WxUSAF Posted February 17, 2012 Share Posted February 17, 2012 Agree fully. Yeah, I never remember NWS putting amounts out this far ahead. Maybe a mention in the AFD but that's different than the public forecast. I think the standard procedure is ~24 hours out. Maybe 36 hours at the outside. If the GFS and Euro also show potential for warning level snow, I'm sure they mention it in the AFD. Link to comment Share on other sites More sharing options...
mappy Posted February 17, 2012 Share Posted February 17, 2012 I think the standard procedure is ~24 hours out. Maybe 36 hours at the outside. If the GFS and Euro also show potential for warning level snow, I'm sure they mention it in the AFD. From LWX A Winter Storm Watch is issued when there is the potential for significant and hazardous winter weather within 48 hours. It does not mean that significant and hazardous winter weather will occur...it only means it is possible. Link to comment Share on other sites More sharing options...
weathergeek Posted February 17, 2012 Share Posted February 17, 2012 IT IS EVIDENT THAT THE STORM SYSTEM WILL DEEPEN OFFSHORE WITH A SOLID SWATH OF PRECIPITATION AND BACKING LOW LEVEL FLOW. PRECIPITATION IS EXPECTED TO BEGIN AS A RAIN/SNOW MIX OVER THE COASTAL LOCALES AND WEST TO THE MAJOR METRO AREAS OF WASHINGTON D.C/BALTIMORE. ALL SNOW IS ANTICIPATED FOR THE HIGHER ELEVATIONS WEST OF THE METRO TO THE ALLEGHENY FRONT. DYNAMIC COOLING AND BACKING FLOW TO THE NORTH WILL COOL THE COLUMN AND CHANGE THE MIXED PRECIPITATION TO ALL SNOW EAST THROUGH THE METRO AND COASTAL LOCALES LATER SUNDAY AFTERNOON INTO SUNDAY NIGHT WITH THE SYSTEM PULLING AWAY THEREAFTER. IT IS MUCH TOO EARLY TO TELL HOW MUCH SNOW WILL FALL AND WHERE. IT DOES APPEAR THAT AT LEAST A LIGHT TO MODERATE ACCUMULATION COULD BE POSSIBLE. WAITING FOR MORE CONSISTENT GUIDANCE BEFORE MAKING THAT DECISION. STAY TUNED.http://forecast.weather.gov/product.php?site=NWS&issuedby=lwx&product=AFD&format=CI&version=1&glossary=1&highlight=off Link to comment Share on other sites More sharing options...
nflwxman Posted February 17, 2012 Share Posted February 17, 2012 The bullseye will move north from CHO. Probably. Maybe 5 miles north to Ruckersville . In all seriousness, this does remind me a lot of 1/30/2010. North trend commencing in T minus 12 hours. Link to comment Share on other sites More sharing options...
WinterWxLuvr Posted February 17, 2012 Share Posted February 17, 2012 I've referenced it, so have others, but remember that the move north with the precip in jan 2010 didn't even show until 24 hours out. In fact at 36 hours all models abandoned us. This may end up better than we think. Link to comment Share on other sites More sharing options...
usedtobe Posted February 17, 2012 Share Posted February 17, 2012 I think the NWS is right on for now. If the other 12z runs are similarly cold as the NAM, they might switch that "rain or snow" to just "snow", but they don't need to be putting amounts out yet. This is still 48hrs+ away. Accumulation totals would probably be added in tomorrow's afternoon update. Perhaps they put out a HWO or something like that this afternoon if the Euro and GFS also show potential warning-level snows. Only heros put out amounts that early and you know what happens to them. We'll probably put up an initial accumulation map after seeing the euro but with the euro and 00Z gGEm showing almost a miss. Why would anyone jump the gun. The 09Z SERF plume diagram is all over the place with amounts. I'd show an annotated version but am doing a CWG post today so I've got to hold off. Link to comment Share on other sites More sharing options...
Ji Posted February 17, 2012 Share Posted February 17, 2012 funny how nobody trusts the NAM 48 hours and its a short range model. When do you trust it...3 minutes before the first flake? Link to comment Share on other sites More sharing options...
PhineasC Posted February 17, 2012 Share Posted February 17, 2012 The GFS doesn't look very good. Link to comment Share on other sites More sharing options...
Ian Posted February 17, 2012 Share Posted February 17, 2012 funny how nobody trusts the NAM 48 hours and its a short range model. When do you trust it...3 minutes before the first flake? it's usually pretty good about 6 hours after the fact. seriously.. it's a travesty of a model in most instances. it has its strengths tho.. like keeping people occurpied until the gfs. Link to comment Share on other sites More sharing options...
TUweathermanDD Posted February 17, 2012 Share Posted February 17, 2012 The GFS doesn't look very good. Looks a little error laden. Link to comment Share on other sites More sharing options...
eurojosh Posted February 17, 2012 Share Posted February 17, 2012 Really? At 48 hours looks pretty darn similar to the NAM, I think... Link to comment Share on other sites More sharing options...
WxUSAF Posted February 17, 2012 Share Posted February 17, 2012 Since Wes can't post it...here's the info from the 9z SREF plumes: BWI: mean snow 0.25", max 0.8", min 0". DCA: mean snow 0.44", max 1.03", min 0" IAD: mean snow 0.4", max 1.01", min 0" RIC: mean snow 0.61", max 1.03", min 0" Still a lot of members with rain for RIC. The mean is biased low by the rainers. None look like misses for RIC. Still a couple members were complete misses for the DC-Balt stations. Link to comment Share on other sites More sharing options...
usedtobe Posted February 17, 2012 Share Posted February 17, 2012 The GFS doesn't look very good. No it doesn't at least at 48 Link to comment Share on other sites More sharing options...
