MillvilleWx

Hey guys! Wanted to clear some things up here. AFJ is an AWOS station that is not listed for the state report of temps. Typically, one office in the state does a state major climo report, along with some reports from their own CWA. My office does a RTP and OSO and LUB actually does a state report. AFJ being an AWOS means the station is 100% controlled and maintained through the FAA. ASOS are maintained and controlled through the NWS. The state of Pennsylvania choses specific stations to include in the state report, typically the major airports and population hubs. KPIT is the main for the Pittsburgh area.

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That band at the back is the leading edge of PVA rotating in from the shortwave trough pivoting through the area. There was likely going to be a large area of ascent in conjunction with that s/w swinging through. Don’t be surprised if that is up near 2”/hr rates moving through parts of NoVA and central areas of MD. This should push many up near, or over the 2” mark with other in the northern tier close to warning criteria, which is likely one reason LWX expanded the warning. Great little storm here. Delayed, but not denied. Ripping fatties is always great .

That 00z GFS run was one of the craziest, most incredible runs I’ve ever seen for CONUS winter prospects. It even destroys us out here with cold and snow. Man, I’d pay good money for that. .

Current HREF (High resolution ensemble forecast) still shows a general 2-4" for much of the area, and that's including the meh 00z HRRR run for most of the area. You can see the NW corridor more in line with the 4-6" prospects, which jives well with what has already fallen since 07/00z. Things still look good to me. I still like my current forecast overall and I had the 1" in there to cover for bad luck and inside the beltways. The snow that does fall will come in pretty heavy. Pixie dust to an onslaught for 2-4 hrs time, then creep off in the dead of night. After midnight is when the rest of the gang will get the goods. Snow is coming guys! Don't fret too much cuz you could be looking at cold dirt like me

Kolaches are one of the top 5 things I've enjoyed since moving to Texas. Just wonderful

I ran out of likes for the day, so TAKE ALL MY LIKES EVERYONE GETTING PILE DRIVED Things look fantastic in the mesoscale sense. It's gonna come in hot and heavy like when I mow my yard in July. Enjoy!

Hey y'all. As promised and hot off the presses. My current forecast thoughts for the storm. I did not include NW side of PA because I did not look that way, but very likely 2-4" with as much as 7" in the higher terrain. Enjoy the snow!!

Final forecast for the region. I may be low balling a bit across Central MD, but I have a feeling someone will get snubbed, but someone nearby could still be a winner. Lots of banding within the initial shield. Enjoy the snow y'all. I'll be living vicariously!! Edit: I might be too high for areas like Loudoun/Fairfax county, but they still look good for 2-4" so it works in this case. Hopefully the slug from the SW really rolls through the region. That could come down hard and fast.

Got a hand it to the RAP, it has been consistent with ascent being maxed over a large area where the HRRR/NAM Nest are not. GFS actually right in line with it too. Hmmmmmmmm

I do miss home and I'm gonna try hard to get back. In the meantime, I always consider you guys great friends and fellow snow weenies, regardless of where I live. Let's bring this one home

Heading into work soon y’all. I’ll have an updated map later this evening. There will be some finagling of the totals and I’ll expand the areal coverage as well. Have a general idea on what to expect, but there’s some boom/bust potential given the setup. I still think a few inches for basically everyone is on the table. Get that nap in today! .

I'm gonna try to have an updated map for you guys later. I have work soon, but should have some time today. Models are still trying to settle the overall setup with the energy transfer idea, but I think the bounds are coming together for the event in the snowfall ranges. I'll try to give y'all the scoop later. Wish I was back east!

Thanks! I was actually at work when I typed that one up, so I couldn’t do the Zoom call this go around either. Last one I was driving 85 mph coming home from Taos, NM lol I am on work in the evenings next 3 nights too, but I promise when there is a chance, I will be there!! Edit: Just a heads up, we legit had no weather going on in my CWA. My TAFs were set, the Upper Air flight was done and I was waiting for long range guidance to come out. I promise I was still working!! Multi-tasking is something I’ve gotten really good at last 6 years haha

Hey @stormtracker, is it okay to post porn on here?

For your viewing pleasure!

Thank you!

I'm thinking the same thing. Didn't want to jump there yet on my map, but I'll probably have an update by tomorrow evening if things keep trending that way.

We hug this till the next better model run, right?

