Christmas Blizzard 12/20 - 12/28

[Tom]

As we get closer to the Christmas holiday weekend, many travelers out west are certainly paying attn to the weather as Mother Nature is delivering a rather potent storm that will target the 4 corners and Rockies.  Big mountain snows are in the forecast up in the Rockies but more importantly, is there a festive miracle brewing for some of our members???  

Out here in the desert Southwest, I am being blessed by the 1st initial wave from the 2nd cutoff system that has been influence by the "Cut off Low is a Weatherman's Woe" part of the pattern off the west coast last week.  In any event, big time rains are expected out here on Friday and the likelihood of December thunderstorms.  I'm thrilled and super excited that the valley should be blessed with well over 1" + qpf and some decent snows in the mountains.  Let's dive in and discuss...this storm will be a LONG duration system...it will literally take a full week to track across the U.S.!

0z Euro...IMHO, the Euro is going to handle this storm much better than the GFS...I remember back in the Autumn we had similar storms and the Euro pretty much locked in on the evolution within 5 days out.  Anyone have the AI models data??  

@CentralNebWeather

 

 

 

I'd like to see the snow streak extend farther East...still plenty of time to see what this system is made of as it will kick start a massive shift in the wx pattern as we close out DEC and 2023.  

[CentralNebWeather]

35 minutes ago, Tom said:

As we get closer to the Christmas holiday weekend, many travelers out west are certainly paying attn to the weather as Mother Nature is delivering a rather potent storm that will target the 4 corners and Rockies.  Big mountain snows are in the forecast up in the Rockies but more importantly, is there a festive miracle brewing for some of our members???  

Out here in the desert Southwest, I am being blessed by the 1st initial wave from the 2nd cutoff system that has been influence by the "Cut off Low is a Weatherman's Woe" part of the pattern off the west coast last week.  In any event, big time rains are expected out here on Friday and the likelihood of December thunderstorms.  I'm thrilled and super excited that the valley should be blessed with well over 1" + qpf and some decent snows in the mountains.  Let's dive in and discuss...this storm will be a LONG duration system...it will literally take a full week to track across the U.S.!

0z Euro...IMHO, the Euro is going to handle this storm much better than the GFS...I remember back in the Autumn we had similar storms and the Euro pretty much locked in on the evolution within 5 days out.  Anyone have the AI models data??  

@CentralNebWeather

 

 

 

I'd like to see the snow streak extend farther East...still plenty of time to see what this system is made of as it will kick start a massive shift in the wx pattern as we close out DEC and 2023.  

That would be nice for Santa and his sleigh. 

[hawkstwelve]

There is a 10 degree difference between the GEFS mean temp at 6AM on Christmas Day when comparing the 06z run from yesterday (42 degrees) and the 06z run today (32). CentralNeb's area shifted from showing 36 degrees to now showing 29.

NWS FSD has started to include snow wording in their forecast and they specifically mention the shift in the ensembles towards cooler temperatures as being a key component of that. If we could continue the cooler shift as we head down the home stretch and nail that aspect down, I'd be more confident that the precip side will work out enough that we can at least score some snow amount on Christmas Day. 

[gabel23]

1 hour ago, Tom said:

As we get closer to the Christmas holiday weekend, many travelers out west are certainly paying attn to the weather as Mother Nature is delivering a rather potent storm that will target the 4 corners and Rockies.  Big mountain snows are in the forecast up in the Rockies but more importantly, is there a festive miracle brewing for some of our members???  

Out here in the desert Southwest, I am being blessed by the 1st initial wave from the 2nd cutoff system that has been influence by the "Cut off Low is a Weatherman's Woe" part of the pattern off the west coast last week.  In any event, big time rains are expected out here on Friday and the likelihood of December thunderstorms.  I'm thrilled and super excited that the valley should be blessed with well over 1" + qpf and some decent snows in the mountains.  Let's dive in and discuss...this storm will be a LONG duration system...it will literally take a full week to track across the U.S.!

0z Euro...IMHO, the Euro is going to handle this storm much better than the GFS...I remember back in the Autumn we had similar storms and the Euro pretty much locked in on the evolution within 5 days out.  Anyone have the AI models data??  

@CentralNebWeather

 

 

 

I'd like to see the snow streak extend farther East...still plenty of time to see what this system is made of as it will kick start a massive shift in the wx pattern as we close out DEC and 2023.  

Boy the snow line is now knocking on my door. Gonna be an interesting next couple days moving forward! I'm just glad to see the amount of moisture with the system. I'm at the point where I don't care what I get, just give my area precip! 

