dwagner88 Posted February 25, 2015 Share Posted February 25, 2015 What is everyone's opinion on these Rap/HRRR simulations that show us getting screwed down here?Haven't seen the HRRR but the last RAP I saw looked ok here. Not crazy like the NAM, but in line with the forecasts from the local guys. Rap and HRRR are not notoriously accurate outside of a few hours. Link to comment Share on other sites More sharing options...
ShawnEastTN Posted February 25, 2015 Share Posted February 25, 2015 Haven't seen the HRRR but the last RAP I saw looked ok here. Not crazy like the NAM, but in line with the forecasts from the local guys. Rap and HRRR are not notoriously accurate outside of a few hours. Yeah I looked at both a couple hours ago, and they looked fine in terms of composite reflectivity. I wouldn't rely on them like dwagner says until this evening. Not to mention that even last weeks cutter the HRRR and RAP were not very accurate even in that 3 hour or so window. Link to comment Share on other sites More sharing options...
ChattChaser Posted February 25, 2015 Share Posted February 25, 2015 Awesome, thanks guys! Link to comment Share on other sites More sharing options...
Carvers Gap Posted February 25, 2015 Share Posted February 25, 2015 What is everyone's opinion on these Rap/HRRR simulations that show us getting screwed down here? I have a low opinion of the RAP...Seems like it always playing catch-up in the northern Valley. The NAM has been good. Looks for trends more than anything. Look like a growth in the precip shield is happening on most models. Bout as good a look as Chatt can get IMHO. If anything, I would worry about mixing. But looks to me like you all are good. Link to comment Share on other sites More sharing options...
Stovepipe Posted February 25, 2015 Share Posted February 25, 2015 13z RAP snow total, the event isn't over at that point: Link to comment Share on other sites More sharing options...
dwagner88 Posted February 25, 2015 Share Posted February 25, 2015 That pivot point along I59 aiming towards this area has my attention. If we are going to bust high, we need to be under that. Both the NAM and the GFS have been hinting at it. GFS fizzles it out before it gets here. Link to comment Share on other sites More sharing options...
Stovepipe Posted February 25, 2015 Share Posted February 25, 2015 And yes RAP/HRRR have to be taken with a huge grain of salt. They have been pretty bad on temps, p-type-, and qpf on a couple of the recent storms. Just have to watch radar and compare to see if they look reasonable. For the last storm I was switching between radar and rap/hrrr laughing my arse off because it was pouring snow outside and the models were initializing dry. Link to comment Share on other sites More sharing options...
Blue Ridge Posted February 25, 2015 Share Posted February 25, 2015 13z RAP snow total, the event isn't over at that point: Man, that paints an ugly dry-slot toward TRI. RAP/HRRR seem to always underestimate the northern valley in particular. Link to comment Share on other sites More sharing options...
dwagner88 Posted February 25, 2015 Share Posted February 25, 2015 I love that spot of 19"+ just south of my Grandmother's house in Greenville, SC. I'll eat my jeans if that happens. Link to comment Share on other sites More sharing options...
Bango Posted February 25, 2015 Share Posted February 25, 2015 This post is a little "imby" but I've noticed how Greenville to Johnson City seems to be caught in screw zones for coastal lows. Maybe this has always been the case but I haven't noticed this trend before the last big coastal storm. Link to comment Share on other sites More sharing options...
BamaChemE Posted February 25, 2015 Share Posted February 25, 2015 What's the QPF for HSV and BHam if someone doesn't mind posting? Link to comment Share on other sites More sharing options...
Carvers Gap Posted February 25, 2015 Share Posted February 25, 2015 Man, that paints an ugly dry-slot toward TRI... Downsloping I think? As the comma slides through, might fill in. Thing is, this storm might be strong enough to overcome it. I am more excited more about the trend...most models are building the precip shield back west. Evolving quickly. I bet it isn't done changing. Link to comment Share on other sites More sharing options...
