MLK 2022 Storm Potential

[toolsheds]

53 minutes ago, Bob Chill said:

I think a lot of the unwillingness to accept the outcome stems from not understanding how low pressure systems evolve. There isn't just a surface low like everyone looks at on TT. There are also mid and upper level lows. At our latitude in the winters, it's not common to have all 3 on top of each other like this. They are usually "slanted" with the surface first and upper last. When you get all 3 spinning together right over top of each other and no cold high feeding the beast,, you better be far NW from the center or you're in big wet trouble.

This all goes back to the "sandwich" dynamics which you explained last year.  Hopefully some on the board can remember this for the future.  :-)

[Weather Will]

What is the criteria for an ice storm warning?

[wolfpackwxDC]

24 minutes ago, Bob Chill said:

That low jump is just a digital thing from what I can tell. Model graphic output is programmed to stamp an L at the lowest pressure but the lowest pressure is fluid so the L jumps around inside the "bag of low pressure". I like using the shaded mslp anomaly maps to just compare the bigger bag (general center) and not the L (specific center). I could be wrong here so someone correct me if so

I always find it odd that people live and die based on where contours are closed and letters are drawn, especially if run to run they move +/- 25 miles.

[stormtracker]

3 minutes ago, Weather Will said:

What is the criteria for an ice storm warning?

1/4" or more.  Could be 1/2" in some states/location

[wolfpackwxDC]

3 minutes ago, Weather Will said:

What is the criteria for an ice storm warning?

Some of these criteria vary from region to region, but here is what LWX has on their site. Looks like .25 inches of ice.

 

https://www.weather.gov/lwx/WarningsDefined#:~:text=A Winter Storm Warning is,weather is occurring or imminent.&text=2) Enough ice accumulation to cause damage to trees or powerlines.,-AND%2FOR&text=AND%2FOR-,3) a life threatening or damaging combination of snow and,or ice accumulation with wind.

[BristowWx]

4 minutes ago, Weather Will said:

What is the criteria for an ice storm warning?

I’ve never experienced a wind driven ice storm here in the piedmont. Feel like if the wind was right it would be snow and the wrong wind direction like this appears so far is rain.  But you never know

[Twilly05]

2 hours ago, Ruin said:

and look at it now its going to go into south central PA straight north. All the talk about cold air surprising this storm went out the window in less then 12 hours. I mean for heavens sake going from right at the coast then to push in western VA in some models is crazy. I even made a joke watch this turn into a apps runner and by god it did. at this point I wouldnt be surprised if it ended up in western PA or if it decided to go more east

I said days ago it would end up either an apps runner/cutter or it would jump to the coast. For snow lovers on the coastal plain, we rolled snake eyes. It “jumped” the wrong way. Smh

[EastCoast NPZ]

5 minutes ago, BristowWx said:

I’ve never experienced a wind driven ice storm here in the piedmont. Feel like if the wind was right it would be snow and the wrong wind direction like this appears so far is rain.  But you never know

Yes.  Wind would mix the surface inversion, scouring out the low level cold .  I don't buy any depiction showing a windy freezing rain scenario. 

[wolfpackwxDC]

Anecdotal analysis...

15z backyard model run: Squirrels are out in force this morning, digging all over the place, despite it being 25 degrees. Much more active than over the past week. Perhaps they know something...

[BristowWx]

4 minutes ago, EastCoast NPZ said:

Yes.  Wind would mix the surface inversion, scouring out the low level cold .  I don't buy any depiction showing a windy freezing rain scenario. 

Hazards aside and impacts..it would be cool to see a wind driven ice storm. ..until it was time to clean up from it

[DDweatherman]

Thinking 4-8” up in Garret Co with the upslope and probably 8-12” in Davis? We were looking in that area but way more in terms of options for the kids in McHenry/Swanton. 

[Random Chaos]

16 minutes ago, EastCoast NPZ said:

Yes.  Wind would mix the surface inversion, scouring out the low level cold .  I don't buy any depiction showing a windy freezing rain scenario. 

I’m not sure that’s quite what is depicted. The wind doesn’t really pick up on the NAM until after the rain transition on the model. That ZR is almost entirely before the big rain mass reaches us. If you look at the 850 winds at 0z Monday on the 12z NAM, the mass of wind has just reached DC and already the ZR has pulled north of DC.

[NorthArlington101]

I’m just (unwisely) hugging the HRRR. Shows a very equitable 3-5” across the region with some banding winners before a little sleet and a little rain.

[CAPE]

The story of this storm really can be told by looking at the 850 mb height/vort and wind panels.

[BristowWx]

1 minute ago, NorthArlington101 said:

I’m just (unwisely) hugging the HRRR. Shows a very equitable 3-5” across the region with some banding winners before a little sleet and a little rain.

That’s the most uniform snow map for such a large area in the history of snow maps

[stormtracker]

Just now, CAPE said:

The story of this storm really can be told by looking at the 850 mb height/vort and wind panels.

Or better yet, by viewing this movie:

[LeesburgWx]

2 minutes ago, NorthArlington101 said:

I’m just (unwisely) hugging the HRRR. Shows a very equitable 3-5” across the region with some banding winners before a little sleet and a little rain.

Would be a major win for everyone if this happened verbatim. But it the HRRR...

[stormtracker]

I'm just going to enjoy whatever we get.  There's going to be snow in the air during daylight.  Window is still open for a surprise or two.  Now that we know what our fate is, time to just get past it, have fun with whatever we get and then forget this one and move to our next threat.  

[Chris78]

Icon slightly better.

A little heavier rates it seems from the WWA. 

Just gotta hope that juices up a bit over the next few runs to maximize the thump while we still have mids.

[NorthArlington101]

That’s the most uniform snow map for such a large area in the history of snow maps

In a way, it makes sense that we all share the same dynamic WAA thump before changing over. It seems unlikely the changeover will move northward in a straight, buzzkilling line, but that map kinda makes sense. I think.

[NorthArlington101]

I'm just going to enjoy whatever we get.  There's going to be snow in the air during daylight.  Window is still open for a surprise or two.  Now that we know what our fate is, time to just get past it, have fun with whatever we get and then forget this one and move to our next threat.  

A smart person would not check this forum or the models until Monday. That’s not me

[WxUSAF]

5 minutes ago, stormtracker said:

I'm just going to enjoy whatever we get.  There's going to be snow in the air during daylight.  Window is still open for a surprise or two.  Now that we know what our fate is, time to just get past it, have fun with whatever we get and then forget this one and move to our next threat.  

Hear hear 

[ChesterfieldVa80]

9 minutes ago, NorthArlington101 said:

I’m just (unwisely) hugging the HRRR. Shows a very equitable 3-5” across the region with some banding winners before a little sleet and a little rain.

Do you have the entire state?

[NorthArlington101]

Do you have the entire state?

This leaves out the SW, which I think you are OK with based on your handle, but if not let me know and I’ll DM you something else.

[wkd]

2 hours ago, MillvilleWx said:

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!" 

 

[MDphotog]

1 hour ago, Weather Will said:

WB 12Z 3K NAM:  not as much precipitation in central zones.That will be interesting to track as well.

I don’t know if South Mountain has that much of a rain shadow effect, but we will see.

[nw baltimore wx]

A little frustrating to see the gfs wrapping the cold air around into the southeast quadrant just as the storm passes our latitude.

[wkd]

2 hours ago, MillvilleWx said:

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 really like your informative posts.  If you get the chance, please transfer to the Mount Holley office.

[MillvilleWx]

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)

[SnowGolfBro]

26/1 in Montclair. Cloudy. Feels like rain lol