Texas Winter 2018-2019

[orangeblood]

Such a shame there wasn't just a little more cold air around....this ULL will be almost 5 STDs below normal, by far the largest departure from normal in the entire Northern Hemisphere and the most I've seen in weeks. This is a rare event in this part of the world, hopefully more than just a few rural counties can capitalize

[weatherdude1108]

So close!


As the upper level low moves north of our area some wrap around precipitation is possible Thursday night. With temperatures dropping to near freezing at the surface and below freezing above the surface a rain/snow mix will be possible across the Edwards Plateau and Hill Country Thursday night and Friday morning. While most areas will not see see accumulations, parts of Burnet and Llano County could see up to an inch of snow accumulation on grassy surfaces. San Antonio and Austin are NOT expected to see the rain snow mix at this time, just a cold light rain.

[snowballzzz]

Looks like this is our only good chance for something through the end of the year and only looking good for those out west.

[Brent]

FWD throws out a nugget for the snow starved metroplex

SNOW POTENTIAL...
This is probably about as difficult as they come for the sole
reason that no arctic airmass is in place across the Plains.
Usually we can look at and track all of the main ingredients that
go into winter weather (cold air, lift, moisture) in a current
analysis. In this case those ingredients are forecast to "appear"
over us. Virtually all of the cooling of the atmosphere we see is
in response to dynamic forcing and lift. In essence, the
deepening of this cyclone is creating its own environment
favorable for winter precipitation. And in that respect we are
totally at the mercy of numerical weather prediction correctly
forecasting the amount of lift and the location of precise
temperature gradients from the impacts of mesoscale lifting and
diabatic cooling effects. The one bit of good news is that model
guidance is in good agreement on the main points of the
forecast...that the western and southwestern zones appear to be
the favored areas where forcing is maximized and strong enough to
cool the atmospheric column below freezing. The bad news of course
is that there`s no guarantee that the upper low will develop in
that spot and take the track its forecast to.

The winter storm watch will continue as is for the western zones,
with the exception of adding Lampasas and Hamilton counties on
the southern edge of it. Rain should begin to change over to snow
once the dynamic lifting can cool the column below freezing. Then
surface temperatures will need to be cooled effectively from the
reservoir of cold air aloft as warmer surface air is vented into
the lower atmosphere due to super-adiabatic lapse rates and
through diabatic heat loss via precipitation either
evaporating or melting in the low levels. The result is that the
warm surface temperatures will cause most of the precipitation to
fall as rain, but eventually a transition of snow should occur as
early as late Thursday afternoon in the western zones. This
transition from rain to snow will also likely occur at the higher
elevations (> 1500 ft) of our western zones before they do in the
elevations that are a few hundred feet lower. Thus high points in
the western CWA (in the winter storm watch area) are most at risk
for multi-inch snow while valleys may see little or no
accumulating snow. In other words, the range for snowfall in the
winter storm watch is from a Trace to 4 inches due to these
uncertainties (and not because we don`t want to try to narrow it
down). We estimate that snow will struggle to accumulate on roads
until about 2 inches falls. Even then we believe that the warm
ground temperatures means that roads will become slushy instead of
icy or snow packed. The combination of high winds when and where
snow is falling could create visibilities of less than a half mile
and also cause travel issues.

Odds are that locations farther to the east (the I-35 corridor)
will not be able to cool the 925mb layer below freezing and precip
will remain all rain. However this is still highly dependent on
the track of the upper low. A track that is shifted about 50 to
100 miles farther north would increase the snow potential for all
of the I-35 corridor (and western zones too). This is because a
more northerly position of the low would be able to grab slightly
cooler air over Oklahoma to wrap into the cyclone. As it stands
now guidance is showing warmer air from northeastern Texas
wrapping into the low which means the northern part of the cyclone
would have difficulty staying cold enough - thus focusing the
snow threat near the track of the core of the upper low. There is
one final caveat, and that is mesoscale frontogenesis can and
often does provide strong enough lift to cool localized layers of
air below freezing. One such band of frontogenesis is forecast to
develop across the I-35 corridor from Hillsboro to the DFW
metroplex into Sherman Friday morning. This would be the time we
could see rain mix with or change over to snow, but I worry we`ll
not know if this will or will not occur until Friday morning.
Right now our message to people for this part of the CWA is that
they need to be aware that localized bands of heavy precipitation
will have the potential to change to snow and thus result in some
accumulations. So plan on rain, but make contingency plans for an
inch or two of snow too. By midday Friday it should be warm
enough everywhere that only rain is possible.

[Quixotic]

All I want for Christmas is an EPO flip.

[BrokenGlassRepublicn]

Meanwhile, today the juniper in the air is kicking my butt. Bad.

[DFW Stormwatcher]

Days like this take me back to 48 hours out from snowmaggedon in 2010. Went back and read the thread again this morning. That was supposed to be too warm at one point. conditions are different, but an above freezing event that could have easily been all rain, instead came down as 12-14 inches of snow. Wet bulbing did the trick, surface temps were cooler. Forecast changed quickly except for a crazy forecast of all time by a person who is no longer here in the forums that happened to come true. There’s a few here who remember that festive time on the boards.We were still forecast to get two inches of snow when there was already 6 on the ground.

[wxman57]

No more Christmas snow miracle across Texas (even Houston) in the 12Z GFS run...

Was Houston ever even in consideration?

Yes, in the 6Z GFS run yesterday for CHRISTMAS DAY (not this week). GFS had snow down to the upper TX coast. ...not that it was likely to happen.

[Lagreeneyes03]

Looks like this is our only good chance for something through the end of the year and only looking good for those out west.

Well that just stinks. I thought there was some storminess after Christmas thru EOY?

