Ji Posted March 5, 2013 Share Posted March 5, 2013 can a pro met tell us which model is right? Link to comment Share on other sites More sharing options...
stormtracker Posted March 5, 2013 Author Share Posted March 5, 2013 If the GFS soundings are colder, I'll start dancing. Link to comment Share on other sites More sharing options...
Symblized Posted March 5, 2013 Share Posted March 5, 2013 nam soundings look like all snow in dc Ditto BWI (as well as point and click downtown Baltimore even). Link to comment Share on other sites More sharing options...
stormtracker Posted March 5, 2013 Author Share Posted March 5, 2013 cold at the sfc throughout. probably a foot+. woo nam. It's odd how the NAM is being (almost) totally ignored it seems. Or maybe I'm wrong and folks are blending it. Link to comment Share on other sites More sharing options...
Ian Posted March 5, 2013 Share Posted March 5, 2013 It's odd how the NAM is being (almost) totally ignored it seems. Or maybe I'm wrong and folks are blending it. it's been pretty rock solid. i guess the question is if it's producing too much precip and if that's impacting the temp profile. Link to comment Share on other sites More sharing options...
WxMan1 Posted March 5, 2013 Share Posted March 5, 2013 Great post and reasoning. Agree with the 4-8 call for immediate DC. Question: regarding the dry punch above -10c...what exactly do you want to see there? Is it a case where you want to see just a touch of drying there for increased instability, but you still want to keep the -10 to -20 layer saturated with respect to ice? Yes. Although you don't necessarily need the moist column to extend much above the -10/-12C layer, since the -10 is usually the cutoff where there's a 50-50 balance btwn ice crystals and supercooled water vapor. Obviously, the colder (deeper) the top layer gets, the more ice nuclei availability, which would be better. -15C is the mean for the best dendritic growth given the vapor pressure differential with respect to ice. So, a dry layer above the -10 to -15C isotherm represents 'potential' instability since, when lifted, you steepen the lapse rate within that layer considering your cooling less at the bottom (moist) portion of that layer -- i.e. moist adiabatic -- compared the the top (drier) part of the layer -- i.e. dry adiabatic. Thus the term 'potential'...you need lift, and you need moisture in the lower part of the layer Link to comment Share on other sites More sharing options...
TL97 Posted March 5, 2013 Share Posted March 5, 2013 The NAM doesn't end until 7AM thursday. Link to comment Share on other sites More sharing options...
wxmeddler Posted March 5, 2013 Share Posted March 5, 2013 Ditto BWI (as well as point and click downtown Baltimore even). It's easy to see on the 4km NAM. If the temp is 32-33 then your keeping the temp isothermal with rates. It quickly jumps up beyond that line. The line at 10z goes from EZF to ADW to Annapolis to Aberdeen. Link to comment Share on other sites More sharing options...
mdhokie Posted March 5, 2013 Share Posted March 5, 2013 it's been pretty rock solid. i guess the question is if it's producing too much precip and if that's impacting the temp profile. remember the red taggers talking about the temp delta between 850 and sfc was was too large for the heavy precip depicted. Link to comment Share on other sites More sharing options...
thesnowsknows Posted March 5, 2013 Share Posted March 5, 2013 It's odd how the NAM is being (almost) totally ignored it seems. Or maybe I'm wrong and folks are blending it. I'm blending. Most others are seeing it black and white I feel. Link to comment Share on other sites More sharing options...
vinylfreak89 Posted March 5, 2013 Share Posted March 5, 2013 anyone have any idea why the NAM has backed down on the -15 VVs? I really didn't think the transfer was going to take away that much from the system with the stronger dynamics. Link to comment Share on other sites More sharing options...
PhineasC Posted March 5, 2013 Share Posted March 5, 2013 If the GFS holds or improves LWX will have to go big with the warnings as there is a threat for some serious heavy wet snow totals. Link to comment Share on other sites More sharing options...
Kmlwx Posted March 5, 2013 Share Posted March 5, 2013 If the GFS holds or improves LWX will have to go big with the warnings as there is a threat for some serious heavy wet snow totals. I generally hate to predict model output but I'd guess it holds similar to last run. Perhaps NAM is a bit high. If we are speaking voodoo style it's probably good that LWX is going a tiny bit low - bodes well for us to get pasted lol. Link to comment Share on other sites More sharing options...
mattmfm Posted March 5, 2013 Share Posted March 5, 2013 Just remarkable differences 12 hours out. If you were to take model output alone, would be more than a foot of snow difference between the GFS and NAM. Link to comment Share on other sites More sharing options...
Ian Posted March 5, 2013 Share Posted March 5, 2013 If the GFS holds or improves LWX will have to go big with the warnings as there is a threat for some serious heavy wet snow totals. Knowing LWX they will bump back to prior totals later Link to comment Share on other sites More sharing options...