Carvers Gap Posted February 25, 2015 Share Posted February 25, 2015 This post is a little "imby" but I've noticed how Greenville to Johnson City seems to be caught in screw zones for coastal lows. Maybe this has always been the case but I haven't noticed this trend before the last big coastal storm.Downsloping is always an issue. However, if this grows into a large storm as I think it will...my only concern is that we don't get too far west. Large storms can overcome downsloping. But yes, it has to be always watched. Link to comment Share on other sites More sharing options...
Blue Ridge Posted February 25, 2015 Share Posted February 25, 2015 This post is a little "imby" but I've noticed how Greenville to Johnson City seems to be caught in screw zones for coastal lows. Maybe this has always been the case but I haven't noticed this trend before the last big coastal storm. There is typically a snow shadow *somewhere* in the northern valley, but the models never seem to hammer it down properly. Downsloping will eat at totals in the Greene, Unicoi, Carter, and Johnson valleys, but rarely is it so strong that it affects JC (obvious counter-example being Saturday's storm). The direction from which the precip is moving makes all the difference. Case in point: no real shadow existed yesterday as the precip moved east. The differences in snow totals were relative to banding than to any sort of downsloping or shadow. Link to comment Share on other sites More sharing options...
jaxjagman Posted February 25, 2015 Share Posted February 25, 2015 What's the QPF for HSV and BHam if someone doesn't mind posting? .78 hsv .98 bhm Link to comment Share on other sites More sharing options...
Stovepipe Posted February 25, 2015 Share Posted February 25, 2015 14z HRRR at 5z: 14z RAP at the same time: Link to comment Share on other sites More sharing options...
Carvers Gap Posted February 25, 2015 Share Posted February 25, 2015 Might not be historic for everyone in E TN...but Chatt may make a run at this. The latest short range models are going crazy over the Carolinas. That is why precip is getting thrown back in large chunks over the mtns. RAP is putting 2.5" liquid equivalent over the Carolinas. Latest had an 1" liquid equivalent over Chatt. Prob some mixing, mostly snow. Boom? Link to comment Share on other sites More sharing options...
Stovepipe Posted February 25, 2015 Share Posted February 25, 2015 MRX: 000FXUS64 KMRX 251534 AAAAFDMRXAREA FORECAST DISCUSSION...UPDATEDNATIONAL WEATHER SERVICE MORRISTOWN TN1034 AM EST WED FEB 25 2015.DISCUSSION...THE FORECAST APPEARS ON TRACK...WITH NO INDICATIONS OF MAJORCHANGES BASED ON THE LATEST OBSERVED AND MODEL DATA. THE HRRR SEEMSTO BE DOING WELL IN DEPICTING THE PRECIP OVER AL AND MS. SOMEEVAPORATION INTO A LOW LEVEL DRY LAYER WILL DELAY PRECIP AT THEGROUND...WITH THE CHA AREA EXPECTED TO SEE SNOW BEGIN IN THE 20-22ZWINDOW. STRONG VERTICAL ASCENT ASSOCIATED WITH AGEOSTROPHIC FORCINGCOULD BRING A PERIOD OF HEAVY SNOW IN SOUTHERN AREAS AROUND 00Z.EXPECT THAT TIMING AROUND KNOXVILLE AND OAK RIDGE WILL BE22-00Z...WITH TRI-CITIES AND SW VA APPROXIMATELY BETWEEN 00Z-02Z.THE WINDOW FOR HEAVY SNOW IS NOT OPEN FOR LONG...AS MIDLEVELMOISTURE IN THE DENDRITE GROWTH ZONE BEGINS TO DISAPPEAR IN THE04-08Z TIME FRAME.FORECAST SNOW AMOUNTS ARE IN LINE WITH THE LATEST SREF...BUT ALITTLE LOW IN SOME SPOTS COMPARED TO THE LATEST NAM...WHICH SPREADS3+ INCH AMOUNTS ALL THE WAY INTO THE PLATEAU. THE HRRR IS ON THEOTHER END OF THE SPECTRUM...SHOWING VERY LITTLE SNOW WEST OF OAKRIDGE. THE NAM IS AN OUTLIER...BUT IT IS NOTABLE THAT THERE IS ACLUSTER OF SREF MEMBERS THAT SHOW SNOW ACCUMULATION SEVERAL INCHESABOVE THE SREF MEAN.WILL KEEP SNOW AMOUNTS AND THE WARNING/ADVISORY AREAS UNCHANGEDFOR THE UPDATE. TEMPERATURES WILL NEED SOME DOWNWARD ADJUSTMENTSAS OBS ARE RUNNING LOWER THAN FORECAST IN SEVERAL SPOTS. Link to comment Share on other sites More sharing options...
