February/March 2021 - Frigid or Flop? Pattern/Longterm Forecast Thread.

[Stovepipe]

1 minute ago, Dsty2001 said:

If that verified the state of Tennessee would be shut down for a week

Knox County would still have virtual school.  For the 10 kids that would still have power.

[VOLtage]

6 minutes ago, Carvers Gap said:

I like my map better.  240 with Kuchera...

Would 1993 be a similar analogue? Assuming that materializes

[Carvers Gap]

3 minutes ago, VOLtage said:

Would 1993 be a similar analogue? Assuming that materializes

Probably 95-96 is closer or maybe an old school overrunning event.  93 was a monster.  That map is the result of two big storms which follow one right after the other.  Spacing is perfect and the cold air boundary is prime.  Assuming the GFS is maybe to quick with its deeper cold, I think a big winter storm is certainly possible over the sub-forum.  

[Carvers Gap]

We just want the cold front to stall south of the forum area for just long enough so that an active southern jet attacks it.  

[Matthew70]

I will cash in just for a 1/4 of those totals.  Been long time since been sledding with kiddos.

[Carvers Gap]

What is wild is that that the 12z GEFS certainly supports something like two snow storms - maybe not that crazy looking, but two decent snows back-to-back.  Cold air intrusions this winter have generally supported snowfall each time they have happened.  We haven't really had an extended shot of cold like is being portrayed.  So, going to be a fun test.

[Carvers Gap]

And to be clear, I would shocked if that map verified...that is just for fun.  However, I do think tracking a significant event or two is not out of the question.  The GFS, CMC, and Euro have been throwing haymakers.  The pattern (IF THE COLD BOUNDARY HOLDS JUST TO OUR SOUTH AND HOLDS WITHOUT GOING TO CUBA), is a great set-up if we can time precip.  We have been tracking this trough amplification since Jan 19th - all the way back in the other thread. Pretty cool.

[PowellVolz]

The cut off on that snow line is not in a great place for us in lower elevations. Would rather see it several 100 miles south of where it is.


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[Shocker0]

37 minutes ago, Holston_River_Rambler said:

yeah. here's the full run. 

 

 

 

Times like this i wish it was like Deal or No Deal where you smash the button to lock in the payout

[PowellVolz]

Times like this i wish it was like Deal or No Deal where you smash the button to lock in the payout

I don’t want any part of that.


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[jaxjagman]

OK,who let the DGEX hijack the Euro?

 

