packbacker Posted December 5, 2017 Share Posted December 5, 2017 Euro with a little clipper love day 5 for NC. Link to comment Share on other sites More sharing options...
Cold Rain Posted December 5, 2017 Share Posted December 5, 2017 Just a reminder, when forecasting snowfall amounts in the SE, it's best to use this simple formula: [(total snowfall from the model with the warmest mid-levels + total snowfall from the model with the warmest boundary layer / 2) + 0.25 (average of all model snow depth)] / 4 - (X" + Y") = Total accumulated snow depth* X sun angle reducer: December = 0, January = 1, February = 2, March = 3 Y warm ground temp reducer: Ground temp < 35 = 0, Ground temp 35 - 40 = 1, Ground temp 40 - 45 = 2, Ground temp 45 - 50 = 3, Ground temp > 50 = Go do something else *A negative number = 0" 7 Link to comment Share on other sites More sharing options...
Lookout Posted December 5, 2017 Share Posted December 5, 2017 20 minutes ago, mackerel_sky said: The trend nobody wanted, is happening! Warmer sucks! But I need the rain, so I like warmer and more precip!! i think you need to ease back on the sarcasm and everything a little. This run of the euro was a good step in the right direction for many...it has quite a bit more precipitation further inland than the prior run and temps aloft look similar to me. Euro is plenty cold aloft for northern half of georgia, sc/western nc. 6 Link to comment Share on other sites More sharing options...
griteater Posted December 5, 2017 Share Posted December 5, 2017 IMO, this is going to continue to tick more amped with more precip inland. I'm just basing it on how it's trending with the wave/trough and sfc low positioning, and how these tend to work with the modeling. I think we would have seen it back off with the 12z runs if we were moving to a weaker solution. Looks good to me in the mtns. East of there it will take some heavy temperature analysis to determine locales with snow. 3 Link to comment Share on other sites More sharing options...
FallsLake Posted December 5, 2017 Share Posted December 5, 2017 1 minute ago, griteater said: IMO, this is going to continue to tick more amped with more precip inland. I'm just basing it on how it's trending with the wave/trough and sfc low positioning, and how these tend to work with the modeling. I think we would have seen it back off with the 12z runs if we were moving to a weaker solution. Looks good to me in the mtns. East of there it will take some heavy temperature analysis to determine locales with snow. As you said before, this is a tough forecast. We could easily just get a lot of cold rain, or somebody could cash out with heavy rates (..like SC November snow). really not sure what to think at this point. 1 Link to comment Share on other sites More sharing options...
No snow for you Posted December 5, 2017 Share Posted December 5, 2017 2 minutes ago, FallsLake said: As you said before, this is a tough forecast. We could easily just get a lot of cold rain, or somebody could cash out with heavy rates (..like SC November snow). really not sure what to think at this point. ULL’s are the best Link to comment Share on other sites More sharing options...
Lookout Posted December 5, 2017 Share Posted December 5, 2017 29 minutes ago, griteater said: Euro looks like a light snow event for the mtns and foothills..into far NE GA...storm is slow to depart...some snow mixed in east of there probably Everything seems to hedge on if there is enough precip to overcome the warm surface layer. Here is the 12z euro valid 12z friday. note the heavy amounts and the much colder temps along that stripe across central ga/sc. 1 Link to comment Share on other sites More sharing options...
Cold Rain Posted December 5, 2017 Share Posted December 5, 2017 6 minutes ago, griteater said: IMO, this is going to continue to tick more amped with more precip inland. I'm just basing it on how it's trending with the wave/trough and sfc low positioning, and how these tend to work with the modeling. I think we would have seen it back off with the 12z runs if we were moving to a weaker solution. Looks good to me in the mtns. East of there it will take some heavy temperature analysis to determine locales with snow. I agree with you. I don't think precip will be much of a problem, when it's all said and done. Will there be a warm layer? We don't know yet. Will the system arrive at such a time as to have given CAA enough of a head-start? We don't know yet. Will the bulk of the precip fall at night? It looks like it now, but that could change. How heavy will the precip be? We don't know yet, although, it will likely be heavy enough for effective dynamic cooling at some locales. Where? We don't know yet, although my best guess for an inch or three of snow (assuming all of these factors line up as favorably as possible) is a line from maybe Roanoke Rapids, to roughly Charlotte though the Upstate and Northern GA and west of there. Still lots of questions to be answered yet. This will likely be a very marginal situation, pretty much across the board, and very much rate driven. 1 Link to comment Share on other sites More sharing options...
