Weather Will Posted February 23, 2022 Share Posted February 23, 2022 WB 21Z SREF Link to comment Share on other sites More sharing options...
NorthArlington101 Posted February 23, 2022 Share Posted February 23, 2022 2 minutes ago, high risk said: This is a fair point. None of these accumulation computations is making any attempt to determine how efficiently the ice can accrete. They're just looking for freezing rain as the precip type at the top of the hour, and if that is found, all of the QPF from the past hour (or in some cases, 3 or 6 hours!) goes into the freezing rain bucket. In fact, only the RAP/HRRR actually have a true tallies of freezing rain and sleet. I feel like I've heard that before, but that bolded part is truly nuts and ends up being so misleading, especially for models that only have those 3/6 hour intervals. Link to comment Share on other sites More sharing options...
NorthArlington101 Posted February 23, 2022 Share Posted February 23, 2022 Just now, Weather Will said: WB 21Z SREF Yeah, if I thought the SREF was a legit model, this would be a worrying/exciting trend. 1 Link to comment Share on other sites More sharing options...
Weather Will Posted February 23, 2022 Share Posted February 23, 2022 WB RDPS - North America 10km ticked South as well. Link to comment Share on other sites More sharing options...
Scarlet Pimpernel Posted February 23, 2022 Share Posted February 23, 2022 15 minutes ago, high risk said: This is a fair point. None of these accumulation computations is making any attempt to determine how efficiently the ice can accrete. They're just looking for freezing rain as the precip type at the top of the hour, and if that is found, all of the QPF from the past hour (or in some cases, 3 or 6 hours!) goes into the freezing rain bucket. In fact, only the RAP/HRRR actually have a true tallies of freezing rain and sleet. Interesting info, thanks. I always take that with a HUGE grain of salt (or sleet?). So are the images that TT and others generate coming directly from model output of this, or do they use some algorithm of their own based on that? Link to comment Share on other sites More sharing options...
high risk Posted February 23, 2022 Share Posted February 23, 2022 9 minutes ago, NorthArlington101 said: I feel like I've heard that before, but that bolded part is truly nuts and ends up being so misleading, especially for models that only have those 3/6 hour intervals. Right! It's most pronounced for the NAM beyond 48 hours or the GFS beyond day 5, as those models have hourly output through those times, although that assumes that the various sites are actually pulling in the hourly data. The bottom line, though, is that it definitely inflates freezing rain and sleet totals. 1 1 Link to comment Share on other sites More sharing options...
high risk Posted February 23, 2022 Share Posted February 23, 2022 2 minutes ago, Always in Zugzwang said: Interesting info, thanks. I always take that with a HUGE grain of salt (or sleet?). So are the images that TT and others generate coming directly from model output of this, or do they use some algorithm of their own baaed on that? I don't know for sure, but I think that they're at least using the precip type information directly from the models and not computing it themselves. Regardless, it's applying an instantaneous precip type to an accumulated precip. 1 Link to comment Share on other sites More sharing options...
Scarlet Pimpernel Posted February 23, 2022 Share Posted February 23, 2022 1 minute ago, high risk said: I don't know for sure, but I think that they're at least using the precip type information directly from the models and not computing it themselves. Regardless, it's applying an instantaneous precip type to an accumulated precip. Thanks. Yeah that certainly makes those plots pretty dubious on the amounts, though perhaps the areal coverage of that ptype might be somewhat more useful. I mean really, 1.50 inches of QPF is not going to give you 1.50 inches of ice of course, to use an extreme example...and which I have actually seen in the past! 1 Link to comment Share on other sites More sharing options...
Weather Will Posted February 23, 2022 Share Posted February 23, 2022 WB 0Z GFS Link to comment Share on other sites More sharing options...
TSSN+ Posted February 23, 2022 Share Posted February 23, 2022 Well northern Maryland into southern pa might be in for some issues for sure. Link to comment Share on other sites More sharing options...
MillvilleWx Posted February 23, 2022 Share Posted February 23, 2022 One of the trends I'm noticing in the area of ice accretion is the NBM coming around now to a more pronounced icing scenario compared to its previous runs. NBM is no where near perfect, but it does take into consideration a lot of different guidance and uses a blend of the data to calculate final ensemble means. It also utilizes FRAM Ice accretion numbers, which is more of a true ice measurement process based on a complex algorithm developed by a myriad of meteorologists and data scientists using both a data driven and physical attribution of ice processes that create the overall environment necessary for ice to accumulate. Long story short, it is immensely more accurate a better measure for overall risk assessment and forecasts within operation settings. NBM likely to exhibit a bit of a warm bias given the overall setup and how it underplays the depth of the surface cold layer due to raw data inputs that can skew a mean upward. So, when the NBM is harping at ice accretion within the realm of being more impactful, one has to take notice. Here's the latest NBM forecast signaling the potential at these leads. It will be something to monitor, and I'll update the forum, when I can on these numbers since FRAM is only accessed through internal collaboration and NBM internal products, or a paid site like Pivotal Weather. This is more significant compared to the previous runs with totals approaching the 0.1" over the M/D and even getting into the outer burbs of the Balt/DC corridor. I know I have not been high on this event given my lack of posting (Also been crazy busy out here!), but there's a chance for a modest impact event that would certainly throw a monkey wrench on the Friday AM commute. Definitely one to keep tabs on, especially north of I-70 and the Parrs ridge front into Western HoCo and MoCo. 5 Link to comment Share on other sites More sharing options...