Deck Pic Posted March 5, 2013 Share Posted March 5, 2013 The NAM has a cold and wet bias...I don't think that changes because it pastes us...I'd blend Link to comment Share on other sites More sharing options...
MN Transplant Posted March 5, 2013 Share Posted March 5, 2013 Friday, LOL Link to comment Share on other sites More sharing options...
Nor Easter Posted March 5, 2013 Share Posted March 5, 2013 Friday, LOL USA_REFD_1000m_075.gif Been watching that piece of Northern Stream NRG over the GL region. Been getting closer and closer to phasing with our storm, 18z finally does and completely stalls the low then pulls it back west...lol..Imagine if that were to speed up some more... Link to comment Share on other sites More sharing options...
WEATHER53 Posted March 5, 2013 Share Posted March 5, 2013 See what we have radiated to by 8pm. If this thing does bomb us, and I am still firmly convinced DCA will not report more than 4" of accumulation, the evaporational dropoff would be one for the record books. Link to comment Share on other sites More sharing options...
DCWeatherGuy Posted March 5, 2013 Share Posted March 5, 2013 The NAM has a cold and wet bias...I don't think that changes because it pastes us...I'd blend I get the NAM's bias rep, but does "blending" really make sense here? It's not like the GFS and NAM are projecting similar events but spitting out somewhat different temp and QPF numbers. These projections are radically different, especially considering how close we are to go-time. I would certainly take a little off the top of the NAM QPF prediction given its history, but if you buy the NAM solution, I don't think you significantly change your projection because the GFS and Euro say a very different storm will produce very different totals. Link to comment Share on other sites More sharing options...
Huffwx Posted March 5, 2013 Share Posted March 5, 2013 Random, maybe banter thread-- Sleeting in blacksburg. Upper 40's. models didn't really have super dry air to support this?? When you see those HUGE dry layers, this happens. ?? Link to comment Share on other sites More sharing options...
psuhoffman Posted March 5, 2013 Share Posted March 5, 2013 Wow, the NAM really throws north the precip shield. Farther than any other model.. by a good 25-50 miles I dont think the NAM throws the precip further north, its northern edge is similar to the globals, the difference is the NAM sets up a deform band along the northern edge of the precip in northern MD and southern PA and sits it there for 12 hours. The globals "hint" at it but instead of putting out .25 qpf in that band every 3 hours, they are putting out .1 and that is the difference between getting .75 and 1.75 along the Mason DIxon line. Maybe the higher res of the NAM is allowing it to see that deform band that often sets up where the moisture convergence is banked up against the confluence. I dont know. Link to comment Share on other sites More sharing options...
Superstorm Posted March 5, 2013 Share Posted March 5, 2013 Wow, the NAM really throws north the precip shield. Farther than any other model.. by a good 25-50 miles I dont think the NAM throws the precip further north, its northern edge is similar to the globals, the difference is the NAM sets up a deform band along the northern edge of the precip in northern MD and southern PA and sits it there for 12 hours. The globals "hint" at it but instead of putting out .25 qpf in that band every 3 hours, they are putting out .1 and that is the difference between getting .75 and 1.75 along the Mason DIxon line. Maybe the higher res of the NAM is allowing it to see that deform band that often sets up where the moisture convergence is banked up against the confluence. I dont know. Great pickup! Link to comment Share on other sites More sharing options...
Ian Posted March 5, 2013 Share Posted March 5, 2013 Link to comment Share on other sites More sharing options...
psuhoffman Posted March 5, 2013 Share Posted March 5, 2013 just a raking If the NAM pulls this off, I promise not to bad mouth it for at least 1-2 weeks NAM would be our perfect solution...12" plus for just about EVERYONE except our far southern zones Link to comment Share on other sites More sharing options...
mitchnick Posted March 5, 2013 Share Posted March 5, 2013 it's gunna' have an eye, mark my words Link to comment Share on other sites More sharing options...
Quasievil Posted March 5, 2013 Share Posted March 5, 2013 NAM would be our perfect solution...12" plus for just about EVERYONE except our far southern zones I WANT to buy into its solution but it has such a history of overdoing QPF. Surprise us. Link to comment Share on other sites More sharing options...
Sparky Posted March 5, 2013 Share Posted March 5, 2013 i wonder if psuhoffman will be worried that the banding is over him on this run dry slot :-/ but its the NAM, aren't we supposed to cut qpf in half or something? Link to comment Share on other sites More sharing options...
Ji Posted March 5, 2013 Share Posted March 5, 2013 I WANT to buy into its solution but it has such a history of overdoing QPF. Surprise us. Usually it gets corrected right before storm though Link to comment Share on other sites More sharing options...
Ji Posted March 5, 2013 Share Posted March 5, 2013 Ian--what's the average of last 5 storms where the minimum has been 3 inches Link to comment Share on other sites More sharing options...
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