primary low looking a little stronger on the 18z Nam?

[colonel717]

Skirting the edge in AGC, is this a DeNAMming

[Ahoff]

Now I’m confused was reading NAM was more south now it looks bad?

[Rd9108]

Just now, Ahoff said:

Now I’m confused was reading NAM was more south now it looks bad?

NAM was never more south. It was colder at first and then the primary held on and went too far north and transfered late. Is it right? Who knows. Looks like we have the usual warm tongue to worry about. RRFS looks better and maybe the hi rez will be better as well.

[colonel717]

3 minutes ago, Ahoff said:

Now I’m confused was reading NAM was more south now it looks bad?

Yep. It was way south but it got stronger and that brought it more north. Skirting the line. But we still do very well in AGC.

[Burghblizz]

We’ll see if it holds on to this at 0Z. I wish for the southern guys it pulled back a little on the tongue - but I still think everyone is fine given it’s about the most north guidance there is.

Totals should still look pretty NAMMY for most. 

[MikeB_01]

Primary for the NAM was stronger. That allowed it to amplify a little more. 

[colonel717]

[Rd9108]

10 minutes ago, colonel717 said:

I mean its very close to comfort. It just makes me nervous that WAA somehow is always undermodeled. Hopefully its different. 

[Rd9108]

3k is colder. 

[colonel717]

3k looks better with a lot of snow left