MO/KS/AR/OK 2019-2020 Winter Wonderland Discussion

[NwWhiteOut]

Some of these maps and runs, my goodness! Still so early which has me so concerned :( . Going to just keep a watch and stay tuned here for sure. Tulsa has snow and sleet in the forecast here from friday into sat. night. Daytime temps look iffy but yea still very far out. Can we possibly break a snowless season for once :) ?

[JoMo]

00z Euro was pretty bad. OK looks pretty good but that's about it. 

[StormChazer]

I know I sound like a broken record, but as of the 06Z GFS, it started trending south again, I suspect if it continues the pattern it's been on, the 12Z will have an even further south solution, and eventually it'll stop trying to keep the colder air north, this is all assuming the Euro is to be believed. Quite honestly, the Euro's run to run consistency since Thursday of last week has been quite impressive, the only changes in it's runs overall have been to bring the precipitation shield further south, causing MO and KS to miss out on the snow, but in terms of where the freezing line sets up, it has been very consistent. Today's runs are very important, we are only 4 days out now from the onset of the freezing precip depicted. If the Euro maintains, and the GFS creeps a little more south, I'd say that should lead to some moderate to high confidence in this storm, and by tomorrow night snow amounts can start to be discussed.

[StormChazer]

Here is every run of the Euro since the noon run on Thursday. I've adjusted the timing only slightly to try and visualize it better to get the frames matched up.

This is more or less, Midnight Friday, so the frames following show a snowy scenario continuing into Saturday, but I thought this a pivotal point in the forecast to display. This is some fantastic run to run consistency, the only run that deviates anything meaningful is the 0Z Saturday run which depicts an icier solution with the colder air more north, before transitioning to snow.

The other thing to notice is the precip shield moving more to the south and leaving KS and MO with less and less, although this hour in the storm doesn't highlight that aspect very well, I'd need to jump ahead 6 more hours for that.

On the other side of things, the GFS has had some flip flopping issues. It'll go 2-3 runs agreeing with the Euro and then BOOM go another 2-3 runs keeping the cold air way north into Kansas, then cave again to the Euro, rinse and repeat. It's done that about 3 times now, and we'll see if the 12z run today brings it more in line with the Euro after seeing it inch southward on the 6Z.

 

Point is, the Euro has been very consistent and handles these things quite well, so that's where I'm putting my faith for now.

[JoMo]

12z GFS def going farther south

[JoMo]

Def something up with the algorithm on the PGFS. Pretty though.

[rockchalk83]

20 minutes ago, JoMo said:

Def something up with the algorithm on the PGFS. Pretty though.

I don’t think it’s an algorithm problem, but more of the GFS-FV3 resolving a closed low at 500 mb, which leads to a more significant moisture envelope in the cold air versus an open wave like the other models seem to be doing. To me, that seems to be the key to the forecast right now and not the cold air.

It is interesting that the GFS, GFS-FV3, plus many of the GFS and EURO ensemble members were progging a closed low scenario during the overnight runs. Something to watch as we get into the mesoscale modeling beginning tomorrow. 

[JoMo]

Man, the Euro is getting more and more disappointing every run. 

[MUWX]

19 minutes ago, JoMo said:

Man, the Euro is getting more and more disappointing every run. 

As expected, it is trending the wrong way for southern Missouri. Nothing unusual there 

[WhiteoutWX]

Much warmer across Oklahoma too on the Euro. Went from being the coldest model to the warmest. 

[StormChazer]

Not sure how to interpret that one. I know we aren't supposed to focus on single model runs, but rather trends. But coldest to warmest has me wondering if this will end up as a run that went out to lunch, or if it's picking up on something. You would think if it was picking up on a warmer solution though that the GFS would have been even warmer.....looking forward to getting some shorter, higher res models into the fray soon. Also very curious now what tonight's Euro shows. I will say looking through the various members for snowfall, there is a very large number of models with high totals.

[The Waterboy]

Will also be curious to see what the Euro ensembles so show.  Hopefully this is a blip and not a trend.  If it’s a trend let’s know sooner rather then later so we can focus on something else the next few days!

[StormChazer]

32 minutes ago, The Waterboy said:

Will also be curious to see what the Euro ensembles so show.  Hopefully this is a blip and not a trend.  If it’s a trend let’s know sooner rather then later so we can focus on something else the next few days!

