beanskip Posted January 25, 2013 Share Posted January 25, 2013 One of my "lessons learned" from last week's debacle is not to ignore short-term trends. Well, the trend in the past 12 hours is to weaken the CAD. Here is the latest Shelby sounding at the "height" (a loose use of the term to be sure given the paltry QPF) of the precip Date: 24 hour Eta valid 0Z SAT 26 JAN 13Station: KEHOLatitude: 35.26Longitude: -81.60-------------------------------------------------------------------------------LEV PRES HGHT TEMP DEWP RH DD WETB DIR SPD THETA THE-V THE-W THE-E W mb m C C % C C deg knt K K K K g/kg------------------------------------------------------------------------------- 0 1000 169 SFC 989 256 0.1 -0.7 94 0.8 -0.3 204 5 274.1 274.7 273.5 284.0 3.66 2 950 579 -1.7 -2.0 98 0.3 -1.9 227 17 275.4 276.0 274.0 284.9 3.47 3 900 1014 3.1 3.1 100 0.0 3.1 251 40 284.7 285.6 281.1 299.6 5.30 4 850 1479 4.7 4.4 98 0.3 4.6 261 57 291.1 292.2 284.9 308.8 6.18 5 800 1973 3.1 2.8 98 0.3 2.9 273 58 294.5 295.5 285.9 311.5 5.87 6 750 2495 2.2 0.4 88 1.8 1.3 270 51 299.0 300.0 287.0 314.7 5.27 7 700 3051 -0.6 -5.7 68 5.1 -2.8 268 50 301.8 302.5 286.3 312.7 3.57 8 650 3640 -2.9 -14.0 42 11.2 -6.8 271 53 305.7 306.1 286.1 312.0 1.98 9 600 4269 -7.5 -17.0 46 9.5 -10.5 275 60 307.5 307.8 286.4 312.9 1.6810 550 4941 -11.1 -31.4 17 20.3 -15.3 281 60 310.9 311.0 286.3 312.7 0.5111 500 5665 -15.9 -33.6 20 17.7 -19.1 282 64 313.7 313.8 287.2 315.3 0.4512 450 6452 -21.0 -48.0 7 27.0 -23.9 284 66 316.8 316.8 287.8 317.2 0.1113 400 7309 -27.6 -46.3 15 18.7 -29.4 278 72 319.2 319.2 288.6 319.7 0.1514 350 8254 -34.6 -54.7 11 20.1 -35.8 275 81 322.1 322.1 289.5 322.4 0.0715 300 9317 -41.1 -53.4 25 12.3 -41.8 277 107 327.4 327.4 291.0 327.7 0.0916 250 10532 -50.2 -55.7 52 5.5 -50.4 278 119 331.5 331.5 292.2 331.8 0.0817 200 11951 -60.3 -65.1 54 4.7 -60.4 286 125 337.2 337.2 293.7 337.4 0.0318 150 13723 -63.4 -72.0 31 8.5 -63.5 285 106 360.8 360.8 298.9 360.9 0.0219 100 16184 -68.9 -82.6 12 13.7 -69.0 277 90 394.5 394.5 304.5 394.5 0.00TRP 0 WND 0 This is very close to a straight rain sounding. Yes, CAD is frequently underforecast, but we also heard about how dynamic cooling with upper lows is underforecast and we know how that turned out. Given that the NAM is best at scouting out CAD and that it was WAAAAAAY too cold with surface and 850 temps last week, I think it's fair to now question whether this will be an all frozen event in the I-85/US74 corridor as we have all be assuming. Link to comment Share on other sites More sharing options...
FallsLake Posted January 25, 2013 Share Posted January 25, 2013 According to the ratios of 3:1 that others were so kind to provide me with last night, I'd say you're looking at roughly an inch of sleet on the ground. Thanks for the info! Link to comment Share on other sites More sharing options...
beanskip Posted January 25, 2013 Share Posted January 25, 2013 Wish I could say I've never made that mistake. I would have to see what images/source you are looking at. Seems like maybe you are looking at 6 hour precip every 3 hours. Link to comment Share on other sites More sharing options...
tnweathernut Posted January 25, 2013 Share Posted January 25, 2013 0z NAM showing a significant winter mess for NE TN...snow...to sleet...to freezing rain. Power could be an issue if the model is correct w/ 0.5 - 0.75 liquid forecast. The tick back south on the 18z with the precip field in northern TN was evidently a "glitch". It has gone right back to putting the bulk of the heavier precip out of KTRI or more specifically Johnson City. It's centered more on the state line and into sw Virginia. This has quickly become a marginal event for JC and points southwest. (though i acknowledge even a little glaze could cause issues) I don't buy the look of .5-.75 on the NAM. I think it's overdone. Just a guess here, but i think it's likely when we take a look at the hi-res version it will look rather "meh" in our area, even up to the state line too (where this run of the NAM shows heavier qpf) Link to comment Share on other sites More sharing options...