CMWF Deterministic FORECAST FOR: BNA    LAT=  36.12 LON=  -86.68 ELE=   591

                                            12Z FEB01
                 2 M     850    1000    FZING    SFC     SFC    6 HR    SNCVR
                 TMP     TMP     850     HGT     WIND    PCP     QPF     LIQ 
                 (C)     (C)     THK    (FT)    (KTS)   TYPES   (IN)    (IN) 
MON 12Z 01-FEB   0.9    -8.0     128     261    31010                           
MON 18Z 01-FEB   2.4    -8.4     128     625    33012                           
TUE 00Z 02-FEB   1.6    -8.8     128     810    33009           0.00            
TUE 06Z 02-FEB  -1.6    -6.8     127       0    33009           0.00            
TUE 12Z 02-FEB  -3.5    -4.7     127       0    34008           0.00            
TUE 18Z 02-FEB   2.4    -5.2     128     325    32008           0.00            
WED 00Z 03-FEB   0.7    -5.0     128     669    34007           0.00            
WED 06Z 03-FEB  -2.7    -3.0     128       0    34005           0.00            
WED 12Z 03-FEB  -4.6    -1.4     128       0    34004           0.00            
WED 18Z 03-FEB   3.7    -1.7     129    7856    35002           0.00            
THU 00Z 04-FEB   1.9     1.0     131    4973    26000           0.00            
THU 06Z 04-FEB  -2.4     4.8     131    8214    16004           0.00            
THU 12Z 04-FEB  -0.6     4.7     132    8145    16006           0.00            
THU 18Z 04-FEB   9.2     6.5     133    9402    17010           0.00            
FRI 00Z 05-FEB  10.6     4.8     134   10006    19013           0.00            
FRI 06Z 05-FEB  10.4     5.9     134    7580    25009           0.24            
FRI 12Z 05-FEB   1.4     1.5     130    5250    32005           0.07            
FRI 18Z 05-FEB   3.7    -2.0     130    2380    32003           0.00            
SAT 00Z 06-FEB   2.6    -2.8     131    2130    16001           0.00            
SAT 06Z 06-FEB  -1.7    -3.4     130    1986    16001           0.00            
SAT 12Z 06-FEB  -2.6    -2.3     130    1581    10005           0.00            
SAT 18Z 06-FEB   6.9    -1.3     131    3278    08006           0.00            
SUN 00Z 07-FEB   3.7    -0.6     131    3348    05006           0.00            
SUN 06Z 07-FEB   1.8    -3.0     130    1989    36003           0.01            
SUN 12Z 07-FEB  -2.3    -6.8     127       1    31012           0.09            
SUN 18Z 07-FEB  -7.7   -19.9     123       0    29015           0.03            
MON 00Z 08-FEB  -9.7   -21.4     123       0    30012           0.00            
MON 06Z 08-FEB -12.2   -23.1     121       0    31010           0.00            
MON 12Z 08-FEB -13.6   -19.5     121       0    33006           0.00            
MON 18Z 08-FEB  -5.8   -12.1     124       0    06000           0.00            
TUE 00Z 09-FEB  -4.0    -6.0     126       0    08003           0.00            
TUE 06Z 09-FEB  -5.0    -5.7     127       0    12004           0.02            
TUE 12Z 09-FEB  -6.1    -4.8     127       0    10003           0.23            
TUE 18Z 09-FEB  -3.7    -4.6     128       0    07004           0.51            
WED 00Z 10-FEB  -2.3    -4.9     128       0    08005           0.45            
WED 06Z 10-FEB  -3.2    -2.0     128       0    01007           0.18            
WED 12Z 10-FEB  -7.0    -7.0     126       0    34008           0.20            
WED 18Z 10-FEB  -5.0    -7.2     126       0    33006           0.00            
THU 00Z 11-FEB  -6.4    -8.0     126       0    33005           0.00            
THU 06Z 11-FEB -11.0    -4.2     127       0    01004           0.00            
THU 12Z 11-FEB -14.3    -1.9     127       0    05005           0.00            

[Stovepipe]

Could someone with weatherbell post an ensemble chart or two when they are ready?  Would very much appreciate it, thanks.

[1234snow]

12z UKMET at hour 144 (end of run) looks similar to the Euro at 500mb.

[Shocker0]

8 minutes ago, PowellVolz said:

I don’t want any part of that.


.

Well I mean I would wait to lock in until tomorrow or so to lock in when these totals have been cut in half lol. Power outtages suck.

[jaxjagman]

[jaxjagman]

1 minute ago, Blue Moon said:

These models need to stop smoking crack. It's wafting over here and making all of us high.

 

[Holston_River_Rambler]

@Stovepipe

Here are what I have so far for the EPS (hrs 60 - 240)

500 mb 

 

850 temp:

 

MSLP:

 

24hr precip:

 

snowfall mean:

 

 

city charts should be out in a bout an hour in weathermodels 

 

individual members for the SE section:

 

 

 

 

 

 

 

[PowellVolz]

[mention=1307]Stovepipe[/mention]
Here are what I have so far for the EPS (hrs 60 - 240)
500 mb 

 
850 temp:

 
MSLP:

 
24hr precip:

 
snowfall mean:

 
 
city charts should be out in a bout an hour in weathermodels 
 
individual members for the SE section:

 
 

 
 
 
 
 

Looks like most of those individual members have something. That’s a great sign.


