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

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There is more than enough in that graphic to prompt TSA to issue a Winter Storm Watch. Wonder if they are waiting to analyze the 00z data first?

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Just now, Wx 24/7 said:

There is more than enough in that graphic to prompt TSA to issue a Winter Storm Watch. Wonder if they are waiting to analyze the 00z data first?

That would be my guess especially with the GFS still being "meh"

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1 minute ago, Wx 24/7 said:

There is more than enough in that graphic to prompt TSA to issue a Winter Storm Watch. Wonder if they are waiting to analyze the 00z data first?

Their discussion below. No mention yet but I would bet you're right.

A

rea Forecast Discussion
National Weather Service Tulsa OK
322 PM CST Wed Dec 5 2018

.DISCUSSION...
The big story continues to be the potential for wintry 
weather Friday into Saturday. Winter weather headlines 
will likely be needed as impactful weather is expected 
across portions of eastern Oklahoma and western Arkansas. 

A cold front is slated to move through eastern Oklahoma 
and western Arkansas on Thursday with the potential for 
rain in the vicinity of the boundary as it moves through 
the area. Temperatures will be noticeably cooler on Thursday
behind the cold front. 

The precipitation shield will begin to return to the north 
on Friday as isentropic lift increases north of the frontal 
boundary as it continues to sag south toward the northern 
Gulf of Mexico. Some of the precipitation along the north edge of 
the precipitation shield may fall as a wintry mix of freezing 
drizzle and light snow Friday. 

The potential for wintry weather really ramps up later Friday 
night into Saturday as an upper level moves out of the Southwest
United States and across the Southern Plains. With this forecast 
Package went with slightly colder surface temperatures than the 
blended model guidance provided and an even blend of the GFS,NAM12
and ECMWF thermal profiles. Stayed fairly close to the WPC QPF 
with a small increase Saturday Night as a nod to the slower moving 
ECMWF. A wintry mix will transition to mostly all snow across the 
majority of the area by Saturday Evening as the cold air deepens 
before ending Sunday Morning.

Of course, it is still early to give any real specific amounts of 
snow and ice. However, it is looking more likely that there will be 
impactful amounts of snow and ice across much of northeast Oklahoma 
and northwest Arkansas Friday Night into Saturday. It all depends on 
the ultimate track and strength of the upper level as it moves across 
the Southern Plains.  

As we move into next week high pressure will build at the surface 
and aloft resulting in a slow warming trend across the region.

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OUN Discussion:

 

Area Forecast Discussion
National Weather Service Norman OK
405 PM CST Wed Dec 5 2018

.DISCUSSION...
We have high confidence in impactful winter weather across the 
forecast area. The main changes were 1) to confined to precipitation 
chances to southern portions of the area through early Friday 
morning, and limited probabilities across northern Oklahoma until 
late Friday/Friday night, 2) to make minor adjustments to ice 
accumulations and amounts, 3) increase snow amounts across portions 
of western and northern Oklahoma, 4) increase precipitation 
probabilities, and 5) significantly lowered post-event temperatures 
Sunday into Monday given expected snow cover. 

Low level saturation near/behind the cold front tomorrow doesn't 
appear to be sufficient for drizzle or freezing drizzle but we'll 
need to watch the trends in the observations. Further south, deeper 
moisture and a more pronounced near-surface saturated layer below 
capping warm/dry layer may yield some drizzle. Temperatures there 
will be warm enough for no freezing concerns. For post-frontal 
temperatures through Friday we went with the low end of model 
guidance (NAM, WRF-ARW) which seems most reasonable given the 
pattern and character of upstream cold/dry cP air mass. 

Models are in fairly good agreement with synoptic scale features. A 
closed mid-upper low will move across the Southwest tomorrow night 
and Friday and through the southern Plains Saturday. Large scale 
ascent and deepening moisture will eventually lead to light 
precipitation across the area, but it's onset, amounts, and 
resultant impacts from icing are probably the most uncertain part 
of the forecast at this point. There will be a west-southwest to 
east- northeast corridor of potentially impactful icing, including
the possibility of tree and powerline damage as well as travel 
problems. This would be commensurate with icing amounts that 
approach or exceed 0.25 inches Friday and Friday night, and 
appears to be most likely across southwest Oklahoma extending up 
near and south of the I-44 corridor. We may need to adjust the 
highest chance of freezing rain further south from current 
graphics based on the latest model forecast soundings which show a
deeper cold layer across the northern half of the area supporting
just light freezing drizzle, and eventually sleet once dendrite 
probabilities increase through saturation <-12C. It's also worth 
noting that our cold NAM/ARW hourly temperatures may not be cold 
enough and at least low-end icing event may evolve further south 
than earlier thought, to around the Red River and into western 
north Texas. 

Where freezing rain does occur, accretion should be tempered by 
latent heat release where temperatures are at or just below 
freezing. But, 10-15 knot northeasterly winds may help offset that 
some. So fairly optimal ice-to-liquid ratio according to the FRAM 
model could develop. Again, potential rainfall amounts will need to 
be monitored closely. Fortunately, this is not expected to be the 
most optimal scenario for significant icing which would occur with 
colder temperatures and higher QPF amounts. 

