Moderately Unstable

There's no specific requirement not to discuss ratings--I think it's reasonable to expect somewhere along path you'll see EF4+ reports...but remember that radars, unless they're DOWs are not measuring the wind AT THE GROUND. That's super critical and why you can't take "wow look at this gate to gate shear" stuff verbatim--that's what's happening a few k feet up. Friction is real, yo. El Reno was an EF5 according to DOW...it's rated EF3. Why? No structures were hit that verified EF5. Same for the Bassfield tornado. Had an EF5 signature at times and would be super easy to believe a monster that big, on the ground that long, produced EF5 winds in a sub vortex somewhere...but clearly didn't do so over a place for which EF5 criteria could be applied. This long track, fatality producing tornado...seems rather clearly destined for EF4+ status with a special wikipedia subsection dedicated to it within the discussion about the overall event. EF5 could have verified if the tornado had gone straight through Brent...looked particularly nasty around then. It may still verify...that's what damage surveys are for. In general though..remember that velocities do not tell you what's happening at the ground unless you're right next to the radar site like now, or using a DOW. It's useful to know what the G2G is, but really the better measure is how high up debris gets lofted. There's a somewhat direct correlation btwn debris height and strength of the tornado.

Yes, he does.

Well, that verified.

Based on the current obs and the earlier modeling I tend to agree with that assessment. As they continue to race NE the downstream environment is highly unstable . They should ingest increasing amounts of SRH so if they stay fairly discrete which seems a reasonable assumption for several reasons, they both do have potential. They're about where you'd expect to see initiation for a cell that was going to take advantage of the environment today and the downstream progs for sig helicity tracks on some of the recent CAMs would, if propagating backward, initiate those cells about in that area. I'll leave it there.

New TOR-W in MS issued. Looks to be going over Chunky right now.

Ding ding ding. For ref, until this AM everyone was talking the evening threat. True instability is lower. But more important (frankly) params are higher. The day ain't over yet. As for critiera: the probability refers to the severe weather type, period. To verify you calculate the density of tornadoes (or wind or hail) in given area and correlate against the percentages delineated. However, hatching verifies separately. That signifies sig severe..sig tor, sig hail, sig wind. To verify that you need requisite # events at the specified threshold per unit area. So far today, neither high risk nor hatching seems to have verified--and particularly that 45% prob did not. Cannot say for certain of course. What is obvious though is, not every tor warning verified (entirely normal), so # tor warnings =/= # tornadoes. Generally, for sig severe vs threat level: USUALLY, the conditions that produce ef4/ef5 and/or long-track tornadoes tend to also be the conditions that produce a lot of tornadoes. It's a venn diagram with significant overlap-- but it is not 100%. In theory you could get 5 EF5s and nothing else and your high risk would bust. You could, conversely, get 100 EF0 and EF1 spin ups, which would verify...given the right delineation of area of couse. It's just that typically (nearly always) we see EF3-5 stuff on days when conditions are outbreak-y. To that end, today has, thus far, had a high end enhanced to mid grade moderate feel to it. If we stopped the clock now, yeah, this isn't the national news event that has been advertised. We've all seen moderate days, and enhanced, that have exceeded what we have seen so far today. To be clear, on a true outbreak day, you (typically) have at least one major tornado hit a populated area and be in the news, with yet more tornadoes ongoing at the time. That's not a rule that pertains to outbreaks and metros--you can of course have 100 tornadoes and have all hit unpopulated forests...it's a probability game. With a true outbreak you almost always get enough tornadoes, several strong, that at least one hits a population center (think Bassfield sized town) and causes major damage. We haven't gotten reports today of mass fatalities. You don't have governors pre declare state wide SOEs unless, being blunt, they expect a body count and a need for S&R and state level disaster recovery resources. That is GOOD, but is an indicator that we probably have not seen a density of tornadoes at any intensity that would verify a HIGH. This is fairly subjective reasoning so take that fwiw, but just my observational experience. But, fun fact, that was round 1. Thermals are more marginal in the evening but the dynamics very much are not. Helicity and such are much higher tonight. That 45% zone...I don't expect it was made for the afternoon stuff. It was made for round 2. I'd bet money on that. Now that may or may not verify vis a vis how discrete the evening cells remain to take advantage of said dynamics but the threat isn't over yet.

