fmsallstars12u Posted January 22, 2013 Share Posted January 22, 2013 Hope this is not a crazy question, I am kinda new and trying to keep up. But, what is a CAD area? Link to comment Share on other sites More sharing options...
franklin NCwx Posted January 22, 2013 Share Posted January 22, 2013 Hope this is not a crazy question, I am kinda new and trying to keep up. But, what is a CAD area? The area just east of the apps. Link to comment Share on other sites More sharing options...
FLO Posted January 22, 2013 Share Posted January 22, 2013 Please don't. I'm in CAE dont want to be teased. I think it's about time to create a dedicated thread for this storm threat. Is a Cold Rain Guarantee in order? Link to comment Share on other sites More sharing options...
sparkync Posted January 22, 2013 Share Posted January 22, 2013 Cold air damming,cold air trapped on the east side of the mountains Link to comment Share on other sites More sharing options...
tnweathernut Posted January 22, 2013 Share Posted January 22, 2013 Hope this is not a crazy question, I am kinda new and trying to keep up. But, what is a CAD area? Hope this is not a crazy question, I am kinda new and trying to keep up. But, what is a CAD area? CAD refers to Cold Air Damming. This is what happens when cold air filters down from further north (because of a high pressure in the northeast which feeds air down the apps) Because of the mountains, it gets trapped and cannot be easily scoured out of the area. In extreme cases, the cold air can filter all the way to Georgia and eastern Alabama. Link to comment Share on other sites More sharing options...
griteater Posted January 22, 2013 Share Posted January 22, 2013 Hope this is not a crazy question, I am kinda new and trying to keep up. But, what is a CAD area? More info on CAD - http://www.theweatherprediction.com/weatherpapers/030/index.html Link to comment Share on other sites More sharing options...
Tyler Penland Posted January 22, 2013 Share Posted January 22, 2013 6z GFS has a nice light freezing rain/sleet event across much of north GA for at least the first half of Friday. Here is the sounding for MBY at 1pm Friday which shows temps in the 20's. Text data off the 6z gives a solid .25" for KGVL dropping most of the precip as ZR. Definitely something to watch here. This new quote coding is weird and annoying lol. Link to comment Share on other sites More sharing options...
Berlin1926 Posted January 22, 2013 Share Posted January 22, 2013 LOL... This seems to be a tricky forecast for NWS offices!? Within 5 miles of our house (Virgilina, VA) there are three different NWS forecasts -- Blacksburg, Wakefield and Raleigh. Based on these we have either a 70% chance of wintry (freezing rain, sleet and snow) precipitation on Friday; a 50% chance of rain and sleet; or, a 20% chance of rain and snow on Thursday night followed by a 50% chance of rain and snow on Friday. The "event" appears to be evolving? Link to comment Share on other sites More sharing options...
Brick Tamland Posted January 22, 2013 Share Posted January 22, 2013 I thought they looked real close for us (Central NC). 2M temps are below freezing at 78 (wityh precip falling) and then just above at 84. I think this was another good trend. Also going on what RAH sayed last night low level cold air will have a harder time being pushed out from what current models indicate. **I personally think we have a good shot at wintery precip, but the big question is going to be type and amounts. The Euro is on our side and it seems the NAM is trending better. I don't think we need much if it's going to be a mix of snow and ice for things to get interesting around here. It might not be good for building a snowman, but it would still cause major problems on the roads with the temps being so cold this week. Link to comment Share on other sites More sharing options...
MotoWeatherman Posted January 22, 2013 Share Posted January 22, 2013 Text data off the 6z gives a solid .25" for KGVL dropping most of the precip as ZR. Verbatim off the 6z GFS I would expect it to start off as sleet then change to snow as the column wet bulbs and then back to sleet/freezing rain up here in our neck of the woods. Link to comment Share on other sites More sharing options...
NGaWxNerd Posted January 22, 2013 Share Posted January 22, 2013 CAD refers to Cold Air Damming. This is what happens when cold air filters down from further north (because of a high pressure in the northeast which feeds air down the apps) Because of the mountains, it gets trapped and cannot be easily scoured out of the area. In extreme cases, the cold air can filter all the way to Georgia and eastern Alabama. I give you an A on your explanation. It helps us rookies when certain acronyms are defined. Link to comment Share on other sites More sharing options...
