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

John1122

By John1122,
in Tennessee Valley

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AMZ8990
AMZ8990

I’m still in Des Moines guys so I figured I would share a pic with y’all.  Light snow most of the day today.  Wind chill tonight is supposed to be around -30!!!  Next 5-7 days are going be brutally co

Math/Met
Math/Met

Carver,  Just wanted to say that you do a great job with these pattern discussions. It always makes for a good read.

Stovepipe
Stovepipe

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TellicoWx

TellicoWx

Posted
Posted
24 minutes ago, Carvers Gap said:

The 12z GEFS mean and GEPS means are bonkers.  The GEPS has 2"+ mean for all of TN and into norther MS and AL. GEFS isn't far from that.  EPS is roiling now.  Let's see if we can hold onto that signal.  Could be a blip, but wow...what a blip if so.

GEFS #19 may have skewed the mean slightly lol

20210131_143207.jpg

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Carvers Gap

Carvers Gap

Posted
Posted
25 minutes ago, Dsty2001 said:

lol just seen on accuweather where they were reporting above normal temperatures for February

Could easily happen.  These patterns with huge temp swings tend to cause huge fluctuations.    Seems like this winter all we need is a 3-4 day cold shot to be in business.   Looks like a strong amplification this weekend, and maybe another mid-month.  If that pans out, we may all be ready for spring.  LOL!

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nrgjeff

nrgjeff

Posted
Posted

Next couple snow chances are covered well above and previous page. I refer to Monday/Tuesday and again sometime late next weekend or early next week, favored areas only - not here in southeast Tenn. In between Thu/Fri looks mostly rain. I'll post about Mon/Tue Feb. 1-2 in its Obs thread shortly.

Figured I'd add some good news on the teleconnection and MJO front for the 10-20 day. First the MJO convection is actually making a move toward the dateline. Couple days ago there was chatter the convection might not follow the Kelvin Wave, which would be such a slap in the face. Still not guaranteed this moderate La Nina; however, it's looking better on satellite. Convection is also north of the equator which is more encouraging than just south (where it can whiff). So fingers crossed on friendly MJO progression. 

Global wind is also elevated, which is opposite the typical La Nina signal. Helps a little with the convection evolution. Also +global wind in February is cold around here (one of the few winter months it's not mild). Might be why the SER forecast thankfully struggles in the 11-15 day. Global background state is more friendly for snow here.

Now we need a region wide system. Can we be clutch or do we choke? I'm hoping February clutch time baby!

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tnweathernut

tnweathernut

Posted
Posted
6 minutes ago, TellicoWx said:

Considering it's coming from MRX, 


The CMC, ECMWF, and some
ensemble members suggest surface low pressure development in the
Gulf and progression to our south and east Saturday into Sunday. If
this occurs, the potential exists for widespread, and potentially
impactful, snowfall accumulation across the area.

Interesting.  That's really bold from a traditionally conservative entity.  Makes me think they are confident of really cold air coming and also confident the storm track stays through the southeast.

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jaxjagman

jaxjagman

Posted
Posted 
National Weather Service Nashville TN
228 PM CST Sun Jan 31 2021

.DISCUSSION...

Model spread has continued to be large for snow events in the mid
state this year, and this event is no exception. The GFS and
Canadian are holding strong at the high end of snow amounts, while
the lower res ECMWF remains at the lower end or around the 10th
percentile. High res CAMs are right around consensus average to
just above average for this event, but enough uncertainty exists
that confidence in snowfall amounts, especially in the advisory
area, is low to medium even this close to the event.

Deep eastern trough currently digging its way south and east today
will be the driver for snow potential over the next 36 hours or
so. Cold front is working its way through the mid state currently,
with northwest winds bringing CAA over the mid state. Precip looks
to arrive more widespread later in the evening, where most of the
area will see rain to start off. On the Plateau and at higher
elevations the changeover to all snow will be after 9 pm but
before midnight, and the rest of the mid state after midnight.
Urban areas, especially the Nashville metro, may see a rain/snow
mix a little longer than other areas as slightly warmer temps may
keep all snow away for a few hours longer. The warmer surface
temps looks to also limit accumulation potential, but more on
accumulations in a bit. Snow will continue into the morning, but
move off to the east by the afternoon. The Plateau will still see
chances for accumulating snow in the afternoon and possibly even
into the evening Monday/overnight Tuesday.

