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February 8 Storm Obs/Discussion


NoVaWx

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Although QPF is rather meager, it looks decent for the higher spots nw of DC up into the MD/PA border on the euro. That's taking into account temps, QPF, and placement of mid level features.

I'd say it's a little better than last night though it still likes its warmth. We're pretty firmly inside the .10 so we could have .15 or so across the region. My graphics are too crude to know for sure.

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I'd say it's a little better than last night though it still likes its warmth. We're pretty firmly inside the .10 so we could have .15 or so across the region. My graphics are too crude to know for sure.

Yeah it looked a little better for your area, but actually cut back in WV a bit. The s/w I thought was a bit better at 00z, but it's not a big deal. It seemed like surface temps dropped to about 35 verbatim by 00z with 850 temps near -4C, so I would think the city could see a 32-33F snow if it came down at a decent clip? I might have to deal with some of the airports when I come in for work tomorrow aftn, which is why I'm sort of interested in it.

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Yeah it looked a little better for your area, but actually cut back in WV a bit. The s/w I thought was a bit better at 00z, but it's not a big deal. It seemed like surface temps dropped to about 35 verbatim by 00z with 850 temps near -4C, so I would think the city could see a 32-33F snow if it came down at a decent clip? I might have to deal with some of the airports when I come in for work tomorrow aftn, which is why I'm sort of interested in it.

I'm very parochial when looking at models nowdays. I'm rooting for the NAM even though I think it overdone.

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Yeah it looked a little better for your area, but actually cut back in WV a bit. The s/w I thought was a bit better at 00z, but it's not a big deal. It seemed like surface temps dropped to about 35 verbatim by 00z with 850 temps near -4C, so I would think the city could see a 32-33F snow if it came down at a decent clip? I might have to deal with some of the airports when I come in for work tomorrow aftn, which is why I'm sort of interested in it.

Oof ! :fulltilt: I'm still keeping the 0.8" I received on Saturday as a best case for this storm, and hoping for better.

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I'm very parochial when looking at models nowdays. I'm rooting for the NAM even though I think it overdone.

LOL, well it's the take what you can get winter. Hopefully you guys get some mood snows. Despite how nice 50F+ temps can be, there is something soothing about the white stuff.

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2" near the PA line in Baltimore, Carroll and Frederick counties seems like a good bet. That said, someone near Westminster is destined to overstate their accums and say they had 3-4".

Probably a safe guess is N&W of I-95 north of DC ... expect anywhere from a trace (near I-95) to up to 2" as one heads NW-ward toward N/N-central MD.

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Probably a safe guess is N&W of I-95 north of DC ... expect anywhere from a trace (near I-95) to up to 2" as one heads NW-ward toward N/N-central MD.

Based on the track of the vort and temperature situation, I don't think the gradient on snowfall will be SW-NE like is often the case (i.e., paralleling I-95), but me closer to E-W, maybe ENE-WSW at most. So I suspect more useful boundaries for snow totals might be Rt-50, I-70, etc...

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Based on the track of the vort and temperature situation, I don't think the gradient on snowfall will be SW-NE like is often the case (i.e., paralleling I-95), but me closer to E-W, maybe ENE-WSW at most. So I suspect more useful boundaries for snow totals might be Rt-50, I-70, etc...

So W of I-95 might do better than E at the same given lattitude?

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So W of I-95 might do better than E at the same given lattitude?

Study this map. Topograhic influence is pretty strong in md during many winter events. You can clearly see the fall line run along the pg, moco, hoco, and aa county lines. Then you get an extra kick in elevation from damascus, mt airy, westminster, and the parrs ridge area.

Generally speaking, anwhere w of the fallline > than areas east with most common setups.

Edit: I want to add some of the reasons behind this too. Many already know this stuff but for those who don't, generally speaking you lose 3 degrees in temp for every 1k feet in elevation gain (called lapse rate). Mt. Airy and Westminster are around 800' in elevation and areas along parrs ridge are up to 1k. I'm at 400' in elevation in Rockville. It doesn't seem like much difference but the elevation change can make a huge difference sometimes. Just think how many times there are marginal surface temps around here? A little elevation change can make a world of difference. While I'm sitting @ 34 here watching flakes melt on contact, my friends in Mt Airy are sitting @ 32 and watching it stick to the roads.

Another thing elevation does is add some lift to the atmosphere (called orographic influence). We generally only think of Garrett Co and lake effect areas for this but the piedmont and parrs can add just enough orographic influence to squeeze out some extra moisture.

Frederick kinda gets shortchanged because of this. You would think that they would do well becuase they are further n&w of dc but Frederick sits in the shadow of the catoctins and parrs depending on whice direction the ll flow is from. It's really cool when you break down the little microclimates around here. Such subtle things can have a pretty decent impact on how things shake out.

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So W of I-95 might do better than E at the same given lattitude?

I think the gradient will be more west-to-east, perhaps ENE-WSW. That said, west is almost always better in our area just because elevation increases that way.

Edit...Grrr, sorry Bristow, my thoughts aren't getting translated into words well here. I think the GRADIENT will be more north-south and the "lines of equal snowfall" will be more west-to-east or perhaps closer to ENE-WSW. Comment about elevation still applies. Sorry for the confusion.

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I think the gradient will be more west-to-east, perhaps ENE-WSW. That said, west is almost always better in our area just because elevation increases that way.

Edit...Grrr, sorry Bristow, my thoughts aren't getting translated into words well here. I think the GRADIENT will be more north-south and the "lines of equal snowfall" will be more west-to-east or perhaps closer to ENE-WSW. Comment about elevation still applies. Sorry for the confusion.