Portsmouth Weather Posted January 25, 2013 Share Posted January 25, 2013 I would have to see what images/source you are looking at. Seems like maybe you are looking at 6 hour precip every 3 hours. As superjames pointed out, that is exactly what I was doing. Thank you guys for the help Link to comment Share on other sites More sharing options...
Shawn Posted January 25, 2013 Share Posted January 25, 2013 The tick back south on the 18z with the precip field in northern TN was evidently a "glitch". It has gone right back to putting the bulk of the heavier precip out of KTRI or more specifically Johnson City. It's centered more on the state line and into sw Virginia. This has quickly become a marginal event for JC and points southwest. (though i acknowledge even a little glaze could cause issues) I don't buy the look of .5-.75 on the NAM. I think it's overdone. Just a guess here, but i think it's likely when we take a look at the hi-res version it will look rather "meh" in our area, even up to the state line too (where this run of the NAM shows heavier qpf) Check out the SREF 700mb RH maps that Dacula had posted earlier. Might come to fruition. Link to comment Share on other sites More sharing options...
Carvers Gap Posted January 25, 2013 Share Posted January 25, 2013 The tick back south on the 18z with the precip field in northern TN was evidently a "glitch". It has gone right back to putting the bulk of the heavier precip out of KTRI or more specifically Johnson City. It's centered more on the state line and into sw Virginia. This has quickly become a marginal event for JC and points southwest. (though i acknowledge even a little glaze could cause issues) I don't buy the look of .5-.75 on the NAM. I think it's overdone. Just a guess here, but i think it's likely when we take a look at the hi-res version it will look rather "meh" in our area, even up to the state line too (where this run of the NAM shows heavier qpf) Could be the NAM being the NAM. RAP reflectivity loop looks reasonable. I am guessing an inch or two of snow w/ enough ice to cause some big traffic issues. Hitting at a bad time for sure. Link to comment Share on other sites More sharing options...
calculus1 Posted January 25, 2013 Share Posted January 25, 2013 Check out the SREF 700mb RH maps that Dacula had posted earlier. Might come to fruition. And then contrast that to what Robert posted on Facebook a few hours ago. Nada once again! Edit: I just realized that the post you were responding to was referencing precipitation in TN. My apologies. But, Robert's quote is still worthy of reading for those of us "Living in the shadow of the Apps," my new caption. The approach of the system means it crosses the mountains, and there is a lot of super dry air along the East Coast. So the 7H moisture panels are very misleading, a better view is the simulated reflectivities on the models. I can see a complete jump in the lee of the Apps somewhere between western/central VA down to the foothills and western Piedmont of NC and northern SC. And then possibly reformation into better precip just east of this region toward dark. Link to comment Share on other sites More sharing options...
HKY_WX Posted January 25, 2013 Share Posted January 25, 2013 looks like about .25 of qpf for avl-gso. not quite an inch of sleet. enough to be a mess friday and friday night. Link to comment Share on other sites More sharing options...
NCSNOW Posted January 25, 2013 Share Posted January 25, 2013 Beanskip I would be shocked if your surface temps make it to freezing once moisture begins. Up top no surprise in being to warm for snow or even sleet. You will have no trouble wet bulbing into the upper 20's. I'm currently at 23 with a dp in the low single digits. This is all about getting qpf and has been since Monday. Fear the dry slot and not surface temps. Polar opposite of last weeks event just hope it doesn't net same result. Link to comment Share on other sites More sharing options...
beanskip Posted January 25, 2013 Share Posted January 25, 2013 Yes -- I'm not saying it's going to get above freezing.What I am saying, though, is that we all ignored soundings that showed it never getting down to freezing even under the best dynamics (I know, I know, totally different setup, but I'm really talking about mentality not meteorology) because we had a narrative in our heads as to what was going to happen. Well, I think those of us in the i85 corridor have been operating under the assumption that whatever falls will be frozen. I just want to at least raise the possibility that a short term model says it could be a close call. Beanskip I would be shocked if your surface temps make it to freezing once moisture begins. Up top no surprise in being to warm for snow or even sleet. You will have no trouble wet bulbing into the upper 20's. I'm currently at 23 with a dp in the low single digits. This is all about getting qpf and has been since Monday. Fear the dry slot and not surface temps. Polar opposite of last weeks event just hope it doesn't net same result. Link to comment Share on other sites More sharing options...
