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Holston_River_Rambler

NAM vs the Euro cage match storm, Feb 20 - 21

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You're not missing anything, as far as I can tell. That's why I said it looks more like wet snow, than what the NAM was depicting as rain. 

Actually what I missed was not looking to see where we went -0c and it looks to be no higher/lower than 850mb. You’re right, definitely wet snow.

 

 

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With the last system, this area got lucky with accumulations because we spent several hours below freezing before precip started. This will not be the case for this system. I predict a RN/SN mix with no accumulation for the valley south of 40, light accumulations in the grassy areas above 1500'. 

Knoxville was 25ish that morning and it didn’t stick to the main roads. Bridges and off/on ramps became pretty bad but that was with only around an inch of snow. That being said, it’s never crossed my mind even at 2-3” that this snow would stick to the roads. Maybe the shaded areas.


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Now that I'm briefing people at work, time to get serious. Unfortunately I'm afraid @dwagner88 is correct on the previous page regarding warmer surface temps compared to Saturday Surprise 8 Feb. 

My concern is actually just the opposite of MRX. They go cold enough to start as snow, changing to rain. I'm thinking, stays warmer overnight than forecast due to increasing clouds. Building HP might help; but, I don't know. We're talking about the southeast the Tennessee Valley in southeast Tenn, lol!

Enough precipitation starting as virga and evaporative cooling could actually bring down temps after it starts. One would hope for that inverted trough to back winds closer to north. Again the trough is not shown in isobars, just a hint in surface wind fields. It's not the 2014 or 2015 storms.

Finally while the track, thickness lines and even progged radar have similarities to Surprise Saturday, the system is quite different. Saturday was a tight feisty little thing. This is a lumbering wave. True it's just right (greater than post-frontal junk, less than WAA beast) it's still a lot different.

I'm sorry my optimism is fading. Head is going with MRX. OHX also concerned about temps. Heart is of course going with bullish GFS runs! Oh, and the 12Z NAM, hello.

Cage Match thread title is just epic! Probably the best in our sub-forum all-time. So I have to add this meme. When snow misses Jayhawks, we go all WWE!

KU_Chair.jpg.fa91d2d3ad5a028c0c382320ff1f2a1d.jpg

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The NAM is definitely determined.  The weak gulf low is a classic moisture pump that normally avoids a raging warm nose. A big H in Iowa with a weak surface reflection near the gulf is snow event 101 here. The million dollar question as always, is the NAM correct?

namconus_ref_frzn_seus_27.png

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Now that I'm briefing people at work, time to get serious. Unfortunately I'm afraid [mention=1313]dwagner88[/mention] is correct on the previous page regarding warmer surface temps compared to Saturday Surprise 8 Feb.  My concern is actually just the opposite of MRX. They go cold enough to start as snow, changing to rain. I'm thinking, stays warmer overnight than forecast due to increasing clouds. Building HP might help; but, I don't know. We're talking about the southeast the Tennessee Valley in southeast Tenn, lol!

Enough precipitation starting as virga and evaporative cooling could actually bring down temps after it starts. One would hope for that inverted trough to back winds closer to north. Again the trough is not shown in isobars, just a hint in surface wind fields. It's not the 2014 or 2015 storms.

Finally while the track, thickness lines and even progged radar have similarities to Surprise Saturday, the system is quite different. Saturday was a tight feisty little thing. This is a lumbering wave. True it's just right (greater than post-frontal junk, less than WAA beast) it's still a lot different.

I'm sorry my optimism is fading. Head is going with MRX. OHX also concerned about temps. Heart is of course going with bullish GFS runs! Oh, and the 12Z NAM, hello.

Cage Match thread title is just epic! Probably the best in our sub-forum all-time. So I have to add this meme. When snow misses Jayhawks, we go all WWE!

KU_Chair.jpg.fa91d2d3ad5a028c0c382320ff1f2a1d.jpg

 

 

The GFS is showing rain at this point but this looks like snow. Also it looks like the winds are N/NE down to the surface. Am I reading this right? 0c is down to 950. Isn’t that low enough?

 

490d59d42d51c491e0c49f2391a45fd5.jpg&key=fd8df4418b508b76025e28100e6f8488f93b011165a8ffc18f12eb11fe829409

 

 

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42 minutes ago, John1122 said:

The NAM is definitely determined.  The weak gulf low is a classic moisture pump that normally avoids a raging warm nose. A big H in Iowa with a weak surface reflection near the gulf is snow event 101 here. The million dollar question as always, is the NAM correct?

 

Always a concern as to whether it's right or not, but we are in a time period where we are no longer talking about the NAM at LR.  At the same time, other modeling has moved steadily toward what the NAM has had all along.  It's probably overdone on amounts, but then again............when is it not?

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Always a concern as to whether it's right or not, but we are in a time period where we are no longer talking about the NAM at LR.  At the same time, other modeling has moved steadily toward what the NAM has had all along.  It's probably overdone on amounts, but then again............when is it not?


3k NAM is really close to the GFS. One says snow, one says rain.

f418f75814ce76c5aeef5a62ae42e51f.jpg


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Just now, PowellVolz said:

3k NAM is really close to the GFS. One says snow, one says rain.
 

It looks more marginal than the last system for areas south of 40.  North of 40 it seems to be a better profile, but more concerns about amount of precip.  As with almost all SE snow possibilities, there are factors for us all to overcome... lol

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It looks more marginal than the last system for areas south of 40.  North of 40 it seems to be a better profile, but more concerns about amount of precip.  As with almost all SE snow possibilities, there are factors for us all to overcome... lol


Nothing close to a slam dunk and I’m sure that’s why MRX is going safe.


