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

[StormChazer]

5 hours ago, StormChazer said:

I went ahead and tallied up the ensembles(not counting control or master) of last night's Euro run.

19 members have Tulsa missing out or getting under 1-2 inches.

12 members put Tulsa RIGHT on that steep gradient(we're talking north Tulsa county gets 8 inches, south Tulsa county gets 1-2 inches), or is within a county away from the high totals.

19 members have Tulsa getting a good dumping of snow.

 

This is the 3rd time I've done this and pretty much we are back to my first analysis where the number was

17

12

21

 

But no doubt we lost some ensembles in the heavy column to the "right on the line" column. 

So the way I see it

38% say heavy snow

38% say little to no snow

24% say within 20 miles you go from no snow to 8 inches. I may be biased because I want this snow, but I feel this category has to lean in the heavy snow category's favor, seeing how cold air tends to spread a little more than models think. I'll do another one of these for the 12Z run today.

 

Here are my findings from this afternoon's run of the Euro.

10 members give little(under 1-2 in) to no snow for Tulsa and surrounding areas.

9 Near misses or right on the steep snow gradient(2 to 8 inches within a span of 20 miles)

31 Heavy snow runs

 

This is a drastic turn around from last night's euro run both in the master solution and the ensembles.

The way I see it as of right now according to the Euro...

20% of little to nothing

18% RIGHT on the line

62% Good, winter storm warning criteria weather

 

[JoMo]

If only the NAM could be trusted from this far out.....

[lokee]

Newest Nam run has the heaviest ice accumulations right along I44 running from Lawton to the SW Okc metro.

[StormChazer]

 

Up to hour 84 and the NAM is doing a number on Oklahoma(much of that is sleet).

[lovableweatherguy]

If only the NAM could be trusted from this far out.....

Wish things would come further north too for us living in STL.

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[WhiteoutWX]

The NAM just locks in that surface cold layer and never relents with a lot of freezing rain and sleet across central OK. Looks like it wants to drop some heavy snow on top of that just after the end of the run too. Seen many times where the global models scour out the cold air too quickly in these types of events. Even though it is long range NAM, meteorologically speaking, there's no reason for the temps to warm at the surface like the GFS is showing if we keep a continued northerly surface wind and attendant cooler/drier air feed. The NAM just seems more realistic to me.

[StormChazer]

6 minutes ago, WhiteoutWX said:

The NAM just locks in that surface cold layer and never relents with a lot of freezing rain and sleet across central OK. Looks like it wants to drop some heavy snow on top of that just after the end of the run too. Seen many times where the global models scour out the cold air too quickly in these types of events. Even though it is long range NAM, meteorologically speaking, there's no reason for the temps to warm at the surface like the GFS is showing if we keep a continued northerly surface wind and attendant cooler/drier air feed. The NAM just seems more realistic to me.

Had a local met say just about the same thing last night. In a cloudy, northerly wind filled day, that 32 degree line isn't going back up into Kansas, it's sticking around.

[JoMo]

12 minutes ago, WhiteoutWX said:

The NAM just locks in that surface cold layer and never relents with a lot of freezing rain and sleet across central OK. Looks like it wants to drop some heavy snow on top of that just after the end of the run too. Seen many times where the global models scour out the cold air too quickly in these types of events. Even though it is long range NAM, meteorologically speaking, there's no reason for the temps to warm at the surface like the GFS is showing if we keep a continued northerly surface wind and attendant cooler/drier air feed. The NAM just seems more realistic to me.

That's usually what happens. Also may have a pretty sharp northern cutoff on the precip as well. 

[WhiteoutWX]

GFS just seems unrealistic to me. However, the keys here are the surface wind direction, as well as keeping steady precipitation falling during the day. I think this may be what is contributing to the warmer solution on the Euro. It brings the precipitation in much later, starting Friday evening really. Without precipitation falling/wetbulbing processes...the marginally cold surface temps will be able to warm sufficiently during the day on Friday, regardless of wind direction. The NAM is really the perfect scenario if you want to lock in the surface cold layer.

[The Waterboy]

4 minutes ago, JoMo said:

That's usually what happens. Also may have a pretty sharp northern cutoff on the precip as well. 

Are you agreeing with his post that the GFS is unrealistic or saying that temps typically warm at the surface in this type of setup?   Just wanted to clarify.  I think it’s the former. 

Sometimes the WAA wins over but that’s usually with more southerly winds.  The high up north hopefully keeps that at bay. 

[The Waterboy]

NWS Tulsa takes the easy road for now.  Can’t say I blame them: 

 

.DISCUSSION...
The most impactful portion of this forecast package occurs on
Friday and Saturday as the potential for wintry weather
continues.

Before we get the winter weather potential, the area will experience
a mostly sunny day on Wednesday with warmer temperatures as
the surface high pressure system over the area Today shifts to the
southeast. Even with the warmer temperatures, readings will be at or
below seasonal normals.

