Mid Atlantic Met Class Thread

[PaEasternWX]

so on the 00z gfs if we see that the day 7 storm vort has darker colors that means more lift hence a better trend?

[BTRWx]

1 hour ago, PaEasternWX said:

so on the 00z gfs if we see that the day 7 storm vort has darker colors that means more lift hence a better trend?

It has nothing to do with model trends, just strength of the system for that particular run.

[heavy_wx]

On 3/3/2012 at 7:08 PM, dtk said:

In many data sets, particularly for observations, the "level" usually is in reference to the amount of processing that has been done to the raw measurement. For NEXRAD, you can find descriptions for

Level2 Here: http://www.roc.noaa.gov/WSR88D/Level_II/Level2Info.aspx

and

Level3 Here: http://www.roc.noaa.gov/WSR88D/Level_III/Level3Info.aspx

Way late, but just to add, there are actually Level 1 WSR-88D radar data. These data are the raw voltage time series at each range gate and are used by the signal processor to calculate the Level 2 "base" moments of reflectivity, mean Doppler velocity, spectrum width, correlation coefficient, differential reflectivity, and differential phase. Level 1 data are not archived because they require more storage space than Level 2 data and very few users find the time series data useful. Time series data can be used to estimate the full velocity power spectrum, which can give us more information about the types of particles within each radar sampling volume.

The Level 2 data are considered "raw" data because little quality control or smoothing is done to the base moments. For example, if you compare differential reflectivity from a Level 2 source to that from a Level 3 source, you can see that the Level 2 data is much noisier. The noise would be further reduced if the radar sent out more pulses, but that would increase the dwell time and lead to less frequent sweep updates.

Level 3 data are thus further processed Level 2 data where the base moments are smoothed to reduce the noise, specific differential phase is calculated from differential phase, and other products such as radar-estimated precipitation are derived. One drawback with the Level 3 data is that only the lowest 4 elevation scans are processed in this way, so information from the higher elevation angles is only available in the Level 2 data.

[heavy_wx]

10 hours ago, psuhoffman said:

Usually when we say vort we mean a vorticity maximum embedded in the 500 mb flow. It's a measure of vertical vorticity or spin along a vertical plane. Positive vorticity advection or pva is important in a basic sense because it enhances lift which is what causes precip. 

The h5 map below shows a vort max. The specifics can get complicated and I am tired but this is a really good explanation I found a while ago. 

http://www.weather.gov/source/zhu/ZHU_Training_Page/Miscellaneous/vorticity/vorticity.html

if you still have any specific questions I'd be glad to try to answer them 

Technically, we correlate synoptic scale lift to differential positive vorticity advection (actually differential cyclonic vorticity advection, to include our friends in the Southern Hemisphere), meaning that PVA increasing with height, not simply PVA, is correlated to lift. However, in the case of cyclogenesis, most of the time PVA is stronger at 500 mb than below so PVA at 500 mb is generally a decent proxy for positive differential PVA.

Of course, a lot of the precipitation associated with cyclogenesis is due to mesoscale processes such as frontogenesis, where semi-geostrophic theory is more appropriate than quasi-geostrophic theory. Check out this presentation for more information about frontogenesis and how it produces lift.

http://www.weather.gov/media/lmk/soo/frontogenesis_lmk2.pdf

[psuhoffman]

28 minutes ago, heavy_wx said:

Technically, we correlate synoptic scale lift to differential positive vorticity advection (actually differential cyclonic vorticity advection, to include our friends in the Southern Hemisphere), meaning that PVA increasing with height, not simply PVA, is correlated to lift. However, in the case of cyclogenesis, most of the time PVA is stronger at 500 mb than below so PVA at 500 mb is generally a decent proxy for positive differential PVA.