Soundings and cross sections show models really focusing in on
orographic lift with this event as northwest wind orientation
lines up well with the higher elevations on the Cumberland
Plateau. Omega values peak just in front of the higher elevations,
and deep moisture is in place overnight through most of the day
Monday. But as the trough moves east, drier air aloft may limit
the heavier snow potential on the Plateau, but still enough near
surface moisture to get a little more accumulation. Current
forecast thinking has the higher elevations of the Plateau seeing
1 to 2 inches, with locally higher amounts definitely possible
especially in the areas that typically see a bit more with this
setup. Just off the Plateau to the west could see around a half
inch or so and even up to an inch, but the western 2/3 of the mid
state will likely see a dusting to a few tenths of an inch.

However, some models are really hitting that orographic lift hard,
with the deep moisture, and squeezing out every possible ounce of
moisture for snow tonight through Monday night. Highest elevations
on the Plateau show around 4 inches with those models, and if
additional moisture moves in, snow starts sooner/continues longer,
those higher amounts will be possible. On the other end, the drier
air may work its way in sooner, or the orographic lift in the
models (especially the higher-res CAMs) may be way overdone, and
the eastern 1/3 may only see a half inch for most with around an
inch or two at highest elevations. Very difficult forecast as very
little change from any variable could result in big swings in
snowfall accumulations in the east.

Another lobe of energy from the upper trough looks to swing
through late Monday/early Tuesday, and may keep the Plateau with
snow a little longer. Otherwise ridging moves in behind the trough
and keeps us dry for a few days. By Thursday, another trough will
move in from the Plains, and bring chances for precip during the
day. Models are not in complete agreement, but the GFS brings
another trough right on its heels and very cold arctic air with it
as well by Sunday morning. The ECMWF and Canadian get on board
about 12 hours later, but 850 mb temps around -22C would yield
some pretty cold lows and even daytime highs. If that forecast
pans out, lows in the single digits will not be out of the
question, but this far out things could trend upward just as
easily. So dont bank on the arctic airmass just yet!

 

 

LOOKING like a good potential we see the coldest air of the season upcoming.Both the Euro and GFS both show single digits upcoming,some spread in the longer range still tho,would be the coldest air we've seen here in quite sometimes

 

  