HurricaneTracker Posted January 25, 2013 Share Posted January 25, 2013 looks like about .25 of qpf for avl-gso. not quite an inch of sleet. enough to be a mess friday and friday night. Yep, and it will be freezing rain on top of that sleet/snow mix. Should be an ugly travel day for sure. Link to comment Share on other sites More sharing options...
WidreMann Posted January 25, 2013 Share Posted January 25, 2013 Yes -- I'm not saying it's going to get above freezing.What I am saying, though, is that we all ignored soundings that showed it never getting down to freezing even under the best dynamics (I know, I know, totally different setup, but I'm really talking about mentality not meteorology) because we had a narrative in our heads as to what was going to happen. Well, I think those of us in the i85 corridor have been operating under the assumption that whatever falls will be frozen. I just want to at least raise the possibility that a short term model says it could be a close call. Last week would have been mostly snow if the precipitation had actually held together. When we had reasonable precip rates, we had all snow. The banding never developed and that big shield of heavier precip never materialized. That was the problem. We knew we would be marginal temperature-wise going in and that was always factored into the equation. There's no missing trend here. Link to comment Share on other sites More sharing options...
beanskip Posted January 25, 2013 Share Posted January 25, 2013 Dude -- I had like a 100 inches of rain and it poured as the 850 low was just to my south. The NAM had me getting 4 inches of snow while the GFS never got me below 35 degrees. On this storm, there is absolutely a trend of the surface 0C line retreating to the north faster and faster each run. Yesterday, my sounding had me a -2 to -3 C during precip. Now it's -.4. If that trend continues, I will end up above freezing at the surface - given the fattness of the warm nose, it will be all rain if that happens. Again,I'm not saying it will -- what I am saying is to ASSUME that it won't happen (like we ASSUMED dynamic cooling would turn my gulley-washer into a snowstorm) would be to repeat the mistakes of last week. Last week would have been mostly snow if the precipitation had actually held together. When we had reasonable precip rates, we had all snow. The banding never developed and that big shield of heavier precip never materialized. That was the problem. We knew we would be marginal temperature-wise going in and that was always factored into the equation. There's no missing trend here. Link to comment Share on other sites More sharing options...
WidreMann Posted January 25, 2013 Share Posted January 25, 2013 Dude -- I had like a 100 inches of rain and it poured as the 850 low was just to my south. The NAM had me getting 4 inches of snow while the GFS never got me below 35 degrees. On this storm, there is absolutely a trend of the surface 0C line retreating to the north faster and faster each run. Yesterday, my sounding had me a -2 to -3 C during precip. Now it's -.4. If that trend continues, I will end up above freezing at the surface - given the fattness of the warm nose, it will be all rain if that happens. Again,I'm not saying it will -- what I am saying is to ASSUME that it won't happen (like we ASSUMED dynamic cooling would turn my gulley-washer into a snowstorm) would be to repeat the mistakes of last week. We knew the first part of the precip would be rain. That was never in question. It actually changed over earlier here than expected and also earlier in some other places to the west. The 850s weren't going to crash until later in the evening. The models never doubted that. Link to comment Share on other sites More sharing options...
Met1985 Posted January 25, 2013 Share Posted January 25, 2013 Yep, and it will be freezing rain on top of that sleet/snow mix. Should be an ugly travel day for sure. It is going to be pretty bad out here no matter how much falls for sure. Link to comment Share on other sites More sharing options...
DaculaWeather Posted January 25, 2013 Share Posted January 25, 2013 GFS just started... Link to comment Share on other sites More sharing options...
Bozart Posted January 25, 2013 Share Posted January 25, 2013 Dude -- I had like a 100 inches of rain and it poured as the 850 low was just to my south. The NAM had me getting 4 inches of snow while the GFS never got me below 35 degrees. On this storm, there is absolutely a trend of the surface 0C line retreating to the north faster and faster each run. Yesterday, my sounding had me a -2 to -3 C during precip. Now it's -.4. If that trend continues, I will end up above freezing at the surface - given the fattness of the warm nose, it will be all rain if that happens. Again,I'm not saying it will -- what I am saying is to ASSUME that it won't happen (like we ASSUMED dynamic cooling would turn my gulley-washer into a snowstorm) would be to repeat the mistakes of last week. Also, I wonder how much our surface winds will work against us. They're going to be southerly, or southwesterly. Not our preferred wind direction for winter precip. In fact, quite unusual. Greg Fishel has mentioned it a couple of times. A south wind tomorrow cannot help anyone whose location is progged to hug that surface wetbulb zero line. Link to comment Share on other sites More sharing options...