Of course, a lot of the precipitation associated with cyclogenesis is due to mesoscale processes such as frontogenesis, where semi-geostrophic theory is more appropriate than quasi-geostrophic theory. Check out this presentation for more information about frontogenesis and how it produces lift.

http://www.weather.gov/media/lmk/soo/frontogenesis_lmk2.pdf

Yea it's a lot more complex then I got into. And someone else (like you) is probably better then me for those that really want to get into the fine details of this.  I did get into some of that stuff in my meteorology classes but I haven't used it all that much and that was 18-20 years ago now.  

Most of us including me probably aren't pouring over all the plots needed to get into each meso scale factor. Wish I had that kind of time. The h5 vorticity is a good poor mans way to get a basic quick look at what's going on. 

Plus usually when we hear a lot of vort max talk it's because we're dealing with a pretty pathetic surface system (like last night) and we're relying on the lift associated with the h5 vort to give us a little something. In this case to pop a weak surface reflection and a very small band of precip. 

I love this stuff. I've wasted days reading through my old textbooks on meso stuff. Of course it's funny cause when it comes to looking at longer range stuff which is usually what I'm doing this year (ugh) the meso stuff could be a waste of time. Even from 48 hours I could spend time looking at where the best lift is based on meso features then the whole synoptic setup shifts 50 miles and it's pointless. 

Really want to go back and finish my meteorology degree but I'm not sure how I would use it. I like teaching (assuming I don't lose my job due to the current financial crisis in Maryland) and have a family to consider. It's probably something I'll do later on just for my satisfaction. Perhaps then get duel certified in science and find a school that would let me teach it as an elective or as a major unit in earth science. 

[heavy_wx]

29 minutes ago, psuhoffman said:

Yea it's a lot more complex then I got into. And someone else (like you) is probably better then me for those that really want to get into the fine details of this.  I did get into some of that stuff in my meteorology classes but I haven't used it all that much and that was 18-20 years ago now.  

Most of us including me probably aren't pouring over all the plots needed to get into each meso scale factor. Wish I had that kind of time. The h5 vorticity is a good poor mans way to get a basic quick look at what's going on. 

Plus usually when we hear a lot of vort max talk it's because we're dealing with a pretty pathetic surface system (like last night) and we're relying on the lift associated with the h5 vort to give us a little something. In this case to pop a weak surface reflection and a very small band of precip. 

I love this stuff. I've wasted days reading through my old textbooks on meso stuff. Of course it's funny cause when it comes to looking at longer range stuff which is usually what I'm doing this year (ugh) the meso stuff could be a waste of time. Even from 48 hours I could spend time looking at where the best lift is based on meso features then the whole synoptic setup shifts 50 miles and it's pointless. 

Really want to go back and finish my meteorology degree but I'm not sure how I would use it. I like teaching (assuming I don't lose my job due to the current financial crisis in Maryland) and have a family to consider. It's probably something I'll do later on just for my satisfaction. Perhaps then get duel certified in science and find a school that would let me teach it as an elective or as a major unit in earth science. 

Yeah, I think folks who have been looking at model data and observations for a while know from experience where to expect the heaviest precipitation in relation to a 500 mb PV max. I like looking at where banding sets up in relation to mesoscale jet streak circulations because it gives some physical insight into why enhanced precipitation may occur over a certain region. Hopefully we have at least one nice example this winter!

I have a friend with a B.S. in meteorology who teaches a meteorology lab at a state university part time, so that could be one option.

[BTRWx]

1 hour ago, heavy_wx said:

Technically, we correlate synoptic scale lift to differential positive vorticity advection (actually differential cyclonic vorticity advection, to include our friends in the Southern Hemisphere), meaning that PVA increasing with height, not simply PVA, is correlated to lift. However, in the case of cyclogenesis, most of the time PVA is stronger at 500 mb than below so PVA at 500 mb is generally a decent proxy for positive differential PVA.