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[John1122]

The pattern looks great, and we see what happens when we are having precipitation events every few days and a -NAO/-AO and a big EPO ridge in Alaska. 

[Holston_River_Rambler]

Here are some individual city charts:

https://imgur.com/a/gD6QByv

 

I put several in there and it would take up too much screen on here, so you'll have to click and look for the closest one for you. 

[Holston_River_Rambler]

We gotta balance out that 12z suite. Here is the new 12z UKMET (out to 168 hours now) with a cutter:

 

 

[BullCityWx]

44 minutes ago, Holston_River_Rambler said:

We gotta balance out that 12z suite. Here is the new 12z UKMET (out to 168 hours now) with a cutter:

 

 

Pretty wild cold at that last frame though. It has Nashville at 1 above and Birmingham at 13.

[John1122]

1 hour ago, Holston_River_Rambler said:

We gotta balance out that 12z suite. Here is the new 12z UKMET (out to 168 hours now) with a cutter:

 

 

I don't know if it's right or wrong but it's just been bad in general this year. 

[Wintersnow888]

NWS Nashville has interesting discussion for next week. I'm kinda new to this and I don't know how to copy the discussion under my forecast and bring it here. But for the first time they are saying a possibility of a heavy snow event for next week. I will try again to import it.

[Wintersnow888]

Well I downloaded the page but I can't figure out how to do it haha. Any suggestions? Anyway if you want to read it , just click anywhere up here in Cumberland county and you should be able to get it.....

[John1122]

Just now, Wintersnow888 said:

Well I downloaded the page but I can't figure out how to do it haha. Any suggestions? Anyway if you want to read it , just click anywhere up here in Cumberland county and you should be able to get it.....

You should be able to copy and paste it. 

[PowellVolz]

Well I downloaded the page but I can't figure out how to do it haha. Any suggestions? Anyway if you want to read it , just click anywhere up here in Cumberland county and you should be able to get it.....

Just copy it off their page and paste it here.


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[Wurbus]

I believe below is what Winterstorm is referring to.

Area Forecast Discussion
National Weather Service Nashville TN
539 PM CST Mon Feb 1 2021

.UPDATE...
FOR 00Z AVIATION DISCUSSION.

&&

.DISCUSSION...

Snow has decreased in coverage this afternoon, but another lobe of
the upper trough looks to dive southward later this afternoon and
evening, giving the Plateau a shot at additional snow
accumulation. Consensus shows the highest elevations between 1 to
2 inches, and around a half inch to an inch elsewhere in the
winter weather advisory area. Extended the advisory through
midnight, but snow may continue into the early morning hours
Tuesday. Rest of the I-65 corridor up to the Plateau could see
some flurries, so another dusting is not out of the question.

Tuesday and Wednesday look to be dry as the upper trough slowly
moves eastward. By Thursday, a Midwest trough will bring a cold
front through the Plains and towards the mid state. Chances for
rain will ramp up later in the day Thursday and especially
Thursday night. Temps look warm enough right now that most of the
precip will be rain, with a slight chance for some snow to mix in
the northwest Friday morning. Models are quick to dry things out
behind the cold front during the day Friday, so started backing
off pops during the day Friday and Friday night. The next trough
for Saturday late in the day and Saturday night may bring a shot
at some light rain and snow, along with additional CAA behind the
previous cold front. Models have been consistent showing this
colder air for a few runs now, and show 850 mb temps around -24C
Sunday evening. This would give us lows in the teens Monday
morning, and highs during the day Sunday only in the 20s.