Carvers Gap Posted February 25, 2015 Share Posted February 25, 2015 MRX:Bout as conservative as it gets. The latest models have trended with much bigger amounts in the Valley. The NAM is not an outlier either as it has support from the RAP.Edit: short range model. Latest GFS still looks out to lunch in the Carolinas alone. They may get much more than the GFS predicts. Link to comment Share on other sites More sharing options...
Stovepipe Posted February 25, 2015 Share Posted February 25, 2015 That NAM has a cobb of 9 inches for Nooga! Link to comment Share on other sites More sharing options...
Carvers Gap Posted February 25, 2015 Share Posted February 25, 2015 Pulled this from the SE forum. Blue Ridge Escarpment's work...RAP. The 12z GFS not even on the same page as short range models. Something has to give... Link to comment Share on other sites More sharing options...
Stovepipe Posted February 25, 2015 Share Posted February 25, 2015 Link to comment Share on other sites More sharing options...
ShawnEastTN Posted February 25, 2015 Share Posted February 25, 2015 Bout as conservative as it gets. The latest models have trended with much bigger amounts in the Valley. The NAM is not an outlier either as it has support from the RAP. Edit: short range model. Latest GFS still looks out to lunch in the Carolinas alone. They may get much more than the GFS predicts. Yeah there is a good chance I think of a bust high here, and they oddly enough elude to it while being conservative. I guess that isn't a bad move, on one hand. They mention the higher totals of the NAM, say its an outlier, but then say that the SREF has a lot of members that are several inches higher than the mean. Why say all that other than to maintain flexibility in future updates. Link to comment Share on other sites More sharing options...
dwagner88 Posted February 25, 2015 Share Posted February 25, 2015 Looks like we have 2 camps. One with a pivot over the valley (NAM, rap, HRRR with temp problems) and the GFS/euro with it over the Carolinas. I know which one I'm rooting for. I don't have any educated opinion as to whether one is more valid than the other though. Link to comment Share on other sites More sharing options...
dwagner88 Posted February 25, 2015 Share Posted February 25, 2015 That NAM has a cobb of 9 inches for Nooga!There will be a lot of tree damage if that verifies. Link to comment Share on other sites More sharing options...
Stovepipe Posted February 25, 2015 Share Posted February 25, 2015 Well that escalated quickly, 14z RAP total snow: Link to comment Share on other sites More sharing options...
Carvers Gap Posted February 25, 2015 Share Posted February 25, 2015 RGEM now has a bigger precip field in E TN. I don't know if the short range trend verifies...but the models seem to be sensing a bigger storm than originally forecast. The radar shows a massive system. So, just how far north can this get? Edit: not nearly as crazy as the RAP. Link to comment Share on other sites More sharing options...
Carvers Gap Posted February 25, 2015 Share Posted February 25, 2015 You folks in the southern Valley might want to start an obs thread for this event. Maybe someone from Bama or Chatt? Link to comment Share on other sites More sharing options...
ShawnEastTN Posted February 25, 2015 Share Posted February 25, 2015 I'm just amazed at the extent of the shield already. Its already (likely virga) into southern west and southern middle TN counties. Atlanta already getting reports of snow/sleet and its before noon. This storm looks like a monster. Link to comment Share on other sites More sharing options...
Stovepipe Posted February 25, 2015 Share Posted February 25, 2015 15z RAP total snow: Link to comment Share on other sites More sharing options...
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