Give it 5 minutes. Takes a few minutes to issue a warning (~5-10 if starting from scratch). Have to define the area, define mean storm motion, expiration time, impact based tags (is it confirmed, radar indicated, what's the threat categorization), etc. Once the NWS says "yep gotta warn that" they can't just hit a button.

I was wondering how long the pds on that was going to take.

Watching that one. I always focus on the lonely duckling away from all the other storms. It's in a good spot.

Okay I was gonna say ...holy gradient batman! We've done well but in line with expectations as best I can tell haha. I consider that a win given how tough this forecast has been. Well, that's impressive and qualifies, but not "Philly". If you hear someone say Philly got X, people think center city+ 5 miles. Higher elevations N&W often do better so while notable Philly folks wouldn't empathize with the sensible weather in Conshy (in this type of setup).

Honestly despite the modeling flaws and the forecast complexity I've been pleasantly surprised by how this event is going. We came in expecting a super messy setup and it has been. Depends where in Philly. My staff in Fairmount report around 4". Here at city ave we got around 5" rather quickly (as expected) and now over to sig sleet. If someone got a golden shovel foot mazeltov to them. Where are the reports of 1 foot?

Mount Holly's writeup also mentioned the sun angle, so it isn't just Glenn. Here's the website I use (both for meteo and other pursuits) plotting solar azimuth for basically any location on earth on any given day (but here linked to Philly): https://www.timeanddate.com/sun/usa/philadelphia. We're up to 38.7 degrees tomorrow at 12:14pm, vs Decem when our angle maxes in the upper 26 degree range. We're heading into the part of the year where the sun angle, day length delta (etc) are all rising rapidly day-to-day. I don't think it matters much for "the thump" but it matters later in the day--so it isn't just cya messaging. They're not wrong. Fun fact: 50 degrees of azimuth is about what you need for UV-B light to reach the surface, and thus, for your skin to produce vitamin D.

Well, of course surface temps are going to be a bit colder. But the thing is, with the track of this system and the LLJ orientation, the sleet line will probably move SW to NE, not S to N. So at least from a timing standpoint...you're not going to stay snow much longer than Philly. A bigger delineator of time would be drawing lines W-E, or ideally NE to SW as I said above. However, I think FZRA is less of an issue for you...so you'll see sleet longer, and may actually get through the entire event without any change to FZRA. From a totals standpoint, since most of the accumulations being progged are based on the front end, I think you might be a touch higher than Philly...so instead of 4-7 I'd say perhaps 5-8 for you guys particularly given the lack of fzra. Ok that's the end of my point-forecasting for now, I have to go back to work hahahaha.

It's aggressive on the changeover...it blasts us with WAA in the mid levels as the coastal approaches. The 12z run held us in the snow camp a bit longer than the 15z run...but on the order of 30 minutes: 1800 vs 1830z. I do very much think FZRA will be a bigger deal--I agree on the impacts...BUT that sort of also depends on the time of day it's falling. Messy-yes, but at 30/31 degrees in the late afternoon it won't be as bad as if it fell overnight with temps in the 20s. If you compare the SREF probabilities for us for ptypes... https://www.spc.noaa.gov/exper/sref/srefplumes/ Or you look at the HREF's probabilities for heavy snow, fzra etc: https://www.spc.noaa.gov/exper/href/?model=href&product=snowfall_001h_prob01&sector=conus And for me combined with the RPM, GRAF, and other guidance...it's really all different flavors of the same thing that we are being told. We know that models have had a cold bias this season, and it would be quite hard to believe in this setup, with the position of the coastal and the 850....that this isn't a "mess" type of event. That doesn't mean the front end won't be fun though. I don't necessarily think we'll see a quarter inch of ice, but looking back at the history this season when it comes to mid level warmth, my money would be on the warmth winning relative to expectations.

At the moment, my thinking is the Philly area sees 1-2" rates between 10AM-1PM. We may pick up 1-2 inches before that time but that's really the "main" period I'm focused on. As we head into the mid afternoon sleet becomes much more likely.

