Western Pa / Pittsburgh area Winter Discussion ❄️☃️

[Ahoff]

19 minutes ago, TimB84 said:

GFS has stopped the bleeding with the SE shift, which is good.

NWS still wants to keep the “heavy at times” wording in for both tomorrow and tomorrow night in our area, despite forecasting only 2-3 inches of snow. 

Yeah, that seems odd to me.  I imagine they are erring on the side of caution with crazy totals, which is what made the initial 6-8" call they had all the more crazy.

The mesos look good to me.  They're not spitting out high amounts, but looking at temperatures we should have some higher ratios that can boost the totals.  Also, for as long as the NAM 12km and NAM 3km have it snowing the lower totals seem too low.  I don't know, we'll see.

[jwilson]

Current model snowfall amounts across Allegheny county with lower totals northwest, higher southeast:

SREF Plumes: Mean - 5" (ranging from ~3" to a little over 8")

UKMET: 4" to 5.5"

NAM: 2" to 4.5"

GFS: 2" to 4"

Para-GFS: 1.5" to 3"

RGEM: 1.5" to 2"

CMC: 1" to 2"

Euro: 1" to 1.5"

Mesoscale Suite - 

HRW WRF-NSSL: 2.5" to 4.5"

WRF-ARW2: 3" to 4"

WRF-ARW: 2.5" to 4"

HRW-NMMB: 2" to 4"

HRRR: 2.5" to 3"

HREF Mean: 2.5"

HRDRPS: 0.5" to 1.5"

Given the spread of 0.5" to 5" or so, landing right in the middle at 2.5" to 3" seems like a fair measure.  That's where the majority of the models land.  UKMET and SREFs are the high-end outliers, with the latter typically overdone anyway.  Also, important to keep in mind on a number of these, the higher end totals only register in the extreme southeastern area of Allegheny.

Tomorrow morning looks like the best chance for heavier rates, and it is when we could pick up 50% or more of our end total in just a couple hours.  Add on hours of "mood flakes" afterward.  We have a northern stream kicker and dry air intrusion to contend with, plus the best forcing remains well south and east of our area.

[SteelCity87]

Feels like even small adjustments to track could add a good bit with this one for sure. 

[TimB]

54 minutes ago, Ahoff said:

Yeah, that seems odd to me.  I imagine they are erring on the side of caution with crazy totals, which is what made the initial 6-8" call they had all the more crazy.

The mesos look good to me.  They're not spitting out high amounts, but looking at temperatures we should have some higher ratios that can boost the totals.  Also, for as long as the NAM 12km and NAM 3km have it snowing the lower totals seem too low.  I don't know, we'll see.

If you told me last night our eventual total would be 1” or less, I would have agreed. I’m not so sure I do now. It’s definitely not a warning level event but it’s probably at least borderline advisory, especially if the highest rates are centered around a rush hour. 
This goes back to the NWS’s idea of “how do we message this so as not to confuse the general public?” that we’ve been talking about all week. Because the general public, especially in Pittsburgh sees “2-3 inches” and thinks, “that’s nothing, it might be a minor inconvenience to me but not much more, and besides, the NWS was badly wrong last time,” whereas if they see “2-3 inches with the heaviest rates centered around the evening rush” (though I don’t think that’s when we get the best rates, even if that’s what NWS implies), then a little more caution is involved. Because we know that a quick 2-3 inches at rush hour will cripple the evening commute around here.

[Ahoff]

5 minutes ago, TimB84 said:

If you told me last night our eventual total would be 1” or less, I would have agreed. I’m not so sure I do now. It’s definitely not a warning level event but it’s probably at least borderline advisory, especially if the highest rates are centered around a rush hour. 
This goes back to “how do we message this so as not to confuse the general public?” Because the general public, especially in Pittsburgh sees “2-3 inches” and thinks, “that’s nothing, it might be a minor inconvenience to me but not much more, and besides, the NWS was badly wrong last time,” whereas if they see “2-3 inches with the heaviest rates centered around the evening rush” (though I don’t think that’s when we get the best rates, even if that’s what NWS implies), then a little more caution is involved. Because we know that a quick 2-3 inches at rush hour will cripple the evening commute around here.

