Deck Pic Posted February 16, 2015 Share Posted February 16, 2015 Maybe it will get Matt up to close to his forecast as his temp call is going to be pretty doggone good. Yes, in this environment, climo (realistic analogs) would support at least 15-1. 11-12 to 1 is more climo, and 20-1 is tough outside of any northern stream clippers. But I must say, the sounding profiles, at least with the 12Z runs, were very good up here, with deep moisture and lift above the -10C isotherm. Averaging out all the various SLRs as well as SLR techniques at work today, I couldn't find any lower than 15-1 (...other than climo). Optimal temps aloft, and very cold surface temps, with the bulk of the accumulating snow occurring after dark = optimal accumulation efficiency for mid Feb. As good as it gets around here really.. -10F to -15F in the snow growth zone is ideal for dendrite growth. NAM had a "warm" layer of -5F from about 800mb-700mb, but in that ideal temp range above that. I think we'll have nice crystal growth. I think 15:1 is probably a touch too high for an area-wide average (maybe more 13-14:1, although maybe I'm splitting hairs), but I think some of the jackpot zones will end up with ratios of 15-17:1. I thought latest NAM soundings didn't look as good for snow growth as GFS, even with the higher QPF...Don't we want the DGZ to pretty much be fully saturated and super thick (~200mb) for >15:1? I too was forecasting with 13.5:1 in mind, even here where lift will be better, but maybe I am too low? I don't remember what soundings looked like on 1/30/10 and I don't trust DCA liquid, but I think we were a solid 17-18:1.... Link to comment Share on other sites More sharing options...
caviman2201 Posted February 16, 2015 Share Posted February 16, 2015 What will be really interesting - just because it hasn't happened in a while - is to watch a storm where not a single flake is wasted. Every single powdery flake will stick to every surface... and cleanup will take a few minutes with a broom. Link to comment Share on other sites More sharing options...
ers-wxman1 Posted February 16, 2015 Share Posted February 16, 2015 I agree with Bob Chill... If the surface low is indeed stronger it will draw more moisture, dynamics and we will see heavier qpf further north... Link to comment Share on other sites More sharing options...
HighStakes Posted February 16, 2015 Share Posted February 16, 2015 yea I think its becoming clear that the northern edge of the heavy snow banding will probably set up somewhere in our area. I think DC is safe. North of York is probably out of it for more then a couple inches. Somewhere in between is where the fringe of the significant snows will set up. I have no idea where that will be, and history suggests it usually ends up north of where models put it 24 hours out, but I am still nervous as usual. I have felt all along this looks like a 4 inch storm for us. Right now I would lean towards higher amounts up to 6 opposed to lesser amounts. If you average out qpf from all the models we are at about .35. Link to comment Share on other sites More sharing options...
ers-wxman1 Posted February 16, 2015 Share Posted February 16, 2015 Should be a good baroclinic zone along the artic airmass for the low to strengthen Link to comment Share on other sites More sharing options...
hosj III Posted February 16, 2015 Share Posted February 16, 2015 I thought latest NAM soundings didn't look as good for snow growth as GFS, even with the higher QPF...Don't we want the DGZ to pretty much be fully saturated and super thick (~200mb) for >15:1? I too was forecasting with 13.5:1 in mind, even here where lift will be better, but maybe I am too low? I don't remember what soundings looked like on 1/30/10 and I don't trust DCA liquid, but I think we were a solid 17-18:1.... Any further north solution is going to get a warmer layer between 700 and 500 mb, over -10 C. IIRC, ratios depend on where the best omega is located. If it is above or below this band we are in business for 15:1 or 20:1, if it is in this band we will have problems. Link to comment Share on other sites More sharing options...
ers-wxman1 Posted February 16, 2015 Share Posted February 16, 2015 The NAM typically gets wetter in the near term. I will feel completely confident if the GFS comes north and wetter. Link to comment Share on other sites More sharing options...
nj2va Posted February 16, 2015 Share Posted February 16, 2015 RGEM meteograms are about 12-13 mm for DC (~0.5"). Link to comment Share on other sites More sharing options...
Deck Pic Posted February 16, 2015 Share Posted February 16, 2015 Any further north solution is going to get a warmer layer between 700 and 500 mb, over -10 C. IIRC, ratios depend on where the best omega is located. If it is above or below this band we are in business for 15:1 or 20:1, if it is in this band we will have problems. yes...I think you want best Omega at around -15.....I'm not too worried about lowering ratios with a further north solution...I have never rooted for less QPF because more would hurt snow growth and I'm not going to start now...more QPF (as snow) is better....the end Link to comment Share on other sites More sharing options...
usedtobe Posted February 16, 2015 Share Posted February 16, 2015 Wes -- Not a perfect match but the Jan 30 2010 event may not be a bad analog (prior to snowmaggedon). Best QPF across central/southern VA, where snow amounts in the 6-12" range were observed. However a good swath of 6-8" of fluff extended well north into the DC metro area, without as much QPF. I wouldn't be surprised if we again see 2 max w-e axes, one farther south where the QPF is higher but perhaps the snow crystals are not as optimal, and maybe another one farther north (typically around I-70 as we often joke about) where the QPF isn't as high but the dendritic growth is optimal. That initial northern "finger" band if you will. It would appear to me however, given the thermal profiles aloft, that even the northern band will be farther south (compared to climo) this go around. That would be my guesss but who knows, we're probably parsing things too much. If I get .60" liquid I'll be supercharged as that will get me 8 inches at the very least unless I'm way off on the fluff factor. If I get 8 then I won't care that much if someone else nearby gets 10 or 12. If I get 5 and the Manchester gets 12 then I'd probalby be ticked off. Link to comment Share on other sites More sharing options...