My current call for the city is 4-7", including a fair amount of sleet, and .1-.2" of ice. This is based on a blend of the RPM and other model guidance (and history of model performance this season wrt mid level warmth). I don't buy all snow. RPM does show a consistent change to sleet and then FZRA on every run. How much the snow total ends up being hinges on how fast mid level warm air comes in...but we will enjoy at least a couple hours of good rates. And I will abs take that.

It is an in house model. It's WSI's (the weather channel's parents') internal convection allowing high resolution model. They're also, fun fact, the one's developing deep thunder (aka graf)--which once operational will use a 15km grid, BUT, will have a 1 way 3 km upscaling in the conus--which they are suggesting will let them do away with convective parameterization (so that they can actually model individual thunderstorm cells). One way because those 3km cells won't then feed back out to the larger domain. Basically the small cells get initialized by the boundary conditions of the larger domain (15km), then, operate independently. Now, if they're successful--this would be fantastic for mesoscale forecasting because it could (theoretically) enable one to almost predict in advance which cells would have sustained rotation with high accuracy and locational precision (SPC and NSSL toolsets allow for meso tracking already but it's more of a general "idea" than precise here at this time type of data...even though the output simulated radar sorta acts as though that isn't the case). But color me skeptical. They're working with IBM on this--I believe with a machine learning type of approach...in any case from what I've seen of the large domain GRAF so far, looks promising. Neither is available to the public (frankly it isn't even available to everyone in the private sector), and they're EXTREMELY protective of access to it, which is why I don't post the maps here. You can get in some actual trouble doing that. Like any model, it's guidance. But for whatever reason, it really is "worth" WSI's protectiveness...it's good. I've used it to chase individual thunderstorms before by using it to time out to a half hour interval where a particular cell would be and where. For mesoscale enhanced setups like this one, it tends to do a good job. WRT the || Euro, keeping up to speed on the rapid-fire-changes of the operational and ensemble guidance while checking model verification and current obs, and doing my day job...haven't had time to look at that today haha. Link?

I love a good finale, don't you? 00z RPM keeps the trend of the 18z and 21z runs....corridor mostly snow, gives 12-16 widespread totals. Places like BAL & IAD are modeled at between 20-24" (outside of our domain but notable). Gotta keep watching this though. There's a sweet spot here for the track of the sfc and 850 low centers. The models have hit that place now. My internal sense here is, the whole 12+" thing...we've been down this road many times. Models a couple days out provide clown like totals. I think we're reaching consensus now that impacts are going to be enough here--in the form of snow--to most likely at some point down the road req a WSW for the corridor and areas NW. Exactly what the totals are...probably too soon to say, but I sure do love the 00z runs coming in now. If I were a TV met this is when I'd start talking more substantively about the "potential".

I was so close to saying something in the 18z time frame...the rpm and graf both supported an insane overrunning banding setup. Clown totals for the corridor and nw, hellish gradient though. They were supportive of 12+ as well on the corridor...down to nothing SE of around Lindenwold. I considered that a good sign bc in earlier storms the rpm picked up on warmth earlier than the globals. That it hasn't here is good. I want to see the full 00z suite before I make further comments. You could tell at 18 from the 3k that the 12km was too amped. Fwiw iirc the 21z rpm had a stripe of 20" totals in the harr ne towards the LV area. I am super hesistant to invest this season given the model insanity but I like this setup. I'm much more bullish about this than I was about the weekend or today. Objectively, not as a weenie--we have good odds here. Buckle up folks.

Sleeper event wrt wkend storm. I told my friend who was supposed to visit this weekend to reschedule. RPM suggests there could be problems and I buy it. Don't think it'll be major, but .1" seems likely...I'd give it 70% odds. With cold sfc temps, that as iceman correctly notes have been cold for awhile, and existing snowpack, this is bad news. You don't need much freezing rain to make travel dangerous. The most deadly winter wx events are the minor ones. Advisory snows etc. People tend to go faster and pay less attention, encounter slick spots they don't see, and then, wham. Bigger events generally cause more people to hunker down and stay home. You don't need 1994 to make for a bad day.