Well, I analyzed the 50 members for snowfall and at least for Tulsa, this is what I came up with.

17 members have Tulsa either entirely missing out on snow, or getting less than 1-2 inches.

12 members put Tulsa a hair away from the heavy totals, we're talking going from 1 to 10 inches in a span of one county.

21 members dump a heavy swath of snow across Tulsa(and most of NE OK), "heavy" being 5+ inches.

 

Still just so much more time to go before zeroing in on the totals, but this run of the Euro has definitely made things much more cloudy. Midnight can come fast enough, haha.

 

 

 

[The Waterboy]

13 minutes ago, StormChazer said:

Well, I analyzed the 50 members for snowfall and at least for Tulsa, this is what I came up with.

17 members have Tulsa either entirely missing out on snow, or getting less than 1-2 inches.

12 members put Tulsa a hair away from the heavy totals, we're talking going from 1 to 10 inches in a span of one county.

21 members dump a heavy swath of snow across Tulsa(and most of NE OK), "heavy" being 5+ inches.

 

Still just so much more time to go before zeroing in on the totals, but this run of the Euro has definitely made things much more cloudy. Midnight can come fast enough, haha.

 

 

 

Is this based on 00z or 12z?   Weather.us didn’t have the 12z ensembles updated yet because I wanted to look at the same thing.  

Still sounds like 50% ish are good.  About all we can ask for right now.  Survive and advance.  

[JoMo]

9 minutes ago, The Waterboy said:

Is this based on 00z or 12z?   Weather.us didn’t have the 12z ensembles updated yet because I wanted to look at the same thing.  

Still sounds like 50% ish are good.  About all we can ask for right now.  Survive and advance.  

There's still a variety of solutions on the 12z Euro ensembles. I think I'll take #44 I think it was. Looked great. Too bad we can't pick a favorite to come true.

[StormChazer]

24 minutes ago, The Waterboy said:

Is this based on 00z or 12z?   Weather.us didn’t have the 12z ensembles updated yet because I wanted to look at the same thing.  

Still sounds like 50% ish are good.  About all we can ask for right now.  Survive and advance.  

Now that I look at it, I think that may still be the 0Z, let me double check. If not, once it's updated I'll do the same thing to compare and contrast.

[The Waterboy]

8 minutes ago, StormChazer said:

Now that I look at it, I think that may still be the 0Z, let me double check. If not, once it's updated I'll do the same thing to compare and contrast.

It’s updated now.  I just looked at Bentonville/Rogers, AR (selfishly since that’s where I am) and 23 members have 6 inches or more.  A lot of those are over a foot.  Anything is still on the table.  

[The Waterboy]

Also, anyone have any thoughts on the 18z NAM at 84 hrs vs the 12z GFS/FV3 at 90?  LP looks more juiced based on precip and further east but still in northern MX (On the NAM).  

I know it’s the NAM at 84 which sucks but maybe it’s worth some banter.  

[StormChazer]

52 minutes ago, StormChazer said:

Well, I analyzed the 50 members for snowfall and at least for Tulsa, this is what I came up with.

17 members have Tulsa either entirely missing out on snow, or getting less than 1-2 inches.

12 members put Tulsa a hair away from the heavy totals, we're talking going from 1 to 10 inches in a span of one county.

21 members dump a heavy swath of snow across Tulsa(and most of NE OK), "heavy" being 5+ inches.

 

Still just so much more time to go before zeroing in on the totals, but this run of the Euro has definitely made things much more cloudy. Midnight can come fast enough, haha.

 

 

 

So the following is the 12Z members and what I found for the immediate Tulsa area...

16 members have Tulsa either missing out or under 1-2 inches.

8 members put Tulsa a hair away or right on the line on heavy totals.

26 members dump a heavy swath of snow across Tulsa and surrounding areas.

 

So comparing the two, the biggest difference is that 5 members shifted from the middle and low column to the high column in Tulsa's favor. So I won't really complain too much about this. Lost ground on the master, but gained ground in the ensembles.

 

[StormChazer]

41 minutes ago, JoMo said:

There's still a variety of solutions on the 12z Euro ensembles. I think I'll take #44 I think it was. Looked great. Too bad we can't pick a favorite to come true.