SnowNiner Posted December 5, 2017 Share Posted December 5, 2017 1 hour ago, CAD_Wedge_NC said: What are you talking about??? Please read more and post less. Perhaps if there's something you don't understand about my post, feel free to ask a question or simply don't reply at all. "Read more and post less" directives are just arrogant and rude. Thanks. 1 Link to comment Share on other sites More sharing options...
Cold Rain Posted December 5, 2017 Share Posted December 5, 2017 2 minutes ago, SnowNiner said: Perhaps if there's something you don't understand about my post, feel free to ask a question or simply don't reply at all. "Read more and post less" directives are just arrogant and rude. Thanks. Yeah, I didn't see anything wrong with what you posted. 2 Link to comment Share on other sites More sharing options...
griteater Posted December 5, 2017 Share Posted December 5, 2017 9 minutes ago, Lookout said: Everything seems to hedge on if there is enough precip to overcome the warm surface layer. Here is the 12z euro valid 12z friday. note the heavy amounts and the much colder temps along that stripe across central ga/sc. In cases like this where the only warm layer is right at the surface, this is what I've used/observed in the past... If surface wet-bulb temperature is... 32: Snow 33-34: Snow or Rain/Snow Mix 35: Rain/Snow mix 36-37: Rain or Rain/Snow mix Link to comment Share on other sites More sharing options...
Lookout Posted December 5, 2017 Share Posted December 5, 2017 5 minutes ago, griteater said: IMO, this is going to continue to tick more amped with more precip inland. I'm just basing it on how it's trending with the wave/trough and sfc low positioning, and how these tend to work with the modeling. I think we would have seen it back off with the 12z runs if we were moving to a weaker solution. Looks good to me in the mtns. East of there it will take some heavy temperature analysis to determine locales with snow. Many more shifts like this 12z euro run vs the 0z run and this event will be quite s bit different than currently advertised. 2 minutes ago, Cold Rain said: Yeah, I didn't see anything wrong with what you posted. I agree...i didn't see anything wrong with it either....so let's end it here. 1 Link to comment Share on other sites More sharing options...
griteater Posted December 5, 2017 Share Posted December 5, 2017 WPC Model Discussion... PREFERENCE: 12Z ECMWF/UKMET/CMC BLEND CONFIDENCE: AVERAGE THE FIRST SHORTWAVE WEAKENING SOUTHEASTWARD FROM CA/AZ SHOWS GOOD AGREEMENT IN THE MODEL GUIDANCE BUT THERE ARE DIFFERENCES TO TALK ABOUT REGARDING A SHORTWAVE AMPLIFYING SOUTHWARD ACROSS THE CNTRL ROCKIES WED/WED NIGHT. MODEL AND DETERMINISTIC TRENDS HAVE BEEN TOWARD THE WEST/MORE AMPLIFIED WITH THE SHORTWAVE VALID THU EVENING. THE 12Z GFS IS THE WEAKEST AND MOST PROGRESSIVE WITH THE POSITIVELY TILTED TROUGH AXIS STRETCHING FROM THE MS VALLEY INTO NRN MEXICO FRI MORNING. GIVEN THE ENSEMBLE TRENDS TOWARD A SLOWER/DEEPER TROUGH AXIS...AWAY FROM THE 12Z GFS AND 00/06/12Z GEFS...DO NOT WANT TO BE ON THE FASTER EDGE OF THE MODELS. THE 12Z UKMET REPRESENTS THE MOST AMPLIFIED SIDE OF THE LATEST DETERMINISTIC MODEL SPREAD BUT IT HAS WEAKENED SOME FROM ITS 00Z CYCLE. FOR FRIDAY...THE 12Z ECMWF TRENDED SLIGHTLY WEST WITH THE NRN PORTION OF THE TROUGH AXIS AND FASTER/EAST WITH THE SRN PORTION OVER SOUTH TEXAS. THE PREVIOUSLY PREFERRED 00Z ECMWF MEAN IS CURRENTLY NEAR A BLEND OF THE 12Z ECMWF/UKMET/CMC. WHICH IS BETWEEN THE PREVIOUSLY MORE AGGRESSIVE DIGGING SEEN IN THE 00Z UKMET/ECMWF AND FLATTER/MORE PROGRESSIVE 12Z NAM/GFS. Link to comment Share on other sites More sharing options...