Of course, a lot of the precipitation associated with cyclogenesis is due to mesoscale processes such as frontogenesis, where semi-geostrophic theory is more appropriate than quasi-geostrophic theory. Check out this presentation for more information about frontogenesis and how it produces lift.

http://www.weather.gov/media/lmk/soo/frontogenesis_lmk2.pdf

What happened to the 101 here? lol

eta: maybe we need a separate thread

[mappy]

13 minutes ago, Bob Chill said:

Start with the very basic ens mean plots. Op models are a bad place to make decisions on longer lead stuff (beyond 5-7 days). They'll jump every run and present all kinds of different  solutions. When the rare case happens like with the blizzard where they don't jump then they definitely carry a good bit of weight. But that hasn't been the case a single time this year so relying on them is bad practice. 

Here's a good exercise. The follow up storm beyond this weekend is a big warm rainer. It's nearly a lock now. Using the MSLP panels from the GEFS/EPS from last night show a very strong signal for a rain storm with low pressure passing to the north. High pressure off the coast and low pressure to the NW = very strong SW midlevel and surface flow. Terrible for winter wx:

 

 

 

 

Mean mid level temps for the same period:

 

 

 

What happens after gets really muddy really quick. First thing to do is think back in history to how often we get storms right on the heels of a strong NW low passage/cold front with a western atlantic ridge. Can you think of many? I can't either. It's worked out before (2014 & 15 we're very kind) but not nearly often enough to invest a whole lot of energy at 7+ day leads.  The timing has to be perfect.  Anything forming along the trailing boundary is going to be a fast mover and we would need everything to come together just right. It's complicated and we don't do complicated well.  

Take a look at this panel. This is right about when the front is clearing after the rain storm. See the red ball off the coast of canada in the wetern atlantic? Think of that as a storm vacuum. Anything running the boundary is going to race to that spot. See the sharp sw-ne gradient on the height contours? Think of those lines as lanes in a highway. The steering mechanism in the upper levels. What we want to see is a big blue ball where the red ball is and a much more w-e gradient with the lines instead of sw-ne. The w-e gradient is called confluence. This blocks storms and provides a feed of cold air from the north. Not the case right now:

 

Ensembles do show the *possibility* of something running the boundary after the cold sweeps in. But it all has to break right. A storm may not form at all. Or it will form harmlessly off the coast and rain/snow on the fishes. Being in the bullseye can work out but if it does happen it will be beating strong odds against it happening vs taking advantage of a favorable setup. 

 

Here's the ens MSLP plots from the GEFS/EPS. You can see the signal for a coastal running the boundary:

 

 

 

 

 

What are the problems with these mean plots? The big one is high pressure placement. It's directly to the west of the storm. What we want to see is high pressure over the top. If that was the case right now it would be a much better storm signal at range. 

 

Unless you want to pay for detailed EPS panels, the best free tools are the basic EPS mean panels on trop tidbits but another fantastic GEFS tool is also available on TT. Never overlook the 24 hour mean precip panels and the individual member low pressure location plots. Gives you an idea how the clusters look and also chances for precip. 

The 0z GEFS actually looks pretty good with both panels for the trailing wave. 

 

Here's the mean precip panel. It's awful wet for the lead time to be honest. .5" QPF @ 216 hours is pretty strong:

 

 

Here's the MSLP member locations. Pretty muddy to be honest but there are some really big hits on the 0z GEFS and also the EPS run so hope is alive:

 

 

 

 

Is there a signal for a follow up storm? Yes, there definitely is. Is it a strong signal? No, definitely not. The setup is tenuous, the lead is long, and going off past history we don't do well with this kind of stuff. 

Now is time to monitor trends. The idea is out there. The possibility is there. If consensus within the ensemble suites keeps improving then it will get more interesting. For right now we just have a modest chance at an unusual way to get a good storm to work out. That's it. 

 

 

[mattie g]

Why do the long-range models suck so bad?