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The biggest plus for the NAM regarding precip type is two fold, moisture arrives earlier and its heavier. The GFS is much warmer because it only has light precip. 

Early arriving moisture is usually a hallmark of overrunning events. 

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1 hour ago, nrgjeff said:

Now that I'm briefing people at work, time to get serious. Unfortunately I'm afraid @dwagner88 is correct on the previous page regarding warmer surface temps compared to Saturday Surprise 8 Feb. 

My concern is actually just the opposite of MRX. They go cold enough to start as snow, changing to rain. I'm thinking, stays warmer overnight than forecast due to increasing clouds. Building HP might help; but, I don't know. We're talking about the southeast the Tennessee Valley in southeast Tenn, lol!

Enough precipitation starting as virga and evaporative cooling could actually bring down temps after it starts. One would hope for that inverted trough to back winds closer to north. Again the trough is not shown in isobars, just a hint in surface wind fields. It's not the 2014 or 2015 storms.

Finally while the track, thickness lines and even progged radar have similarities to Surprise Saturday, the system is quite different. Saturday was a tight feisty little thing. This is a lumbering wave. True it's just right (greater than post-frontal junk, less than WAA beast) it's still a lot different.

I'm sorry my optimism is fading. Head is going with MRX. OHX also concerned about temps. Heart is of course going with bullish GFS runs! Oh, and the 12Z NAM, hello.

Cage Match thread title is just epic! Probably the best in our sub-forum all-time. So I have to add this meme. When snow misses Jayhawks, we go all WWE!

KU_Chair.jpg.fa91d2d3ad5a028c0c382320ff1f2a1d.jpg

@Holston_River_Rambler has shown himself to be a master thread namer. 

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39 minutes ago, John1122 said:

The RGEM still wasn't much but it was quite a bit more North and West with precip. 

This is true.  Great little short range model.  Still not a big hit, but I though about a 100-125 mile jog to the Northwest.

 

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Time of day is a big deal at this time of year.  Agree with those mentioning that.  I also agree with John about true overrunning events arriving early.  These types of systems are just pain in the butt to forecast though.  Late winter/early spring storms usually have a card or two up their sleeves.  For future reference, it has come north quite a bit to where it almost where it was originally forecast.  So, need to file that away from any potential future windows.  LR modeling after this event is not exactly benign.  So, we probably need to learn as much as we can from this one as there may be more like it.  I suspect this has the potential to  continue to track northward right up to verification with some hiccups at times.  I originally thought it would stop.  Looks like it paused and is trending north again.  That tells us that we need systems tracing south of Birmingham(at 5-6 days) to have a chance in this situation at this time of year.  

But the great thing about this thread and others, so many great contributors both new and old.  I say it all the time, that is my favorite part of these events - just seeing the growth of this forum.  This subform began with a handful of patrons.  Still plenty of room to grow, but I think this is what we envisioned when we first started kicking this around years ago.  The Tennessee Valley region IMHO is incredibly difficult to figure out because it has so many unique nuances, regions, and micro-climates.  We aren't really the Plains and we really don't have a true EC climate.  These systems leave the Rockies and roll 1,500 miles over flat land and then slam into the Plateau, the Smokies, and roll over the TN river twice.  (not forgetting about the Ozarks, Arkansas folks...they count as well).   I say this often, our weather is impacted by the Pacific, Great Lakes, GOM, and Atlantic.  Not many places can say that.  Things can and do get wild.  Anyway, again just glad to see all of the interaction.

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MRX starting to change their stance on this. Even saying they believe the temp profiles on the mods are to high.


“Went ahead and issued a Winter Weather Advisory for the mountains
where confidence in increasing for some impactful snow
accumulations on Thursday. Across mountain areas where
temperatures will be below freezing, total accumulations are
expected to be between 2 to 4 inches with locally higher amounts
above 4000 feet.

For lower elevations of the valley and plateau, confidence is
still significantly lower. Anticipate temperatures to be lower
than much of current guidance suggests with strong dynamic lift
within the right-entrance region of a strong upper jet. Saturation
is present through the DGZ, and the thermal profile should
support snow for much of the area, including valley locations.
However, with much of the snow forecast to occur during the middle
of the day, and the increased sun angle in late February, expect
it will be difficult to accumulate much of the snow. For this
reason, current forecast shows that most accumulations outside of
the mountains will be light and limited to mainly grassy
surfaces. Most snow will likely melt on contact. Do not expect
many impacts to travel across lower elevations with the exception
of reduced visibility and potential slick spots if snow rates are
heavier than anticipated for a short period of time”


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54 minutes ago, Holston_River_Rambler said:

@Carvers Gap

 

SENIOR DUTY METEOROLOGIST NWS ADMINISTRATIVE MESSAGE
NWS NCEP CENTRAL OPERATIONS COLLEGE PARK MD
1620Z WED FEB 19 2020

NCO is working to recover a WCOSS dissemination issue causing
current model data to be delayed.


Liddick/SDM/NCO/NCEP

Sounds like their supercomputer lost its ability to speak to everyone else for a bit.  LOL. Welp...

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Just now, PowellVolz said:


MRX’s region is what I was getting at. Where most of us live. I was being silly.


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LOL.  I understand it now...I was like, what airport code is CWA?  Figured it was a joke, just didn't get the acronym.  As an airport code, it is still funny.  Our system is basically going to go to central Wisconsin...

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