I certainly wouldn't have said that, lol.  We were still in a decent space for a few inches yesterday, hell the snow all day yesterday amounted to a sneaky 1.6".  2" should be pretty easy to achieve, but anything can happen.

[TimB]

1 hour ago, Ahoff said:

I certainly wouldn't have said that, lol.  We were still in a decent space for a few inches yesterday, hell the snow all day yesterday amounted to a sneaky 1.6".  2" should be pretty easy to achieve, but anything can happen.

I would say I went to bed last night thinking there was a very real possibility if not likelihood that yesterday would officially be the snowiest day of this week. It’s still a possibility, but a lot less likely.
 

Edit: this was before I saw the 12z Euro.

[dj3]

Pretty disappointing end to an awesome period of tracking over the last month or so. I was thinking we had a chance at something big coming out of a long -AO, -NAO pattern but didn't catch the breaks this time. 

[Ecanem]

The NAM is a good 50+ miles north of both the GFS and the Euro as well as it has a much broader precipitation shield.  

Actually looking at the 12z model suites.  NAM and HRRR are further north and again much broader precip shield whereas Euro has a huge cutoff and even leaves central PA out to dry.  

It's pretty amazing again how inconsistent these models are this close to the storm.  

[Ahoff]

4 minutes ago, Ecanem said:

The NAM is a good 50+ miles north of both the GFS and the Euro as well as it has a much broader precipitation shield.  

Actually looking at the 12z model suites.  NAM and HRRR are further north and again much broader precip shield whereas Euro has a huge cutoff and even leaves central PA out to dry.  

It's pretty amazing again how inconsistent these models are this close to the storm.  

Mesos are better for close range.

[TimB]

So the NWS thinks most of Allegheny County gets 3-4” of snow (so low end advisory level), but isn’t confident enough to issue an advisory. That doesn’t bode well.

[Ahoff]

21 minutes ago, TimB84 said:

So the NWS thinks most of Allegheny County gets 3-4” of snow (so low end advisory level), but isn’t confident enough to issue an advisory. That doesn’t bode well.

It is odd, because they bumped the range from 2-3" to 3-4", added some southern counties into advisories, and the point and click has Thursday as snow and Thursday night as heavy snow, but nothing.  They are truly baffling.  To me snow and heavy snow for most of tomorrow would indicate at least advisory level snow.  Very interesting, but really not surprising.

[north pgh]

19 minutes ago, TimB84 said:

So the NWS thinks most of Allegheny County gets 3-4” of snow (so low end advisory level), but isn’t confident enough to issue an advisory. That doesn’t bode well.

Agreed that these models can't come to an agreement. 1-5 inches is a broad range on the models.

For those of you that like the Short term 18 HRRR it looks a little better than most for our area. It looks like there is a first batch of snow that starts after midnight and gives us an inch or two by morning. Then after a break in the morning some more light snow moves in during the afternoon giving us another 1-2 inches. This would give pretty much everyone in Allegheny County 3 inches by tomorrow night. At this point I would be okay with that. 

I know this model changes hour to hour but I take more faith in this model as we are this close to the storm time. Regardless, snowflakes will be flying most of the day tomorrow so I will enjoy what falls. 

 

[north pgh]

3 minutes ago, Ahoff said:

It is odd, because they bumped the range from 2-3" to 3-4", added some southern counties into advisories, and the point and click has Thursday as snow and Thursday night as heavy snow, but nothing.  They are truly baffling.  To me snow and heavy snow for most of tomorrow would indicate at least advisory level snow.  Very interesting, but really not surprising.

I think that if things play out we may upgrade to an advisory if rush hour is bad. This is part of the AFD:

Bordered this with an advisory for 3-6 inches of accumulation from
eastern Westmoreland southwest to Wetzel. 3 inch/12 hour criteria is
borderline in this area, but impact to morning commute can also
justify this advisory. Would not be surprised if advisory needs a
northern expansion as we get closer to the event.

