MillvilleWx

The last time we had a pressure perturbation like that, it was after I had the three enchilada combo at Abuelo’s .

Hey guys! Just a heads up with the European output. It is a model that struggles a lot of time with the finer transition periods and is likely missing some ZR in the mix. There will likely still be some freezing rain to contend with, despite what the model signifies. This is where mesos come in handy. Some areas may see little ice, but other areas that typically hold the cold better will, so keep that in the back of your thoughts for the storm.

No problem! There's a method to the madness. One of the biggest things I utilize is the CIPS analogs with recognition of key features and then compare to previous events. I also have a pretty good memory for weather, so I remember setups with a similar evolution in certain areas of the forecast and weight that towards guidance. Blending guidance can be good for a complex situation, but sometimes intuition with the meteorology at hand can take precedence, especially for something historical or heavy climo based (Elevation dependent storms are big with this). Knowing your geography and how things typically unfold is important. Nailing forecasts exactly is extremely difficult, but the key is to stay within a bounds that can verify an Advisory or Warning when you put one out. As an NWS met, I think about being within reason and adjustments up are okay compared to adjustments down. Impact based forecasting. I want to be as close to right as possible, but not missing too much. In this case, it's hard to create a forecast when the transition time frame is uber important. That can make or break a forecast.

No problem! I think in a local sense that area will have a higher chance of being impacted moderately to major. The elevation factor is key for them with orographic enhancement of the precip locally while locking in the cold temps at the surface. Blended guidance was fairly bullish for their impacts, so that is key in this forecast from myself. Those topographic features are important for an event like this. I honestly COULD be a little low on snow totals across the MD line, but it'll be +/- 1-2" max, so I'll hold what I have for the time being. Stay safe up there!

Here you go y'all on my breakdown of the event. I am low on the north side into your necks of the woods, but I can make a separate map later that will give a rough estimate, or I can give a breakdown by towns/regions later via text. Happy tracking!

Alright y'all. I think I have time to delve into some details on this event and my forecast will be the last thing I post if you want to jump to it, now's your chance! Anyway, the setup is one that is complicated in the evolution, but the ground truth makes perfect sense meteorologically. Leading into the event, a cold HP over the top will deliver some pretty chilly air to the east coast with wedging down as far as northern GA. Traditionally, this would spell a pretty significant snow/ice storm for the piedmont and areas NW. There will be significant storm, but how we get there will determine the fate of the sub-forum. That fate will make some people sad, but it unfortunately is how it is and how we will roll, so lets dig in. First off, a potent upper-low (ULL) is currently traversing the south plains into the Arklatex and will round the corner this evening and move through the Deep south. This ULL will be matured and ready to go as it moves eastward overnight into tomorrow morning prior to making the turn NE after it enters GA. Over the N Atlantic, a beast of a low pressure will meander for about 12-18 hrs before slowing pulling eastward due to limited blocking over Greenland. This will allow for spacing to occur to our NE and weak ridge extension from the Atlantic over New England. This allows our HP to the north to scoot eastward, generating an onshore pattern for later in the storms life cycle (More on that in a bit). Off to the NW over Canada, a progressive shortwave trough will dig into the northern plains with eyes on the Midwest/OH Valley by Monday. This is what will cause a fair bit of commotion in the overall setup as the shortwave will "capture" the ULL over the east and begin to lasso it in place while tilting the trough negative as it wanders nearby. The associated surface low over the SE will motion to the north, then NW as the anchored 500mb presence will drive the low pressure towards the ULL as the features try to stack on top of each other, which is known as an occlusion. While this is all happening, the low pressure along the Atlantic coast will bomb out on its journey north, generating a prominent low-level jet (LLJ) in the lower confines of the boundary layer (PBL). Remember that HP that moved out into the Atlantic, well that in tandem with the developing LLJ will couple to create a "fire hose" effect of warm, moist air within the 850-700mb layer in the atmosphere. Figure Below shows a 7 StDev u-vector component. That screams warm/moist air funneling due west off the Atlantic. This is caused by the tandem of the base of the HP off the coast and the counter-clockwise flow around our surface low. This is what will be aimed at the area during the storms life cycle as it moves into the region. In the very beginning of the storm, the antecedent airmass is still pretty cold with near to below 0C temps through the column above. The leading precip will help wet bulb temps a bit with an initial start as snow, but the vigor of the LLJ will allow for the warm air aloft to quickly notch above freezing with areas to the SE seeing the transition first. Due to the increasing pressure gradient pattern and slow warming of the PBL, winds will increase areawide, leading to a mixing out of the cold surface inversion layer in place. This is why temps on models appear to "jump" to near and above freezing despite the cold air that was in place. There is no refresh of cold air to lock into place, so the warmer air above is able to mix appropriately and nothing can fight it back. As the storm begins its occlusion phase, guidance wants to have the stacking phenomena occur pretty much overhead or very close by. ULL's are dynamic and a mature mid-latitude cyclone has multiple parts that make it tick. As the low becomes stacked and the phase between the Midwest shortwave and ULL occur, the storm will drift off to the NE given the lack of blocking and the region will be on the backside of the flow at all levels. A strong vort max on the base of the mean trough axis will pivot through on Monday AM with a potential to kick off some light to moderate snow showers before pulling NE due losing the areal ascent on the underside of the trough. Way out west in the mountains, a continuous westerly flow pattern found on the western flank of the low/trough pattern will induce a period of upslope snowfall under cold upper-level conditions, leading to a higher-ratio powder that occurs over the traditional spots in Garrett/Tucker counties in MD/WV respectively. This will add to the synoptically drive snowfall with the storm, putting those areas in the best chance to reach double digits, despite the fact they will likely mix with sleet/freezing rain for a time during the storms height at their latitude. Overall, this is still a pretty high profile event due to expected winds and widespread impacts from N GA up into New England. As fate would have it, it's just not a pure snow event due to the lack of reinforcing cold air and the positioning/magnitude of features that occur overhead. That's just meteorology for you, but one cool thing to take away is the satellite will be pretty incredible, and will fit the textbook of a classic Norwegian Modeled Mid-Latitude Cyclone (Gotta love the Nords for their expertise on this matter ) In any case, there will still be winter weather in the area, and here's my thoughts displayed. I utilized a blend of NBM interpretation and hi-res guidance as they begin to narrow down the goal posts in terms of precip/timing/temps. There's a MEDIUM confidence on this forecast as there could be a slight bust either way, so keep an eye on those short term trends tomorrow to see what could be occurring. For now, look for a wintry mess with all the trimmings. Second Call (Potentially Final outside Minor Adjustments)

Thank you for the kind words. I thank everyone who appreciates the time I spend on here trying to instill some knowledge of meteorology, and some wit to kind of bring in my personality I love this forum despite the fact some people can drive me crazy, but that is what the ignore feature is for! I used to be a mega weenie and lived/died by every model. But you know, life is short and weather will always be here. I have reaped the benefit of seeing some incredible weather over the 31 years of my life, and there will be a lot more coming. I take what comes at me and make it my own. If something looks like crap, I'll close the blinds when it occurs, but every moment I get to watch snow fall, even if it gets torched or washed away, I will do it. It makes me happy and I cherish every moment it happens. Some people have this aura when it comes to severe weather, but I get it through the formation and precipitation of ice crystals. Been through a lot in my last 6 years and I did some reflecting in the recent years, and I have made my own path. Hopefully the next journey leads me back to the land I grew up. Life chapters are interesting. Some are long. Some are short, but it's still life. Take it as it comes and make your own destiny. Only you control it Take care sir!

I want to make sure anyone interested in meteorology and wants to follow along with storms now and of the future; the upper level evolution is the driver the atmosphere. What happens up top will reflect what happens below it. Once you understand the dynamics of the levels 700mb and up, you can be a better forecaster. Cold and warm air will always have the ability to be washed out by an evolving surface and low-mid level pattern. This storm is no different. Sampling is a smaller issue at range than it ever has been due to GOES 16/17 and the countless reconnaissance we have delivered over the course of the past 10-15 years. Yes, some minor shifts that could play major components to a pattern evo can occur when a specific feature is sampled over land, but the discourse of, "Changing to tunes of 100s of miles" is ancient history. Overall, this has been a pretty well documented storm with minor adjustments here and there, but in a setup where every 10 miles counts and timing is everything, they are magnified. I didn't post last night for two reasons: 1) I was tired and my wife was finally off. I wanted to spend some time with her and we watched some of our favorite shows. It was a wonderful evening. 2) I wanted to see if models held serve on what the hi-res guidance has been insinuating recently, and it looks like they are. This will lead to a forecast shift myself, which I'll have today. For those interested in meteorology, I will preface by saying this will be a sight to watch unfold. Result you are looking for may be damned, but take it from someone only getting more wind and absolutely no precip from 2000 miles away; enjoy the meteorology and learn, or I would find something to do on Sunday evening that will take your mind off it all. Ice will be coming, and there's nothing we can do to stop it. Pattern is still loaded in the long range. We are okay for now. Enjoy your Saturday!! Life is too short to worry about what Mother Nature is gonna do. "We'll weather the weather, whatever the weather, whether we like it or not!"

I'm not a fan of the parent 12km NAM at all. I think it's a trash model, but the 3km is better at handling details like warm noses and mesoscale banding and such. Now is still a bit far out for those details, so that's why I would monitor it and not take it as gospel. It's just one way this pattern can play out, but that's the nature of this beast. Time will tell. I want to see y'all get snow. That would suck

NAM Nest is trending to an all out ice storm with very little snow. It would actually be a legit ice storm north and west of the Piedmont as depicted. South of the fall line would be basically a marginal winter event before rising above freezing. If that holds, forecasts will need to be changed drastically. Not going to pull the trigger yet, but the NAM Nest is good at these events once inside 36 hrs. Will be something to monitor.

Solid map @Ellinwood We are both on the same page, which I like to be in a tough forecast.

Banana

I haven't examined the Pittsburgh area too much, but you guys will be well away from any warm boundary layer advection outside a slight climb as the SLP gets into PA. I think WSW criteria snowfall is certainly at play for you guys. I really like the Laurels for this one. This is a great storm for places like JST/Altoona area. I think you guys will get some love out that way.

If y'all have any questions to the map, tag me and I'll try to answer them. I'll have a longer write up later today after work on my thoughts. I'll likely post in the MA thread, but I'll copy the post here for all to read. Thanks for the feedback guys

First Call Map I'll have more on my current thoughts later today when I get a chance. I also want to see any shifts in the ULL track and timing of vertical stack with the SLP. Some changes may occur in the next 24-36 hrs for my forecast, but zones should stay relatively the same.

Still haven’t looked at a dang thing, but I too am interested in the Nest, starting tomorrow. Nest did amazing with March 2017. This is a good setup for it. .

Just a heads up for everyone in here; I am going to be busier than a one armed coat hanger today at work so I will not have any time to look at a single model run for the 12z suite until perhaps very late in the afternoon. Might be more likely after I get off work. Too much going on. Storm wise: My thoughts have not changed on expected impacts. There will be a strong nose of warm air nestled between 850-700mb as the LLJ on the eastern side of the cyclone will be robust, approaching 2-3 StDev above normal for climo, which is impressive to say the least. I mentioned this before but the u-vector component with the wind is going to be off the charts. This is both good and bad. The good is the advection of moisture is going to be stout to the point that people are continuingly underestimating what kind of front end thump we are looking at. The 850-700mb frontogen pattern expected is bananas. 1-2"/hr snowfall rates will be COMMON with this storm on the front end. Add in the orographic ascent typical for the area and things will come in like a wall of white. WAA snows wait for no man. Despite the drier antecedent airmass in place, things will moisten up rapidly. I wouldn't even worry about that part. The bad part of the stronger u-vector component will be the mix line racing in tandem with the precip field. Things will changeover likely a little faster than what you would want, but I do feel the globals are overestimating the scouring of the SURFACE cold a bit too much. Piedmont areas, especially anywhere above 500' AGL may struggle to warm much above freezing with freezing conditions remaining out near I-81, west of the BR. This is textbook for a storm like this. What to look for: When does the storm stack? Is there an adjustment on the strength and longitudinal shift of the mean trough/ULL that develops over the Deep South? Where is the SLP located when the turn north occurs? Are there any significant trends with regards to thermals as the system arrives? What is the DEPTH of the warm nose being advected into the region? Is there a change in the speed of the N/S vort that is supposed to phase into the disturbance? These are the questions to make a checklist for. Today should shed more light on the prospects, but I feel the NAM Nest range is when things will have a better indication on the finer details, so don't worry about banding prospects until we get closer to game time. That's all I have for now. Enjoy the tracking today y'all! Hopefully there's a little bit of a SE trend to get more love to the sub

That was a solid adjustment from the GFS after gleaning over it. Ignore the developed ptype algorithm maps for the time being. Soundings tell the story and climo wise we're beginning to see how this would usually shape up. The wall of snow is still well within reason. I-81 corridor still favored, but the metros will not get shutout. I love the cold antecedent airmass leading in too. I have no changes to what I've made previously.

That is amazing. I was 5 years old for those storms and my first weather memory is actually from the Blizzard of 96. Absolutely incredible scene in my neighborhood with piles only beaten by 2003 and 2010. I wish I was older so I can have a fonder appreciation for that storm, but now I live through the meteorology. Glad you got to experience and remember it all!

Truth. I just see the make up with the strength of the LLJ and 700mb moisture flux can kind of combat the inevitable flip and keep the storm within reason for the DC metro area. A 3-6"/4-8" with more north and west is what I'm projecting right now, which is what happened in 1996. Evo is sort of similar, and it has higher grades for the 500 and 850mb height pattern which are good levels to look at with CIPS when it comes to similarities. Final forecast won't be out till Sunday with a first guess on Saturday. Still too much to parse to make a distinct call atm. One things for sure, it's not going to be lacking moisture. Have a theta-E advection regime most would enjoy during severe season. Talk about your influx of mid and boundary layer moisture.

I...... Jk. I think your area will be right on the tightrope. If the GFS was right, you'd flip to sleet. Euro would be a high chance of staying all snow. I think your area could do very well with this system as well.

@mappy When I saw that map posted without a legend, you were the first person I thought of. I had a feeling you were ready to lose your mind with that one haha

Those of you in the LSV should get a good whack from this system. Areas like Franklin/Adams/York counties should clean up along the southern tier before any flip occurs. I think a spot like @Cashtown_Coopshould get hammered along with those along I-81 up to Harrisburg. I'll poke in over the next succession of days. Look forward to living vicariously

Wrong storm. That was the Blizzard of 1996 which was its predecessor. This was afterwards. They got 6-10" at Dulles from this one according to the snow data