FallsLake Posted November 12, 2013 Share Posted November 12, 2013 This one is going to be forced primarily by strong frontogenesis, so what is coming towards the mountains isn't what we're looking for. The band coming across the mountains will almost definitely dry up in 20 to 30kts of downslope flow - this is the direct effects of the positively tilted trough on the wind field. If our trough had been neutrally tilted, winds would have been more southwesterly, allowing moisture to be transported into the region (along with surface cyclogenesis), rather than drying up in downslope flow. The only thing that may allow us to see a few token flakes today is the incredible horizontal temperature gradient (especially aloft), which results in a secondary restoring circulation - i.e. frontogenesis - which will result in a renewed area of lift just *behind* the front. Hopefully, this will result in some rain changing to snow for just an hour or so this afternoon. I think the HRRR probably has a good handle on how today's scenario will play out. It shows the secondary area of precipitation developing behind the front over VA and making it's way southward across NC. Looking at the soundings, there is probably only a 1-2 hour window for any one area to see any snow, and not all areas will see anything or may only see rain if moisture doesn't hang around long enough or if rates aren't strong enough to cool the lowest 1,000 feet or so of the atmosphere. As others have already said, the strength of this fall front is the story here - and it may be strong enough to generate a few snow showers on it's own despite an otherwise unfavorable precipitation pattern. Great explaination! Link to comment Share on other sites More sharing options...
Shack Posted November 12, 2013 Share Posted November 12, 2013 The wind map is pretty impressive this morning in locating the front... http://hint.fm/wind/ Way cool. And you can zoom in, too. Link to comment Share on other sites More sharing options...
Met1985 Posted November 12, 2013 Share Posted November 12, 2013 This one is going to be forced primarily by strong frontogenesis, so what is coming towards the mountains isn't what we're looking for. The band coming across the mountains will almost definitely dry up in 20 to 30kts of downslope flow - this is the direct effects of the positively tilted trough on the wind field. If our trough had been neutrally tilted, winds would have been more southwesterly, allowing moisture to be transported into the region (along with surface cyclogenesis), rather than drying up in downslope flow. The only thing that may allow us to see a few token flakes today is the incredible horizontal temperature gradient (especially aloft), which results in a secondary restoring circulation - i.e. frontogenesis - which will result in a renewed area of lift just *behind* the front. Hopefully, this will result in some rain changing to snow for just an hour or so this afternoon. I think the HRRR probably has a good handle on how today's scenario will play out. It shows the secondary area of precipitation developing behind the front over VA and making it's way southward across NC. Looking at the soundings, there is probably only a 1-2 hour window for any one area to see any snow, and not all areas will see anything or may only see rain if moisture doesn't hang around long enough or if rates aren't strong enough to cool the lowest 1,000 feet or so of the atmosphere. As others have already said, the strength of this fall front is the story here - and it may be strong enough to generate a few snow showers on it's own despite an otherwise unfavorable precipitation pattern. Thanks for the explanation. At least it will be cold and windy today and feel like Fall/Winter. Link to comment Share on other sites More sharing options...
GaWx Posted November 12, 2013 Share Posted November 12, 2013 Temps are ALWAYS a problem in the south . Rain today! And with this post, we've officially just entered the rain = evil season where nonwintry precip. is treated as an absolutely horrible thing by many on the bb (but certainly not Tony). It is happening about a month early thanks to the snow threat. Of course, it is silly to treat rain as evil when one considers that some 98% of the winter's liquid equiv. falls as rain on avg. at ATL and some 95% or so does the same at RDU. Brick usually is the one to start the rain = evil season, but I guess he's been too busy doing extra early campaigning for WoTY. Link to comment Share on other sites More sharing options...
Stovepipe Posted November 12, 2013 Share Posted November 12, 2013 Flurries in Nashville right now. Northwest TN (Paris) reported a snow shower earlier. Link to comment Share on other sites More sharing options...
DaculaWeather Posted November 12, 2013 Share Posted November 12, 2013 I lived in Paris TN when I was in the 2-4 grade. See what I'm missing out on now! Link to comment Share on other sites More sharing options...