[Tom]

1 minute ago, gabel23 said:

Boy the snow line is now knocking on my door. Gonna be an interesting next couple days moving forward! I'm just glad to see the amount of moisture with the system. I'm at the point where I don't care what I get, just give my area precip! 

This system has a little bit of DEC ‘09 flavor…just lacking the cold air…

[Clinton]

If only it could be just a little colder.

[hawkstwelve]

Both the GFS and CMC continue to not really play ball with this storm. Nothing but rain here. Lame.

[Timmy Supercell]

3 hours ago, Tom said:

As we get closer to the Christmas holiday weekend, many travelers out west are certainly paying attn to the weather as Mother Nature is delivering a rather potent storm that will target the 4 corners and Rockies.  Big mountain snows are in the forecast up in the Rockies but more importantly, is there a festive miracle brewing for some of our members???  

Out here in the desert Southwest, I am being blessed by the 1st initial wave from the 2nd cutoff system that has been influence by the "Cut off Low is a Weatherman's Woe" part of the pattern off the west coast last week.  In any event, big time rains are expected out here on Friday and the likelihood of December thunderstorms.  I'm thrilled and super excited that the valley should be blessed with well over 1" + qpf and some decent snows in the mountains.  Let's dive in and discuss...this storm will be a LONG duration system...it will literally take a full week to track across the U.S.!

0z Euro...IMHO, the Euro is going to handle this storm much better than the GFS...I remember back in the Autumn we had similar storms and the Euro pretty much locked in on the evolution within 5 days out.  Anyone have the AI models data??  

@CentralNebWeather

 

 

 

I'd like to see the snow streak extend farther East...still plenty of time to see what this system is made of as it will kick start a massive shift in the wx pattern as we close out DEC and 2023.  

I'm just wondering, how often can t'storms around Christmas time occur out in the Ohio Valley region? I guess if there's no way to stop the warm up, let's make good use of it with something exciting.  

[CentralNebWeather]

39 minutes ago, Clinton said:

If only it could be just a little colder.

Canadian and GFS look vastly different with the wraparound. Canadian much farther west. 

[hawkstwelve]

Only thing keeping my hopes up after looking at those downright ugly deterministic runs is their respective ensembles don't really agree with them. 12z GEFS is actually an increase in mean snowfall totals vs 06z run and is much more generous overall vs the main GFS run. Average for Sioux Falls by end of Christmas day is 1.4 while the deterministic run left me with absolutely nothing.

Could this be a case where the main models pullback on snow chances about five days out only to revert and more closely follow their ensemble guidance 24-48 hours later? Certainly would not be the first (or second, or fifth) time that has happened.

[hawkstwelve]

Here's a comparison of the 12z GFS and 12z CMC ensembles through Thursday morning.

Overall while the CMC ensembles are slightly more generous, this is actually pretty decent agreement with not only the amounts but also the placement with the axis of heavier snowfall. Unless this changes and drastically cuts back totals to be more in line with the deterministic runs, I'm keeping hope alive.

[Tom]

12z Euro... @CentralNebWeather switchover happens right around midday on Christmas day...

 

[hawkstwelve]

12z Euro looking much better overall vs the GFS/CMC solution.

Unfortunately it shows freezing rain/snow/sleet falling from Noon on Christmas Day through the day Tuesday and even into Wednesday. If we could keep that precip form as snow, it has a good look for some decently hard snowfall Christmas night.

 

24-hour precip from Noon Christmas Day through Noon Tuesday. Pretty nice precip rates and if 10:1 ratios were realized it would be a hefty snowfall.

 

As it stands though, a good chunk of that falls as freezing rain. Here are snowfall totals ending midnight on Wednesday. Looks nice for CentralNeb's area as he's able to avoid most of the nasty wintry precip. Sure hope the freezing rain aspect doesn't play out like this.

[hawkstwelve]

Regardless of how precip form eventually turns out, look at these precip totals ending 6PM Wednesday. 

Wowza. Talk about some very beneficial precip in areas that really need it. If this storm revisits us in January and we have even slightly more cold air to work with you better watch out folks.

[Minny_Weather]

30 minutes ago, hawkstwelve said:

Regardless of how precip form eventually turns out, look at these precip totals ending 6PM Wednesday. 

Wowza. Talk about some very beneficial precip in areas that really need it. If this storm revisits us in January and we have even slightly more cold air to work with you better watch out folks.

I'd rather have an inch or two than nothing. At least it looks like whatever I may get will stick around for once.

