Texas Winter 2021-2022

[wxman57]

You know it's been a bad night of model runs when you check in late night and the last post was at 8:00 pm by rhe Heat Miser lol

Yep, and the first post in the morning is from me. The NAM's "icemageddon" is fading away, and the HRRR indicates only a small area of sleet in the Hill Country and heavier sleet in far south TX. Euro does indicate about an inch of snow in the D-FW area next Wednesday. However, the ECMWF is alone in that forecast.

[Haris]

Well we got a watch buts it’s overkill given the lack of agreement and overall trends. 12 HRRR was step in right direction (for winter weather lovers) but outlier

[txtwister78]

[url]https://i.ibb.co/Qc5HDWn/0-EAD5061-6743-4-FC0-8-CA0-A237-DAAEBD0-D.jpg [/url]


Well we got a watch buts it’s overkill given the lack of agreement and overall trends. 12 HRRR was step in right direction (for winter weather lovers) but outlier

Agree on the overkill but we've seen time and time again these "events" overperform anytime you have disturbances/energy coming out of Mexico so my guess is the NWS is keeping that in mind just to be safe. They did indicate in their overnight discussion however that this would likely be changed to a winter weather advisory.

Right now trends have been highest from San Antonio points south. The air in the HC is going to be bone dry (negative dewpoint readings per some of the models Thursday afternoon) and so my guess is the precip won't be heavy enough to even reach the ground up in that region unless something changes.

[gboudx]

From jeff for you STX folks.

Mixture of winter precipitation will be possible over much of SE TX Thursday night.

Forecast Changes:
Expansion of the potential of rain, freezing rain, and sleet across much of SE TX.

Discussion:
Strong cold front will move across SE TX this evening between 600pm and midnight. Cold modified arctic air mass will surge into the region with temperature falling quickly into the 40’s and then on into the 30’s for most areas by sunrise Thursday. Scattered showers and thunderstorms with the front will end and push offshore. Strong north winds of 25-35mph with gust to 40mph on Thursday will drive wind chills into the 10’s and 20’s over the area. Moisture lingers in the post frontal air mass and an upper level disturbance will approach from the west Thursday into Thursday night. This disturbance will yield lift across the cold air dome which will slowly deepen with time. Model profiles show a fairly stout warm layer above the ground on Thursday morning, but this layer cools and erodes into Thursday evening resulting in the potential for a transition of light rain to sleet or even a few flurries.

Main questions continue to be how quickly the surface freezing line can progress southward Thursday evening and how quickly does the moisture depart the area. The freezing line will progress southward Thursday evening, but how much it will overlap with falling precipitation is the key for any light accumulation amounts. Think areas along a north of a Wharton to Pearland to Liberty line may see a mixture and transition from rain to rain/sleet mix or light freezing rain. Trajectory of this cold air mass is more toward SC TX so expect the freezing line to advance quickly southward to our west over the coastal bend and even S TX while it will only slowly move southward over SE TX… it will likely be colder in Victoria and Corpus Christi than Houston on Thursday night.

Impacts:
It does not take much accumulation of freezing rain/drizzle to cause issues on bridges and overpasses, but very warm conditions today should help to mitigate accumulations on Thursday night as ground temperatures will likely only cool to the upper 30’s by that time additionally, surface temperatures only cool toward 31-35 which is generally marginal for ice formation on bridges and overpasses. The higher bridges and flyovers have the best ability to cool toward the air temperature and thus have the best potential for any light accumulations. Light accumulations (trace-.01) of an inch of ice may occur on elevated surface such as trees, powerlines, rooftops, and vehicles. Really not thinking there will be much accumulation as what falls will be light and surface temperatures likely very marginal.

Winter Storm Watches have been issued to the west and southwest of SE TX where the potential for ice accumulation is higher and temperatures 2-3 degrees colder. May see a winter weather advisory or winter storm watch for portions of SE TX (Matagorda Bay area) later today or early Thursday.

Monitor forecasts closely for changes…a reduction of surface temperatures 1-3 degrees over SE TX or precipitation lingering longer on Friday morning would result in higher potential for accumulations especially on bridges and overpasses.