RGR. Got it and thanks. makes more sense now. I was looking at where I am in relation to Wes in MD. I am almost due west of him by about 60 miles near Gainesville. Be interesting to see how the gradient looks tomorrow.

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Study this map. Topograhic influence is pretty strong in md during many winter events. You can clearly see the fall line run along the pg, moco, hoco, and aa county lines. Then you get an extra kick in elevation from damascus, mt airy, westminster, and the parrs ridge area.

Generally speaking, anwhere w of the fallline > than areas east with most common setups.

Edit: I want to add some of the reasons behind this too. Many already know this stuff but for those who don't, generally speaking you lose 3 degrees in temp for every 1k feet in elevation gain (called lapse rate). Mt. Airy and Westminster are around 800' in elevation and areas along parrs ridge are up to 1k. I'm at 400' in elevation in Rockville. It doesn't seem like much difference but the elevation change can make a huge difference sometimes. Just think how many times there are marginal surface temps around here? A little elevation change can make a world of difference. While I'm sitting @ 34 here watching flakes melt on contact, my friends in Mt Airy are sitting @ 32 and watching it stick to the roads.

Another thing elevation does is add some lift to the atmosphere (called orographic influence). We generally only think of Garrett Co and lake effect areas for this but the piedmont and parrs can add just enough orographic influence to squeeze out some extra moisture.

Frederick kinda gets shortchanged because of this. You would think that they would do well becuase they are further n&w of dc but Frederick sits in the shadow of the catoctins and parrs depending on whice direction the ll flow is from. It's really cool when you break down the little microclimates around here. Such subtle things can have a pretty decent impact on how things shake out.

Nice post and I can attest to elevation effects. I sit at just under 200' elev and Dec 5 2009 was painful to see that just 10 miles from me and about 100 higher in elev was the diff between a dusting to 3"

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Study this map. Topograhic influence is pretty strong in md during many winter events. You can clearly see the fall line run along the pg, moco, hoco, and aa county lines. Then you get an extra kick in elevation from damascus, mt airy, westminster, and the parrs ridge area.

Generally speaking, anwhere w of the fallline > than areas east with most common setups.

Edit: I want to add some of the reasons behind this too. Many already know this stuff but for those who don't, generally speaking you lose 3 degrees in temp for every 1k feet in elevation gain (called lapse rate). Mt. Airy and Westminster are around 800' in elevation and areas along parrs ridge are up to 1k. I'm at 400' in elevation in Rockville. It doesn't seem like much difference but the elevation change can make a huge difference sometimes. Just think how many times there are marginal surface temps around here? A little elevation change can make a world of difference. While I'm sitting @ 34 here watching flakes melt on contact, my friends in Mt Airy are sitting @ 32 and watching it stick to the roads.

Another thing elevation does is add some lift to the atmosphere (called orographic influence). We generally only think of Garrett Co and lake effect areas for this but the piedmont and parrs can add just enough orographic influence to squeeze out some extra moisture.

Frederick kinda gets shortchanged because of this. You would think that they would do well becuase they are further n&w of dc but Frederick sits in the shadow of the catoctins and parrs depending on whice direction the ll flow is from. It's really cool when you break down the little microclimates around here. Such subtle things can have a pretty decent impact on how things shake out.

Good informative post.

Case in point about the valley affect around here. October 2011 storm.

post-114-0-70037500-1328641617.jpg

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Study this map. Topograhic influence is pretty strong in md during many winter events. You can clearly see the fall line run along the pg, moco, hoco, and aa county lines. Then you get an extra kick in elevation from damascus, mt airy, westminster, and the parrs ridge area.

Generally speaking, anwhere w of the fallline > than areas east with most common setups.

Edit: I want to add some of the reasons behind this too. Many already know this stuff but for those who don't, generally speaking you lose 3 degrees in temp for every 1k feet in elevation gain (called lapse rate). Mt. Airy and Westminster are around 800' in elevation and areas along parrs ridge are up to 1k. I'm at 400' in elevation in Rockville. It doesn't seem like much difference but the elevation change can make a huge difference sometimes. Just think how many times there are marginal surface temps around here? A little elevation change can make a world of difference. While I'm sitting @ 34 here watching flakes melt on contact, my friends in Mt Airy are sitting @ 32 and watching it stick to the roads.

Yup. I think one of the best recent examples of this was 12/5/09, when elevation was a huge factor, and being west or east of the fall line was the difference between getting 3-6" or getting a coating. It was that storm which got everyone annoyed at my elevation (I was a weenie who rubbed it in way too much). 10/29 is another example, though the rain/snow line was a bit further N/W than the fall line.

Frederick kinda gets shortchanged because of this. You would think that they would do well becuase they are further n&w of dc but Frederick sits in the shadow of the catoctins and parrs depending on whice direction the ll flow is from. It's really cool when you break down the little microclimates around here. Such subtle things can have a pretty decent impact on how things shake out.

This too.

This average snowfall map nicely shows how that valley screws the Frederick area, and how Carroll county (psuhoffman/Mt vortmax) can be so snowy. In Baltimore county (where I live), it seems like every mile can make a difference.

md-snow-avg.gif

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One of the more promising events I've forecast this winter...

20120208_MAsnowInitial.png

Plenty of cold air aloft, but surface temperatures look to hurt the initial snowfall accumulations before either the rates get high enough of the surface temperature cools to the freezing mark. Higher elevations stand a better chance of snow (both for surface temperatures and for snow ratios).

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That it does Fozz, while I have you beat with latitude, you have me beat with elevation and during October that elevation was key.

Yes, I think being further west and away from any reservoir also helped, but it wasn't a huge difference. I only got an inch or so. The really lucky areas were Parkton and the M/D line, where they got 4-6". We were so painfully close......

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