The next big trough may be Tuesday/Wednesday of next week, and
models are surprisingly consistent this far out with upper level
features and even the surface low. With cold air already in
place, a trough develops in the southern Plains and tracks
eastward. This trough would bring Gulf moisture northward, with a
nice overrunning/isentropic lift snow event if model solutions pan
out. Right now models place the warm front right through the mid
state, so it could even be snow north of I-40, rain in northern
AL, and a mix in between. Still a lot that can change between now
and then, including abandoning the trough entirely, so dont count
on heavy snow just yet. But with the potential cold late this
weekend, and a potential heavy snow setup next week, winter isnt
releasing its grip anytime soon!

[Holston_River_Rambler]

New GFS (version 16, supposedly operational at some point this month) has two storms as well. It suppresses the Euro's second one, but has another overrunning event right afterwards. 

[Wurbus]

And for good measure, below is MRX's discussion tonight.

AREA FORECAST DISCUSSION
National Weather Service Morristown TN
619 PM EST Mon Feb 1 2021

.UPDATE...
FOR 00Z AVIATION.

&&
.DISCUSSION...
Quick update to Beef PoPs up a bit mainly north in portions of
the winter weather advisory area given the latest trends and high
resolution model output. Otherwise, previous forecast still looks
to be on track.

&&
.AVIATION...
00Z TAF DISCUSSION.

Will see snow showers and flurries at times especially TRI and TYS
tonight, but these will decrease and end from southwest to
northeast later tonight/Tuesday. MVFR conditions for the most
part tonight although lower conditions to IFR (or even lower)
will certainly be possible in heavier snow showers especially TRI.
Clouds will break up with VFR conditions arriving first at CHA by
early Monday and then TYS and eventually TRI during the day.
Winds will generally be from the northwest and west 8-12kts with a
few higher gusts.

&&

.PREV DISCUSSION...
/ISSUED 336 PM EST Mon Feb 1 2021/
SHORT TERM...(Tonight through Tuesday)...
An upper low continues to slide east across the central
Appalachians at this time fostering deepening cyclogenesis along
the eastern seaboard. Closer to home across East TN and southwest
VA/NC, deep nwly flow packing plenty of moisture (thanks to the
GLC) continues to spill into the region. With that, scattered to
numerous snow showers will become increasingly focused on the high
terrain of the Cumberland Plateau and the southern Appalchians,
with the most efficient snowfall favored across East TN and
southwest VA given enhanced orographic lifting. This overall
synoptic pattern will persist through the overnight into/through
Tuesday morning before deeper moisture advection wains leading to
a slow decline in precipitation production along the terrain, at
least through Tuesday afternoon. This will favor lowering pops
amidst continued mostly cloudy skies through Tuesday morning with
some scattering of clouds later in the period. Low temperatures
tonight will fall into the 20s for all locales outside of the high
terrain where values in the teens are favored. High temperatures
on Tuesday will peak a few degrees higher than today given
marginally improved insolation and less evaporative/dynamic
cooling as precipitation coverage decreases in the valley. Details
on snow totals and any other hazards below.

For the plateau, expecting the current lull in activity to end later
this evening as another piece of vort energy advects southeast
across the region. Therefore will expand the current Winter Weather
Advisory across the Plateau through 1AM ET.  Snowfall will likely
persist beyond this timeframe, but the most significant
accumulations should end. Looking at the valley, along/north of I40
cannot rule out an occasional snow shower drifting downstream from
the northern Plateau and the Black Mountains of KY.  This could
result in some light accumulations (an inch or less) with Black Ice
being an additional concern given temperatures in the 20s amidst wet
roadways.  Further north along the I81 corridor into southwest VA,
accumulations will be slightly higher with a couple inches possible,
highest for elevations above 2500ft such as High Knob VA where snow
totals could exceed 4 inches or so. As stated above, the heaviest
accumulations still look to reside along the East TN mountains where
upslope flow will be greatest. Totals for the mountains remain in
the 4-6 inch range for elevations around 3kft, with totals
increasing sharply to 8-12 inches above 4kft, possibly as high as 14-
16 inches above 5kft.