FLweather Posted December 5, 2017 Share Posted December 5, 2017 34 minutes ago, LovingGulfLows said: If we learned anything from January this year, warm noses are not easy to "scour out". I'd be very skeptical of models showing heavy snow through dynamic cooling. The is no warm nose. Issue is marginal BL temps. The lowest 1500 feet or so. Above that all the data if seen supports snow. It's either gonna rain or snow. 1 Link to comment Share on other sites More sharing options...
southernskimmer Posted December 5, 2017 Share Posted December 5, 2017 Quote The is no warm nose There was no warm nose on the modeling last year either 3 Link to comment Share on other sites More sharing options...
ILMRoss Posted December 5, 2017 Share Posted December 5, 2017 39 minutes ago, LovingGulfLows said: If we learned anything from January this year, warm noses are not easy to "scour out". I'd be very skeptical of models showing heavy snow through dynamic cooling. Different set up. That event featured a strong low pressure and generally amped set up. This event has a much weaker low, with less warm air advection that could strengthen a warm nose. Temps at low levels are the problem, and that's one of the *few* things that could be modeled completely wrong given the modeled precipitation rates. 1 Link to comment Share on other sites More sharing options...
snowlover91 Posted December 5, 2017 Share Posted December 5, 2017 2 minutes ago, southernskimmer said: There was no warm nose on the modeling last year either There was on the NAM but people discounted it because it was the NAM. Typically around here the model with the most aggressive warm nose oftentimes ends up being close to reality, though not always. The NAM has a similar temp profile to the Euro with the warm nose getting as far inland as Rocky Mount to RDU. This seems to be the consensus for now but will change as models figure out the dynamics and timing of everything. The warm nose modeled on the Euro and NAM seems to be in the 750-850mb layer. 1 Link to comment Share on other sites More sharing options...
packbacker Posted December 5, 2017 Share Posted December 5, 2017 23 minutes ago, Cold Rain said: I agree with you. I don't think precip will be much of a problem, when it's all said and done. Will there be a warm layer? We don't know yet. Will the system arrive at such a time as to have given CAA enough of a head-start? We don't know yet. Will the bulk of the precip fall at night? It looks like it now, but that could change. How heavy will the precip be? We don't know yet, although, it will likely be heavy enough for effective dynamic cooling at some locales. Where? We don't know yet, although my best guess for an inch or three of snow (assuming all of these factors line up as favorably as possible) is a line from maybe Roanoke Rapids, to roughly Charlotte though the Upstate and Northern GA and west of there. Still lots of questions to be answered yet. This will likely be a very marginal situation, pretty much across the board, and very much rate driven. Whatever trend doesn't give us snow...we can miss them in any which direction. The good news I do think someone gets snow Friday/Saturday...my money would be in the GSP to foothills to Roanoke area. GEPS with the NW trend...where it stops nobody know. 1 Link to comment Share on other sites More sharing options...
WarmNose Posted December 5, 2017 Share Posted December 5, 2017 If I remember correctly, last year before our January event the GFS sniffed out our warm nose 24-48 hours in advance. It showed it on the SC GA border sneaking up into the southern part of upstate SC. Edit: it could have been the NAM I don't remember Link to comment Share on other sites More sharing options...
FallsLake Posted December 5, 2017 Share Posted December 5, 2017 4 minutes ago, WarmNose said: If I remember correctly, last year before our January event the GFS sniffed out our warm nose 24-48 hours in advance. It showed it on the SC GA border sneaking up into the southern part of upstate SC. Edit: it could have been the NAM I don't remember Yep, it was the NAM. 2 Link to comment Share on other sites More sharing options...
