March 13/14th PSU Storm

[Thanatos_I_Am]

Any word on 18z ICON?

[DC2Winston]

2 minutes ago, clskinsfan said:

It really depends where you are and the temps where you are which is effected by elevation. We all have micro climates where we live. And most of us know what to expect in a storm like this. The only thing I am really looking at at this point is QPF and storm track. From there I know what will happen based on my climo.

Speaking of micro-climates, by far the worst for snow I've found living around DMV for 20 years - is Crystal City in Arlington, VA.  Obviously it's close to DCA but still.  Something about that little area is a torching oven.  Very, very rare to seem much snow accum on roads for any length of time. 

[caviman2201]

5 minutes ago, WxUSAF said:

There's plenty of consensus. The apparent differences all appear due to mesoscale features like banding from what I can see. Cyclogenesis and storm track are pretty locked in among the globals. And none of the globals are really going to nail the banding. It's a nowcast thing mostly. This is why snow forecasts are always a range.

Yea, but the range is usually a couple inches... for my location, very close to the R/S line, I could be looking at 2-3" of wet slop that gets vaporized as soon as the March sun rises or 8-10" of mostly snow.  That's a huge difference 36h from onset.

[vinylfreak89]

So after reviewing the models, I think I can tell a bit what is causing the splitting/dryer look. There is a pretty significant trend (150 miles in 4 runs) to slow down the SS feature. This does not really delay the advance of WAA precip as the dynamics for that are way in front. The northern stream feature is barely slowing down and it's this change in orientation that is causing the strength of the southern shortwave and best dynamics to vary slightly. The 12z JMA is an example of everything coming together perfectly and no interference being run by the northern shortwave. The 2 maxes I think are due to the model trying to sense the energy transfer. One thing I think that is poorly modeled that I've seen time and time again is the affect of strong frontogenesis which almost always appears east of modeled. If you remember both the 2/5/10 storm and last year's blizzard, the best dynamics looked to be around the fall line 24-36 hours around game time and they ended up in Baltimore /NE MD. I think we see something similar this go around, but a 25-50 mile west version which put the big cities in the best dynamics. Of course it's impossible to nail down where the best dynamics banding is going to set up, but I think that secondary band is due to an overestimation of the orographic enhancement. I have a suspicion that will end up very close to or just west of the big cities (basically the current dryslot area). The one thing that worries me still is this all coming together for us too late, but at this point, we need to rely on nowcasting for that. 24 hours from now, hopefully we have a solid wall headed at us, not some spotty instability convective blobs like the models show.

Sent from my HTC 10 using Tapatalk

[eurojosh]

6 minutes ago, clskinsfan said:

It really depends where you are and the temps where you are which is effected by elevation. We all have micro climates where we live. And most of us know what to expect in a storm like this. The only thing I am really looking at at this point is QPF and storm track. From there I know what will happen based on my climo.

Even if there are some periods of powder, it will be heavy concrete for most by 2pm...

[baltimoreguy]

Tony Pann from WBAL tweeted the following. I have no idea what it means and think he is a poor forecaster 

To all the forecasters: noticing a big difference in model snow output from private sources and WSI MAX. The Euro and the GEM specifically.

[Amped]

Euro gives me 15 and the GFS gives me 14.  Lotta uncertainty

[clskinsfan]

2 minutes ago, PennQuakerGirl said:

Ah, makes sense! Thank you! <3

And I will add. My area is A LOT easier to forecast for than DC.  My area is always colder. The city usually sits right on the fall line. It is very hard to forecast there. But they still have their own micro climates. Someone NW of DC like Bob knows his climo. And knows he will do much better than DCA. Someone SE of DC knows they will see less. It is actually a pretty amazing weather area that we live in.

[WxUSAF]

2 minutes ago, caviman2201 said:

Yea, but the range is usually a couple inches... for my location, very close to the R/S line, I could be looking at 2-3" of wet slop or 8-10" of mostly snow.  That's a huge difference 36h from onset.

I understand what you're saying, but that difference could be 10 miles or two degrees. You know you're going to be close to the line because the consensus has it close to you.

[hosj III]

In case anyone needs a reminder to the last time we got 6-10" at 32-33 degrees: 

 

[WxMan1]

LWX has done a good job at splitting counties for WW watches and warnings...they need to do the same for N-NW PG and AA Counties.  I mean, the N-NW portions of those counties stand just as good a chance to get warning criteria given their location relative to the fall line.

[WxUSAF]

4 minutes ago, baltimoreguy said:

Tony Pann from WBAL tweeted the following. I have no idea what it means and think he is a poor forecaster 

To all the forecasters: noticing a big difference in model snow output from private sources and WSI MAX. The Euro and the GEM specifically.