SnowNiner Posted January 22, 2013 Share Posted January 22, 2013 Consider me confused. The models seems to be indicating a Low going up the apps or towards Ohio. How is CLT supposed to get frozen precipitation out of this? I understand the principal of CAD and how it's going to be relatively cold, but I don't see a mechanism to get both moisture AND cold in here at the same time when our Low is well to the west. Experience tells me this system is a very cold rain, or dry. At best maybe something token at the onset for I-40 north. Or is the synoptic set up that the Low is going to trend south? No comprendea Link to comment Share on other sites More sharing options...
fmsallstars12u Posted January 22, 2013 Share Posted January 22, 2013 The area just east of the apps. Thank you Link to comment Share on other sites More sharing options...
fmsallstars12u Posted January 22, 2013 Share Posted January 22, 2013 Cold air damming,cold air trapped on the east side of the mountains Thank you Link to comment Share on other sites More sharing options...
WilkesboroDude Posted January 22, 2013 Share Posted January 22, 2013 I have noticed when following clippers there is usually a correction north from 4-5 days in. This would be detrimental to snow/ice chances on a major scale, but wouldn't necessarily rule it out. Trends in the coming 24 hours will be crucial. There will be some tap (probably light tap) from the Gulf of Mexico. If this was a straight up clipper I wouldn't even be following it so closely right now. Link to comment Share on other sites More sharing options...
fmsallstars12u Posted January 22, 2013 Share Posted January 22, 2013 Thanks for all the info on the CAD areas...you guys are great!! Link to comment Share on other sites More sharing options...
Cold Rain Posted January 22, 2013 Author Share Posted January 22, 2013 I thought they looked real close for us (Central NC). 2M temps are below freezing at 78 (wityh precip falling) and then just above at 84. I think this was another good trend. Also going on what RAH sayed last night low level cold air will have a harder time being pushed out from what current models indicate. **I personally think we have a good shot at wintery precip, but the big question is going to be type and amounts. Yeah, I like the trends, and at this point, that's the most important thing to take into account. Many areas though, are right on the edge, so even small trends north can put many of us out of the game for something other than a little wintry mix at the onset. Of course a little bit farther south than what the Euro shows will put many in the path of a significant winter storm. The air mass in place is going to be highly supportive of a winter event. This we know. But how that northern stream energy sees the arctic air mass and where it might reform the low along the boundary and how it feels that kicker wave coming in behind it are still up in the air. I think there's only so far south this can go, and a low tracking overhead is not a high confidence winter storm in my book...especially with energy over the Lakes interfering with cold air transport. But the trends are encouraging, so maybe our luck will turn with this one. The RAH disco was a good one and is encouraging also. Link to comment Share on other sites More sharing options...
DCMetroWinston Posted January 22, 2013 Share Posted January 22, 2013 One thing that you guys have taught me is that the models tend to underestimate the strength and resilience of an entrenched CAD in central NC and VA. The trends with this are very good in light of a preexisting CAD situation. Link to comment Share on other sites More sharing options...
Snowless in Carrollton Posted January 22, 2013 Share Posted January 22, 2013 CAD refers to Cold Air Damming. This is what happens when cold air filters down from further north (because of a high pressure in the northeast which feeds air down the apps) Because of the mountains, it gets trapped and cannot be easily scoured out of the area. In extreme cases, the cold air can filter all the way to Georgia and eastern Alabama. But is this potential event late in the week one of those "extreme" cases where the cold air reached all the way to Atlanta and East Alabama ? I just have lots of doubts about any ice potential all the way to the Alabama border. I can see us getting screwed out of wintry weather for the 2nd time in a week. Link to comment Share on other sites More sharing options...
WilkesboroDude Posted January 22, 2013 Share Posted January 22, 2013 Yes, please. Before the kid gets out of class and dooms us. For my area, I would have made it yesterday. Still too uncertain for me for places like Raleigh and Charlotte. I believe this storm will be another who got something and who got nothing. Good luck on whoever makes it...I like my position here in the northern foothills better than the last storm, which still produced. Link to comment Share on other sites More sharing options...
griteater Posted January 22, 2013 Share Posted January 22, 2013 Consider me confused. The models seems to be indicating a Low going up the apps or towards Ohio. How is CLT supposed to get frozen precipitation out of this? I understand the principal of CAD and how it's going to be relatively cold, but I don't see a mechanism to get both moisture AND cold in here at the same time when our Low is well to the west. Experience tells me this system is a very cold rain, or dry. At best maybe something token at the onset for I-40 north. Or is the synoptic set up that the Low is going to trend south? No comprendea I'd say you are spot on SnowNiner. Unless the 500mb vort max trends way south, the moisture will be quite limited. You can see this by how the southeast is in the thin portion of the high 700mb Relative Humidity (i.e. south of the comma head that develops). The cold air ahead of the system is impressive though. Greensboro has a temperature of 27 with a dewpoint of 1 at 10AM on Friday on the GFS. CLT can see significant ice with a low passing well to the NW, but you need a high that is anchored in over the NE, and more precip in the southern stream. Link to comment Share on other sites More sharing options...