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

[psuhoffman]

With the down period we're in I thought it was a good time to resurrect this thread and further the discussion from last year.  I realized lately that while we did a good job touching on what is a perfect pattern for snow that we didn't really discuss all the different variables that factor into the "trade off" that happens when there is a less then perfect pattern.  And those scenarios make up 90% of our snowfall events so it's not really useful to only focus on the textbook perfect HECS setups. 

So first of all its important to look into the WHY of the textbook HECS cases first for comparison.

This is the composite H5 mean of our 6 unquestioned HECS events in the last 40 years. 

So what makes that the "perfect" look.  The single most important feature is what sin the box there...the ridge over trough in the north atlantic centered over greenlands longitude.  The ridging over greenland is what we call the greenland block.  The trough south of it is the 50/50 low.  The ridging forces systems under it which promotes the troughing into the 50/50 locations.  The combination of flow around the Greenland high and the 50/50 low promotes cold air into the northeast US.  Also, confluence (merging of air flow) promotes high pressure.  The confluence of the flow around the 50/50 with where it meets the westerly flow of the jet coming across the CONUS promotes high pressure to our north.  This is even more pronounced with a split flow. 

Also keep in mind these features arent all or nothing.  That isn't JUST a -NAO, its a greenland block.  Not ever bit of ridging over greenland is a block.  Yes it helps but that look there is classic because its a perfect block.  The strength of that block will really slow down the flow and force systems under it.  Keep that in mind when we look at the other features on that map.  The indication of an STJ is there with the lower heights down along the gulf coast.  That is of course desirable.  But look at the Pacific.  Without that look in the atlantic that would be crap.  I made the point about the blocking because people keep throwing around the whole Pacific v Atlantic thing and its not an all or nothing debate.  With just some nao ridging that pacific would probably blast pacific air across.  Yes there is a split flow indicated there but that trough location off the west coast isn't gonna cut it without the atlantic blocking.  So yea if we only have some nao help having a crap pacific will ruin it.  But if its one of those rare cases with off the charts 3std blocking then you actually WANT the crap pacific. 

The attempt at ridging in the east virtually ensures that a system will attack the blocking from the southwest.  But with that blocking...the chances of a cut to our NW are low so when ends up happening is it attacks the high, runs right into it, WAA thumps us to high heaven, then gets forced east under it.  Its our dream scenario.  Without the less then favorable pattern out west we would just be cold and dry.  Notice there is no big blue ball of death over the eastern US.  If there was we would be cold/dry with that blocking.  You need there to be an attempt at ridging up the east coast to back the flow and force a storm up into the blocking.  But that ONLY works with that level of blocking.  Without it that same look is a cutter pattern.  There are lots of variables playing off each other.

So this is a closer in view of the surface and h5 for 1996, the perfect example.

Notice where the flow is aimed.  With that H5 low where it is, without the blocking holding in the confluence to our north that storm would have cut.  But it cant.  Most extra tropical cyclones are baroclinic meaning they develop along tight temperature gradients or fronts which provide potential energy.  Once they occlude they can become baratropic where the temperature profile is more uniform around the low.  But that process rarely happens before our latitude in the development cycle.  So for our purposes storms will follow the path of least resistance and fuel source along the temperature gradient boundary.  That boundary cannot penetrate up the east coast inland past our latitude because of the resistance from the flow around the high to our north.  So the low is going to transfer to where there is a natural baroclinic zone, the coast.  The temperature gradient between the land and ocean creates a natural location for the storm to jump.  This places us in the battleground.  The WAA from the south trying to overrun the cold is tremendous.  The circulation from the high increases the CCB and convergence with enhances lift.  Its perfect.  And the blocking combined with the attempt at ridging into the east gives us a HUGE window of opportunity. 

Basically a low that tracks anywhere into that box is going to transfer to where we want it off the VA capes.  Once there we are good no matter what happens.  That is what makes this the perfect setup, the combination of what would usually be a trough axis too far west forcing a system right up at us but then running into a cold air mass blocked in by the north atlantic pattern.  Its our money pattern. 

I am reviewing all this because once its obvious WHY this is the perfect pattern and all the variables and trade offs that play into that we can then look at different looks and examine the different trade offs that make less then ideal patterns work out for us. 

[psuhoffman]

So I liked this example of a pretty good storm from 2004 across our area because it deals with the trade off between the PNA and atlantic.  In this case the blocking and 50/50 location would be way too suppressed if it weren't for an absolutely crap pna pattern. 

There is a trough in the west there but thats actually good here because look at where the 50/50 is.  If it werent for the attempts to pop a ridge in the east and cut something to our west anything coming at us from the south would be suppressed.  This worked out because the system tried to go west and was forced under us.  So too much of a good thing in the atlantic was offset by what would normally be a worse PNA look.  If we actually had what we usually consider a "good PNA" there it would have been cold/dry and a snowstorm along the southeast coast maybe. 

[BTRWx's Thanks Giving]

4 minutes ago, psuhoffman said:

So I liked this example of a pretty good storm from 2004 across our area because it deals with the trade off between the PNA and atlantic.  In this case the blocking and 50/50 location would be way too suppressed if it weren't for an absolutely crap pacific pattern. 

There is a trough in the west there but thats actually good here because look at where the 50/50 is.  If it werent for the attempts to pop a ridge in the east and cut something to our west anything coming at us from the south would be suppressed.  This worked out because the system tried to go west and was forced under us.  So too much of a good thing in the atlantic was offset by what would normally be a worse PNA look.  If we actually had what we usually consider a "good PNA" there it would have been cold/dry and a snowstorm along the southeast coast maybe. 

Good stuff! Interesting to see 2004 has the warm blob.

[psuhoffman]

But what about some looks if we have to go it without NAO help?  There are ways to get snow without that kind of textbook blocking but it requires trade-offs with other variables. 

So what about an EPO driven pattern with a positive NAO.  This is the early December 2002 storm. 

A LOT of these storms coming up will be the "thread the needle" type.   NAO blocking gives us that HUGE window.  With most other setups the problem is minus that blocking we have to rely on a tradoff between other pattern drivers to line the trough axis up just right.  If the trough sets up just west we rain.  If it sets up just east we watch a fish storm pass by.  We don't have a large margin for error.  Still most of our snow comes from less then perfect setups with a little luck.  This one was primarily EPO driven.  We did line up a favorable 50/50 and even though it was transient it was there at the right time to promote confluence and cold right as the system approached.  Most of these h5 plots are the day before the storm to show the setup.  You see the indication of the system coming at us from the southwest but you DONT see some big huge trough over the east.  Again on almost all of these you will notice the lowest height anomalies are centered to our north or northeast NOT over us or to the southwest of us.  Keep that in mind when we start to see how this next pattern is evolving.  We dont want some huge blue ball over the United States with high pressure blasting down to Arkansas if we want snow.  Here the extreme EPO combined with a favorable 50/50 set the table for a good storm minus any NAO help. 

[psuhoffman]

What if we don't have NAO or 50/50 help.  The best bet in that case is to root for a gradient boundary storm.  A wave along the boundary mostly moving west to east of southwest to northeast.  Something overly amplified is very unlikely to work in that setup.  And it will require a better EPO to offset the other missing pieces.  This is a good example. 

Now we have a positive NAO and a WAR.  You would think uh oh, but the EPO is textbook and again notice the center of the lower heights are to our north.  In this case the setup places the boundary south of us and a wave was able to ride along and we win.  The key here is where the lower heights set up downstream from the EPO placing us right along the boundary.

Early March 2014 and feb 1996 are other examples of a gradient boundary storm that worked out.  Different moving parts but similar in that the lower heights centered to our north and a system rode the boundary set up through our area. 

[BTRWx's Thanks Giving]

3 minutes ago, psuhoffman said:

What if we don't have NAO or 50/50 help.  The best bet in that case is to root for a gradient boundary storm.  A wave along the boundary mostly moving west to east of southwest to northeast.  Something overly amplified is very unlikely to work in that setup.  And it will require a better EPO to offset the other missing pieces.  This is a good example. 