My vote would go to #49; would make up these past few snowless years. If only! Haha

[StormChazer]

GFS is up and running. Will post thoughts shortly!

[MUWX]

24 minutes ago, StormChazer said:

So the following is the 12Z members and what I found for the immediate Tulsa area...

16 members have Tulsa either missing out or under 1-2 inches.

8 members put Tulsa a hair away or right on the line on heavy totals.

26 members dump a heavy swath of snow across Tulsa and surrounding areas.

 

So comparing the two, the biggest difference is that 5 members shifted from the middle and low column to the high column in Tulsa's favor. So I won't really complain too much about this. Lost ground on the master, but gained ground in the ensembles.

 

Did this for the Springfield area as well: except I went little (3 or less), some (3-6), and a lot (6+), also included the control and master:

Little: 27

Some: 11

A lot: 14

 

Don't feel great about that, but its better than nothing I suppose. I will have to compare those numbers to 0z when I get the chance.

[David Reimer]

Area Forecast Discussion
National Weather Service Norman OK
332 PM CST Mon Dec 3 2018

.DISCUSSION...
Obviously the primary focus is on a potentially impactful winter
weather event late this week into the weekend. A more more detailed
discussion of the meteorology, uncertainties, confidence, etc.,
can be found below, but first a few key points:

- Dry/uneventful weather with below normal temperatures and a
gradual warming trend through mid-week.

- Next round of precipitation expected to start Thursday, with
coverage/probabilities increasing substantially Thursday night into
Friday, lasting through Saturday.

- Shallow cold surface layer starts to transition rain into freezing
rain and sleet Thursday night into Friday across at least the
northern 2/3rds of the area. A transition to snow is expected deeper
in the colder air across northern Oklahoma.

- As cold advection continues and sub-freezing temperatures deepen
with cooling aloft Friday night into Saturday, snow will become the
dominate precipitation type across at least the northwest half of
the area.

- Given the uncertainties we just have two rather vague graphics out
on precipitation type for now, and are beginning to message
safety/preparedness.

*The above describes the most likely scenario. Although confidence
at this time range is slightly above average, there are still
aspects of this system that are quite uncertain--especially
temperatures.

Meteorological Analysis:

WV loop and 500-mb analysis show broad cyclonic flow across much of
the country. A departing shortwave that was accompanied by a period
of ascent and deeper mid-level saturation has moved east of the
area. Periods of mid-level radar returns from virga, or perhaps
brief non-measurable precipitation have ended as a result. An
extensive area of low stratus from the northern Plains and Midwest
slowly crept southward through across northern Oklahoma this morning
and has halted near I-40 this afternoon. To its north, temperatures
are colder than previously anticipated, with only modest warming
across southern portions of the area that have been mostly clear.

Northerly winds will decrease tomorrow and become light or even
become southerly across western sections of the area. Temperatures
should be slightly warmer, though southerly warm advection/downslope
regime is not expected to kick in for a more significant warmup.
Meanwhile, another weak perturbation in west-northwesterly flow
aloft should bring additional mid-level cloud cover to mainly
norther portions of the area, probably oriented along a ~500-mb
frontogenesis band oriented west-northwest to east-southeast across
the area. This saturation shouldn`t be deep enough for precipitation
but similar to this last system, some virga or perhaps very light
non-measurable precipitation may occur. Again, this should be close
to the Kansas border.

Wednesday, southwesterly 850-mb flow strengthens and we should warm
to at least early December climo temperatures. It`s possible
temperatures could exceed current forecast values which were not
changes from model consensus blends.

Northern stream shortwave activity will send a cold surge(s)
southward toward the area late in the week. The first cold front
is expected to move through later in the day Thursday.
Precipitation chances near/ahead of the front should be minimal
until large scale ascent increases markedly toward the predawn
hours Friday morning, and especially during the day Friday.
Thermal profiles in forecast soundings suggest light freezing rain
where temperatures fall below freezing Thursday night. This would
be generally near and north of the I-40 corridor, most likely.

On Friday, deepening/digging mid-upper low will move east across
Baja California. Mid-level height falls and large scale ascent
will increase across the area. Isentropic ascent will strengthen
as southerly flow increases atop cold shallow air mass in response
to entrance region of powerful upper jet shifting northeastward.
The degree of cold air at the surface will dictate precipitation
type. Models have been fairly consistent with the track of deep
low to our south and enhancement of north-northeasterly surface
flow maintaining these cold surface temperatures. But details with
magnitude of upstream cold air will be better understood once
model run-to-run consistency with northern stream shortwave
activity improves.

