Joshfsu123 Posted March 15, 2014 Share Posted March 15, 2014 oh wow..yeah, that is definitely an improvement. 3 to 5...holding firm. That's what I would go with... not convinced the cutoff will be as sharp but maybe the HP will be strong enough. 12z NAM is improvement and hopefully the other 12z models follow suit. Link to comment Share on other sites More sharing options...
Bob Chill Posted March 15, 2014 Share Posted March 15, 2014 If the 12z euro steps north from 0z then I'll be pretty much convinced it's not a coincidence. There must be something to it. If it steps south I'm going to throw rocks at squirrels Link to comment Share on other sites More sharing options...
mdsnowlover Posted March 15, 2014 Share Posted March 15, 2014 I think 3 to 5 is a reasonable forecast at this point, no? wbal is forecast 1-4 in so your probably right Link to comment Share on other sites More sharing options...
Deck Pic Posted March 15, 2014 Share Posted March 15, 2014 The 700 mb chart from NAM gives a good idea of onset and cutoff of the precipitation. This 12 Z run shows precip from hour 33 to hour 48. The suppression is not north to south, it is northwest to southeast suggesting Wes' area may hold on to the snow a little longer. So lots of people will get precipitating snow but it looks like light snow for 15 hours. Link to comment Share on other sites More sharing options...
mdsnowlover Posted March 15, 2014 Share Posted March 15, 2014 The 700 mb chart from NAM gives a good idea of onset and cutoff of the precipitation. This 12 Z run shows precip from hour 33 to hour 48. The suppression is not north to south, it is northwest to southeast suggesting Wes' area may hold on to the snow a little longer. So lots of people will get precipitating snow but it looks like light snow for 15 hours. just like the last storm, hello spring!! Link to comment Share on other sites More sharing options...
Interstate Posted March 15, 2014 Share Posted March 15, 2014 I think we're starting to get into it's "money" time period, but the bouncing around is troubling from a forecasting standpoint. Agreed... 50 mile shift is getting 1-2 to 6-10 Link to comment Share on other sites More sharing options...
Ian Posted March 15, 2014 Share Posted March 15, 2014 Take a nap till 2. Link to comment Share on other sites More sharing options...
Bob Chill Posted March 15, 2014 Share Posted March 15, 2014 Take a nap till 2. Could you imagine if the nam was running hourly today? Link to comment Share on other sites More sharing options...
winterymix Posted March 15, 2014 Share Posted March 15, 2014 The NAM shows over 12 hours of precipitation but intensities appear light so in DC you are going to hope the good stuff occurs late at night. It could happen, NAM shows light to moderate in DC from 9Z to 12Z. Monday AM rush hour could be fun even with 2 to 4 if most of it sticks late at night. Link to comment Share on other sites More sharing options...
Ian Posted March 15, 2014 Share Posted March 15, 2014 Nam goes from .96 last night to zero this morning to Shhhhh skip it at least it's still got the second phantom low. Link to comment Share on other sites More sharing options...
ers-wxman1 Posted March 15, 2014 Share Posted March 15, 2014 I would not expect much of a shift from where it is now. If anything a tad north to correct on the NAM and EURO. GFS may come a bit south on its gradient on the 12z run. Still...south of I-70 and especially Loudoun through DC and points south should get in on the good stuff. It will be tight quarters north of I-70 and the area north of the mason Dixon line and northeast through Philly, Central and Northern NJ and NYC metro area will likely get ripped off again. We will make out best on the WAA dump late Sunday evening into the predawn hours Monday. Just my 2 cents... We'll see. Link to comment Share on other sites More sharing options...
T. August Posted March 15, 2014 Share Posted March 15, 2014 at least it's still got the second phantom low. At hr 84 it brings light precip back into the DC area. Looks like there's more to come afterwards too. Link to comment Share on other sites More sharing options...
Interstate Posted March 15, 2014 Share Posted March 15, 2014 The NAM shows over 12 hours of precipitation but intensities appear light so in DC you are going to hope the good stuff occurs late at night. It could happen, NAM shows light to moderate in DC from 9Z to 12Z. Monday AM rush hour could be fun even with 2 to 4 if most of it sticks late at night. I know tomorrow it is suppose to be cooler... but road temps will be a problem for stickage http://www.chart.state.md.us/travInfo/weatherStationData.asp Link to comment Share on other sites More sharing options...
winterymix Posted March 15, 2014 Share Posted March 15, 2014 I need that bad boy to sashay north a skosch. The way it looks now, I'll be able to look south and see accumulating snow while standing on brown lawn. Link to comment Share on other sites More sharing options...
mitchnick Posted March 15, 2014 Share Posted March 15, 2014 At hr 84 it brings light precip back into the DC area. Looks like there's more to come afterwards too. rain http://mag.ncep.noaa.gov/Image.php?fhr=084ℑ=data%2Fnam%2F12%2Fnam_namer_084_850_temp_ht.gif&model=nam&area=namer¶m=850_temp_ht&group=Model+Guidance&preselected_formatted_cycle_date=20140315+12+UTC&imageSize=M&ps=model Link to comment Share on other sites More sharing options...