[Minny_Weather]

GEFS is pretty bad for here. All but 2 or 3 of the members show rain as the sole ptype for the system.

[bud2380]

40 minutes ago, hawkstwelve said:

Regardless of how precip form eventually turns out, look at these precip totals ending 6PM Wednesday. 

Wowza. Talk about some very beneficial precip in areas that really need it. If this storm revisits us in January and we have even slightly more cold air to work with you better watch out folks.

This is sorely needed in Iowa and many other locations in the midwest.  So hopefully this at least comes close to panning out.  I'd rather have snow, but we'll take the rain for sure. 

[CentralNebWeather]

1 hour ago, Tom said:

12z Euro... @CentralNebWeather switchover happens right around midday on Christmas day...

 

Whoa, just seeing this. 1st day of final exams here at the high school just finished.  We end the semester tomorrow with day 2. Looks like plentiful moisture, in different forms. Will be exciting with this happening on Christmas afternoon and evening potentially. Forecasts now have inserted 1-3” of snow Christmas night. Still aways to go. 

[CentralNebWeather]

1 hour ago, hawkstwelve said:

12z Euro looking much better overall vs the GFS/CMC solution.

Unfortunately it shows freezing rain/snow/sleet falling from Noon on Christmas Day through the day Tuesday and even into Wednesday. If we could keep that precip form as snow, it has a good look for some decently hard snowfall Christmas night.

 

24-hour precip from Noon Christmas Day through Noon Tuesday. Pretty nice precip rates and if 10:1 ratios were realized it would be a hefty snowfall.

 

As it stands though, a good chunk of that falls as freezing rain. Here are snowfall totals ending midnight on Wednesday. Looks nice for CentralNeb's area as he's able to avoid most of the nasty wintry precip. Sure hope the freezing rain aspect doesn't play out like this.

Could get pretty interesting around here if we get freezing rain/sleet before a changeover to snow. We are hosting Christmas, so no travels for us. 

[jaster220]

3 hours ago, hawkstwelve said:

Only thing keeping my hopes up after looking at those downright ugly deterministic runs is their respective ensembles don't really agree with them. 12z GEFS is actually an increase in mean snowfall totals vs 06z run and is much more generous overall vs the main GFS run. Average for Sioux Falls by end of Christmas day is 1.4 while the deterministic run left me with absolutely nothing.

Could this be a case where the main models pullback on snow chances about five days out only to revert and more closely follow their ensemble guidance 24-48 hours later? Certainly would not be the first (or second, or fifth) time that has happened.

Op should be treated no more importantly than any other ENS member. Basically, that's all it is.

[jaster220]

10 minutes ago, CentralNebWeather said:

Could get pretty interesting around here if we get freezing rain/sleet before a changeover to snow. We are hosting Christmas, so no visitors for us. 

Corrected.

[Clinton]

12z GFS now with over 3 inches of rainfall for mby that's unheard of here in December. 

[Black Hole]

1 hour ago, jaster220 said:

Op should be treated no more importantly than any other ENS member. Basically, that's all it is.

Yep. This is especially true for the EPS where the ensembles have the SAME resolution as the deterministic. In the very short term the deterministic should still have the edge due to no perturbations, but past 48 hours or so the accuracy is identical. 

For other model systems the operational usually has double the resolution, which again matters in the first 2-3 days, but beyond that the ensemble mean has more skill. 

[Black Hole]

Here are some charts for my area. First 24-hr rainfall. You can see we have two different waves. The first and weaker one will arrive tomorrow night into Friday morning. The 2nd, stronger wave will be Sat-Sun (23-24th). A lesser number of ensembles also hit us with the wrap around into the 25th.

 

Interestingly enough, for those that do have the wraparound, a few are cold enough for snow. Meaning its not impossible we get a little bit on Christmas day. Of course I think the real odds of that are probably about 2% but I guess its something.

It's also worth nothing that we will have some instability with the 2nd wave so thunderstorms are possible. PWAT will be well above 1" so locally heavy rainfall may also occur. Lastly, much cooler temperatures will settle in the 25th onwards. 

 

 

[CentralNebWeather]

NWS Hastings afternoon disco:

Saturday-Tues storm system still our overall-biggest concern/issue: Unfortunately we are still a few days away from gaining any semblance of "higher confidence" in exactly how this system plays out, but if anything latest trends point toward increasing potential for at least spotty (and most likely weaker) thunderstorm activity mainly Sat evening into Sunday daytime, and PERHAPS a bit more snow accumulation potential mainly Sunday evening into Monday night (including Christmas).