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

                                            12Z JAN31
                 2 M     2 M     2 M     SFC     SFC    6 HR    FROZN   TOTAL
                 MXT     MNT     TMP     DEW     WIND    QPF     PCP    CLOUD
                 (F)     (F)     (F)     (F)    (KTS)   (IN)    (IN)    (PCT)
SUN 12Z 31-JAN                  51.1    50.2    21010                     79    
SUN 18Z 31-JAN  55.1    49.8    52.1    45.9    30008                    100    
MON 00Z 01-FEB  52.1    41.2    41.1    31.2    30010   0.01    0.00     100    
MON 06Z 01-FEB  41.1    35.4    35.3    29.6    31010   0.00    0.00     100    
MON 12Z 01-FEB  35.3    33.2    33.1    28.5    32010   0.06    0.06     100    
MON 18Z 01-FEB  35.2    33.0    35.3    26.5    32012   0.02    0.02     100    
TUE 00Z 02-FEB  37.1    34.2    34.0    21.7    33009   0.00    0.00      13    
TUE 06Z 02-FEB  34.0    28.2    28.2    19.0    33010   0.00    0.00      66    
TUE 12Z 02-FEB  28.2    25.6    25.6    17.5    33008   0.00    0.00      67    
TUE 18Z 02-FEB  35.8    25.5    36.1    20.6    33008   0.00    0.00       2    
WED 00Z 03-FEB  39.6    32.9    32.7    21.4    33006   0.00    0.00       0    
WED 06Z 03-FEB  32.7    26.7    26.6    22.5    33005   0.00    0.00       0    
WED 12Z 03-FEB  26.6    24.3    24.7    22.0    36004   0.00    0.00      36    
WED 18Z 03-FEB  38.0    24.6    38.3    24.1    00001   0.00    0.00      88    
THU 00Z 04-FEB  42.8    35.5    35.2    27.5    12002   0.00    0.00      72    
THU 06Z 04-FEB  35.2    30.0    30.4    23.6    16005   0.00    0.00      96    
THU 12Z 04-FEB  35.2    30.3    35.3    24.4    16008   0.00    0.00      99    
THU 18Z 04-FEB  50.5    35.3    50.7    35.3    18012   0.00    0.00     100    
FRI 00Z 05-FEB  53.3    50.5    52.1    47.6    19013   0.02    0.00     100    
FRI 06Z 05-FEB  53.3    49.5    48.9    48.6    29013   0.50    0.00      97    
FRI 12Z 05-FEB  48.9    35.5    35.4    28.1    28008   0.05    0.00      68    
FRI 18Z 05-FEB  40.6    33.4    40.8    19.6    27009   0.00    0.00       0    
SAT 00Z 06-FEB  44.0    36.5    36.4    22.0    24005   0.00    0.00       0    
SAT 06Z 06-FEB  36.4    33.2    33.3    21.8    21006   0.00    0.00       0    
SAT 12Z 06-FEB  33.3    32.1    32.0    22.1    19006   0.00    0.00       0    
SAT 18Z 06-FEB  53.0    31.9    53.3    27.2    20007   0.00    0.00       0    
SUN 00Z 07-FEB  55.2    45.4    45.1    32.6    14004   0.00    0.00     100    
SUN 06Z 07-FEB  46.9    38.6    38.5    35.1    03007   0.03    0.00     100    
SUN 12Z 07-FEB  38.5    26.2    25.5    22.2    33014   0.37    0.20     100    
SUN 18Z 07-FEB  26.6    19.9    24.2    12.0    30011   0.06    0.06      87    
MON 00Z 08-FEB  25.2    18.9    18.7     1.4    31012   0.00    0.00      75    
MON 06Z 08-FEB  18.7    10.6    10.5    -5.9    32008   0.00    0.00       0    
MON 12Z 08-FEB  10.5     6.6     6.5    -8.3    32008   0.00    0.00       0    
MON 18Z 08-FEB  15.4     5.9    15.7    -8.2    31006   0.00    0.00       0    
TUE 00Z 09-FEB  19.4    12.7    13.7    -7.3    32005   0.00    0.00       0    
TUE 06Z 09-FEB  14.7    10.4    11.6    -7.1    02004   0.00    0.00       7    
TUE 12Z 09-FEB  12.6     9.6     9.9   -10.5    02004   0.00    0.00       2    
TUE 18Z 09-FEB  24.3     8.8    24.6    -6.9    34004   0.00    0.00       0    
WED 00Z 10-FEB  27.8    19.5    19.5    -2.5    35005   0.00    0.00      70    
WED 06Z 10-FEB  20.2    16.1    16.1    -5.9    02004   0.00    0.00      89    
WED 12Z 10-FEB  16.8    13.7    15.3    -9.2    03004   0.00    0.00     100    





 
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jaxjagman

jaxjagman

Posted
Posted

Euro is even colder in the east,with a nice 1040+ artic high nosing down into the lower OV,guess we shall see

  