MillvilleWx Posted February 23, 2022 Share Posted February 23, 2022 This is the current CIPS Analog guidance with probability of ZR exceeding 3+ hrs within the domain inside a 48hr period. This is centered at 00z Friday, so there's a pretty solid signal for some ZR over areas north of I-70 as shown just using CIPS guidance. Link to comment Share on other sites More sharing options...
nj2va Posted February 23, 2022 Share Posted February 23, 2022 LWX posted watches for Garrett/Allegany in MD and Mineral County in WV. Up to 0.3” ice and 1” of snow/sleet. Good write-up too by LWX explaining the set-up and possibilities: Complex (but somewhat typical for this area) storm system will affect the area Thursday into Friday. A lead shortwave will be responsible for an initial round of precipitation Thursday, then a stronger shortwave will force an area of low pressure to develop along the stalled front to our south, before tracking to our west and north Thursday night and possibly redeveloping offshore Friday. Meanwhile, a strong Arctic high will be located over Canada feeding cold/dry air southward which will become dammed east of the Appalachians. The atmosphere may be cold enough (or at least wet bulb low enough) for precipitation to start as some snow or sleet for parts of the area. However, the air aloft will warm with time, eventually leading to a rain or freezing rain scenario. Surface temperatures are always tricky during CAD, but probabilities support the greatest chance of any icing generally north and west of I-95...but particularly within a couple counties of the PA border where the greatest QPF is expected Thursday night to Friday morning. In some of these areas, especially in the Cumberland MD area, the wedge may not break until the trailing cold front arrives later Friday morning. Some of the factors that will have an effect on this system: 1. There will be an interesting play between air temperatures and precipitation with the initial round Thursday due to wet bulb processes, which may ultimately determine the strength/breadth of the CAD. 2. There will be very dry air at the surface, so precipitation could have a hard time progressing northward Thursday. 3. While not a common solution in models, there is some potential for a more prolonged period of sleet near the PA border which could reduce freezing rain accumulations. 4. For much of the area, temperatures will be marginal for the event, and the preceding days have been very warm. Any areas where freezing rain is light or brief may not have as much of an impact as it would otherwise. 5. Uncertainties about if and how much temperatures drop Thursday evening and rise thereafter, as well as QPF during the second wave, which will largely be focused north of the area. In the end, issued a Winter Storm Watch due to the potential of more than a quarter inch of ice for Allegany, Garrett (especially eastern), and Mineral Counties. This is based on a combination of NBM probabilities, QPF forecasts, and CAD climatology. Interesting enough, if western Garrett stays warm and sees mostly rain, we may have to monitor localized minor hydro issues. It`s also possible places like Catoctin Mountain could near a quarter inch of ice, but confidence/areal coverage is expected to be much lower in these areas. We will evaluate the need for advisories/warnings later today. Link to comment Share on other sites More sharing options...
mappy Posted February 23, 2022 Share Posted February 23, 2022 8 hours ago, stormtracker said: In all seriousness, this is a Mason Dixon event and it looks like it could be impactful up there. @mappy Good luck. I'll send you pics with my lights on. blah Link to comment Share on other sites More sharing options...
MN Transplant Posted February 23, 2022 Share Posted February 23, 2022 I would say that it is going to rain, but now it appears that it’ll barely do that in the DC area. 2 Link to comment Share on other sites More sharing options...
Ji Posted February 23, 2022 Share Posted February 23, 2022 I would say that it is going to rain, but now it appears that it’ll barely do that in the DC area.We might be the worst city in the east in terms of getting bad weather. Our location is wretched Link to comment Share on other sites More sharing options...
WxUSAF Posted February 23, 2022 Share Posted February 23, 2022 44 minutes ago, MN Transplant said: I would say that it is going to rain, but now it appears that it’ll barely do that in the DC area. Time to wake up the drought thread?? 2 1 Link to comment Share on other sites More sharing options...
Weather Will Posted February 23, 2022 Share Posted February 23, 2022 WB 6z EURO has backed off amounts even along the MD/PA border. Everyone above freezing by 9am Friday. 1 Link to comment Share on other sites More sharing options...