On Thursday, we will see a cold front move through the region with precipitation
developing in the vicinity of the boundary. The precipitation will continue
Friday north of the frontal boundary with strong isentropic lift in place across
the region. The type of precipitation on Friday will be mostly rain with a wintry
mix possible on the northern edge of the precipitation shield. More of a wintry mix
is expected Friday Night into Saturday as an upper level low moves out of northern
Mexico and across the Southern Plains. The precipitation is expected to transition to
mostly snow as we move through Saturday Night as the upper level low moves over
the area and off to the east. The precipitation is expected to come to an end by
Sunday Morning.

With that said, it is still way too early to focus on exact precipitation types and
amounts as the upper level low that will drive what is expected to happen is still out
over the Pacific Ocean. The forecast will continue to be refined over the next couple of
days.

[JoMo]

1 minute ago, The Waterboy said:

Are you agreeing with his post that the GFS is unrealistic or saying that temps typically warm at the surface in this type of setup?   Just wanted to clarify.  I think it’s the former. 

Sometimes the WAA wins over but that’s usually with more southerly winds.  The high up north hopefully keeps that at bay. 

Globals typically scour out the low level cold too quickly. However, with that being said, there's usually a stronger warm nose aloft than the models project which results in mixed precip falling farther north than what the models think. With a northerly fetch of cold, dry air at the surface, that should help wet bulb down surface temps, if precip is falling. 

[StormChazer]

20 minutes ago, The Waterboy said:

NWS Tulsa takes the easy road for now.  Can’t say I blame them: 

 

.DISCUSSION...
The most impactful portion of this forecast package occurs on
Friday and Saturday as the potential for wintry weather
continues.

Before we get the winter weather potential, the area will experience
a mostly sunny day on Wednesday with warmer temperatures as
the surface high pressure system over the area Today shifts to the
southeast. Even with the warmer temperatures, readings will be at or
below seasonal normals.

On Thursday, we will see a cold front move through the region with precipitation
developing in the vicinity of the boundary. The precipitation will continue
Friday north of the frontal boundary with strong isentropic lift in place across
the region. The type of precipitation on Friday will be mostly rain with a wintry
mix possible on the northern edge of the precipitation shield. More of a wintry mix
is expected Friday Night into Saturday as an upper level low moves out of northern
Mexico and across the Southern Plains. The precipitation is expected to transition to
mostly snow as we move through Saturday Night as the upper level low moves over
the area and off to the east. The precipitation is expected to come to an end by
Sunday Morning.

With that said, it is still way too early to focus on exact precipitation types and
amounts as the upper level low that will drive what is expected to happen is still out
over the Pacific Ocean. The forecast will continue to be refined over the next couple of
days.

Haha, I was thinking the exact same thing. This is very much a "I don't want to deal with this until tomorrow, so I'll just insert of bunch of agreeable statements that don't actually clear anything up", and like you said, I really don't blame them one bit lol.

[StormChazer]

GFS went a touch cooler than the 12Z run, so there is a cooling trend the last couple runs now.

[Weatherdemon]

OUN Discussion:

DISCUSSION... No significant changes to the previous forecast. The focus  continues to be primarily on winter weather that is expected late  this week into Saturday. Will be a little more brief on meteorological details given time constraints today, but will try and explain our latest thinking for this complicated forecast below.   Latest visible satellite shows persistent low stratus across much of the area. Mid level saturation atop the stratus layer resulted in either deep enough saturation or a seeder feeder scenario to  where some reports of snow flurries were received today.  Precipitation was all non-measurable today though. A weak  shortwave within west- northwesterly flow helped force the mid- level saturation and is now shifting east. Low level southerly  flow/veered 850-mb flow should result in warmer temperatures  tomorrow and less cloud cover as stratus erodes.   On Thursday, a cold front sent south by northern stream shortwave  will reach the area bringing colder temperatures. Sub-freezing  temperatures should cover the northeast two thirds of the area by  Friday morning. We adjusted hourly temperatures to show little or no  increase during the day. Northeast winds and cold advection in a  shallow layer along with clouds and precipitation generally yields  little diurnal swing in temperatures. Given this, we have  emphasized freezing rain potential roughly along and just south of the I-40 corridor. Further north, a less pronounced warm nose and overall deeper colder air mass should support some sleet and  snow.   As we've been saying the last couple days, confidence in position/timing of synoptic features and resulting forcing for ascent/precip/QPF is fairly high for the time range, but the main uncertainties are with magnitude of cold air. Models may not be parameterizing boundary layer conditions optimally to guide our precipitation type forecast (i.e., rain vs freezing rain). Furthermore, they've already struggled with boundary layer conditions in the short term (i.e., moisture and stratus issues the last two days). Upstream air mass behind aforementioned cold front may not modify significantly given snow cover down to I-70, and any errors in low-level dew points will have implications for wet bulb temperatures as well. So, the precipitation type forecast remains uncertain.   Even with the higher confidence in synoptic features, a slight  deviation of the track to the south and/or slight slowing and  deepening of the closed mid-upper low may delay or lower  precipitation chances across the north on Friday. But as of now, this seems like a pretty straight forward isentropic ascent scenario with high probabilities of at least 0.10-0.25 inches of QPF widespread. Icing near or slightly below freezing temperatures wouldn't be efficient enough for a straight 1:1 correlation of icing amounts, but given potential error in QPF amounts and possibility of slightly colder air than currently anticipated, we're emphasizing the freezing rain potential. Details in boundary layer T/Tw will become more clear in subsequent forecasts as the event nears.   Applying conceptual models, we're likely to see a fairly substantial TROWAL/deformation snow band into Saturday, with potential for 3-5 (locally higher) snowfall amounts. Right now given the thermal structure in Bufkit soundings and resultant ptype transition, it appears the higher amounts would be over western and northern Oklahoma. But, confidence in accumulating snow is increasing