T. August Posted March 15, 2014 Share Posted March 15, 2014 rain http://mag.ncep.noaa.gov/Image.php?fhr=084ℑ=data%2Fnam%2F12%2Fnam_namer_084_850_temp_ht.gif&model=nam&area=namer¶m=850_temp_ht&group=Model+Guidance&preselected_formatted_cycle_date=20140315+12+UTC&imageSize=M&ps=model lol I didn't even think about that... Link to comment Share on other sites More sharing options...
stormtracker Posted March 15, 2014 Author Share Posted March 15, 2014 Yeah, I read that and literally scratched my head. It's not light snow for 15 hours. At any rate, the NAM is a decent hit for Mid March. Link to comment Share on other sites More sharing options...
Bob Chill Posted March 15, 2014 Share Posted March 15, 2014 I dug back a little. The 3/3 event had nearly a 1040 hp pressing in. This one is nearly 10mb weaker. I know it's not that simple because of heights, proximity to the lp, etc but I don't think this setup will be as efficient at squashing the northern edge. Other factors can result in a further south solution with all features of course. But seeing a gradient as tight as the nam raises s flag in my mind. Link to comment Share on other sites More sharing options...
winterymix Posted March 15, 2014 Share Posted March 15, 2014 Yeah, I read that and literally scratched my head. It's not light snow for 15 hours. At any rate, the NAM is a decent hit for Mid March. Fine. Scratch your head over the SREF plume. This is 3 hour increments of snow at DCA and the event happens during roughly 15 hours. Link to comment Share on other sites More sharing options...
Ian Posted March 15, 2014 Share Posted March 15, 2014 At hr 84 it brings light precip back into the DC area. Looks like there's more to come afterwards too. we may get a bit of light precip partly from interaction with the next wave in the northern stream but i'd be willing to bet the nam is garbage on how it tracks the low. Link to comment Share on other sites More sharing options...
cae Posted March 15, 2014 Share Posted March 15, 2014 total for storm is .42" at BWI and .63" DCA (thru 18Z Monday) marked improvement from 6Z About 0.16" in Towson, which is better than the essentially 0" for the 06z NAM. As sharp as the northern gradient is, the southern gradient looks even sharper -- it still looks like someone on the south side of this storm could go from 12" modeled snow to 0" (or vice versa) pretty quick. Link to comment Share on other sites More sharing options...
winterymix Posted March 15, 2014 Share Posted March 15, 2014 SREF gives 7.5" to DCA but perhaps the south trend hasn't taken it's cut yet. Link to comment Share on other sites More sharing options...
Ian Posted March 15, 2014 Share Posted March 15, 2014 I dug back a little. The 3/3 event had nearly a 1040 hp pressing in. This one is nearly 10mb weaker. I know it's not that simple because of heights, proximity to the lp, etc but I don't think this setup will be as efficient at squashing the northern edge. Other factors can result in a further south solution with all features of course. But seeing a gradient as tight as the nam raises s flag in my mind. this airmass is definitely less impressive if still impressive. the NAM does a good job modeling the sharpness of an edge which is perhaps legit but location is another story. Link to comment Share on other sites More sharing options...
Ian Posted March 15, 2014 Share Posted March 15, 2014 SREF gives 7.5" to DCA but perhaps the south trend hasn't taken it's cut yet. srefplumtotalsnodca.jpg 0.5" to 17" for me. Those are really useful. Link to comment Share on other sites More sharing options...
winterymix Posted March 15, 2014 Share Posted March 15, 2014 0.5" to 17" for me. Those are really useful. Throw out the outliers and deal with the black line mean. Link to comment Share on other sites More sharing options...
chris87 Posted March 15, 2014 Share Posted March 15, 2014 Fine. Scratch your head over the SREF plume. This is 3 hour increments of snow at DCA and the event happens during roughly 15 hours. sref 9Z runtime 3 hr sno_dca.jpg it's usually pretty smart to take an ensemble range of start/stop time -- find a 15 hour duration then divide the mean qpf by 15 hours because you know it's probably going to have a linear precip rate over those 15 hours Link to comment Share on other sites More sharing options...
stormtracker Posted March 15, 2014 Author Share Posted March 15, 2014 it's usually pretty smart to take an ensemble range of start/stop time -- find a 15 hour duration then divide the mean qpf by 15 hours because you know it's probably going to have a linear precip rate over those 15 hours 0.5" to 17" for me. Those are really useful. And he used them to make his point. Link to comment Share on other sites More sharing options...
Ian Posted March 15, 2014 Share Posted March 15, 2014 And he used them to make his point. I've become rabidly anti snow algorithm recently. SREF is a good tool in many ways but not sure the snow plumes are that helpful to most forecasts. Link to comment Share on other sites More sharing options...
winterymix Posted March 15, 2014 Share Posted March 15, 2014 it's usually pretty smart to take an ensemble range of start/stop time -- find a 15 hour duration then divide the mean qpf by 15 hours because you know it's probably going to have a linear precip rate over those 15 hours So...rough math suggests DCA gets 0.5" snow an hour for 15 hours per SREF. So what accumulates will be the hours without March high sun angle. Link to comment Share on other sites More sharing options...
winterymix Posted March 15, 2014 Share Posted March 15, 2014 And he used them to make his point. The SREF and 12z NAM support each other although the NAM shows the south trend and therefore the SREF is overdoing north of DCA. Tell me how I busted Tuesday. Link to comment Share on other sites More sharing options...
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