RevWarReenactor Posted February 23, 2022 Share Posted February 23, 2022 23 minutes ago, Weather Will said: WB 6z EURO has backed off amounts even along the MD/PA border. Everyone above freezing by 9am Friday. Good. Honestly who wants bad icing? If we stay below 32 the entire event; that would have my attention. But the idea we get a warm nose way up into PA would generally mean any ice accumulation would eventually commence with its melting processes. Link to comment Share on other sites More sharing options...
psuhoffman Posted February 23, 2022 Share Posted February 23, 2022 We’ve acknowledged we’re losing some marginal snow events (which is why our mean is falling) due to climate change. But I think that extends even more drastically to ice events. They are all marginal by nature, happening along a narrow scope of conditions where the boundary layer is just cold enough despite warmth above. And the boundary layer is the most affected by warning and especially warning due to increased UHI effects which extend well beyond metro areas now in a lesser but still real way. I’m not saying ice storms are impossible now but I think they are a lot harder to come by here than 20 years ago. I’ve seen a few setups Ute last 5 years that I thought synoptically should support icing that ended up 35 degree rain. 5 Link to comment Share on other sites More sharing options...
nw baltimore wx Posted February 23, 2022 Share Posted February 23, 2022 1 hour ago, WxUSAF said: Time to wake up the drought thread?? Here we go again... 4 Link to comment Share on other sites More sharing options...
Baltimorewx Posted February 23, 2022 Share Posted February 23, 2022 1 hour ago, psuhoffman said: We’ve acknowledged we’re losing some marginal snow events (which is why our mean is falling) due to climate change. But I think that extends even more drastically to ice events. They are all marginal by nature, happening along a narrow scope of conditions where the boundary layer is just cold enough despite warmth above. And the boundary layer is the most affected by warning and especially warning due to increased UHI effects which extend well beyond metro areas now in a lesser but still real way. I’m not saying ice storms are impossible now but I think they are a lot harder to come by here than 20 years ago. I’ve seen a few setups Ute last 5 years that I thought synoptically should support icing that ended up 35 degree rain. For sure..I think we need a pretty wild set up to get a significant ice storm particularly E of the blue ridge at this point, along PA line maybe being the exception Link to comment Share on other sites More sharing options...
Weather Will Posted February 23, 2022 Share Posted February 23, 2022 WB 12Z 3K NAM: this starts in the far west/southwest suburbs in the am and moves N and NE during the afternoon tomorrow. Marginal temps low to mid 30s for most areas but everyone goes well above freezing after 9 am Friday. Link to comment Share on other sites More sharing options...
clskinsfan Posted February 23, 2022 Share Posted February 23, 2022 Its pretty cool how the short range models are picking up the COD against the western side of the Blue Ridge. Cant say I ever remember seeing that in the past. I still dont expect this to be a big deal. Even out here in the Shen Valley. But thought that was neat. Link to comment Share on other sites More sharing options...
WinterWxLuvr Posted February 23, 2022 Author Share Posted February 23, 2022 15 minutes ago, clskinsfan said: picking up the COD I like Cod. Tilapia too. Trout. But the best is Crappie 1 Link to comment Share on other sites More sharing options...
stormtracker Posted February 23, 2022 Share Posted February 23, 2022 3 minutes ago, WinterWxLuvr said: I like Cod. Tilapia too. Trout. But the best is Crappie Hopefully the models will pick up on SAL. Best fish ever. Heavy on the Omega-3 2 Link to comment Share on other sites More sharing options...
WesternFringe Posted February 23, 2022 Share Posted February 23, 2022 9 minutes ago, Weather Will said: WB 12Z 3K NAM: this starts in the far west/southwest suburbs in the am and moves N and NE during the afternoon tomorrow. Marginal temps low to mid 30s for most areas but everyone goes well above freezing after 9 am Friday. In my experience, one can divide the modeled freezing rain by 5 or 10, and it might verify. I would love to be wrong and wake up to a legit ice storm. Link to comment Share on other sites More sharing options...
CAPE Posted February 23, 2022 Share Posted February 23, 2022 Tilapia 2 1 Link to comment Share on other sites More sharing options...
pazzo83 Posted February 23, 2022 Share Posted February 23, 2022 2 hours ago, psuhoffman said: We’ve acknowledged we’re losing some marginal snow events (which is why our mean is falling) due to climate change. But I think that extends even more drastically to ice events. They are all marginal by nature, happening along a narrow scope of conditions where the boundary layer is just cold enough despite warmth above. And the boundary layer is the most affected by warning and especially warning due to increased UHI effects which extend well beyond metro areas now in a lesser but still real way. I’m not saying ice storms are impossible now but I think they are a lot harder to come by here than 20 years ago. I’ve seen a few setups Ute last 5 years that I thought synoptically should support icing that ended up 35 degree rain. yeah i honestly can't remember the last real ice storm I experienced. there might've been one in NYC while I lived there - but as you say, climate change + the UHI makes them a real rarity (especially the UHI in Manhattan) Link to comment Share on other sites More sharing options...
high risk Posted February 23, 2022 Share Posted February 23, 2022 Surface temps around the metro area tomorrow evening, and the precip totals won't be huge, but there is a pretty clear signal for a period of sleet or freezing rain for a lot of us. Even if sfc temps warm up above freezing, there is a still a cold layer immediately above in pretty much all guidance for at least a few hours. 4 Link to comment Share on other sites More sharing options...
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