Deck Pic Posted March 4, 2013 Share Posted March 4, 2013 this air mass is VERY similar to 2/23/87.....maybe a tad better....DCA was 42 when precip started that evening and within 90 minutes they were ++SN and 33 pretty much all night.....Sun angle and day time will be more of an issue with this one so we wont get the same ratios at the lower elevations....but 33-34 should be easy Link to comment Share on other sites More sharing options...
stormtracker Posted March 4, 2013 Author Share Posted March 4, 2013 Link to comment Share on other sites More sharing options...
SomeguyfromTakomaPark Posted March 4, 2013 Share Posted March 4, 2013 Temp setup reminds me a good bit of April '97. DC probably start off as some light rain, and flip fairly quickly to heavy, wet snow. Would agree spot on with Matt's temp guess, 33-34 DCA, 32-33 NW DC. Sounding are pretty good considering how marginal this is. How much did DC get during that storm? I lived in Northern Westchester County NY (about 40 miles North of NYC) and we got pummeled, 16-18 inches of paste, major power outages, and thundersnow. Link to comment Share on other sites More sharing options...
HighStakes Posted March 4, 2013 Share Posted March 4, 2013 Except until a day ago he was saying it was around march 15th. A blind squirrel finds a nut. Today he said shades of April 82' just 2-3 weeks earlier for the rest of March. There was also mention of a big high slipping into the northeast next week. I think you can figure out on your own what he thinks this leads too. Link to comment Share on other sites More sharing options...
wxmeddler Posted March 4, 2013 Share Posted March 4, 2013 I just took a look at the model soundings for DCA. Outside of a mix of RASN at the start and maybe a mix of snow and sleet for an hour or less at 9z Wed. It is in fact all snow. It may mix at the very tail end with lower rates too. All in all 85-95% of the precip from the NAM is snow. As always.. it's the NAM. Link to comment Share on other sites More sharing options...
clskinsfan Posted March 4, 2013 Share Posted March 4, 2013 That only through 1:00 PM Wednesday though correct? Link to comment Share on other sites More sharing options...
TL97 Posted March 4, 2013 Share Posted March 4, 2013 That's only through 1 pm wednesday Link to comment Share on other sites More sharing options...
stormtracker Posted March 4, 2013 Author Share Posted March 4, 2013 That only through 1:00 PM Wednesday though correct? Oh damn, I thought it said 10pm. Link to comment Share on other sites More sharing options...
PDIII Posted March 4, 2013 Share Posted March 4, 2013 Man if the NAM verified it would be a NESIS 4 IMO, heavy snow from you guys to SNE. This is what I was talking about earlier... this seems to be getting bigger and bigger each run.. not 1993 by any stretch (that was just different).. but if this were early Feb and the temps were in the 20s.. it would be top ten (if it verified). Link to comment Share on other sites More sharing options...
packbacker Posted March 4, 2013 Share Posted March 4, 2013 Temp profiles for IAD and DCA, for those that are interested... http://68.226.77.253/text/meso/NAM_kiad.txt http://68.226.77.253/text/meso/NAM_kdca.txt Link to comment Share on other sites More sharing options...
TalcottWx Posted March 4, 2013 Share Posted March 4, 2013 Note the accumulation map from lwx's end time. That might confuse some Link to comment Share on other sites More sharing options...
tdmorrow Posted March 4, 2013 Share Posted March 4, 2013 They take the correct approach to snowfall accumulations maps and that is to put a range you are very confident in and increase it as we get closer. Link to comment Share on other sites More sharing options...
PDIII Posted March 4, 2013 Share Posted March 4, 2013 Look at the time.. Ending 1:00 PM... Wed... that is only half of the period. Link to comment Share on other sites More sharing options...
Jim Posted March 4, 2013 Share Posted March 4, 2013 Just looking at the NAM soundings, it appears there could be a mix in the beginning (9Z Wednesday) with a 0C isothermal layer from about 800mb-900mb. However, once pass 9Z it appears to shift to a pure snow scenario the rest of the way. This analysis is looking at a point over Silver Spring, MD. Link to comment Share on other sites More sharing options...
clskinsfan Posted March 4, 2013 Share Posted March 4, 2013 Temp profiles for IAD and DCA, for those that are interested... http://68.226.77.253/text/meso/NAM_kiad.txt http://68.226.77.253/text/meso/NAM_kdca.txt They both look good. Link to comment Share on other sites More sharing options...
