TheClimateChanger

2 minutes ago, KPITSnow said:

Ok that makes more sense.

Yeah, sleet is like 3:1, maybe 4:1. Would take a full inch of precipitation to lay down 3" of sleet. I will say normally when we get sleet, there is at least some mangled snowflakes mixed in. And perhaps the occasional changeover to heavy, wet snow with dynamic cooling of the column during periods of heavier precipitation. So we could get a bit more accumulation than the models are showing. It seems the Pivotal algorithms are set up to completely discard mixed precipitation as snowfall, which is why it keeps showing the razor sharp cutoff from 12+ to little or nothing.

1 minute ago, TimB84 said:

0.25”+ is red. I don’t see any red on that map.

Sorry, I edited my reply. I was still viewing the old map. Refreshed to the new one when I posted.

My edit:

Actually they just changed it. I was wrong. Now they show generally less than a tenth of inch of icing. I had to refresh my browser for the new map.

3 minutes ago, TimB84 said:

That’s significantly less bullish than they were on the ice potential earlier. The previous package had over a quarter inch for much of the metro.

Actually they just changed it. I was wrong. Now they show generally less than a tenth of inch of icing. I had to refresh my browser for the new map.

3 minutes ago, TheClimateChanger said:

It looks like the NWS updated the expected snowfall map. Looks like totals have been bumped up a bit. I think it looks pretty reasonable at the moment. The 2.3 inch amount is for downtown Pittsburgh. The airport would be closer to the 3" line - probably checking in about 2.8 or 2.9 taking this forecast literally. I'd say it looks good, but I might place the initial over/under value for the airport closer to 4". The NWS is also forecasting the potential for 0.2-0.3" of ice through much of the area.

Really I think with the current trends, we could see all zones get bumped up one tier. Might be more in line with a blend of the NAM/GFS at this point. Would also coordinate better with the snowfall map from NWS CLE which has 6-8 in the southern counties.

It looks like the NWS updated the expected snowfall map. Looks like totals have been bumped up a bit. I think it looks pretty reasonable at the moment. The 2.3 inch amount is for downtown Pittsburgh. The airport would be closer to the 3" line - probably checking in about 2.8 or 2.9 taking this forecast literally. I'd say it looks good, but I might place the initial over/under value for the airport closer to 4". The NWS is also forecasting the potential for 0.2-0.3" of ice through much of the area.

I saw this in the Ohio thread from a TV meteorologist in Cleveland. Brings a foot and a half of snow all the way to the Ohio River in eastern Ohio... what model is showing that? I thought this might raise spirits here though. Lol.

I don't really understand why the forecast still has mid and upper 30s on Thursday? Even the warmer NAM has temps below freezing by daybreak, and drops it into the upper 20s during the afternoon Thursday. GFS shows mid 20s Thursday afternoon. If temps are 25-28F, that also calls into question the theory that the ice won't accumulate much at 31F, no?

Probably too late in the game to get to Pittsburgh, but it is now starting to show heavy snow in parts of the NWS office's CWA. Even the much warmer NAM now brings 8-12"+ to Mercer, Venango, and Forest Counties. Far cry from the 3-6" in the WSW. Might be able to get those higher totals to come down another row of counties further south though.

This is one case where the maps that include sleet accumulation are probably more realistic, rather than a sudden decrease from 12" of snow to 0" of snow.

It does try to nose the warmth back up, which pushes the sleet back over Pittsburgh. At 21Z Thursday, its 30F at PIT (versus 31F on the prior run), but Charleston, WV is 10 degrees colder at the same time than the prior run (40F versus 50F).

Oh yeah, it is. Big time. Mix line down near Greene/Washington County border - and this is only early afternoon Thursday!

NAM caving? I haven't even looked at the sensible weather yet, but the 2M temperature at 15Z on Thursday (what is that about 1 PM, I think?) in Pittsburgh is now shown on the 12z run as 27F in Pittsburgh versus 31F at the same time on the 6z run.

4 minutes ago, Floydbuster said:

Woah. That's all of the state being pounded by high accumulations. 

Well, this particular map does include sleet so it’s inflated somewhat due to that in the south. But I liked it because it looks impressive and really screws over the typical north and west crowd. 

5 minutes ago, Burghblizz said:

That boundary is tight. GFS was actually a little colder than 12Z, but didn’t extend the wave of precip as far into Friday. But it largely held serve.

The NAM wasn’t anything great for us, but does get a raging sleet storm pretty close. 

Still think this feels like big hit for NW PA/NE OH. My glimmer of hope is that I have seen the rushing of cold air undermodeled here, similar to the way warm air advecting often is. 

I think that's the one missing variable. If we can get that boundary through, then winds shift to the north. With north winds, the typical warm nose is non-existent at least at the surface which would allow any mode of wintry precipitation to occur over plain rain.

9 minutes ago, RitualOfTheTrout said:

Alright…wtf… who stole the GFS super computer cluster and is running it in their basement with modified physics code?  It can’t be this different from the rest and be correct can it? Lol

That's a depth positive change map, which includes sleet as snowfall... similar to this one from Pivotal:

2 minutes ago, KPITSnow said:

I was honestly hoping that it would put this to bed, but it didn't. AMazing how wildly different the NAM and GFS are.

Why are they so different? I think it was hour 72 or somewhere around there... the NAM had Charleston, WV at 55, and the GFS at 32?

10:1 Ratio:

0z GFS (Kuchera ratio):

The 0z GFS still looks like a decent hit.

Well, alrighty then, better get the generator ready…

59 minutes ago, Floydbuster said:

Hmmm. Not bad but hoping for a few inches more. That map gives me about 6-8 inches.

Here's the updated map through Friday morning. Looks reasonable, except there's a strange band across the SE portion where snowfall suddenly jumps 2+" across no more than like 5 miles.

Not much snow on the NAM, but it does seem to be trending towards a pretty substantial mixed precipitation event. Shows about 1-2" of sleet or sleet/snow mix in the north, with a band of up to an inch of freezing rain through the metro area.

Here's the official NWS forecast through Thursday at 7 PM: