MillvilleWx

Once the low surface low reflection showed to be at the mouth of the bay, it was destined to have mixing issues further inland as the 925/850mb winds would throw the warmer air back further towards I-81. The Euro is actually similar to the GFS at 5H with just different SLP placements once we get to the slot near ORF. Models being jumpy right there mean they are struggling to identify where the primary surface low will be located as there is a distinct double barrel look now on all guidance, something I pointed out last night. Until that gets figured out, it'll be doing some moving and shaking with regards to the warm boundary layer intrusion. The CAD on the model is actually very solid leading in, and is actually the strongest surface ridge extension of all guidance. That's also another reason why the warm air made it so far west. The 1038 HP over Canada in tandem with a more tucked SLP at the mouth of the Chesapeake created a strong u-vector component to the wind field, forcing the easterlies to protrude as far west as I-81. It does correct and things improve with 3 hrs time, so it's not unreasonable to say that can easily shift back. In either case, that area of Rt15 on west is still the ground zero for this storm, IMO. I-95 to Rt15 will likely mix for a time with the further east areas mixing the longest. The deformation axis is still epic, so the back end love will be higher ratio love and can pile up quick. I still think the jack lies from WV Panhandle to the Catoctins up to HBG in PA. Northern Carroll/Balt Co into SoPA will also have the outside chance at the jack pending the overall evolution of the deformation band that is bound to establish itself. Like I said before, this is not totally figured out in the synoptic scale, so expect some movement here and there.

Well, the 00z runs were pretty much a great run for all of the sub-forum, and being totally serious, the CMC actually had some room for improvement (Yes, it could've been a whole lot better) and the GFS finally got a grip and has a surface reflection more indicative to its 5H progression. There wasn't much of a shift at 5H outside the eventual close off over DE, but that's something that won't be solved until closer to game time. CAD sig on both the CMC and GFS were classic for a precursor to a major snow for the Balt/DC megalopolis with the wedge down to SC/N GA. One of the biggest differences between the GFS and CMC was actually the extension of dry air at 7H that lead to the storm cutting off a bit abruptly. The 700mb moisture field was actually a good 1 deviation drier than the GFS as a whole, which would limit some of the total moisture content available for the storm. The + Theta-E advection nose was focused well to the north of the area on the CMC where all other models have it right into the sub-forum. One of the biggest reasonings was the CMC actually led an open 7H depiction until just north of our latitude, so that would cause the heaviest plume to be centered over NJ/NY/PA instead of MD/VA. I'm not too worried about that unless it's a pattern the other models pick up. In any case, both would provide warning criteria snows for much of the area. The deformation axis on the GFS is sublime with a co-located 7H and 85H frontogen placed along I-95 with 7H extension back to the western folks. There's a classic "warm nose" indication at 850mb that we see with bombing cyclones in these parts, and that's actually a good thing because that's an indicator of prime moisture advection into the boundary layer in co-location with the lift. This will be a fun event for many and we haven't even talked about banding yet. Good times

I told y'all not to worry

What day is it? Ugh Mids suck Anyway, quick thoughts on 18z: I didn’t see any appreciable changes with regards to the overall setup. GFS is jumpy right now and is on the most extreme envelope of western solutions at this point. The post early from Tomer Burg showing the 5H progs compared to ensemble mean says a lot. I think that might’ve been the most westward extent of the theta-E advection we could get in this setup. CAD still looks good. EPS is actually fairly solid with LP centers within a reasonable envelope favoring the same areas I mentioned before. Rt15 on west is sitting very pretty. I-95 and east will likely see a ptype shift during storm height before the Deform pivots through as the storm moves NE. The northern tier into PA will see it the longest. Don’t live and die by a model run y’all! Everything seems a go. 00z will ultimately shed more light, but don’t expect until Monday until the Synoptic details are more a bit more concrete. Then it’s meso time and banding. Talk to y’all later on the graveyard. Pass the Caffeine .

Night crew check in after 6 hrs of sleep (Will be heading back to bed shortly) Few thoughts gazing through things: 1. Initial thoughts holding with regards to ptype and where the best spots look to be. Fall line and west should remain majority snow unless we see a more amplified surface reflection. EPS showed more mixing out to even I-81, but if you look closely at the low clusters, everything that was inland was sub 990 with some at the low to mid 980’s. Remember the ptype algorithm is a smoothed mean that takes into account ALL members of the ensemble package. Even a few over amped members can skew the mean warm and could correct later in time as we get closer and filters the noise. 2. The confluence signature is becoming a positive feedback here with a classically aligned height pattern to our north that will pay dividends. High pressure over Quebec is consistently modeled around 1036-1038, which is solid for a snow event west of the fall line, so long as the low doesn’t over amplify. 3. Snow maps are fun, but best to look at QPF charts and base soundings. One of the bog things to look for in this storm is the CCB action on the final half of the system. Primary 8-10:1 caveats aside for areas along and west of the fall line for the first half of the storm, but this will have 15-20:1 potential within the deformation axis as 7H frontogenic progs have been off the charts across central MD, NoVa, Panhandle WV, into SoPA. There will be a nose of + theta-E advection when this begins to wrap as it crosses OCMD latitude. Where that points will be key in determining who gets the love on the back half. Even so, it’ll slowly gain latitude and sweep through to the east, so the ending of the system could be epic for many. It’s very classic in a Mid Atlantic MECS. 4. All that said, the typical Rt15 on west crew is in the best shape with elevated areas along Pars Ridge to Mappy sitting in a solid area due to elevation and mesoscale tendencies with bombing surface reflections. The lack of dry NW winds on the back half of the storm signify an expansive qpf shield is likely with this event, so even out to the mountains should see some love. Hancock on east is the best areas with some upslope component likely out near Garrett. 5. Sleet will undoubtedly occur for areas in the Blue Ridge in VA once south of Front Royal, but they could get smacked before a change over as southerlies scream out with the low reflection moving north. 6. Anyone who knows their climo should weight it in the result. You know your tendencies and nothing in this storm suggests a sway from the norm. A stronger high around 1040 would be what causes the mentality to shift, but it’ll likely fall short. Now if you’ll excuse me, I’m gonna go back to sleep and I’ll be back on the night shift tonight to add more tired thoughts to this event. Be happy y’all. There’s a storm brewing! .

Absolutely agree. We've seen this movie before and the usual suspects will be at wits end watching CC/ZDR on Day 0 while the western crew is nuking fatties and posting 1-2"/hr rates for hours on end. No arctic airmass leading in or drilling in like some storms, so this one will be borderline for fall line on east and Frederick on west will be sitting pretty solid

The GFS basically outlining a massive mauling NW of the fall line with Rt15 on west absolutely destroyed. One things for sure, this thing will not be lacking precip at this rate. Gonna come down to ptype and meso.

This will be a primary snow or rain storm with a touch of sleet on the dividing line. This is not the type of event for prolonged ZR as the surface will not be arctic cold leading in and the boundary layer warmth will reflect back to the surface where the 925mb easterlies take affect.

Be careful with the Euro spatial winds. They are typically way over done and should be adjusted by 40-60% pending the setup. I don't foresee a blizzard in the cards for the MD latitude. Best chance is likely NJ

Trailing shortwave pushing eastward.

A stronger CAD signature allows for more breathing room within the boundary layer and a chance for colder surface temps at the beginning of the storm. One of the main things we've seen with these types of setups is the leads trend colder in the short term at the surface, but are a little warmer in the boundary layer above. A colder start means more wiggle room if there is an anomalous easterly component in the lower wind field. A strong easterly will not be denied, but it can be held off a bit. A solution like the CMC would be the best of both worlds.

So, looking at each of the 3 major globals, one of the main differences in each run with regards to ptype output is due to the low level wind differences for each run. The GFS has the most consolidated look and is further off the coast, so it's a large coverage of full snow, but doesn't max out the totals like the Canadian as it's more dynamic with a bombing cyclone tucked closer to the coast. There's a textbook deformation axis along the I-95 corridor and everyone gets pummeled. One of the biggest takeaways is the CMC and Euro both showing a double barreled low along the east coast, which will have impacts on the inward extent of the lower boundary layer wind field which could cause precip issues for those near I-95. The European is the most pronounced with the low structure over the Delmarva and 925/850mb easterlies extending back towards I-81. The warm fetch in the boundary layer would create a nose that would change the ptype from snow to sleet or even rain the further to the east you go. This is a classic WCB to CCB transition zone and will delineate the deformation axis where the two intersect. The CMC has the double barrel look as well, but the westward low is right along the coast, which is ~50-75 miles east of the Euro. And what do you know, everyone is all snow. It was that close. Both runs were similar in evolution, but the Euro was slightly more amplified. The stronger CAD signature is massive and was shown on every model run this evening. Keep that working and let the UL pattern fall over the next succession of days. A lot to track and we haven't even touched the mesoscale. 00z Euro 925mb Winds and MSLP CMC 925mb Winds and MSLP

I don't think some will realize how close that particular run was to being an all timer for most of the sub-forum. The western crew are in immaculate shape right now. I mentioned last night Rt15 on west is in the sweet spot in my eyes, but everyone could easily cash with this one.

Guys, verbatim, the Euro is a HECS for areas west of Rt15 out towards I-81. If you looked at the trend from previous run, there were only minor changes, but one of them was a stronger antecedent airmass with a CAD wedge stemming from a 1037 high over Ottawa. 75 miles could make all the difference. There was a pristine deformation axis on this run that spanned all of I-81 from Front Royal to Harrisburg. You can't hate the run at this lead, but just be cautious if you live along the 95 corridor. This is pretty par for the course. One things for sure, it's a QPF bomb.

I haven't seen 7H frontogenesis like this on a snow storm potential for the area since 2016. Both the GFS and CMC are stone cold assassins. I'll post more analysis comparing model runs after the Euro.

This is a trend on the GEFS that should be noted for future runs. The CAD wedge is much more pronounced with a stronger HP over Quebec, and that will pay dividends in at least a better winter precip opportunity. You can also see the tongue of higher Theta-E's on this panel as well with the warmer trend in temps along the SE coast. That is further amplified on the next run, and is classic indication of a bombing surface cyclone at Mid Atlantic latitude.

You go to bed after a mid and wake up to jubilation, mixed with temperament, sprinkled with DT lashing and Ji concerned despite incredibly solid model runs. The GFS is on an island with regards to intensity compared to the other “Good” globals. Nature is healing .

I told you to wear shoes

06z GFS much nicer run compared to 00z. It even has a chance at some appetizer snow for Monday. Rain verbatim, but the idea that precip gets much farther north is a big shift

One of the biggest differences I see from the 12z to the 00z of the ECMWF is the low level warm intrusion from the low tucked closer to the coast in tandem with a stronger surface ridge to the north. 925mb wind field is out of the east for several hrs at 50+kts extending inland to the 81 corridor. This is a dominant warm nose causing the increase in temps at the surface and within the lower confines of the boundary layer. Anytime you get an anomalous u-vector wind without a strong antecedent airmass in place, it would cause issues with p-type extending very far inland. It's a key difference between the two runs and say something compared to the GEM. The UL progression screams big storm at minimum as 5H evolution shows a negatively tilted trough cutting through Tennessee and immediate height falls downstream, along with large region of diffluence ahead of the s/w trough. A slightly stronger area of confluence would help considerably for a more widespread snowfall for the sub-forum, but any type of evolving system will have its boundary aligned SW/NE in a developing storm like this. This is why I relayed that as a bet, I would think the fall line will once again be the point of interest with some degree of movement to the west, pending both the amplitude of the trough and confluent area as storm approaches. Right now, I think the elevated areas west of 95 would be the target chance with Rt15 on west probably in the best spot right now. Won't take much though to get everyone potentially in the game. As things go, I'm happy to see the vigor of the s/w trough still being modeled, which is the ingredient to watch if we want any storm at all.

Agreed. I meant to say GDPS (GEM) for my previous post, so I'll have to make that correction. The GEFS def showed more promise than the OP, so that's actually pretty nice to see. This is the time frame where ensembles I think can earn their stripes more than OP. Leaves window open on what could happen with a smoother mean. The trend is in the right direction right now. Only 20 more runs to go! lol If I was a betting man, I would bet on a storm for someone in here. Most likely the NW of 95 crew, but I wouldn't discount the eastern crew either.

The 5H depiction on the GDPS is more indicative of a snow event compared to the GFS as the wave is stronger with a neg-neutral tilt as it traverses the Tennessee Valley. GFS is a bit more flat and pos-neutral tilt in the same time frame. Still a ways out, but the setup is there for a modest event for the Mid Atlantic. I'll be keeping tabs through the next several days while I'm on mid shifts. I like seeing the high over Quebec and weak blocking in the northern latitudes. Keep those in play, and it'll be about timing of the disturbance. A little more amplitude in the trough will pay dividends.

I too use the 48 hr HRRR for all my short term forecasts. In a totally unrelated story, I might be looking for a new job soon /j

Shouldn't "Ji complains" just be a Free Space?

That is gut wrenching. I am so sorry