ECMWF Deterministic FORECAST FOR: TYS    LAT=  35.82 LON=  -83.98 ELE=   981

                                            12Z JAN31
                 2 M     2 M     2 M     SFC     SFC    6 HR    FROZN   TOTAL
                 MXT     MNT     TMP     DEW     WIND    QPF     PCP    CLOUD
                 (F)     (F)     (F)     (F)    (KTS)   (IN)    (IN)    (PCT)
SUN 12Z 31-JAN                  38.0    35.9    14004                     98    
SUN 18Z 31-JAN  50.2    37.9    50.4    46.3    22005                     95    
MON 00Z 01-FEB  52.4    47.5    47.4    46.6    27005   0.03    0.00     100    
MON 06Z 01-FEB  47.5    36.9    36.8    34.6    28005   0.10    0.00      96    
MON 12Z 01-FEB  36.8    32.3    32.3    30.0    27004   0.04    0.03      99    
MON 18Z 01-FEB  33.9    32.0    33.6    24.5    32008   0.07    0.07     100    
TUE 00Z 02-FEB  33.7    31.0    31.0    24.2    32006   0.05    0.05      98    
TUE 06Z 02-FEB  31.0    27.2    27.2    19.9    33008   0.06    0.06     100    
TUE 12Z 02-FEB  27.3    26.5    26.7    20.5    33006   0.01    0.01      99    
TUE 18Z 02-FEB  30.3    26.5    30.5    19.3    34008   0.03    0.03      99    
WED 00Z 03-FEB  35.7    28.2    28.0    18.0    32005   0.00    0.00       0    
WED 06Z 03-FEB  28.1    19.6    20.0     9.4    01004   0.00    0.00       2    
WED 12Z 03-FEB  22.0    16.1    17.9    12.9    08002   0.00    0.00      39    
WED 18Z 03-FEB  35.0    17.4    35.3    18.0    35003   0.00    0.00       0    
THU 00Z 04-FEB  38.4    25.9    28.4    19.2    20002   0.00    0.00       0    
THU 06Z 04-FEB  30.0    22.1    23.3    18.2    10003   0.00    0.00      96    
THU 12Z 04-FEB  25.9    22.9    25.8    18.6    11003   0.00    0.00      97    
THU 18Z 04-FEB  44.0    25.8    44.2    20.1    20003   0.00    0.00     100    
FRI 00Z 05-FEB  48.0    42.5    45.5    27.6    20008   0.00    0.00      99    
FRI 06Z 05-FEB  47.1    44.0    46.4    44.0    19011   0.07    0.00     100    
FRI 12Z 05-FEB  48.9    41.5    41.1    39.8    28009   0.47    0.00     100    
FRI 18Z 05-FEB  41.4    36.2    40.3    27.6    25009   0.01    0.00      63    
SAT 00Z 06-FEB  43.6    35.1    34.7    19.2    26006   0.00    0.00       0    
SAT 06Z 06-FEB  34.8    29.1    29.2    19.8    21004   0.00    0.00       0    
SAT 12Z 06-FEB  29.3    27.7    28.0    20.4    19004   0.00    0.00       0    
SAT 18Z 06-FEB  49.3    28.0    49.5    24.8    23005   0.00    0.00       0    
SUN 00Z 07-FEB  51.7    38.7    39.5    27.4    10003   0.00    0.00       6    
SUN 06Z 07-FEB  40.6    35.5    36.9    30.7    06003   0.02    0.01     100    
SUN 12Z 07-FEB  36.9    32.7    32.6    32.4    36004   0.58    0.48     100    
SUN 18Z 07-FEB  34.8    27.6    27.3    21.2    28009   0.22    0.20      94    
MON 00Z 08-FEB  27.3    20.4    20.2    12.1    29010   0.00    0.00      89    
MON 06Z 08-FEB  20.2     7.6     7.4    -4.4    28008   0.01    0.01       9    
MON 12Z 08-FEB   7.4    -0.2    -0.4    -9.1    29006   0.00    0.00      13    
MON 18Z 08-FEB  10.4    -1.0    10.6    -5.8    30005   0.00    0.00       1    
TUE 00Z 09-FEB  14.4     6.9     8.0    -4.0    30004   0.00    0.00       0    
TUE 06Z 09-FEB  11.6     2.9     7.1    -5.8    05002   0.00    0.00       0    
TUE 12Z 09-FEB   7.8    -1.2     0.3    -9.1    08003   0.00    0.00       9    
TUE 18Z 09-FEB  17.8    -0.6    18.0    -2.3    20001   0.00    0.00      24    
WED 00Z 10-FEB  21.1    12.6    13.3     1.0    12002   0.00    0.00      10    
WED 06Z 10-FEB  15.9     5.9     7.7    -5.2    05004   0.00    0.00       5    
WED 12Z 10-FEB   9.3     5.1     5.9    -6.8    05003   0.00    0.00      45
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Daniel Boone

Daniel Boone

Posted
Posted
3 hours ago, Carvers Gap said:

Could easily happen.  These patterns with huge temp swings tend to cause huge fluctuations.    Seems like this winter all we need is a 3-4 day cold shot to be in business.   Looks like a strong amplification this weekend, and maybe another mid-month.  If that pans out, we may all be ready for spring.  LOL!

Accublunder did like CPC a few days ago and pulled the trigger on what looked like the mjo going warm phases. Accublunder also going with Nina Climo.

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jaxjagman

jaxjagman

Posted
Posted

Euro wasnt as cold that run but still colder than we seen in recent years,also  DP'S would say dry to the bone  for Mid Tn anyways

  