WilkesboroDude Posted January 22, 2013 Share Posted January 22, 2013 Consider me confused. The models seems to be indicating a Low going up the apps or towards Ohio. How is CLT supposed to get frozen precipitation out of this? I understand the principal of CAD and how it's going to be relatively cold, but I don't see a mechanism to get both moisture AND cold in here at the same time when our Low is well to the west. Experience tells me this system is a very cold rain, or dry. At best maybe something token at the onset for I-40 north. Or is the synoptic set up that the Low is going to trend south? No comprendea More of a hybrid with some light Gulf tap. Read the AFD's from the NWS, not the dry clipper statements from the board here. Link to comment Share on other sites More sharing options...
tonysc Posted January 22, 2013 Share Posted January 22, 2013 More info on CAD - http://www.theweatherprediction.com/weatherpapers/030/index.html Well I knew what CAD was but not to this extent. Interesting reading. So it sounds like that just about every "surprise" snowstorm in western North and South Carolina are the result of CAD events. Link to comment Share on other sites More sharing options...
Lookout Posted January 22, 2013 Share Posted January 22, 2013 I haven't been on very much or following the models but at first glance, at least a period of freezing precip can be expected in north ga. I know the initial wedge appearance, wetbulbs, and depth of the wedge look pretty good per gfs sounding. Will look closer at this after the new runs come in. Can't believe we finally my favorite to talk about though. Very nice surprise..just hope there is enough precip to actually matter Link to comment Share on other sites More sharing options...
calculus1 Posted January 22, 2013 Share Posted January 22, 2013 According to the 06Z GFS, Hickory would look to start out as snow and then transition to a pretty decent amount of ZR/IP on Friday. That surface layer is quite cold: Date: 3 day AVN valid 6Z FRI 25 JAN 13Station: KHKYLatitude: 35.73Longitude: -81.38-------------------------------------------------------------------------------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 244 SFC 979 412 -6.4 -15.0 50 8.6 -8.5 104 3 268.4 268.6 265.8 271.8 1.22 2 950 646 -7.0 -17.7 42 10.7 -9.5 111 7 270.0 270.2 266.6 272.9 1.00 3 900 1064 -10.0 -20.0 44 10.0 -12.1 134 8 271.2 271.3 267.1 273.7 0.86 4 850 1505 -8.1 -24.3 26 16.2 -11.3 237 9 277.6 277.7 270.8 279.5 0.63 5 800 1981 -2.6 -23.9 18 21.2 -7.8 273 24 288.3 288.4 276.9 290.5 0.69 6 750 2495 -0.9 -18.9 24 18.0 -6.2 285 34 295.6 295.8 281.0 299.2 1.14 7 700 3044 -1.8 -20.4 23 18.6 -7.2 288 39 300.5 300.7 283.0 304.0 1.08 8 650 3631 -4.1 -26.1 16 22.1 -9.6 287 44 304.4 304.5 284.1 306.7 0.70 9 600 4258 -7.2 -32.3 11 25.1 -12.5 284 49 307.8 307.9 285.1 309.3 0.43 10 550 4931 -11.0 -37.4 9 26.4 -15.6 280 54 311.0 311.1 286.1 312.1 0.28 11 500 5657 -14.8 -35.6 15 20.9 -18.5 280 59 315.0 315.1 287.5 316.3 0.37 12 450 6448 -18.6 -27.8 45 9.1 -20.6 282 66 319.8 320.0 289.6 322.8 0.87 13 400 7319 -22.6 -25.3 78 2.8 -23.2 282 68 325.7 325.9 291.7 329.9 1.22 14 350 8287 -29.2 -30.5 89 1.3 -29.5 282 73 329.3 329.5 292.4 332.5 0.86 15 300 9369 -37.4 -41.5 65 4.1 -37.8 291 87 332.6 332.7 292.8 333.9 0.33 16 250 10598 -48.4 -50.0 83 1.6 -48.4 289 98 334.2 334.2 293.0 334.8 0.16 17 200 12022 -61.6 -61.8 98 0.1 -61.6 291 99 335.1 335.2 293.2 335.3 0.05 18 150 13767 -67.7 -68.7 87 1.0 -67.7 296 106 353.5 353.5 297.4 353.6 0.02 19 100 16196 -71.9 -80.8 25 8.9 -71.9 281 81 388.8 388.8 303.6 388.9 0.01TRP 0 WND 0 Sounding variables and indices1000-500 mb thick: 5412.58 mFreezing level: Surface below freezingWetbulb zero: Below groundPrecipitable water: 0.22 inches Date: 3.5 day AVN valid 18Z FRI 25 JAN 13Station: KHKYLatitude: 35.73Longitude: -81.38-------------------------------------------------------------------------------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 