NOVAForecaster Posted March 4, 2013 Share Posted March 4, 2013 Look at the time.. Ending 1:00 PM... Wed... that is only half of the period. This will be updated again at what time? Link to comment Share on other sites More sharing options...
dynasty Posted March 4, 2013 Share Posted March 4, 2013 any idea how this will affect the middle part of delaware or is this the wrong place to ask From about dover to about 30 miles north of that Link to comment Share on other sites More sharing options...
jc_cshmny Posted March 4, 2013 Share Posted March 4, 2013 This will be updated again at what time? Around 10pm I think...for time ending Wed 7:00pm. Link to comment Share on other sites More sharing options...
tdmorrow Posted March 4, 2013 Share Posted March 4, 2013 15z SREF Plumes went up across the board: APG from 8.68 to 9.83 BWI 11.99 to 12.99 IAD 14.47 to 15.19 DCA 12.62 to 13.09 Link to comment Share on other sites More sharing options...
dsnowman Posted March 4, 2013 Share Posted March 4, 2013 The NWS is just starting to update their grids. Using Centreville, VA as a reference point (some mentioned it earlier as a good place), they are calling for 3-5 inches Tuesday night alone. Which syncs with the above map of 8-10 for that area by 1pm. Looks like even that area will flip back/forth between snow/sleet/rain during the event. So they seem to be riding these higher GFS/NAM-like QPF totals. Link to comment Share on other sites More sharing options...
scratchart Posted March 4, 2013 Share Posted March 4, 2013 I just took a look at the model soundings for DCA. Outside of a mix of RASN at the start and maybe a mix of snow and sleet for an hour or less at 9z Wed. It is in fact all snow. It may mix at the very tail end with lower rates too. All in all 85-95% of the precip from the NAM is snow. As always.. it's the NAM. Perhaps this isn't the time or place for this question, but how could the NAM soundings be >85% snow on 2"+ QPF but spit out that clown map that shows maybe 3" of snow for DC? Wouldn't the clown map take the soundings into account? Link to comment Share on other sites More sharing options...
tdmorrow Posted March 4, 2013 Share Posted March 4, 2013 What will benefit us is that the timing of the most marginal temps seems to line up pretty well with the best vertical velocity and highest rates. Link to comment Share on other sites More sharing options...
gymengineer Posted March 4, 2013 Share Posted March 4, 2013 Perhaps this isn't the time or place for this question, but how could the NAM soundings be >85% snow on 2"+ QPF but spit out that clown map that shows maybe 3" of snow for DC? Wouldn't the clown map take the soundings into account? There are two types of clown maps---snowfall and snow depth.The snow depth ones are the much lower ones. For example, compare instantweathermaps' snowfall vs. snow depth map. Edited to add: I'm sure the snow depth ones have some melting algorithm based on the surface temperature (35 F at DCA verbatim from the NAM at 18Z). Link to comment Share on other sites More sharing options...
Ian Posted March 4, 2013 Share Posted March 4, 2013 Look at the time.. Ending 1:00 PM... Wed... that is only half of the period. kind dumb to have a map out for part of the storm but then again that map has always been kinda dumb Link to comment Share on other sites More sharing options...
eurojosh Posted March 4, 2013 Share Posted March 4, 2013 Perhaps this isn't the time or place for this question, but how could the NAM soundings be >85% snow on 2"+ QPF but spit out that clown map that shows maybe 3" of snow for DC? Wouldn't the clown map take the soundings into account? I don't think the clown maps are that complex - don't they just take QPF at 2m temps and run with it? Link to comment Share on other sites More sharing options...
wxmeddler Posted March 4, 2013 Share Posted March 4, 2013 Perhaps this isn't the time or place for this question, but how could the NAM soundings be >85% snow on 2"+ QPF but spit out that clown map that shows maybe 3" of snow for DC? Wouldn't the clown map take the soundings into account? Yes, but they do a very poor job at it. Often times they take surface temps way too seriously or on the flip side they put the rates too high. They also put out just the true snowfall. Which is not the case in the real world because of compaction; which with very wet snow can be quite significant. The only way to truly tell is with interval rates and looking at soundings. Edit: Also it doesn't consider the depth of the cloud and at what height and temperature your seeder feeders are. 1" precip of small plated snow from shallow clouds with tops of -7°C is way different from 1" of precip from 25kft tops with temps at -30°C and a tall dendritic growth layer. Link to comment Share on other sites More sharing options...
TalcottWx Posted March 4, 2013 Share Posted March 4, 2013 kind dumb to have a map out for part of the storm but then again that map has always been kinda dumb It spells out they aren't highly confident on full totals Link to comment Share on other sites More sharing options...
gymengineer Posted March 4, 2013 Share Posted March 4, 2013 Yes, but they do a very poor job at it. Often times they take surface temps way too seriously or on the flip side they put the rates too high. They also put out just the true snowfall. Which is not the case in the real world because of compaction; which with very wet snow can be quite significant. The only way to truly tell is with interval rates and looking at soundings. I believe that poster was just looking at snow depth maps. What you say about the snowfall ones is true, of course. Link to comment Share on other sites More sharing options...
clskinsfan Posted March 4, 2013 Share Posted March 4, 2013 GFS crushing almost all of VA at 39. Link to comment Share on other sites More sharing options...
blazeKing Posted March 4, 2013 Share Posted March 4, 2013 Gfs looks about the same thru 39 .. low slightly south and slower , still kinda warmish Link to comment Share on other sites More sharing options...
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