 

[mlgamer]

35 minutes ago, CentralNebWeather said:

NWS Hastings afternoon disco:

Saturday-Tues storm system still our overall-biggest concern/issue: Unfortunately we are still a few days away from gaining any semblance of "higher confidence" in exactly how this system plays out, but if anything latest trends point toward increasing potential for at least spotty (and most likely weaker) thunderstorm activity mainly Sat evening into Sunday daytime, and PERHAPS a bit more snow accumulation potential mainly Sunday evening into Monday night (including Christmas).

 

Back in the glory years we'd often get thunderstorms a day or two before a big snowstorm. Don't see much of that here anymore and I think a big reason is we don't get the clashes of very warm moist air with very cold air masses here like we used to.

[hawkstwelve]

GFS shifts axis further east and actually has snow falling on Christmas Eve here. 

[hawkstwelve]

Meanwhile, nothing but cold rain for me the entire time on the CMC. CentralNeb's area and points west get pounded though. 

[CentralNebWeather]

19 minutes ago, hawkstwelve said:

Meanwhile, nothing but cold rain for me the entire time on the CMC. CentralNeb's area and points west get pounded though. 

Will be interesting to watch this unfold in the coming days. CMC also puts down freezing rain here in the transition. Could get awfully messy the later we get on Christmas Day and overnight. 

[hawkstwelve]

Fairly sizable shift to the NW with the heaviest band on the 00z vs 12z ECMWF.

Total snow through 9AM Tuesday and CentralNeb is scoring big time on this run. This all falls after Noon on Christmas Day. And the low is still hanging around the NE/KS/MS border at that point. 

[CentralNebWeather]

NWS Hastings morning disco:  

If upcoming model/ensemble runs trend toward the deterministic 00Z ECMWF...the threat of wintry weather/travel issued could be more of a concern Christmas Day into Tuesday, as this runs shows a more organized upper low with a more favorable track and more precipitation over the area (and potentially more wind?). Will be interesting to see how things trend the next couple days...again, those with travel plans especially Sunday night on should pay close attention the forecast.

[Tom]

1 hour ago, CentralNebWeather said:

NWS Hastings morning disco:  

If upcoming model/ensemble runs trend toward the deterministic 00Z ECMWF...the threat of wintry weather/travel issued could be more of a concern Christmas Day into Tuesday, as this runs shows a more organized upper low with a more favorable track and more precipitation over the area (and potentially more wind?). Will be interesting to see how things trend the next couple days...again, those with travel plans especially Sunday night on should pay close attention the forecast.

This storm reminds me of similar ones we tracked in years past that had similar characteristics where a secondary stronger impulse of energy comes up from the deep south/GOM and wraps around into the cold sector.   Man, this could be a hellova storm for you!  

[Tom]

Out here, this is a storm that I've been yearning for (and the local mets) in terms of Heavy Rainfall...as for Snow, it is going to be a warmer system and not as much as one would want to see for the mountains.  Very heavy rain is expected tomorrow and a Flash Flood Watch has been issued for the valley and surrounding areas where 1- 1.5"+ of liquid can be expected.  The CAM's are really starting to show the potential of training thunderstorms.  I've seen a set up like this in the early Spring but never during the Winter season.  Should be an eventful day for the state of Arizona.  Prob going to finish up some Christmas shopping today as it will be a gorgeous day in the mid 70's and sunshine!

 

 

 

Up in Flagstaff, the highest peaks will get a good dose of White Gold...and the White Mountains to my East.

[hawkstwelve]

12z GFS making a slight move towards the Euro with more wraparound precip being shown than previous runs.

 

Still rather lackluster on snowfall amounts. Although it introduces some snow for Kansas and W Iowa with that more stout backside precip.

[hawkstwelve]

Total snow through noon on Wednesday, 12z vs 00z GEM.

 

Also a nice swing to colder temperatures on Christmas Day when comparing those same two runs.

[hawkstwelve]

12z GFS also swung cooler for Christmas than it's previous run.

This is one of the most important aspects, IMO. We need to continue seeing trends over the next couple days towards cooler conditions for Christmas and Tuesday if we want a chance at meaningful snowfall.

[Minny_Weather]

I'm definitely more interested in the secondary low than the Xmas Eve low at this point, at least as it pertains to here in Alex. About 60 miles West and I could be in the discussion for appreciable snow totals. Xmas Eve is 100% going to be rain for here. 

.... However, the Xmas Eve low SHOULD bring some good thunderstorm potential where I will be in Houston. If only it were during the day so I could have some daytime heating to work with, supercells wouldn't be out of the question. 