Referring to the electronic dumpster fire that is the RPM?

[smokeybandit]

AA county could see totals of a foot in the NW corner and 2" in the SE corner.

 

[Fozz]

12 minutes ago, CARDC79 said:

Speaking of micro-climates, by far the worst for snow I've found living around DMV for 20 years - is Crystal City in Arlington, VA.  Obviously it's close to DCA but still.  Something about that little area is a torching oven.  Very, very rare to seem much snow accum on roads for any length of time. 

College Park is probably just as bad for snow. I've seen snow melt on contact on the sidewalks in late January at 20 degrees. It's like the ground has an oven underneath it.

[WxMan1]

1 minute ago, smokeybandit said:

AA county could see totals of a foot in the NW corner and 2" in the SE corner.

 

Agreed.  Which is why it should be split for Winter weather WWA purposes. 

[Cobalt]

Incredible totals from the WRF-ARW model. Not sure how credible this is however.

[osfan24]

3 minutes ago, Fozz said:

College Park is probably just as bad for snow. I've seen snow melt on contact on the sidewalks in late January at 20 degrees. It's like the ground has an oven underneath it.

I echo this. It's unbelievable. They always seem to get less than areas nearby and it does seem like it's really hard for the snow to stick to concrete surfaces.

[hosj III]

DWD-ICON looks similar to 12z. 30mm ish in DC. Thermals to come.

[osfan24]

Just now, Cobalt said:

Incredible totals from the WRF-ARW model. Not sure how credible this is however.

It's not. It's giving Easton area almost a foot of snow. They will be lucky to get anything. If they get a foot, we all might get 2 lol.

[caviman2201]

2 minutes ago, Cobalt said:

Incredible totals from the WRF-ARW model. Not sure how credible this is however.

I wish it were because seeing some decent totals on the Eastern Shore would make me far more comfortable with my own situation... 

[osfan24]

TWC still going big. Has DC to Bmore in the 12-18. Looks like generally forecasting for 15 inches.

[87storms]

2 minutes ago, osfan24 said:

TWC still going big. Has DC to Bmore in the 12-18. Looks like generally forecasting for 15 inches.

i never really quite understood the point of forecasting that high unless there's model consensus.  better to stay conservative until you get closer to gametime.  i guess they feel pretty comfortable about it.  that said, i remember back in the 90s they would over-predict for the dc to bmore corridor on the regular, not taking into account the fall line.

[WinterWxLuvr]

TWC is just like all the media.  They're more interested in ratings.

[osfan24]

2 minutes ago, 87storms said:

i never really quite understood the point of forecasting that high unless there's model consensus.  better to stay conservative until you get closer to gametime.  i guess they feel pretty comfortable about it.  that said, i remember back in the 90s they would over-predict for the dc to bmore corridor on the regular, not taking into account the fall line.

That's funny because I feel like it's usually the opposite. I feel like even when we get our big ones and there is consensus that it's definitely going down, they start low and continue to increase amounts right up to and even through the storm. That's why I'm surprised they are so bullish, especially with the temp concerns and models showing so many different amounts.

[Cobalt]

NWS 8-12" in NW DC and points west. Up from their previous map

[87storms]

3 minutes ago, osfan24 said:

That's funny because I feel like it's usually the opposite. I feel like even when we get our big ones and there is consensus that it's definitely going down, they start low and continue to increase amounts right up to and even through the storm. That's why I'm surprised they are so bullish, especially with the temp concerns and models showing so many different amounts.

i almost never go to them for snowfall maps.  why even both doing that when you have great local forecasters.  not saying the weather channel doesn't know their ish but i just really don't take them seriously when it comes to localized details.  i actually find accuweather to be pretty good when it comes to getting a general idea about a storm.  fwiw, they have dc in the 6-12" range, though right on the cusp.

[Cobalt]

3 minutes ago, 87storms said:

i almost never go to them for snowfall maps.  why even both doing that when you have great local forecasters.  not saying the weather channel doesn't know their ish but i just really don't take them seriously when it comes to localized details.  i actually find accuweather to be pretty good when it comes to getting a general idea about a storm.  fwiw, they have dc in the 6-12" range, though right on the cusp.

Looked like DC was snugly in the 6-12" zone

[yoda]

Just now, snjókoma said:

12z para GFS

Can you change the map to the NE region and repost?

[Amped]

12 minutes ago, 87storms said:

i never really quite understood the point of forecasting that high unless there's model consensus.  better to stay conservative until you get closer to gametime.  i guess they feel pretty comfortable about it.  that said, i remember back in the 90s they would over-predict for the dc to bmore corridor on the regular, not taking into account the fall line.

NWS is smarter.  12-18" causes mass hysteria,  8-12" people will relax

[snjókoma]

12z GFS para