Ian Posted February 16, 2015 Share Posted February 16, 2015 Wes -- Not a perfect match but the Jan 30 2010 event may not be a bad analog (prior to snowmaggedon). Best QPF across central/southern VA, where snow amounts in the 6-12" range were observed. However a good swath of 6-8" of fluff extended well north into the DC metro area, without as much QPF. I wouldn't be surprised if we again see 2 max w-e axes, one farther south where the QPF is higher but perhaps the snow crystals are not as optimal, and maybe another one farther north (typically around I-70 as we often joke about) where the QPF isn't as high but the dendritic growth is optimal. That initial northern "finger" band if you will. It would appear to me however, given the thermal profiles aloft, that even the northern band will be farther south (compared to climo) this go around. jan 2010 may not be a bad base though this seems further north with high qpf than that was.. we were not expecting quite as high of totals the day prior, numbers were upped into the end tho. Link to comment Share on other sites More sharing options...
WEATHER53 Posted February 16, 2015 Share Posted February 16, 2015 Looking good down in the origin zone, gonna be juicer for DC like 0.75", still think 15" is max potential on this with 6-10" likely. Link to comment Share on other sites More sharing options...
Deck Pic Posted February 16, 2015 Share Posted February 16, 2015 The NAM typically gets wetter in the near term. I will feel completely confident if the GFS comes north and wetter. Yes...I don't want to overstate the importance of this GFS run, but 0.42' QPF at 18z for DCA was not awe inspiring in terms of pulling the trigger for 7-8"+ Link to comment Share on other sites More sharing options...
Ian Posted February 16, 2015 Share Posted February 16, 2015 The NAM typically gets wetter in the near term. I will feel completely confident if the GFS comes north and wetter. Euro was wet.. I still hold that the drying east of the Apps was at least partly bunk on early runs.. it's been filling in. There may be some shadow close by not all the wya to the coast IMO with that track. Link to comment Share on other sites More sharing options...
usedtobe Posted February 16, 2015 Share Posted February 16, 2015 yes...I think you want best Omega at around -15.....I'm not too worried about lowering ratios with a further north solution...I have never rooted for less QPF because more would hurt snow growth and I'm not going to start now...more QPF (as snow) is better....the end Actually for stick around for awhile factor the higher QPF and a little lower fluff facto is a plus and in terms of snow removal the weight of the snow is what matters not the inches measurement. Link to comment Share on other sites More sharing options...
Yeoman Posted February 16, 2015 Share Posted February 16, 2015 GFS is Amped Link to comment Share on other sites More sharing options...
HighStakes Posted February 16, 2015 Share Posted February 16, 2015 jan 2010 may not be a bad base though this seems further north with high qpf than that was.. we were not expecting quite as high of totals the day prior, numbers were upped into the end tho. In that storm didn't the precip advance into the region directly from the south and tomorrow it will be overspreading the region from wsw. Don't know if it really makes a difference though. Link to comment Share on other sites More sharing options...
PhineasC Posted February 16, 2015 Share Posted February 16, 2015 GFS is Amped Looks too amped to my trained eye. Link to comment Share on other sites More sharing options...
BTRWx Posted February 16, 2015 Share Posted February 16, 2015 In that storm didn't the precip advance into the region directly from the south and tomorrow it will be overspreading the region from wsw. Don't know if it really makes a difference though. I keep seeing that case study get thrown around, but I'm not so sure which one you're referring to. There's no way this has the qpf of Snowmageddon 1 or 2 if that's the one...? Link to comment Share on other sites More sharing options...
Ian Posted February 16, 2015 Share Posted February 16, 2015 In that storm didn't the precip advance into the region directly from the south and tomorrow it will be overspreading the region from wsw. Don't know if it really makes a difference though. Further SW initially than modeled here I think. The low appears it was a little south per NARR http://mp1.met.psu.edu/~fxg1/NARR/2010/us0130.php Link to comment Share on other sites More sharing options...
HighStakes Posted February 16, 2015 Share Posted February 16, 2015 I keep seeing that case study get thrown around, but I'm not so sure which one you're referring to. There's no way this has the qpf of Snowmageddon 1 or 2 if that's the one...? 1/30/2010. Not the blizzards Link to comment Share on other sites More sharing options...
PDIII Posted February 16, 2015 Share Posted February 16, 2015 Looks like a little later start time. Link to comment Share on other sites More sharing options...
Deck Pic Posted February 16, 2015 Share Posted February 16, 2015 I think we just need to toss the GFS at this point, and assume despite the upgrade it has a long way to go... Link to comment Share on other sites More sharing options...
Expat Posted February 16, 2015 Share Posted February 16, 2015 Is it me or does the precip field look larger? Link to comment Share on other sites More sharing options...
Ian Posted February 16, 2015 Share Posted February 16, 2015 GFS appears to have ticked slightly north with higher totals. I believe it is too south/dry. Link to comment Share on other sites More sharing options...
Ian Posted February 16, 2015 Share Posted February 16, 2015 I think we just need to toss the GFS at this point, and assume despite the upgrade it has a long way to go... Same issues here as before. Euro is going to win this one heh. Link to comment Share on other sites More sharing options...
McQuackleton Posted February 16, 2015 Share Posted February 16, 2015 Total Run Link to comment Share on other sites More sharing options...
AlaskaETC Posted February 16, 2015 Share Posted February 16, 2015 GFS not very different from 18z. Link to comment Share on other sites More sharing options...
Fozz Posted February 16, 2015 Share Posted February 16, 2015 QPF so far looks just about identical to 18z in central/northern MD Link to comment Share on other sites More sharing options...
PhineasC Posted February 16, 2015 Share Posted February 16, 2015 A bit better than 18Z but not too exciting. Link to comment Share on other sites More sharing options...
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