downeastnc Posted January 25, 2013 Share Posted January 25, 2013 21 here already tonight, looks like we might hit that forecasted low of 17 setting the stage for what is the real question........one thing folks here in the east need to remember is there are still tons of trees weakened in Ireneand even more dead or broken limbs from Irene. We end up with ice and that could be problematic, especially if we get .25-.50" of ice. Link to comment Share on other sites More sharing options...
jrips27 Posted January 25, 2013 Share Posted January 25, 2013 Lets see if the GFS keeps the slightly wetter solution here in North Georgia. Link to comment Share on other sites More sharing options...
packbacker Posted January 25, 2013 Share Posted January 25, 2013 RGEM stays consistent.... Link to comment Share on other sites More sharing options...
calculus1 Posted January 25, 2013 Share Posted January 25, 2013 RGEM stays consistent.... What's the link for these nice color images of the Canadian? Also, the precip looks pretty solid on this map. No shadow in the lee of the Apps in NC. Heavy ice accretion in SW NC and NE GA. Decent snow amounts in NE NC. The Canadian...for the win?? Link to comment Share on other sites More sharing options...
chapelhillwx Posted January 25, 2013 Share Posted January 25, 2013 What's the link for these nice color images of the Canadian? Also, the precip looks pretty solid on this map. No shadow in the lee of the Apps in NC. Heavy ice accretion in SW NC and NE GA. Decent snow amounts in NE NC. The Canadian...for the win?? http://collaboration.cmc.ec.gc.ca/cmc/cmdn/pcpn_type/pcpn_type_gem_reg.html Link to comment Share on other sites More sharing options...
strongwxnc Posted January 25, 2013 Share Posted January 25, 2013 And as backer stated, been consistent over the past few runs. http://collaboration.cmc.ec.gc.ca/cmc/cmdn/pcpn_type/pcpn_type_gem_reg.html And skip, bet the trends my friend What's the link for these nice color images of the Canadian? Also, the precip looks pretty solid on this map. No shadow in the lee of the Apps in NC. Heavy ice accretion in SW NC and NE GA. Decent snow amounts in NE NC. The Canadian...for the win?? Link to comment Share on other sites More sharing options...
superjames1992 Posted January 25, 2013 Share Posted January 25, 2013 The RGEM could be the real winner with this system. It's showed the same solution (more or less) for a couple days now while the other models have been all over the place. Link to comment Share on other sites More sharing options...
calculus1 Posted January 25, 2013 Share Posted January 25, 2013 The surface wet-bulb freezing line is already way south. ATL, GSP, and CAE are all already north of that line. Link to comment Share on other sites More sharing options...
beanskip Posted January 25, 2013 Share Posted January 25, 2013 Wow, that's a shame. I know you've got the whole crumudgeon schtick going,but I always count on you for some intellectual heft. Not this time. I don't know what your point is here, but here is mine: Last week, I was under a winter storm watch for 2-4 inches of snow and got nada. The reason: even when the NAM and Canadian said the driving rain at my house would changeover to snow, it remained just driving rain. In retrospect, the RAP and NAM gave clues -- they both showed a trend of warmer BL within 24 hours of the event. Sure enough, even when precip was heavy, I did not change over. Now, I'm seeing a similar trend -- late -- that cuts across what has been conventional wisdom in my area (which is different than yours). That conventional wisdom -- the CAD will lock in and keep the I-85/US74 crowd below freezing at the surface throughout. I'm suggesting that the conventional wisdom is wrong is something to consider. We knew the first part of the precip would be rain. That was never in question. It actually changed over earlier here than expected and also earlier in some other places to the west. The 850s weren't going to crash until later in the evening. The models never doubted that. Link to comment Share on other sites More sharing options...
CaryWx Posted January 25, 2013 Share Posted January 25, 2013 RGEM has Brick in the sweet spot Link to comment Share on other sites More sharing options...
weatherlover Posted January 25, 2013 Share Posted January 25, 2013 Where is the moisture at?? I look on the national radar and there is NOTHING for what looks to be 100's of miles from here?? Is something just going to "magically" appear overnight?? Link to comment Share on other sites More sharing options...
calculus1 Posted January 25, 2013 Share Posted January 25, 2013 http://collaboration.cmc.ec.gc.ca/cmc/cmdn/pcpn_type/pcpn_type_gem_reg.html Thanks! Great site. And as backer stated, been consistent over the past few runs. http://collaboration.cmc.ec.gc.ca/cmc/cmdn/pcpn_type/pcpn_type_gem_reg.html And skip, bet the trends my friend Yes, let's hope they're right. The RGEM could be the real winner with this system. It's showed the same solution (more or less) for a couple days now while the other models have been all over the place. True. I just looked at some of the prior runs, and they have all shown the same results: a big ice storm for a good portion of the SE. Link to comment Share on other sites More sharing options...
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