The most optimal icing setup for our area happens with a
pronounced northern stream wave that is able to dislodge a
significant artic air mass and send it south before a lagging
southern stream system approaches our area. In this case, the two
waves aren`t in phase optimally and the cP surge(s) aren`t
particularly cold. So, efficient icing from low-mid 20F
temperatures isn`t expected. Rather, some impacts in the form of
elevated surfaces accumulating ice may occur, but rather
inefficiently as much of the freezing rain should occur with
fairly warm temperatures right around freezing.

It`s worth noting that most deterministic and ensemble guidance
is still fairly tightly clustered on storm total QPF ranging from
around 2.0" in the southeast to around 0.5" in the northwest. So,
confidence in the synoptic scale pattern and probabilities of
precipitation are above normal for this time range. It`s the
temperature forecast, and how critical it will be given the
position of the 32F line that is less confident.

Here are a couple possible scenarios that could deviate from
current expectations:

1) If northern stream shortwaves are more optimally timed and more
substantially amplified sending colder air southward, icing
potential will increase. This is the worst case scenario for
impacts, but seems unlikely at this point.

2) If the southern stream system digs further and closes off more,
thereby slowing some, we could see more significant preceding
warm advection and more of the area receiving rain. This is the
best case scenario for impacts as rain-ice-snow transition would
be quicker.

The 03.12 ECMWF was slightly slower/deeper and warmer which would
support scenario #2 above, but unfortunately this appears to be an
outlier among its ensembles when we compare to the ECMWF-ensemble
mean. So it doesn`t appear to be a trend that we can lock onto at
this point.

BRB

[JoMo]

18z GFS with a brief close off and farther north:

[StormChazer]

Tulsa thoughts on the upcoming system.

"The strong system in the southern stream over the E Pac is forecast to move
across the southern tier of states, and will tap a plentiful
moisture source from the Gulf to produce widespread precipitation
over the south central states. Coincidentally, a strong shortwave
trough in the northern stream will force a cold front thru the
region Thursday with colder air filtering into the region thru the
weekend as surface high pressure settles south into the central
Plains. This one-two punch on the separate streams of the
westerlies tends to bring some of the bigger winter weather events
for our part of the world.

Using a blend of the thermal profiles aloft and the raw surface
temps (which have trended warmer slightly) from the GFS/ECMWF,
and using the latest QPF (the character of which is very similar
between the GFS/ECMWF), this forecast will continue to suggest
the potential for a winter storm across portions of NE OK and NW
AR. Snow and sleet are expected to be the primary winter weather
types, with some very light icing possible at precip onset down
along the I-40 corridor. Rain will be predominant thru much of the
event south of I-40, with a change over expected toward the end
of the event Sat/Sat night and thus lighter accums. The details
will continue to be refined in the coming days, especially as we
get into the time frame of the NAM and its better handling of cold
air in a day or so. Stay tuned for updates. Travel impacts across
portions of the region are looking more likely."

[StormChazer]

For those wondering, here is the current snow pack. It's going to stay cold up in Nebraska, so should be interesting to see if this has any affect in speeding up the cold air.

[ouamber]

Well, now both GFS and V3 have went north and Tulsa is in the screw zone.  The snow maps look weird how it goes NE and then due east.  Why can't it just give all of us something instead of screwing someone to the north or someone to the south? Terrible.

[JoMo]

Weeklies still don't look bad. Small mid-month warmup before colder by Christmas all the way through the end of the run in Mid-Jan. Retrogression of the trough up in the Alaska area leading to a nice -EPO. 

[StormChazer]

24 minutes ago, ouamber said:

Well, now both GFS and V3 have went north and Tulsa is in the screw zone.  The snow maps look weird how it goes NE and then due east.  Why can't it just give all of us something instead of screwing someone to the north or someone to the south? Terrible.

No need to throw in the towel. It’s 1 run. This far out, so much is still subject to change. The Euro ensembles showed that the Euro master didn’t line up too well, it could very well dip back down tonight for all we know. I’d wait until Wednesday before getting too upset!

[StormChazer]

I’ll agree the snow line confuses me.