DopplerWx Posted November 12, 2013 Share Posted November 12, 2013 well the 12z hires nam shows a nice batch of precip over western nc and then eastern nc down to northern sc this afternoon/evening. i think this will provide some nice early season snow showers for a good portion of nc, and that is a win in my book for november 12th! Link to comment Share on other sites More sharing options...
FLweather Posted November 12, 2013 Share Posted November 12, 2013 This one is going to be forced primarily by strong frontogenesis, so what is coming towards the mountains isn't what we're looking for. The band coming across the mountains will almost definitely dry up in 20 to 30kts of downslope flow - this is the direct effects of the positively tilted trough on the wind field. If our trough had been neutrally tilted, winds would have been more southwesterly, allowing moisture to be transported into the region (along with surface cyclogenesis), rather than drying up in downslope flow. The only thing that may allow us to see a few token flakes today is the incredible horizontal temperature gradient (especially aloft), which results in a secondary restoring circulation - i.e. frontogenesis - which will result in a renewed area of lift just *behind* the front. Hopefully, this will result in some rain changing to snow for just an hour or so this afternoon. I think the HRRR probably has a good handle on how today's scenario will play out. It shows the secondary area of precipitation developing behind the front over VA and making it's way southward across NC. Looking at the soundings, there is probably only a 1-2 hour window for any one area to see any snow, and not all areas will see anything or may only see rain if moisture doesn't hang around long enough or if rates aren't strong enough to cool the lowest 1,000 feet or so of the atmosphere. As others have already said, the strength of this fall front is the story here - and it may be strong enough to generate a few snow showers on it's own despite an otherwise unfavorable precipitation pattern. Thanks for the explaination 1300m. That model looks to be farily accurate from my standpoint atleast what I see on radar atm and the amount of clouds developing looking back towards the W/NW towards Danville area. Link to comment Share on other sites More sharing options...
Naby Posted November 12, 2013 Share Posted November 12, 2013 On the main model page it's on the top right "NCEP GFS"...This link is where it goes: http://models.weatherbell.com/xgfs.php Thank you! Link to comment Share on other sites More sharing options...
WNC_Fort Posted November 12, 2013 Share Posted November 12, 2013 We'll there are definelty some nice big dark clouds up here near UNCA. But it feels very warm. Looking forward to some flurries! Link to comment Share on other sites More sharing options...
RevDodd Posted November 12, 2013 Share Posted November 12, 2013 Alas for snowhounds, NAM appears to be coming in warm with that moisture. Soundings here wouldn't support snow making. Link to comment Share on other sites More sharing options...
DopplerWx Posted November 12, 2013 Share Posted November 12, 2013 fwiw 12z gfs shows snow showers for mid nc down to even columbia, may be too warm though. Link to comment Share on other sites More sharing options...
DaculaWeather Posted November 12, 2013 Share Posted November 12, 2013 Nomograms: http://www.daculaweather.com/4_nomogram_master.php Link to comment Share on other sites More sharing options...
Stovepipe Posted November 12, 2013 Share Posted November 12, 2013 HRRR suggests cumberland plateau, possibly tri-cities, mountains, and central/southern NC, possibly northern/central SC will be the flake winners. NC/SC has the time of day advantage. Link to comment Share on other sites More sharing options...
RevDodd Posted November 12, 2013 Share Posted November 12, 2013 Per the GFS, the 0Z sounding for Faynam... Link to comment Share on other sites More sharing options...
DaculaWeather Posted November 12, 2013 Share Posted November 12, 2013 Soundings: http://www.daculaweather.com/4_sounding_eastern_region.php Link to comment Share on other sites More sharing options...
1300m Posted November 12, 2013 Share Posted November 12, 2013 Per the GFS, the 0Z sounding for Faynam... 00sounding.png Believe it or not, that would be a snow sounding if you could get enough moisture to fall. There's enough dry air below 850mb that evaporative cooling would cool the column to below freezing. However, it's going to take a little bit of time to moisten up that column, and the question will be is there enough moisture available? Link to comment Share on other sites More sharing options...
