Dandridge Dollop 12/24/20 Storm Thread (Winter Wonderland)

[snowbird1230]

Does this keep adjusting south  and west all night?

[bluegrassweather71]

Suddenly I feel the KY plateau area (London, Corbin) is back in play 

[Carvers Gap]

WRF-ARW now has this... had been all over the place.  Good model and we needed it on board in some fashion or another.  You know, I am not sure this is really trending west as much as the lee side low is backing the flow of the storm.  That is causing the flow to back just enough that the cold catches the precip and then orographic lift does its thing as well.

[snowbird1230]

Fwiw Asheville NC local news WLOS  just doubled their snow totals since 6 o'clock news 

[John1122]

1 minute ago, Carvers Gap said:

WRF-ARW now has this... had been all over the place.  Good model and we needed it on board in some fashion or another.  You know, I am not sure this is really trending west as much as the lee side low is backing the flow of the storm.  That is causing the flow to back just enough that the cold catches the precip and then orographic lift does its thing as well.

You're likely correct. In this case I'm mainly referring to the precip shield. Modeling notoriously under estimates the N and W side of precip fields.  

[Blue Ridge]

A note for all trying to predict MRX’s next move:

The overnight AFD and update package usually hits around 0300. As with the afternoon suite, this is sometimes delayed during active weather. Highly unlikely we see any alteration to the warning/advisory package until then.

[Jed33]

Add the WRF-NMM. Looks a lot like the 3k NAM. Think the hi-res models may be on to something.

[Stovepipe]

It's times like these that I like to pour a scotch, settle in by the fire, and curl up to a late night Euro run.

[Carvers Gap]

The models and digital stuff that I take to with me from this point onward are these:  a couple of more runs of the Euro, the RGEM, the ARW, and radar returns.  I just keep it simple with those four.  All we can do at this point is monitor trends.  Most good storms have an uptick in good trends right up to the event as models don't seem to ever catch-up to good storms.  No idea if that happens with this.  Depending on a lee side low is tricky business, but most modeling has it and climatology support that on a strong front like this per MRX. 

[Carvers Gap]

3 minutes ago, John1122 said:

You're likely correct. In this case I'm mainly referring to the precip shield. Modeling notoriously under estimates the N and W side of precip fields.  

LOL, just now saw your comment.  Snowbird's comment was the one that got me to thinking, and I was referring to that.  And yes, very much agree with you and snowbird.  I was just thinking it is not so much an adjustment in track as it is in flow backing...and your comment is spot on as well.  When a slp forms, modeling has trouble with the NW quadrant.  Will be a triumph in modeling if globals and mesoscale models successfully depict a finesse situation like a lee side low.  Modeling has come a long way.

[Carvers Gap]

That little lee side low might be a bit stronger as well, and is being better depicted as we get closer.

[Carvers Gap]

7 minutes ago, Stovepipe said:

It's times like these that I like to pour a scotch, settle in by the fire, and curl up to a late night Euro run.

Just drank some Mayfield's eggnog.  Man, the wind is howling here.  

[snowbird1230]

I don't think we are done here..with the trends, we may play catch up right up until go time.

[TellicoWx]

Something to remember also about the GFS, it has a big convective feedback bias...could affect it's modeling of the precip shield

[PowellVolz]

Something to remember also about the GFS, it has a big convective feedback bias...could affect it's modeling of the precip shield

Isn’t it usually to progressive also?


.

[Carvers Gap]

0z CMC looks like it is going to hold serve again.

[TellicoWx]

Just now, PowellVolz said:

Isn’t it usually to progressive also?


.

If you loop all the 0z models at the same time frame, the LP placement is very close amongst all them...it's progressive bias is at longer range.

[Stovepipe]

1 minute ago, Carvers Gap said:

0z CMC looks like it is going to hold serve again.

[John1122]

Christmas morning at 7. Still bands of snow in the valley region at this point. 

[TellicoWx]

Don't let @McMinnWx see the CMC lol jk

[Carvers Gap]

...And when I say "holds serve," I generally mean the storm is still there, trends haven't completely altered the idea of where the storm was depicted during previous runs, the synoptic set-up is still pretty much the same,  and accumulations are generally where they were placed during the previous runs.  Looks like the CMC might have indeed shaved some off the southwest edge near south/middle TN.  Overall, the look is pretty similar on the 0z CMC.

[BlunderStorm]

3 minutes ago, John1122 said:

Christmas morning at 7. Still bands of snow in the valley region at this point. 

 

[John1122]

03z 39 hour RAP.

[VOLtage]

If the current trends hold, MRX may have to extend the WSW's farther west to include the Valley.

[MattPetrulli]

Ill take my 2-4" of snow but I'm more interested in the convective bands depicted by 3k NAM and HRRR 

[Carvers Gap]

FWIW, the 0z GEFS ensemble mean is a pretty decent improvement from 18z.

[BlunderStorm]

4 minutes ago, Carvers Gap said:

FWIW, the 0z GEFS ensemble mean is a pretty decent improvement from 18z.

Yep. Not sure what it's ensemble members are smoking in the deep south though...

[Carvers Gap]

10:45 MRX Updtate...

.DISCUSSION...
Showers have increased dramatically across middle Tennessee ahead
of mid level trough as intense low pressure area over the western
Great Lakes moves into southern Canada and the associated cold
front is now moving into west Tennessee late this evening. A line
of showers and thunderstorms was moving through west Tennessee at
this time.

Strong south to southeast winds from the pressure gradient from
higher pressure over western North Carolina to the lower pressure
west of the eastern mountains was producing wind gusts already
above 60 mph and winds to around 35 to 40 mph have occurred in
isolated spots in the valley. Have sped up timing of the higher
pops slightly with update from southwest to northeast and bumped
lows up a degree or two over southern and central valley.
Temperatures are being held up in many places by the winds and
lows may have already occurred over the northeast half of the
area...or will occur around sunrise when cold front moves through
western sections of the forecast area. Updated forecast sent. Will
update WSW and SPS products shortly.

[TellicoWx]

1/2" Hail report as line went thru Selmer, TN

[ShawnEastTN]

10:45 MRX Updtate...

.DISCUSSION...Showers have increased dramatically across middle Tennessee aheadof mid level trough as intense low pressure area over the westernGreat Lakes moves into southern Canada and the associated coldfront is now moving into west Tennessee late this evening. A lineof showers and thunderstorms was moving through west Tennessee atthis time.Strong south to southeast winds from the pressure gradient fromhigher pressure over western North Carolina to the lower pressurewest of the eastern mountains was producing wind gusts alreadyabove 60 mph and winds to around 35 to 40 mph have occurred inisolated spots in the valley. Have sped up timing of the higherpops slightly with update from southwest to northeast and bumpedlows up a degree or two over southern and central valley.Temperatures are being held up in many places by the winds andlows may have already occurred over the northeast half of thearea...or will occur around sunrise when cold front moves throughwestern sections of the forecast area. Updated forecast sent. Willupdate WSW and SPS products shortly.

Hmm... "Will update WSW and SPS products shortly"

Sent from my SM-G965U using Tapatalk