We trended more aggressive with sleet potential given strengthening 
warm nose aloft and it's possible that sleet could at least briefly 
be the dominate precipitation type in a band from southwest/west-
central Oklahoma eastward along and either side of the I-40 
corridor, especially Friday evening and overnight. Saturday morning, 
as the closed low passes to our south cooling aloft will support all 
snow. There are some model differences by then with regards to the 
degree at which the low becomes closed. However, ECMWF matches well 
with its ensemble mean counterpart, and the spread in GEFS members 
is minimal for this time range as well. Deterministic GFS matches 
this reasonably well, and the GFS-FV3 is slightly more closed 
off/anomalous. All this is to say that although some slowing or 
slight variations in track could alter ptype placement and amounts, 
overall confidence is fairly high given that the peak of the event
is about 3 days out. 

The aforementioned described synoptic setup is favorable for
development of a pronounced TROWAL and deformation snow event as
the deep low passes south and southeast of the area. One potential
limiting factor for more robust snowfall amounts could be mixing
of sleet given currently depicted thermal profiles, but current
thinking is that models could be too aggressive with this and a
longer duration of moderate to heavy snow could form across
portions of the area. 2-4 inch snowfall amounts should be common
across much of the area (especially the northwest half), and there
could be a band of 6+ inches given impressive QPF amounts that
have been consistent in models. 

We lowered temperatures after the system departs given likely snow
cover. 

BRB/PW

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Pretty surprised Tulsa hasn't issued the watch yet....and this evening's NAM run is going to be a very important one as it'll have more information to go off of.

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2 minutes ago, StormChazer said:

Pretty surprised Tulsa hasn't issued the watch yet....and this evening's NAM run is going to be a very important one as it'll have more information to go off of.

CH 9 in OKC has 4-8 inches from SW OK through NE OK. Width covers virtually all of NE OK. along with .25 of ice in the same area.

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13 minutes ago, Weatherdemon said:

CH 9 in OKC has 4-8 inches from SW OK through NE OK. Width covers virtually all of NE OK. along with .25 of ice in the same area.

Where's Mike Morgan to get the hype train started? Channel 4 will no doubt have some high amounts! I live in Tulsa, but that guy is fun to watch when I'm in OKC!

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9 minutes ago, ouamber said:

Where's Mike Mitchell to get the hype train started? Channel 4 will no doubt have some high amounts! I live in Tulsa, but that guy is fun to watch when I'm in OKC!

You mean Mike Morgan?

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1 minute ago, OUGrad05 said:

I expected NWS to have a winter storm watch up in Tulsa but they don't yet.  Must be hanging on for the 00Z data.

Especially since your threshold for a watch is 4". 

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2 minutes ago, Wx 24/7 said:

Especially since your threshold for a watch is 4". 

With GFS lingering at 1 inch that may have the hesitating.  There's still some variables to work out on this thing.  

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This storm may have started out looking like an ice event days ago, but I think the true story will be heavy deformation snows on the backside of the system. NAM is painting quite the potent band, and while it's temperature are marginal verbatim, just looking at the synoptic features and applying conceptual models, it will be a heavy, wet pastejob of a snowstorm for someone over western OK, possibly extending into northern/central OK depending on the track. This would likely continue on east from there. I think the GFS is total trash at this point. NAM and Euro all the way. But JMHO...

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Tulsa NWS needing more data before issuing watch.

Area Forecast Discussion
National Weather Service Tulsa OK
933 PM CST Wed Dec 5 2018

...UPDATE...

.DISCUSSION...
A rather wide range of temperatures was observed this evening,
with low dewpoints/light winds allowing a few spots to quickly
fall below forecast lows already. Have generally lowered temps
across most of the area the remainder of the night, although
increasing clouds should keep lows from completely bottoming out.

Quick look at the 00Z NAM doesn't clear up the winter weather
potential, as it maintains a band of significant snow/sleet northwest
of I-44 with a secondary max across parts of northwest AR. NAM has
been consistent with previous runs but also a significant outlier
as far as amounts go. A winter storm watch will likely be needed,
but don't have the confidence yet to put one out without seeing
more 00Z data/model runs

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6 minutes ago, MUWX said:

I think it's going to be really depressing to watch this one from the republic/Springfield area. 

Maybe, storm won't be fully sampled until tomorrow and any big changes in modeling will probably happen at that point. 

I remember, many years ago, a snowstorm that was supposed to impact the Springfield CWA. They had warnings up, the models had been indicating heavy snow with a low tracking to the south. Wichita looked at the satellite loop, visibly saw the low tracking farther NW, and immediately cancelled their warnings in SE KS. The models were wrong. The heavy snow was confined to central and western KS with rain in SW MO. It was an awful, awful bust. 

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8 minutes ago, JoMo said:

Maybe, storm won't be fully sampled until tomorrow and any big changes in modeling will probably happen at that point. 

I remember, many years ago, a snowstorm that was supposed to impact the Springfield CWA. They had warnings up, the models had been indicating heavy snow with a low tracking to the south. Wichita looked at the satellite loop, visibly saw the low tracking farther NW, and immediately cancelled their warnings in SE KS. The models were wrong. The heavy snow was confined to central and western KS with rain in SW MO. It was an awful, awful bust. 

Yeah, I'm holding out hope for the sampling shift. I can't imagine this board in a miss like that!

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4 minutes ago, Weatherdemon said:

GFS at 3.3 inches by 21z Sat in Tulsa. That's already 2 inches more than previous run.

GFS just playing catchup. Gets the overall look a little better this time but the QPF is too low on the backside of the low. 

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