[RitualOfTheTrout]

46 minutes ago, TimB84 said:

So the NWS thinks most of Allegheny County gets 3-4” of snow (so low end advisory level), but isn’t confident enough to issue an advisory. That doesn’t bode well.

This is the criteria for an advisory:

A winter storm event (sleet, snow, freezing rain, snow and blowing snow, or a combination of events) is expected to meet or exceed local winter weather advisory criteria in the next 12 to 36 hours but stay below warning criteria. Criteria for snow is 4 inches or more in 12 hours or less covering at least 50 percent of the zone or encompassing most of the population. Use "mid-point" of snowfall range to trigger advisory (i.e 2 to 5 inches of snow = advisory). Criteria for ice is any ice accumulation less than 1/2 inch over at least 50 percent of the zone or encompassing most of the population. Winter Weather Advisory can also be issued for black ice. This is optional.

Given the significant NW cutoff will create a steep gradient that will bisect Allegheny county I wouldn't be confident that 50 percent of the county sees 4 inches or more based on current guidance would you? Now my understanding is these rules aren't absolute, they can for example take into account time of day (evening / morning commute) or be more likely to issue an advisory for the first snow of a season etc. Based on the text in the discussion and the fact we probably see the biggest amounts overnight into the morning commute and it's likely the city gets at least 3 inches they will probably expand to include Allegheny unless as we draw closer the short term models lower totals further.

I don't get all riled up over what the NWS posts for any area in terms of warning / advisory etc. It doesn't affect what we actually get and usually they err on the side of issuing something to raise awareness over doing nothing.

 

[TimB]

8 minutes ago, RitualOfTheTrout said:

This is the criteria for an advisory:

A winter storm event (sleet, snow, freezing rain, snow and blowing snow, or a combination of events) is expected to meet or exceed local winter weather advisory criteria in the next 12 to 36 hours but stay below warning criteria. Criteria for snow is 4 inches or more in 12 hours or less covering at least 50 percent of the zone or encompassing most of the population. Use "mid-point" of snowfall range to trigger advisory (i.e 2 to 5 inches of snow = advisory). Criteria for ice is any ice accumulation less than 1/2 inch over at least 50 percent of the zone or encompassing most of the population. Winter Weather Advisory can also be issued for black ice. This is optional.

Given the significant NW cutoff will create a steep gradient that will bisect Allegheny county I wouldn't be confident that 50 percent of the county sees 4 inches or more based on current guidance would you? Now my understanding is these rules aren't absolute, they can for example take into account time of day (evening / morning commute) or be more likely to issue an advisory for the first snow of a season etc. Based on the text in the discussion and the fact we probably see the biggest amounts overnight into the morning commute and it's likely the city gets at least 3 inches they will probably expand to include Allegheny unless as we draw closer the short term models lower totals further.

I don't get all riled up over what the NWS posts for any area in terms of warning / advisory etc. It doesn't affect what we actually get and usually they err on the side of issuing something to raise awareness over doing nothing.

 

Ah, that’s where I was mistaken. Somewhere along the line I believed 3” was an advisory here. And no, I don’t have confidence that any part of Allegheny County gets 4”. I think it’s possible in some SE areas of the county, but not with any confidence.

Maybe I’m getting confused because my mind’s current threshold between “this storm sucked” and “this storm didn’t suck” is at about 3”.

[RitualOfTheTrout]

Nothing to add outside what has already been said for the upcoming event.

On a side note, took a walk late this morning and it was in the teens, but the sun was out. I could feel the warmth through all the layers and the cold air, even saw some areas of snow melting. Snow pack retention portion of the season is nearly at an end. It's been great having all these days below freezing and overcast. It's nice only having to dry the dogs paws off from some melted snow rather than trying to clean mud when they come in and out.

March has to be my least favorite month aside from it being cutoff low season which can produce some interesting storms. Outside of something special its really a blah month.

[RitualOfTheTrout]

2 minutes ago, TimB84 said:

Ah, that’s where I was mistaken. Somewhere along the line I believed 3” was an advisory here.