Well, with finally some time tonight, thought I'd throw out some thoughts on the setup for Thursday Night into Friday AM for a nice little snowfall entering the area. There's another pretty decent signal for a marginal to moderate event areawide given all the different features at play. So first off, our culprit is currently peddling out over ID/WY border with sites on the central plains by morning indicative of very progressive flow within the northern region of the jet. This system will be quick mover, but there's some definitive details that make this a chance to a more prolific storm than many of our rapid movers in the past. First off, the thermal environment is pretty ripe with the 95 corridor only going a bit above freezing for tomorrow PM before slowly taking a dive after peak diurnal max. West of the fall line should stay near to below freezing, which bodes well for the "stickage" factor. Every single flake outside the beltways of the big cities should stick pretty quickly at the first snowfall. So, one of the factors we have going in the positive is one we often fight in these parts. That should not be a problem this go around! Now lets take a look at the meat and potatoes of the event with the mid and upper levels that will make this event. First image below is the 00z NAM Nest from this evening at 500mb There is a prolific 500mb jet max that will be rounding the base of the trough with the left exit region placed over our area (Inside the box). The divergent depiction out ahead of the main trough axis is a classic for developing qpf fields downstream of the mean trough axis. Also notice the tilt of said 500mb axis going negative as it progresses through the OH Valley. This is also a positive indication for the area as historically, we tend to see a robust response east of the BR with ascent maximized along the Alleghany front out into the Piedmont area. This is no different, and the signals below 500mb are certainly there. Below is a gif of the same 00z NAM Nest run of the 700mb horizontal temp advection and frontogenic forcing. Something important to note here is the robust warm horz. temp advection signal developing over SoVA, moving NE into the sub-forum. This is also a classic indication of a good moisture signal for the area when it comes to these events. If you take a look at the concurrent 700mb temperatures within that area of + horizontal temp advection, you can see these are very cold temps aloft within the mid-levels, which is very important for snow growth and attendant ratios that could occur where there is precip. -11 to -17C is the sweet spot for the DGZ (Dendritic Growth Zone) as this is where ice crystallization has the best environment for developing its core structure and maintaining a defined appearance upon its descent. But, temps are not the only thing of note here when it comes to the best snowflake formation....lift is also necessary. This is where that + horizontal temp advection comes into play. This provides a great deal of ascent within the 700mb layer, which is important for crystallization and snow structure. It is apparent that there is a 6 hr window where this is a huge positive for much of the area from SW VA up into portions of Southern PA (Mainly up into I-81 corridor near Chambersburg) then east into much of NoVA/Central MD/Northern half of the Eastern Shore. This is where banding is most likely to occur and there WILL be maxima and minima that occur due to the prominent banding features likely within this setup. Someone will get crushed and someone settling outside a band can get squeezed here, so despite being a solid areawide snow potential (forecast later) there will be big winners and losers. So, how good is the profile we are talking about for this system? Let's take a look at a few examples of areas that get hit pretty solidly during the event. Here is an example from JYO that shows a robust area of ascent within that layer b/w 850-600mb, which are the most important layers for snow growth and expected ratios from a storm. This snapshot was taken at the peak of the mid-level ascent caused by the frontogenic forcing at 850-700mb when the jet streak pinpoints the area within the left exit region of the core jet max. With a sounding like this, 12-15:1 are not just a possibility, they are a given. Here's an image an hour later downstream near BWI This is an even more robust signature of mid-level ascent within the DGZ, indicative of a potential for pretty sizeable flakes within a significant band presence. This is what we want to see in a setup like this where the pattern is progressive, but the upper levels are favorable. As long as we can right the path here with the current outlook, this will be a nice storm for a majority of the sub-forum. So, how much snow we talking? Well, let's take a look at a few things. For me, precip panels will tell a lot of the story because ratios for the storm will be congruent with the banding and overall precip totals throughout the event. Here's a 3hr precip gif for the area leading in till 12z Fri AM Notice there is a primetime period likely just before midnight until about 5am Friday AM. This is when most of the snowfall will occur, so any totals we have will be in a relatively short period of time. However, considering the banding potential and primed thermal environment, an advisory snowfall for pretty much everyone is well within reason. Someone will likely get the benefit of the deformation band that develops on the western flank of the developing SLP off the Atlantic coast, and that's where the WSW criteria snowfall will have the best chance. Here's a snapshot of the total precip for the event. The maxima on the eastern shore is a product of the deformation axis being pegged in that location via the NAM Nest, but of course that is not set in stone and will not likely be solved until late tomorrow when the ingredients all come together. Here's my current thinking in terms of snowfall for the storm This a general 2-6" event for most, but the upslope areas out west are an area I have higher confidence in the biggest totals of the event. Secondary maxima near the Catoctin front and on the Eastern Shore where I believe the deformation axis provides a big punch. The caveat is if the low gets cranking earlier, that could be on the other side of the bay, so keep an eye out for those next 12-18 hrs of model runs to see if any trends are picked up. That's all for now y'all Edit: Bit of a crude transition across St. Mary's county. Apologies for that look!