Lastly, would like to stress that totals across the Plateau and
especially in the valley are event totals which are impacted by
melting through the event given warm ground temperatures.  Thus
these totals may not reflect accumulations at any given time.

LONG TERM...(Tuesday Night through Monday)...

Key Points:

1. Mostly dry and seasonally cold to start the period with
moderation to near normal temperatures on Thursday.

2. Precipitation chances return Thursday night into Friday with some
changeover to snow possible Friday night.

3. Low confidence for potential snowfall Saturday into Sunday.

4. Very cold temperatures arrive Sunday into Monday with wind chills
below 0 in the higher elevations Sunday night.

Tuesday Night through Friday

At the start of the period, the system currently impacting the area
will be centered along the New England coast. This comes with
mid/upper ridging west of the Mississippi River and 1,025mb surface
high pressure centered over the upper Mississippi River Valley. This
setup provides a continuation of northerly/northwest flow with deep
moisture having progressed off to the east. Nevertheless,
indications of low-level moisture below 850mb will keep low-end
chances for lingering flurries and light snow showers in the
mountains. Otherwise, the main weather factor will be cold
temperatures, combined with persistent winds due to a notable
MSLP/low-level height gradient. While radiational cooling will be
limited, synoptically-driven CAA and subsidence will allow for
temperatures to drop well-below freezing and into the teens in the
higher elevations. Wind chills near 0 are possible in the TN
mountains with values in the teens likely elsewhere. On Wednesday,
high pressure dominates with continued northerly flow keeping
temperatures relatively cool.

For Wednesday night into Thursday morning, the next system of
interest develops via cyclogenesis on the leeward side of the
central Rockies. This comes in association with a deepening
shortwave out of Saskatchewan/Manitoba and a phase lag between this
trough and the thermal (1,000mb-500mb thickness) trough. Mid/upper
ridging moves to the east and leads to height rises locally. These
height rises and increasing southerly flow ahead of the next system
provide WAA and a recovery of temperatures to near normal for
Thursday. Confidence remains lower for the timing, track, and
evolution of the surface low into Thursday night, but the overall
consensus is for a track into the Great Lakes Thursday night with
the associated cold front moving through the area on Friday morning.
The GFS is more aggressive with CAA and lingering moisture with the
CMC and ECMWF suggesting only light snow showers on the back edge.
Nevertheless, PoPs are highest into Friday morning with continued
uncertainty for the rate of changeover to snow on Friday.

Saturday through Monday

For the end of the period, confidence in another chance for snow
remains low with decently high confidence for very cold temperatures
by the end of the period. All deterministic and ensemble model
guidance shows deep, anomalous mid/upper troughing in the east by
Sunday with Arctic high pressure moving in from the Northern Tier.
The GFS and CMC deterministic both suggest chances for light snow
Saturday into Sunday morning from upper-level jet divergence with
the ECMWF suggesting a surface low to develop in the Gulf and track
to our south. The ECMWF solution is the outlier, however, as
ensembles all point towards only light snowfall potential outside of
northwest flow in the mountains. Nevertheless, ensemble solutions
point towards 500mb height anomalies of -20 dam or lower with
deterministic guidance showing anomalies near record-breaking levels
of -40 dam or lower. For 850mb temperatures, values to -10 to -20
degrees Celsius continue to look likely across the area within all
ensemble and deterministic guidance. At any rate, well-below normal
to potentially record-breaking temperatures are expected with higher
chances for the latter if a snowpack develops prior to the arrival
of the Arctic high. Based on the consensus of low-level temperatures
and MSLP gradients ahead of the Arctic high, wind chills below zero
are likely in the mountains with single-digits a possibility area-
wide into Monday morning. Also, multiple days of subfreezing
temperatures are likely in many parts of the area. Due to continued
uncertainty for snowfall and ongoing weather, HWO wording will be
left out again with addition possibly needed on later shifts.