Gotcha, yeah that would make all the difference. NWS has a page with all the definitions / criteria for our area for all the different headlines they issue: https://www.weather.gov/pbz/winterterms

[TimB]

5 minutes ago, RitualOfTheTrout said:

March has to be my least favorite month aside from it being cutoff low season which can produce some interesting storms. Outside of something special its really a blah month.

This. It’s essentially April, except sometimes instead of getting 1-2” inches of snow overnight that melts before noon the next day, you can sometimes get 4-8” of snow that melts before noon (think 2018).

[Ecanem]

Welp. It’s a WWA. We can expect about .5” of snow (this is sarcasm) 

[dj3]

40 minutes ago, RitualOfTheTrout said:

Nothing to add outside what has already been said for the upcoming event.

On a side note, took a walk late this morning and it was in the teens, but the sun was out. I could feel the warmth through all the layers and the cold air, even saw some areas of snow melting. Snow pack retention portion of the season is nearly at an end. It's been great having all these days below freezing and overcast. It's nice only having to dry the dogs paws off from some melted snow rather than trying to clean mud when they come in and out.

March has to be my least favorite month aside from it being cutoff low season which can produce some interesting storms. Outside of something special its really a blah month.

I was pleasantly surprised how well we maintained snow pack during the days leading up to Monday night. Overcast and cold temps makes a difference for sure. I'll still enjoy lighter events if we get them in March but if we're not tracking a big storm I wouldn't be upset about a quicker flip to spring.

[TimB]

1 hour ago, dj3 said:

I was pleasantly surprised how well we maintained snow pack during the days leading up to Monday night. Overcast and cold temps makes a difference for sure. I'll still enjoy lighter events if we get them in March but if we're not tracking a big storm I wouldn't be upset about a quicker flip to spring.

I hope it’s not a third straight year with less than 1.5” of total snowfall beyond March 3rd, but as long as spring is seasonable and not the kind of year where you have to turn the a/c on well before Memorial Day, I can live with that.

[Rd9108]

I like March snowstorms. They seem to overperform for us and we usually don't worry about temps it seems. I remember a few years ago one March storm where we got like 8 inches overnight. Quick hitter but gone in a day. 

[TimB]

9 minutes ago, Rd9108 said:

I like March snowstorms. They seem to overperform for us and we usually don't worry about temps it seems. I remember a few years ago one March storm where we got like 8 inches overnight. Quick hitter but gone in a day. 

Believe it or not, that’s the only time this century and only the second time since the big one that we’ve gotten 6” of snow on a single calendar day in March (3/21/18). 

[CoraopolisWx]

1 hour ago, dj3 said:

I was pleasantly surprised how well we maintained snow pack during the days leading up to Monday night. Overcast and cold temps makes a difference for sure. I'll still enjoy lighter events if we get them in March but if we're not tracking a big storm I wouldn't be upset about a quicker flip to spring.

That freezing drizzle Saturday night put a nice crust on the pack, maybe it survives until the next cold stretch.

[TimB]

8 minutes ago, CoraopolisWx said:

That freezing drizzle Saturday night put a nice crust on the pack, maybe it survives until the next cold stretch.

That’s a tough ask, depends on which model is closer on the extent of warmth later next week. GFS keeps us not terribly far above freezing but the Euro sends our temps soaring. Maybe the snowpack will slow that down too, though.

[stjbeautifulday]

Accuweather says 4-8. NWS says 2-4 in the advisory.  And weather.com point and click says 1-2.   (In Moon).  What a confusing storm. 

[southpark]

1 minute ago, stjbeautifulday said:

Accuweather says 4-8. NWS says 2-4 in the advisory.  And weather.com point and click says 1-2.   (In Moon).  What a confusing storm. 

accuweather just wants the clicks on their site...but I would love it if we got that much...but I don't see it happening...in other news snow is breaking out south of the city much earlier than expected.

[Rd9108]

Srefs are up to about 4 inches. Just padding the stats and we get to enjoy a long duration snowfall. 

[Ahoff]

29 minutes ago, Rd9108 said:

Srefs are up to about 4 inches. Just padding the stats and we get to enjoy a long duration snowfall. 

Well, they were over 6" earlier, so...wrong direction.

[Mailman]

Starting to come down nicely here.