[Minny_Weather]

I've always loved the AFDs that come out of the Houston/Galveston office, and this is no exception. This is the standard that all offices should be held to during active periods. I actually learned a lot of what I know now from reading their discussions.

Quote

.LONG TERM...
(Saturday through Wednesday)
Issued at 417 AM CST Thu Dec 21 2023

On Saturday, an upper level trough with a weakening embedded upper
level low will be positioned over the Four Corners region and moving
eastward. Southwesterly flow aloft persists as a result, which
keeps us in a favorable position for additional rounds of PVA to
generate lift. PW values remain in the 1.4"-1.7" range (90th
percentile: ~1.37"), so we`ll have plenty of moisture in place.
Notable amounts of instability aren`t added into the equation
until Saturday night/Sunday...this is when an instability axis
slides over Southeast TX due to a surface low developing in the
Central Plains. This surface low is generated through lee
cyclogenesis from another upper level trough moving down from the
PNW and sort of absorbs the previously mentioned upper level
trough. The tightening pressure gradient will lead to some breezy
southeasterly winds on Saturday afternoon/night, but not quite
breezy enough for a Wind Advisory. A cold front will be
associated with this surface low, and it just so happens to push
through on the night of Christmas Eve...but that deserves to be
discussed in its own paragraph.

During the afternoon hours on Christmas Eve, Southeast TX will be in
the warm sector of the previously mentioned surface low as it tracks
northeastward towards the Upper Midwest. This means we`ll have
instability to go along with the moisture and lift that continue to
prevail over the region. As far as shear goes...there is a 35-45
knot LLJ that develops over Northeast TX on Christmas Eve morning,
so the better shear will remain off to our north. The shear and
instability don`t look to be in phase at the moment (higher
amounts of instability to the southwest and higher amounts of
shear to the northeast along with different timings). On top of
that, overcast skies and rain ahead of the approaching front will
limit daytime heating...so not much support there either. Long
story short, I`m not seeing much in favor for strong or severe
storms to develop...that`s not to say a strong storm can`t
develop, but the probability of it is on the slim side.

Confidence is higher on heavy rainfall though with the bulk of the
rain falling in the late morning to early evening hours on
Christmas Eve. Rainfall totals between Saturday and Christmas Eve
will generally be in the 1-3" range. However, with PW values
above the 90th percentile, locally heavy rainfall will be possible
and these higher rainfall rates could lead to isolated street
ponding in low-lying areas and areas with poor drainage. Areas
east of a College Station-Sugar Land-Angleton line remain in a
marginal risk (level 1 out of 4) of excessive rainfall for
Christmas Eve. A slight risk (level 2 out of 4) of excessive
rainfall has been added back for areas east of a Crockett-
Coldspring-Liberty line. Models have trended towards the heaviest
rains pushing out eastward by midnight as the cold front pushes
through. Santa...you`d have a much easier time doing your annual
deliveries if you start from the Brazos Valley and work your way
southeastward from there as conditions will gradually improve in
that direction following FROPA. Lingering rainfall will be
possible for a few hours after midnight though, so you`ll probably
still need Rudolph and his shiny nose (I`d even say it glows!) to
guide you through some areas.

Models continue to trend dry for Christmas Day (Monday) with PW
values quickly dropping to the 0.3"-0.5" range by sunrise, so I`ve
dropped PoPs to 10% or less...it`s a Christmas miracle!!!
Temperatures on Christmas will top out in the low to mid 60s (this
is slightly cooler than previous forecasts depicted) with lows in
the upper 30s to mid 40s. With drier air likely prevailing through
midweek, rain chances remain slim to none. It`s worth noting a
rather robust jet streak will remain overhead through Wednesday,
which should only keep some scattered upper level clouds around.
Things get a bit wishy-washy after this point though with maybe
another FROPA midweek (too early to lock that in), but at least
temperatures look to remain generally in the upper 50s to low 60s
for highs and 30s/40s for lows after Christmas. While we`re on the
topic of temperatures, Saturday and Christmas Eve will feature
highs in upper 60s to low 70s, which is about 6-8°F above normal.
Astronomical Winter may start today (Winter Solstice occurs at
9:27pm CST tonight), but it won`t really feel like winter (our
version of it at least) till after Christmas.

 

[Black Hole]

Suddenly looking questionable for some flakes to mix in (at least in the general area) Christmas day.

[hawkstwelve]

4 minutes ago, Black Hole said:

Suddenly looking questionable for some flakes to mix in (at least in the general area) Christmas day.

12z CMC brought the snow much closer to your neck of the woods than previous runs.