I get a kick out of this forum hahaha. RPM has trended N. Gives the corridor marginal warning level snow. See if that holds. Have been busy w scholastic stuff this week so I haven't followed this one to closely. That said I think a good rule of thumb with the currebt pattern is..if a model shows a medium range hit, ignore. If a model shows a lr hit, pay attention. For a given sfc low, expect a South bias. If a model says big hit, prolly a small hit. Model says small hit, get big hit. A lot of mets suspect lack of airplane data is hurting models. This winter has been interesting in that the model biases have been glaring and obvious. Would be a good year to use if teaching a fcsting class and wanted to give model bias examples. Not subtle. Wrt watch advisory warning...it wouldn't make sense to issue a watch (imho). A watch is a timing issue. A storm is expected to occur, but not certain yet, couple days away. Same as other nws watch types. Bc they've issued an advisory step one would be ammending advisory to mention high end potential. If model and nowcast trends this pm suggest warning crtieria are more likely they would prolly then upgrade to WSW. If you took curr guidance verbatim it would qualify as a wsw in spots. Since models are not infallable, may see later tnght. Folks have already noted earlier precip onset vs short range models. Ratios will work in our favor. (I'm partly joking on the long range vs medium range remark but gosh does it feel that way!).

La niña who?

Hi. Philly guy here. We have more than 0. I don't provide storm updates on here bc I live in a high rise building and have no place to put a snow board. I am 3 NW of CC. We had heavy, 1.5-2" snow rates for an hour or so while a band translated through..around 15 mins of which I'd characterize with the charming euphamism of "puking snow" (note: if that happens to you, see your doctor). Was very fun to watch. My place looks out over Fairmount park. The trees and surfaces have a solid few inches. I can't say exactly how the roads are as I haven't been out but I expect looking out that at least 3" has fallen on grassy surfaces and previously snow covered surfaces at least where I'm at. It is still snowing lightly now. Temps have been 32-34 the last few hours so I'd be very unsurprised if roads are just wet in the lower elevation areas. I'll take it.

First off, *congratulations*. Getting into a post bach meteo program isn't easy, and securing funding isn't a guarantee. I'll give you my two cents. Unlike in ugrad, grad school is all about your advisory-professor and how well you can fit into the program. I'm not the smartest person in the world, in fact I was often envious of my classmates for being so much faster than I was all the time! But I know how to communicate well, and I know how and where to get data. That is what you need to be successful. In stem you'll find many folks are great with numbers but can't speak or write to save their lives. Be a good communicator. Know how to explain what you do to others. Profs, potential employers etc. Where you go should depend on where you want to work. Choose a school where you can work with a prof that matches your specific interests. That's going to be important to keep you going when you're cranking out 16 hr days and yelling at code on your comp. Research the profs at MSU, see if they align with your goals. Read their papers. Write down intelligent questions, and then email those profs and ask them about those papers. If the convo goes well, ask them about your concerns. You're going to be there, you've been accepted, they won't kick you out for asking. When you go apply for a job--at noaa or wherever, your hiring manager will want to know about your research. What you did, why you did it, what you learned. Where you went to school comes up low on the list, same deal with course grades. They matter-- but they aren't what your hiring manager cares about. They do care that what you studied and know how to do matches their job needs though. I cannot stress enough that it isn't like ugrad. Realize that as a masters student, you are considered a professional student. As such, it isn't about prestige...it's about what YOU do, and how. You're in the driver's seat. You get to decide what you learn and what you put into the world. Choose the school that let's you do what you want to do. MU

I mean, as I said last night in reply to Ralph's post asking if anyone thought there was room to bust...I'll repeat, there is. That said, for a modest event like this, really the absolute lowest snow amount that qualifies for a WSW (5"): https://www.weather.gov/phi/WinterWx (Note-- above map is for a *12* hour event)...your low end estimate is going to be low somewhat often. It's unlikely the region on the whole sees <1". It is quite possible we end up with more spots getting advisory level snow totals though than warning. This will be a dynamics battle: cooling from the strong fgen, versus marginal bl temps and an eh airmass. Round 1, ding ding.