RickinBaltimore Posted February 17, 2012 Share Posted February 17, 2012 Looks a little error laden. What would be the reason for that? I'm not seeing the model right now, I'm just wondering what the errors would be. Link to comment Share on other sites More sharing options...
SomeguyfromTakomaPark Posted February 17, 2012 Share Posted February 17, 2012 The surface low is definitely SW at 48 from its position at 54 on 6z, but maybe its just a little slower. Link to comment Share on other sites More sharing options...
Bob Chill Posted February 17, 2012 Share Posted February 17, 2012 Precip a bit further south and less organized. slp a touch slower and further south. We'll see if it matters in a few mins i guess. Link to comment Share on other sites More sharing options...
North Balti Zen Posted February 17, 2012 Share Posted February 17, 2012 No it doesn't at least at 48 Looks a little better at 54, though, I think. Link to comment Share on other sites More sharing options...
yoda Posted February 17, 2012 Share Posted February 17, 2012 12z GFS certainly taking its time... precip barely into DCA at 18z SUN Link to comment Share on other sites More sharing options...
baroclinic_instability Posted February 17, 2012 Share Posted February 17, 2012 Looks a little error laden. Really? At 48 hours looks pretty darn similar to the NAM, I think... It looks pretty realistic and normal, and honestly, while folks may want to "lock" onto a solution, that just doesn't happen with systems like this when they have such a GOM tap. Grossly too much latent energy available here, and the final solution of this system will move around like this since the GFS/NAM/GEM/UK/and ECMWF will all be dependent upon the activation of sub-grid convective schemes and how they develop that DMC...which is not necessarily something that will be well handled by the deterministic guidance. Link to comment Share on other sites More sharing options...
CoastalWx Posted February 17, 2012 Share Posted February 17, 2012 It's a bit weaker and south with the heavier snows. Link to comment Share on other sites More sharing options...
CoastalWx Posted February 17, 2012 Share Posted February 17, 2012 It looks pretty realistic and normal, and honestly, while folks may want to "lock" onto a solution, that just doesn't happen with systems when they have such a GOM tap. Grossly too much latent energy available here, and the final solution of this system will move around like this since the GFS/NAM/GEM/UK/and ECMWF will all be dependent upon sub-grid convective schemes and how they develop that DMC...which is not necessarily something that will be well handled by the guidance. This thing is going to have a ton of convection. Southern stream systems always do. Link to comment Share on other sites More sharing options...
baroclinic_instability Posted February 17, 2012 Share Posted February 17, 2012 It's a bit weaker and south with the heavier snows. It is a tick S and drier, but it actually isn't that different overall even though it gets there in a vastly different manner. Link to comment Share on other sites More sharing options...
usedtobe Posted February 17, 2012 Share Posted February 17, 2012 It looks pretty realistic and normal, and honestly, while folks may want to "lock" onto a solution, that just doesn't happen with systems like this when they have such a GOM tap. Grossly too much latent energy available here, and the final solution of this system will move around like this since the GFS/NAM/GEM/UK/and ECMWF will all be dependent upon the activation of sub-grid convective schemes and how they develop that DMC...which is not necessarily something that will be well handled by the deterministic guidance. How the convective schemes handle the convection will play a big role in where the models put their lows and that convection may or may not be in the wrong spot. That's the big rub. Link to comment Share on other sites More sharing options...
weathafella Posted February 17, 2012 Share Posted February 17, 2012 GFS and UKMET are near whiffs. Excellent hit for RIC but not much for the DC/BW metro and north. I doubt that happens though it is a cause of concern given the Euro at 0Z. Link to comment Share on other sites More sharing options...
Bob Chill Posted February 17, 2012 Share Posted February 17, 2012 The biggest difference is the track of the surface low vs 6z. It's a bit slower but more importantly is further s&w. 12z backed off on the heavy precip to the n&w too. It's a game of inches for sure but this run took a couple inches away. (lol- unintended pun). Link to comment Share on other sites More sharing options...
Ji Posted February 17, 2012 Share Posted February 17, 2012 it's usually pretty good about 6 hours after the fact. seriously.. it's a travesty of a model in most instances. it has its strengths tho.. like keeping people occurpied until the gfs. dont let Ryan Mahue hear you say this Link to comment Share on other sites More sharing options...
SomeguyfromTakomaPark Posted February 17, 2012 Share Posted February 17, 2012 Looks like DC total precip would be under 0.5 this run. Link to comment Share on other sites More sharing options...
CoastalWx Posted February 17, 2012 Share Posted February 17, 2012 It is a tick S and drier, but it actually isn't that different overall even though it gets there in a vastly different manner. The difference I see, is up in New England. Heights are flatter and more west to even west-northwest flow helping to flatten the height field. Link to comment Share on other sites More sharing options...
baroclinic_instability Posted February 17, 2012 Share Posted February 17, 2012 How the convective schemes handle the convection will play a big role in where the models put their lows and that convection may or may not be in the wrong spot. That's the big rub. Yeah agreed, I will probably give more consideration to the convective environment here the next day, it is going to be crucial. SPC outlooks will also be worth reading. Link to comment Share on other sites More sharing options...
Midlo Snow Maker Posted February 17, 2012 Share Posted February 17, 2012 Looks a little error laden. why? because it does not show enough snow for your back yard? Link to comment Share on other sites More sharing options...
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