FLweather Posted November 12, 2013 Share Posted November 12, 2013 The skys back towards the N/W really starting to get better cloud growth. Its darkening and thickening. Last few frames show a good band developing east of Roa, Lyn and martinsville. http://radar.weather.gov/ridge/radar.php?product=N0R&rid=FCX&loop=yes Link to comment Share on other sites More sharing options...
RevDodd Posted November 12, 2013 Share Posted November 12, 2013 Believe it or not, that would be a snow sounding if you could get enough moisture to fall. There's enough dry air below 850mb that evaporative cooling would cool the column to below freezing. However, it's going to take a little bit of time to moisten up that column, and the question will be is there enough moisture available? Agree entirely, 1300m. Hoping the recent juicing trend will at least give us more than a nice virga display. None of it will stick around, but dangit ... if we're going to get this cold, at least have something to show for it! Link to comment Share on other sites More sharing options...
DopplerWx Posted November 12, 2013 Share Posted November 12, 2013 Agree entirely, 1300m. Hoping the recent juicing trend will at least give us more than a nice virga display. None of it will stick around, but dangit ... if we're going to get this cold, at least have something to show for it! latest RAP shows a band of decent precip this afternoon/night. Link to comment Share on other sites More sharing options...
Disc Posted November 12, 2013 Share Posted November 12, 2013 Link to comment Share on other sites More sharing options...
packfan98 Posted November 12, 2013 Share Posted November 12, 2013 Don't hug the RAP (aka CRAP) model too closely! I have been suckered in by it too many times over the past two or three years. It promises really heavy returns and keeps pushing it back later until it disappears. Right now, it's showing over .15 qpf. If I get that much IMBY I will gladly eat my hat! latest RAP shows a band of decent precip this afternoon/night. Link to comment Share on other sites More sharing options...
triadwx Posted November 12, 2013 Share Posted November 12, 2013 Light flurry action starting here on the ASU campus. Link to comment Share on other sites More sharing options...
superjames1992 Posted November 12, 2013 Share Posted November 12, 2013 Man, Pack. I've been burnt in the past by the RAP, too. Let's just hope it is right this time. Link to comment Share on other sites More sharing options...
Met1985 Posted November 12, 2013 Share Posted November 12, 2013 We have snow!!!!!! Rain just changed to snow a bit ago. Temp has dropped fast. Down to 30 degrees. Link to comment Share on other sites More sharing options...
DopplerWx Posted November 12, 2013 Share Posted November 12, 2013 great to see some snow reports already, enjoy it guys! Link to comment Share on other sites More sharing options...
FLweather Posted November 12, 2013 Share Posted November 12, 2013 Man, Pack. I've been burnt in the past by the RAP, too. Let's just hope it is right this time. I hope so too.... Even though composite view of the radar still nice band developing south of Martinsville. First though hopefully get these temps down some before the precip moves it. It did spike to 56 here a little while ago but at 51 Link to comment Share on other sites More sharing options...
WeatherNC Posted November 12, 2013 Share Posted November 12, 2013 I would be happy to see a few flurries this evening but not overly optimistic. 12z GFS is still less than 1/10", with timing somewhere between 8am-midnight. It does appear too warm initially with the last 600-1k ft above freezing, taking into account very - rates , drizzle. I for one am ready for winter, wind is starting to pick up and temps should start to fall shortly. Link to comment Share on other sites More sharing options...
LithiaWx Posted November 12, 2013 Share Posted November 12, 2013 Rain changing to snow on a moisture starved FROPA. Pretty lame. Grays to those seeing token flurries. Link to comment Share on other sites More sharing options...
chapelhillwx Posted November 12, 2013 Share Posted November 12, 2013 Good luck to all those who might see flakes. Temp here has skyrocketed. 69 degrees while it's snowing in the mountains; pretty impressive. Link to comment Share on other sites More sharing options...
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