Now we have a positive NAO and a WAR.  You would think uh oh, but the EPO is textbook and again notice the center of the lower heights are to our north.  In this case the setup places the boundary south of us and a wave was able to ride along and we win.  The key here is where the lower heights set up downstream from the EPO placing us right along the boundary.

Early March 2014 is another example of a gradient boundary storm that worked out.  Different moving parts but similar in that the lower heights centered to our north and a system rode the boundary set up through our area. 

Gee, 3/3/14 looks atrocious from h5 alone. Very interesting!

[psuhoffman]

Our only snow event in 1995 was primarily PNA driven with a lucky trough axis in the east that worked out.

[psuhoffman]

And sometimes we just get lucky with almost nothing going for us.  This looks like crap but the PV lobe over quebec and the ridging on the west side of Hudson Bay forces that system out of the southwest to bowl east under us and we got our only decent snow of the 1997 winter in a crap pattern. 

[psuhoffman]

We can add more of these but one thing you will notice with almost all of the is no big huge blue ball over the eastern US.  We want the lower heights at H5 centered to our north, and preferably to our northeast to get snow.  That is the most important and most common theme of all of our snow events both big and moderate.  Keep an eye on where the troughing sets up next time if the EPO reloads.  Hopefully not right over us or to our south next time. 

[showmethesnow]

@psuhoffman

Nice writeup. Might crack open the Kocin books and get some ideas to add to this over the coming days.

[nj2va]

Great stuff PSU...thanks for doing the analysis on this.

[psuhoffman]

35 minutes ago, nj2va said:

Great stuff PSU...thanks for doing the analysis on this.

You're welcome. I enjoy it. The thing is it's rare to get the ideal setup.  Most of the time the trick is looking at all the variables and how they trade off each other to see if we can place the boundary just south of us as a system comes along. The atmosphere acts like waves and these things we call epo,pna,ao,nao are just our measure of how the waves are behaving in a specific location. It's good to quantify that but the truth for getting snow here is all about how all the waves in the jet play off each other to determine the location of a synoptic system along the temperature boundary as it passes our longitude.  There are a ton of variables at play and each one changes exactly what we want from the others.  What combination of things will get a system to track just to our south. That's the game. There are lots of ways to get there but it's complex predicting how all the factors influence each other. 

[Lowershoresadness]

since 1970 what decade has produced the most snow for our area?

[psuhoffman]

Adding march 2015 as an example of an epo driven pattern with no Atlantic help that worked. 

again the negatives are centered to our north. In this case we needed a wave to run north pulling the boundary through then a second wave got us. 

[psuhoffman]

35 minutes ago, Lowershoresadness said:

since 1970 what decade has produced the most snow for our area?

DCA avg snowfall

1970s: 14.58

1980s: 17.08

1990s: 12.94

2000s: 12.68

2010s: 18.4

[Lowershoresadness]

7 minutes ago, psuhoffman said:

DCA avg snowfall

1970s: 14.58

1980s: 17.08

1990s: 12.94

2000s: 12.68

2010s: 18.4

interesting  thanks psu.  

[showmethesnow]

1 hour ago, psuhoffman said:

You're welcome. I enjoy it. The thing is it's rare to get the ideal setup.  Most of the time the trick is looking at all the variables and how they trade off each other to see if we can place the boundary just south of us as a system comes along. The atmosphere acts like waves and these things we call epo,pna,ao,nao are just our measure of how the waves are behaving in a specific location. It's good to quantify that but the truth for getting snow here is all about how all the waves in the jet play off each other to determine the location of a synoptic system along the temperature boundary as it passes our longitude.  There are a ton of variables at play and each one changes exactly what we want from the others.  What combination of things will get a system to track just to our south. That's the game. There are lots of ways to get there but it's complex predicting how all the factors influence each other. 