[Ralph's Weather]

All I want for Christmas is an EPO flip.

https://www.esrl.noaa.gov/psd/forecasts/reforecast2/teleconn/images/4indices.png

I like the looks of that. PNA falling back towards neutral indicates a Plains trough while the falling EPO indicates a building NW North American ridge. The changing NAO also is a sign of activity. This is the type data to watch vs model runs at this range.

Heck those indices would suggest a semi torch right now and we are talking low 60s with a chance for snow in the middle of the torch haha.

[ThunderSleetDreams]

All I want for Christmas is an EPO flip.

https://www.esrl.noaa.gov/psd/forecasts/reforecast2/teleconn/images/4indices.png

I like the looks of that. PNA falling back towards neutral indicates a Plains trough while the falling EPO indicates a building NW North American ridge. The changing NAO also is a sign of activity. This is the type data to watch vs model runs at this range.

Heck those indices would suggest a semi torch right now and we are talking low 60s with a chance for snow in the middle of the torch haha.

Modoki Ninos are my quan.

[Brent]

No more Christmas snow miracle across Texas (even Houston) in the 12Z GFS run...

Was Houston ever even in consideration?

Yes, in the 6Z GFS run yesterday for CHRISTMAS DAY (not this week). GFS had snow down to the upper TX coast. ...not that it was likely to happen.

Maybe someday....

[TheProfessor]

Don't lose hope DFW fam. As I said, the placement of this low is very important. There's going to be a sharp cutoff with this system when it comes to snow. So if the low ends up 25 miles in any direction from forecast, it can end up a pretty big forecast buster. The time frame is now approaching on the HRRR, it's been further west than the WRF models, but it seems to favor their stronger storm solution(on the 12z and 18z runs) . It's probably time to stop using the global models and even the 12 km NAM. Instead the WRF, HRRR, 3km NAM, and RAP should be use to try to pin down where the low will end up.

[Quixotic]

All I want for Christmas is an EPO flip.

https://www.esrl.noaa.gov/psd/forecasts/reforecast2/teleconn/images/4indices.png

I like the looks of that. PNA falling back towards neutral indicates a Plains trough while the falling EPO indicates a building NW North American ridge. The changing NAO also is a sign of activity. This is the type data to watch vs model runs at this range.

Heck those indices would suggest a semi torch right now and we are talking low 60s with a chance for snow in the middle of the torch haha.

Yep. I like it. It’s on a separate page but the AO is going to go negative as well and for Texas, that’s much more important than the NAO. If we keep getting bowling balls we will cash in ala 2009-10 and 1963-64 and 1977-78.

I did a cluster K means analysis based on projected teleconnection indices that were most likely and 63-64, 76-77 and 09-10 came up for each month. Other years were 65-66 and 86-87 (oddly enough).

77-78 was a beast but it didn’t really get going until after Xmas.

[Ntxw]

All I want for Christmas is an EPO flip.

https://www.esrl.noaa.gov/psd/forecasts/reforecast2/teleconn/images/4indices.png

I like the looks of that. PNA falling back towards neutral indicates a Plains trough while the falling EPO indicates a building NW North American ridge. The changing NAO also is a sign of activity. This is the type data to watch vs model runs at this range.

Heck those indices would suggest a semi torch right now and we are talking low 60s with a chance for snow in the middle of the torch haha.

Yep. I like it. It’s on a separate page but the AO is going to go negative as well and for Texas, that’s much more important than the NAO. If we keep getting bowling balls we will cash in ala 2009-10 and 1963-64 and 1977-78.

I did a cluster K means analysis based on projected teleconnection indices that were most likely and 63-64, 76-77 and 09-10 came up for each month. Other years were 65-66 and 86-87 (oddly enough).

77-78 was a beast but it didn’t really get going until after Xmas.

This period in general is a warm spell across the continent, cooler across the south. We just happen to have a freak strong storm crossing the region.

[Yukon Cornelius]

URGENT - WEATHER MESSAGE
National Weather Service Norman OK
252 PM CST Wed Dec 12 2018

...High Wind Watch in Effect for Thursday...

OKZ027-039-045-TXZ090-131200-
/O.NEW.KOUN.HW.W.0007.181213T1200Z-181214T1200Z/
Grady-Stephens-Jefferson-Clay-
Including the cities of Chickasha, Tuttle, Duncan, Waurika,
Ringling, Ryan, and Henrietta
252 PM CST Wed Dec 12 2018

...HIGH WIND WARNING IN EFFECT FROM 6 AM THURSDAY TO 6 AM CST
FRIDAY...

The National Weather Service in Norman has issued a High Wind
Warning, which is in effect from 6 AM Thursday to 6 AM CST
Friday.

* WINDS...North 30 to 40 mph with gusts up to 60 mph.

* TIMING...Thursday morning through Friday morning.

* IMPACTS...Travel will become difficult, particularly for high
profile and larger vehicles on east-west highways. Lightweight
items may be blown around. Reduced visibility may occur due to
blowing dust.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A High Wind Warning means a hazardous high wind event is expected
or occurring. Sustained wind speeds of at least 40 mph or gusts
of 58 mph or more can lead to property damage.

60mph gusts

[bubba hotep]

00z 12K NAM running... Bone dry over DFW through 36 hrs lol....

[Brent]

00z 12K NAM running... Bone dry over DFW through 36 hrs lol....

a foot in that same area east of Abliene I'm a little surprised the bullseye literally has not moved really yet

DFW barely even gets rain

[bubba hotep]

00z 12K NAM running... Bone dry over DFW through 36 hrs lol....

Same story with 3k NAM and 36 hr HRRR...

[rwfromkansas]

Unbelievable. Now not even rain? Nuts. Will see what things look like tomorrow.