 

 

[Wx 24/7]

It has been so long I have forgotten the time frame in which we can expect to see Winter Storm Watches hoisted if they wind up being necessary. Are we looking 36 hours in advance or so?

[StormChazer]

5 minutes ago, Wx 24/7 said:

It has been so long I have forgotten the time frame in which we can expect to see Winter Storm Watches hoisted if they wind up being necessary. Are we looking 36 hours in advance or so?

I’m with you! Haha

I think maybe 48? Because they upgrade to warning usually 24 hours out. I think?.....

[JoMo]

9 minutes ago, Wx 24/7 said:

It has been so long I have forgotten the time frame in which we can expect to see Winter Storm Watches hoisted if they wind up being necessary. Are we looking 36 hours in advance or so?

24 to 72 hours I believe. Warning is like 36 hours?

[Will (little rock)]

Fyi, NAM slowly coming in, fingers crossed for colder trend

[The Waterboy]

18z FV3 was a train wreck. 

[StormChazer]

This is looking like an ever colder nam run I think.

[Will (little rock)]

Just now, StormChazer said:

This is looking like an ever colder nam run I think.

I agree, the HP seems slightly farther south as well

[lokee]

8 minutes ago, StormChazer said:

This is looking like an ever colder nam run I think.

I agree as well.  However the moisture is not there in this run in the early morning hours.

[MUWX]

Is it acceptable to extrapolate the nam out to about 120 hours.... asking for a friend lol 

[WhiteoutWX]

NAM hangs the energy back and is slower like the Euro. But it’s also more consolidated and amped with the upper energy. Closes off at 500mb and looks to have quite the backside snows. Really this is a much different storm depiction altogether than what was being shown yesterday and previously. Models were then showing mostly a warm air advection/overrunning scenario and open wave. This is a more consolidated storm. Long range NAM so beware but the Euro was also slower so this could be the start of a trend. 

[rockchalk83]

3 minutes ago, WhiteoutWX said:

NAM hangs the energy back and is slower like the Euro. But it’s also more consolidated and amped with the upper energy. Closes off at 500mb and looks to have quite the backside snows. Really this is a much different storm depiction altogether than what was being shown yesterday and previously. Modes were then showing mostly a warm air advection/overrunning scenario and open wave. This is a more consolidated storm. Long range NAM so beware but the Euro was also slower so this could be the start of a trend. 

With a more amped system as the NAM & Euro would depict, is there a chance the system moves back north? The 18z GEFS seemed to suggest some decent snow accumulations into southern Kansas and Missouri. 

[JoMo]

7 minutes ago, MUWX said:

Is it acceptable to extrapolate the nam out to about 120 hours.... asking for a friend lol 

Used to do it with GFS extensions. Was called the DGEX but they shut it down last year I think?

[MUWX]

2 minutes ago, JoMo said:

Used to do it with GFS extensions. Was called the DGEX but they shut it down last year I think?

I remember that, it used to have some wild stuff. Didn't know it was gone, havent looked at it in years. 

[JoMo]

13 minutes ago, MUWX said:

I remember that, it used to have some wild stuff. Didn't know it was gone, havent looked at it in years. 

Yeah, I can't remember a single time it was right, but it was fun looking at the 36" snowstorms it showed. NAM is pretty useless until the system gets sampled over the SW.

[WhiteoutWX]

53 minutes ago, rockchalk83 said:

With a more amped system as the NAM & Euro would depict, is there a chance the system moves back north? The 18z GEFS seemed to suggest some decent snow accumulations into southern Kansas and Missouri. 

Really would depend on the track of the upper low. But usually more amped equals further north. Until the other models start showing it though I'm not quite biting yet.