Pretty much why I really don't focus on the indices that much. Looking at the model maps gives you a much better idea of how everything is working/evolving with each other. That's why I have to laugh every time someone throws out the absolute that the "x indice value or y indice value means no snow or cold for us'. 

[Lowershoresadness]

hey guys keep dropping knowledge in here. The only thing I know right now is where all the colors should be to get snow

[RDM]

On 1/30/2017 at 10:26 AM, psuhoffman said:

Yea it's a lot more complex then I got into. And someone else (like you) is probably better then me for those that really want to get into the fine details of this.  I did get into some of that stuff in my meteorology classes but I haven't used it all that much and that was 18-20 years ago now.  

Most of us including me probably aren't pouring over all the plots needed to get into each meso scale factor. Wish I had that kind of time. The h5 vorticity is a good poor mans way to get a basic quick look at what's going on. 

Plus usually when we hear a lot of vort max talk it's because we're dealing with a pretty pathetic surface system (like last night) and we're relying on the lift associated with the h5 vort to give us a little something. In this case to pop a weak surface reflection and a very small band of precip. 

I love this stuff. I've wasted days reading through my old textbooks on meso stuff. Of course it's funny cause when it comes to looking at longer range stuff which is usually what I'm doing this year (ugh) the meso stuff could be a waste of time. Even from 48 hours I could spend time looking at where the best lift is based on meso features then the whole synoptic setup shifts 50 miles and it's pointless. 

Really want to go back and finish my meteorology degree but I'm not sure how I would use it. I like teaching (assuming I don't lose my job due to the current financial crisis in Maryland) and have a family to consider. It's probably something I'll do later on just for my satisfaction. Perhaps then get duel certified in science and find a school that would let me teach it as an elective or as a major unit in earth science. 

PSU -  You and I exchanged notes some time ago about finishing your degree.  Go for it!  Do it now and don't look back.  No doubt I'm not aware of your particular family situation.  And you're obviously thinking about them too.  Just think of this...  how will you feel 20 years from now if you don't finish it? 

Up until my sophomore year at Wright State U. my full intentions were to become a pro met.  It was what I wanted to do since the age of 5 or 6, other than be a fireman like my dad, which all young boys want to be.  Half way through my sophomore year I spent the night shift with a pro met at the NSW office at Dayton Airport.  The Met who allowed me to shadow him was nice, but he told me several things that did not paint a rosy picture.  At that time nearly all NWS work was 12 on, 12 off 4 days a week.  (that's ok - often worked 12 hour days in my career including one 65 hour stint - not advisable)  Then he said I had to get your MS - (that was ok as I planned to transfer to PSU).  Then the kicker...  and this was circa 1982.  He told me the NWS was closing 50+ weather stations in the coming years as part of a large computer consolidation program (maybe Wes remembers that...).  Most the positions being impacted were going to be cut through retirements.  So the job outlook was not so great.  Since I could not see myself on TV, thought I better find something else for a career.  So I became an engineer. 

Even though I didn't go the Met route, my career took me to various posts overseas where I was able to experience some of the "best" Mother Nature can muster, wrt the weather.  From 3 meter snows in the Swiss Alps, to monsoon rains in Delhi to incredible thunderstorms in Bkk, to 60 foot snows in Japan and skiing down a snow capped Mt. Fuji,... I've been very fortunate.  However, I've never stopped wondering - what if....   Would love to have the creds to spend a winter month in the Mt. Washington station.  But that's likely never to happen.  You are still young enough you can do this.  With the following you have in the forum, you could make weather a full time gig.  Go public, start your own web site and incorporate. (it's very easy to start a S-Corp or LLC).  No doubt others in the forum would be very supporting and help promote you for all you've given the forum.  No doubt as well you've be heads and shoulders about our oft referenced famous JB (or infamous - haha). 