These maps are mainly for probabilistic usage for EM's and decision makers. They can be disseminated to the public to convey highest and lowest potentials, but that is typically not advised and we stick with the range of the 45-55th percentile outcomes with the 50% as the expected.

Hey y’all. I’ll have more thoughts on this little event for the area, tomorrow. I got a case of food poisoning yesterday evening and it sucked the life out of me today. I’ll be better tomorrow and will reflect my thoughts. Have a great night and get some sleep! .

So it seems I overestimated the ground warmth and despite my diatribe being pretty ominous, I might have low balled. I’m glad it’s breaking that way. Went conservative and SUPRISE!! A blitzing to remember. Enjoy the snow y’all. I’ll be living vicariously .

Well, I finally got to look at things for the storm and man, it's a pretty dynamic setup that should drop the hammer SOMEWHERE in this sub-forum, but the question is....where? Let's take a look at the 500mb setup There's a prolific 500mb shortwave (s/w) currently rotating around the base of a mean trough with closed reflection over northern AL. Historically, this is a great position for the sub-forum to cash in, so long as the ULL doesn't mess itself on the trek eastward. As you can see, it is forecasted to not only hold, but actually strengthen as it crosses the App front with a negative tilt of the shortwave trough. This provides a textbook level divergent signature downstream ahead of the ULL and attendant s/w. What happens is an explosion of the precip field with convective prevalence due to maxed ascent on the left exit region of the 500mb jet max. Also, here's another piece to tickle the fancy.... Here is the 700mb presentation on Monday morning. A closed 700mb low cuts across the NC/VA line which is a fantastic track for areas near Rt 50 and south as VV's will be off the charts on the northern periphery of the 7H low. This puts the NoVA area from Fairfax to the east in the core of the ascent within the mid-level profile. Looking at the 7H frontogen picture using the NAM Nest, you can see a distinct signature over NoVA into SoMD and the lower Eastern Shore with a convergent pattern within and just north of the main frontogenic forcing. This is where the most prolific banding would occur for those with winter precip. Another maximum will occur on the lead side of the low due to the moisture fetch off the Atlantic from SE flow (This is actually important for the snow lovers on the Lower Eastern Shore). Now, go back and look at the 500mb gif I posted above, There's a s/w zipping eastward out of the northern Midwest that will put a straight edge to the northern side of the precip field. It's a developing confluent signature that will create a sharp cutoff on the northern side of the mid-level moisture field, which means someone will get hung out to dry, literally where this ends up developing. I will say there is a distinct northern mini max potential about 30-50 miles south of the main convergent area created by the confluence. This area typically maxes with the localized ascent, plus the favorable thermodynamics at play. Don't be surprised of some interesting totals coming out of areas within that zone to the north of where the main area gets slammed. So, when it comes to the dynamic nature of the mid and upper-levels, there will be no shortage of ascent to work off, and that in turn will help establish a healthy area of precip for the event, especially those within the perfect setting of the mid and upper closed lows. Now, lets talk about the caveat to the setup, thermal profiles. Right now, we have modest cold air advection (CAA) areawide with drier boundary layer air working behind the front that slid through earlier. This is important as wet-bulbing at both the lowest 100m of the boundary layer AND the layer b/w 600-800mb will generate the ptype separation a few hrs after the precip begins. Right now, thermals are borderline for the first 3-6 hrs of the event as sleet will likely mix or be the predominant ptype for the very beginning. As the mid and upper levels traverse eastward, you'll see a considerable cooling aloft that will mix into the boundary layer and change everything to snow from northwest to southeast. Areas on the very northern edge might only see a brief period of liquid and/or sleet before completely changing to snow. I think the area from Rt 50 south to the AKQ area will be the sleet zone for the first stage of the event. This area is also in the benefit of being within the "crush zone" for precipitation due to the expected ascent from the mid-level frontogen. There will probably be a period where sleet/snow mixes with massive flakes before shifting to all snow and then raging with continuous large aggregates. Boundary layer will be improving through the AM, so ratios will start pretty meager, but quickly shift to a climo norm, perhaps final 3 hrs ending around an avg of 12:1 with some places seeing 15-20:1 pending local banding. As I see it, there will be a line about 30-50 miles wide of pretty decent snowfall with the northern edge tapering back in a gradient caused by the confluent area to the north. Here's my current thoughts on snow totals. This is all from everything I've looked at and adjusted based on current ground temps needing some time to recover from the warmth earlier today. Hope everyone here gets some snow. Enjoy y'all!!

Shortwave trough over AL is pretty fierce this evening. Friends in AL reporting TSSN in Tuscaloosa. That ain't too shabby. Looking at stuff now. Will report back in time.