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Jan 11-12 Model/Forecasting Discussion


Ji

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GFS BUFKIT puts the snow growth region at -20 to -12°C... which is actually perfect for dendrite growth.

http://eprints.lib.h...29_p321-335.pdf (see page 326-327)

Its has more to do with how thick that layer is, the temperature below the layer, the omega in the layer, the height of the layer, and the moisture profile in and below the layer.

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:o (This is the responses I got from Earthlight re the Euro ensembles. The 2nd quote is re SLP)

They look pretty good for you guys. I can't really see the precipitation on the ensembles..it's pretty muted as the Euro has like 50 ensemble members. But the surface low tracks from OBX to just off Ocean City, MD. At 96 hours it has precipitation for most of the area with H85 temperatures below zero..the 850 line runs basically directly over OC MD and then off the coast. 32 F line runs through DC or maybe a hair east.

Sub 1004mb at that time off OC..gets to high 990's southeast of LI.

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Hey dudes. Yeah the ensembles are good..similar to the OP. Might be a hair further north if anything. They have shifted more amplified compared to the 12z ensembles, too. The rest was quoted by Yoda.

The one concern would be the primary low going into the OH Valley. But as it stands now the trough digging west to east saves the situation as the H85 temps cool...the coastal deepening offshore is working with us too.

If you guys need any more details, let me know.

Good luck :thumbsup:

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Could be its 3 AM... but 06z NAM looks more amp'd at 36

At this point, I wouldnt care what the 06z NAM shows, though it did look pretty amped up at 00z.

You have the best ensembles (Euro) showing a pretty big hit. Obviously we've seen the issues with the models this year, but at this point, you probably can't ask for much more. The only thing I would be concerned about in the DC area is the primary low going too deep into the OH Valley....but the 5h low kind of does a backhoe dig and prevents the mid-level warming from getting past RIC so in this case you could get away with it, but its something to watch that could change down the road if we get a more amped up vortmax that goes further NW.

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At this point, I wouldnt care what the 06z NAM shows, though it did look pretty amped up at 00z.

You have the best ensembles (Euro) showing a pretty big hit. Obviously we've seen the issues with the models this year, but at this point, you probably can't ask for much more. The only thing I would be concerned about in the DC area is the primary low going too deep into the OH Valley....but the 5h low kind of does a backhoe dig and prevents the mid-level warming from getting past RIC so in this case you could get away with it, but its something to watch that could change down the road if we get a more amped up vortmax that goes further NW.

Definitely makes sense. you wouldn't happen to have a guess at QPF would you? About the same as the OP?

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At this point, I wouldnt care what the 06z NAM shows, though it did look pretty amped up at 00z.

You have the best ensembles (Euro) showing a pretty big hit. Obviously we've seen the issues with the models this year, but at this point, you probably can't ask for much more. The only thing I would be concerned about in the DC area is the primary low going too deep into the OH Valley....but the 5h low kind of does a backhoe dig and prevents the mid-level warming from getting past RIC so in this case you could get away with it, but its something to watch that could change down the road if we get a more amped up vortmax that goes further NW.

Yup...agree on all points. If there's a situation where many can get away with a primary so far northwest..this is it.

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Definitely makes sense. you wouldn't happen to have a guess at QPF would you? About the same as the OP?

QPF looks similar to OP....hard to say since its more smoothed, but its similar. The OP run had some more defined gradient bullseyes. But of course, qpf shouldn't be a concern right now.

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That's a very amped up look on the 84h NAM. That would certainly get pretty good precip into the region. There's kind of "sweet spot" that you are aiming for because this isn't a typical miller A with a trough coming out of the gulf....this is coming in more from the west and trying to dig its grave as it heads east...so it produces the "hybrid" scenario....one decent low in the OH Valley and another on the coast. Again, like Mar 1960.

I'm sure someone like Wes could expand on this idea when he sees it as he has forgotten more than I know on snow setups...especially down there. But there's kind of a slot that you are aiming for with this track since its going through the OH Valley. But I would say the NAM is pretty good...optimal would have the 5h vortmax a little further south, but as is, its not bad.

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Yes it is. The low is over eastern NC...

nam_pcp_084l.gif

Surface low.. is broad on the coast.. with a very small area of 1012 mb just south of nc coast ene of Myrtle Beach.

Look at the surge of warmth at the 850 mb up into central Va. :x

nam_850_084l.gif

850 low over Ohio.....

nam_sl8_084l.gif

Cold though from 1000mb to 850 mb... :x

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Surface low.. is broad on the coast.. with a very small area of 1012 mb just south of nc coast ene of Myrtle Beach.

Look at the surge of warmth at the 850 mb up into central Va. :x

850 low over Ohio.....

Cold though from 1000mb to 850 mb... :x

Its definitely a fine line there. You need the vortmax to rip far enough north to get good forcing int he mid-levels for heavier precip but also don't want the primary to be too strong too far NE into the OH Valley....the further northeast you are like where psuhoffman, Phineas and Chuck are, probably the better. The trajectory of the shortwave makes it kind of an issue for mid-level warming if it goes too strong.

I think where you guys are in RIC want it to stay weaker or be further south initially.

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Its definitely a fine line there. You need the vortmax to rip far enough north to get good forcing int he mid-levels for heavier precip but also don't want the primary to be too strong too far NE into the OH Valley....the further northeast you are like where psuhoffman, Phineas and Chuck are, probably the better. The trajectory of the shortwave makes it kind of an issue for mid-level warming if it goes too strong.

I think where you guys are in RIC want it to stay weaker or be further south initially.

Yea its a head scratcher here in Richmond. I'm not very comfortable with the idea of snow with this dual low structure...

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The 6Z GFS is completely different already through 66 hours. This run may produce a coastal hugger. Hard to say what exactly it will do for DC/BA yet, looks like coastal regions may end up better here.

Actually out to sea too much....needs to be a little more robust, but it still hits with some modest qpf.

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Actually out to sea too much....needs to be a little more robust, but it still hits with some modest qpf.

Yeah I see that now, the upper wave is too flat. I still honestly don't buy the GFS and the way it plows the wave through that ridge and remains so flat and pathetic. GFS op continues to remains a stalwart though.

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Yeah I see that now, the upper wave is too flat. I still honestly don't buy the GFS and the way it plows the wave through that ridge and remains so flat and pathetic. GFS op continues to remains a stalwart though.

Agreed...I'll go with the Euro ensembles at this point...even though that is a cop out. But they are king even in this model-troubled winter. I would actually be worried about a further north and more robust solution. The -NAO is impressive but its in the process of breaking down....we are seeing one of the few breakdowns this winter (then it will probably build back after 7-10 days). But most big snowstorms over the EC occur when the nao breaks down...not when it ramps up.

The Archambault events are when it ramps up to negative, but that is precip and not snow....a lot of the snowstorms were when it went from negative to positive. Or negative to neutral.

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