FallsLake Posted December 5, 2017 Share Posted December 5, 2017 Here's the JMA: Link to comment Share on other sites More sharing options...
snowlover91 Posted December 5, 2017 Share Posted December 5, 2017 3 minutes ago, WarmNose said: If I remember correctly, last year before our January event the GFS sniffed out our warm nose 24-48 hours in advance. It showed it on the SC GA border sneaking up into the southern part of upstate SC. Edit: it could have been the NAM I don't remember It was definitely the NAM, the GFS was one of the colder solutions from what I recall. When the NAM is colder than the GFS it always gets my interest... surface temps will be marginal 32-34 but cold enough IMO. The key is where the 750-850mb warm nose sets up. Right now the NAM sets that up along the I-95 corridor or just to the west of it favoring RDU to CLT and points west. That seems quite reasonable given climo as well. Link to comment Share on other sites More sharing options...
mrdaddyman Posted December 5, 2017 Share Posted December 5, 2017 Everybody just loves to trash the NAM but it is excellent with sniffing out a warm nose. It hasn't missed one yet in the last 5+ years for MBY. Don't discount it. That would be very unwise. 2 Link to comment Share on other sites More sharing options...
griteater Posted December 5, 2017 Share Posted December 5, 2017 ^JMA looks like a whopper. On the flip side, the DWD-ICON and UKMet pretty much limit precip from getting NW of a line from Atlanta to Greensboro to Norfolk Link to comment Share on other sites More sharing options...
packbacker Posted December 5, 2017 Share Posted December 5, 2017 EPS looks a hair closer to coast of previous runs but might be just spread decreasing. That's a fairly good track for central NC. 3 Link to comment Share on other sites More sharing options...
packbacker Posted December 5, 2017 Share Posted December 5, 2017 Still positively tilted but man is that close. I would sacrifice a car topper for a big event for 85 and points west. 2 Link to comment Share on other sites More sharing options...
BullCityWx Posted December 5, 2017 Share Posted December 5, 2017 34 minutes ago, griteater said: In cases like this where the only warm layer is right at the surface, this is what I've used/observed in the past... If surface wet-bulb temperature is... 32: Snow 33-34: Snow or Rain/Snow Mix 35: Rain/Snow mix 36-37: Rain or Rain/Snow mix I've been wondering how 11/19/2000 works out as an analog to this. I need to look into it. https://www.wunderground.com/history/airport/KCLT/2000/11/19/DailyHistory.html?req_city=&req_state=&req_statename=&reqdb.zip=&reqdb.magic=&reqdb.wmo= Link to comment Share on other sites More sharing options...
mackerel_sky Posted December 5, 2017 Share Posted December 5, 2017 20 minutes ago, packbacker said: Whatever trend doesn't give us snow...we can miss them in any which direction. The good news I do think someone gets snow Friday/Saturday...my money would be in the GSP to foothills to Roanoke area. GEPS with the NW trend...where it stops nobody know. You tease! Link to comment Share on other sites More sharing options...
packbacker Posted December 5, 2017 Share Posted December 5, 2017 Op Euro QPF...if nothing else it should be a wet SE Thursday-Saturday. Link to comment Share on other sites More sharing options...
griteater Posted December 5, 2017 Share Posted December 5, 2017 GSP Discussion... In response to encroaching positive tilt l/wv trough and developing upper jet dynamics, pcpn shield is progged to expand and develop back northward into the cwfa Thursday night. 05/12z SuperBlend and WPC guidance limits the increase to just chance pops thru the piedmont by daybreak Friday. Deeper forcing should increase into Friday with favorable upper jet positioning. Based on this, have increased precip chances to mid-chance with the best response slated to be atop the piedmont. Critical 85-70h thickness values should hover along the southeast fringe of the cwfa through Friday...a rough estimate of the rain/snow line for the bulk of the event. However, warm blyr temperatures makes it questionable on just how much snow would accumulate SE of I-85 where the liquid equiv QPF is the greatest. At this point, best combination of QPF and favorable temperatures looks to be North and NW of CLT where if any heavier bands are able to form would produce an inch of snow accumulation. 1 Link to comment Share on other sites More sharing options...
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