Speaking of my dad, he's a good example of never too late.  My dad was an electronic technician for his work - retired from Wright Patterson AFB.  Was also a volunteer fireman for over 50 years and in the first graduating class of paramedics in the state of Ohio.  He did all that with an 8th grade education.  Went away from home at the age of 15 to work, and then joined the AF at 17.  But he always regretted not finishing High School.   So in his early 70's he got his GED.  One of the proudest moments of his life!  Just a little analogy about it never being too late.

Please forgive the long winded note.  I really hope you find the way to finish up those last few classes.  Then if you do go pro and go online, I'll be among the first to subscribe and proudly so.  Take care, Rob

[nj2va]

7 hours ago, psuhoffman said:

You're welcome. I enjoy it. The thing is it's rare to get the ideal setup.  Most of the time the trick is looking at all the variables and how they trade off each other to see if we can place the boundary just south of us as a system comes along. The atmosphere acts like waves and these things we call epo,pna,ao,nao are just our measure of how the waves are behaving in a specific location. It's good to quantify that but the truth for getting snow here is all about how all the waves in the jet play off each other to determine the location of a synoptic system along the temperature boundary as it passes our longitude.  There are a ton of variables at play and each one changes exactly what we want from the others.  What combination of things will get a system to track just to our south. That's the game. There are lots of ways to get there but it's complex predicting how all the factors influence each other. 

What I liked most about your analysis today is you focused not just on the blockbuster patterns where a cloud sneezes and we get 20”.  The tricky setups where one “bad” thing is offset by timing and help from another feature was helpful to read.  

[gymengineer]

22 hours ago, psuhoffman said:

With the down period we're in I thought it was a good time to resurrect this thread and further the discussion from last year.  I realized lately that while we did a good job touching on what is a perfect pattern for snow that we didn't really discuss all the different variables that factor into the "trade off" that happens when there is a less then perfect pattern.  And those scenarios make up 90% of our snowfall events so it's not really useful to only focus on the textbook perfect HECS setups. 

So first of all its important to look into the WHY of the textbook HECS cases first for comparison.

This is the composite H5 mean of our 6 unquestioned HECS events in the last 40 years. 

 

So what makes that the "perfect" look.  The single most important feature is what sin the box there...the ridge over trough in the north atlantic centered over greenlands longitude.  The ridging over greenland is what we call the greenland block.  The trough south of it is the 50/50 low.  The ridging forces systems under it which promotes the troughing into the 50/50 locations.  The combination of flow around the Greenland high and the 50/50 low promotes cold air into the northeast US.  Also, confluence (merging of air flow) promotes high pressure.  The confluence of the flow around the 50/50 with where it meets the westerly flow of the jet coming across the CONUS promotes high pressure to our north.  This is even more pronounced with a split flow. 

Also keep in mind these features arent all or nothing.  That isn't JUST a -NAO, its a greenland block.  Not ever bit of ridging over greenland is a block.  Yes it helps but that look there is classic because its a perfect block.  The strength of that block will really slow down the flow and force systems under it.  Keep that in mind when we look at the other features on that map.  The indication of an STJ is there with the lower heights down along the gulf coast.  That is of course desirable.  But look at the Pacific.  Without that look in the atlantic that would be crap.  I made the point about the blocking because people keep throwing around the whole Pacific v Atlantic thing and its not an all or nothing debate.  With just some nao ridging that pacific would probably blast pacific air across.  Yes there is a split flow indicated there but that trough location off the west coast isn't gonna cut it without the atlantic blocking.  So yea if we only have some nao help having a crap pacific will ruin it.  But if its one of those rare cases with off the charts 3std blocking then you actually WANT the crap pacific. 

 

The Greenland block is so strong in the other five events that PDII's decidedly different look didn't even water it down in your composite map. I think 02/03 is a fun season to look at because even less than 'lock and loaded' DC looks-- including you pointing out how the 12/02 and the early 2/03 moderate events happened- yielded an extreme seasonal total.