179 SFC 971 412 -3.3 -9.5 62 6.2 -5.2 211 9 272.2 272.5 269.6 277.5 1.92 2 950 584 -5.7 -10.2 71 4.5 -7.0 211 13 271.4 271.7 269.0 276.5 1.85 3 900 1006 -5.9 -7.9 86 2.0 -6.5 215 26 275.4 275.8 272.3 281.9 2.34 4 850 1460 1.6 1.1 97 0.5 1.4 230 43 287.8 288.7 282.1 301.7 4.89 5 800 1950 1.8 1.5 97 0.4 1.7 246 51 293.1 294.1 284.8 308.6 5.33 6 750 2470 0.0 -0.2 98 0.3 -0.1 258 57 296.6 297.5 285.8 311.4 5.02 7 700 3021 -2.7 -3.0 98 0.3 -2.9 262 60 299.5 300.3 286.2 312.6 4.37 8 650 3605 -6.5 -6.7 98 0.3 -6.6 260 62 301.6 302.3 286.2 312.4 3.55 9 600 4226 -10.1 -11.5 89 1.4 -10.6 262 66 304.4 304.9 286.3 312.7 2.63 10 550 4894 -12.1 -15.2 78 3.1 -13.1 268 72 309.7 310.1 287.6 316.6 2.13 11 500 5620 -14.7 -22.2 53 7.5 -16.7 270 79 315.1 315.3 288.5 319.4 1.29 12 450 6411 -19.2 -30.3 37 11.1 -21.4 268 86 319.1 319.3 289.2 321.6 0.68 13 400 7278 -24.4 -34.7 38 10.3 -26.1 265 94 323.3 323.4 290.3 325.1 0.50 14 350 8237 -31.1 -40.2 40 9.1 -32.1 265 99 326.8 326.9 291.2 328.0 0.33 15 300 9310 -39.5 -44.8 57 5.2 -39.9 265 109 329.7 329.7 291.9 330.6 0.24 16 250 10531 -49.2 -53.3 62 4.1 -49.3 268 115 333.0 333.0 292.6 333.4 0.11 17 200 11960 -58.6 -60.7 77 2.1 -58.6 269 113 340.0 340.0 294.4 340.2 0.05 18 150 13740 -64.1 -68.0 59 3.9 -64.1 271 105 359.7 359.7 298.7 359.8 0.03 19 100 16187 -68.7 -78.7 22 10.0 -68.8 270 93 395.0 395.0 304.5 395.0 0.01TRP 0 WND 0 Sounding variables and indices1000-500 mb thick: 5441.04 mFreezing level: Surface below freezingFreezing level: 860.57 mb = 1364.36 m = 4476.20 ftFreezing level: 749.48 mb = 2475.74 m = 8122.40 ftWetbulb zero: Below groundPrecipitable water: 0.70 inches Link to comment Share on other sites More sharing options...
burgertime Posted January 22, 2013 Share Posted January 22, 2013 Well this is interesting 12z GFS slightly colder and low is a little further south @78. Has ZR for north GA at that hour. Link to comment Share on other sites More sharing options...
burgertime Posted January 22, 2013 Share Posted January 22, 2013 @81 freezing drizzle in much of NC...north GA still freezing. Nice CAD sig. Link to comment Share on other sites More sharing options...
tnweathernut Posted January 22, 2013 Share Posted January 22, 2013 But is this potential event late in the week one of those "extreme" cases where the cold air reached all the way to Atlanta and East Alabama ? I just have lots of doubts about any ice potential all the way to the Alabama border. I can see us getting screwed out of wintry weather for the 2nd time in a week. This is NOT an extreme case, but some areas of Georgia (and certainly the Carolinas) could squeek out some frozen precipitation. (especially the further north one goes into NC. Most of the precip will be north of the track and that track is well north of MOST of our areas here in the SE (on most modeling). If I were in eastern Kentucky or parts of Virginia, and certainly WV I'd not be getting much sleep this week. As it stands, the trends would have to be pretty dramatic for something significant in the TN valley. CAD areas of NC could have the second best shot at something more significant, 2nd only to those further north in Virginia and points west through parts of Kentucky. This is still all evolving though, so nothing is set in stone. Link to comment Share on other sites More sharing options...
burgertime Posted January 22, 2013 Share Posted January 22, 2013 This run gives N GA, upstate of SC and NC a very light glaze. Euro needs to really be watched. The GFS is VERY light on QPF. Link to comment Share on other sites More sharing options...
burgertime Posted January 22, 2013 Share Posted January 22, 2013 N GA could end up with the max of .25 of QPF....mountains around .20 and the usual zones between the mountains and eastern NC are around .10 per the GFS. Link to comment Share on other sites More sharing options...
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