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

                                            00Z FEB01
                 2 M     2 M     2 M     SFC     SFC    6 HR    FROZN   TOTAL
                 MXT     MNT     TMP     DEW     WIND    QPF     PCP    CLOUD
                 (F)     (F)     (F)     (F)    (KTS)   (IN)    (IN)    (PCT)
MON 00Z 01-FEB                  40.9    32.4    30009                    100    
MON 06Z 01-FEB  40.9    34.7    34.6    27.2    31010                    100    
MON 12Z 01-FEB  34.6    33.0    33.0    28.4    32010   0.05    0.05      99    
MON 18Z 01-FEB  36.6    32.9    36.7    24.2    33012   0.01    0.01      96    
TUE 00Z 02-FEB  38.3    34.4    34.3    21.9    33009   0.00    0.00      25    
TUE 06Z 02-FEB  34.3    28.2    28.1    18.3    33010   0.00    0.00      73    
TUE 12Z 02-FEB  28.1    26.1    26.2    18.3    33008   0.00    0.00      74    
TUE 18Z 02-FEB  35.7    26.0    36.0    20.8    32008   0.00    0.00       2    
WED 00Z 03-FEB  39.0    32.5    32.4    21.8    33007   0.00    0.00       3    
WED 06Z 03-FEB  32.4    26.3    26.3    22.4    34005   0.00    0.00      10    
WED 12Z 03-FEB  26.4    24.8    25.0    21.8    35004   0.00    0.00      33    
WED 18Z 03-FEB  38.8    24.8    39.1    22.9    33003   0.00    0.00      68    
THU 00Z 04-FEB  42.4    36.3    35.9    25.8    18001   0.00    0.00      92    
THU 06Z 04-FEB  36.0    28.7    29.2    23.6    15004   0.00    0.00      99    
THU 12Z 04-FEB  32.2    29.1    32.3    22.7    16007   0.00    0.00     100    
THU 18Z 04-FEB  48.5    32.4    48.8    30.2    17010   0.00    0.00      99    
FRI 00Z 05-FEB  52.9    48.7    52.9    43.4    19013   0.00    0.00      99    
FRI 06Z 05-FEB  54.2    52.8    53.4    51.9    21014   0.11    0.00      99    
FRI 12Z 05-FEB  53.5    37.6    37.7    34.0    29006   0.19    0.00     100    
FRI 18Z 05-FEB  43.5    37.1    43.7    24.4    29007   0.00    0.00       0    
SAT 00Z 06-FEB  46.4    36.6    36.3    24.5    29005   0.00    0.00       0    
SAT 06Z 06-FEB  36.9    28.5    28.7    21.9    17004   0.00    0.00       0    
SAT 12Z 06-FEB  29.3    27.3    27.5    21.6    15005   0.00    0.00       0    
SAT 18Z 06-FEB  47.5    27.4    47.7    24.0    17004   0.00    0.00      65    
SUN 00Z 07-FEB  50.0    41.8    41.5    31.3    03002   0.00    0.00      81    
SUN 06Z 07-FEB  42.6    37.3    38.9    28.7    34004   0.00    0.00      98    
SUN 12Z 07-FEB  39.7    33.5    33.2    30.5    32008   0.00    0.00      95    
SUN 18Z 07-FEB  34.9    30.0    35.1    17.2    32008   0.00    0.00       0    
MON 00Z 08-FEB  35.8    27.4    27.2     8.4    31008   0.00    0.00      88    
MON 06Z 08-FEB  27.2    18.7    18.7    -0.7    32005   0.00    0.00       0    
MON 12Z 08-FEB  18.7    16.0    16.2    -4.4    30006   0.00    0.00       0    
MON 18Z 08-FEB  21.0    16.0    21.2   -16.1    32010   0.00    0.00       0    
TUE 00Z 09-FEB  21.7    16.8    16.7   -17.7    00006   0.00    0.00       0    
TUE 06Z 09-FEB  16.7    13.9    13.8   -19.5    00006   0.00    0.00      25    
TUE 12Z 09-FEB  13.8    12.2    12.1   -24.1    02005   0.00    0.00      69    
TUE 18Z 09-FEB  24.1    12.2    24.4   -25.3    35003   0.00    0.00       0    
WED 00Z 10-FEB  27.5    21.4    21.6   -15.8    36005   0.00    0.00       0    
WED 06Z 10-FEB  21.7    16.7    16.7   -17.5    36005   0.00    0.00       0    
WED 12Z 10-FEB  16.7    13.0    13.0   -17.1    02005   0.00    0.00       0    
WED 18Z 10-FEB  26.7    12.6    27.0   -21.0    36004   0.00    0.00       0    
THU 00Z 11-FEB  30.6    22.7    23.3   -11.9    00004   0.00    0.00       0
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1234snow

1234snow

Posted
Posted

Haven’t looked at many overnight models but the trends on the GFS are intriguing for next weekend. The wave is trending flatter which is leading into more of an overrunning event. Precip doesn’t make it north of Chatty. Stripe of snow from middle MS/AL all the way to the outer banks of NC on 6z GFS.

All in all the 6z GFS advertising 4 waves from hour 126 to the end of the 384 hour run and plenty of cold air. Hard not to have some type of optimism for the next 2 weeks looking at that.

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