[jaguars_22]

Looking at the IR of the pacific there is a big clump of moisture heading this way. Idk I still think this storm over performs and the icy mess spreads out more

[orangeblood]

Long range guidance continues to remain consistent on keeping the Negative EPO in place through February and in turn below normal temps for most of the lower 48.

[wxman57]

12Z HRRR & NAM continue to back away from "icemageddon". Just a few spots of sleet with the HRRR and the NAM only has significant sleet in the lower RGV. I think the NAM is still way overdoing it there. The air across Kansas and Nebraska just isn't that cold. Simply bring the air southward to sea level dry adiabatically would mean adding 20 deg to Amarillo's temp (32+20=52) and 15 deg to OKC's temp (39+15=54). Both areas will have colder temps tonight, but that may just barely get SE TX to 32-34F with a warm layer aloft over a very shallow sub-freezing layer. Sleet would be possible, but no accumulations.

[jaguars_22]

WXMAN does this include Victoria? Or could I see some icy roads here?

[Iceresistance]

Friday morning is expected to be bitterly cold, with KFOR has a low of 10°F, 0z CMC goes down to 5°F, 0z CMCE has a mean low temperature of between 5°F & 9°F in Oklahoma. But I'm thinking down to the Lower Teens right now.

[wxman57]

WXMAN does this include Victoria? Or could I see some icy roads here?

There could be a very thin layer of sub-freezing air up around 1000 ft or so. Surface temperatures will likely be well above freezing, though. Could see a few sleet pellets mixed in with the rain tomorrow night. They should quickly melt.

[Iceresistance]

Wind Chill Watch in effect for Southern Texas.

[Portastorm]

Looking at the IR of the pacific there is a big clump of moisture heading this way. Idk I still think this storm over performs and the icy mess spreads out more

FWIW, the Texas Tech WRF model is trending with the HRRR and showing more precip here (south central TX) than what others like the NAM are showing. Tech's WRF model sometimes does a great job. Honestly have no clue how it's been performing lately.

We need to turn this thing around. I'm seeing too many wxman57 posts about "no snow/ice for you." Time to rally the troops against the Heat Miser!

[wxman57]

Looking at the IR of the pacific there is a big clump of moisture heading this way. Idk I still think this storm over performs and the icy mess spreads out more

FWIW, the Texas Tech WRF model is trending with the HRRR and showing more precip here (south central TX) than what others like the NAM are showing. Tech's WRF model sometimes does a great job. Honestly have no clue how it's been performing lately.

We need to turn this thing around. I'm seeing too many wxman57 posts about "no snow/ice for you." Time to rally the troops against the Heat Miser!

HRRR does indicate cold air aloft over Austin with the warm nose just touching freezing. Could yield some snowflakes for you (briefly) tomorrow afternoon.

[jaguars_22]

What is causing all the precip to fall around corpus instead of Victoria? It looks like it all comes together in the Alice area?

[wxman57]

What is causing all the precip to fall around corpus instead of Victoria? It looks like it all comes together in the Alice area?

Front stalls offshore and a low forms on the front east of South TX. This keeps the precipitation confined to coastal counties nearest the low. As the low tracks east across the Gulf, the precip will track eastward along the upper TX and LA coasts.

[TeamPlayersBlue]

The wet bulb temp is below 32F for SE Tx for friday morning. Unfortunately, the models are showing the precip staying further south or off the coast. Key will be where the divergence and the most lift from overrunning occurs.
So in my opinion, whatever falls out of the sky in SE Tx will be wintery, not just a flat rain.

I'm still a bit of a novice on where gulf lows form under certain situations and also have trouble finding data in the models for divergence. These two things are key with the ULL rolling through big bend area. The setup is pretty nice for SE Tx, as long as the cold air is in place. Very similar to 2004 snowstorm, but it was much colder in 2004.

[orangeblood]

Next week looks interesting if the Arctic Front arrives a little sooner, before this stout S/W kicks out of the southwest....Euro starting to go there

[wxman57]

The wet bulb temp is below 32F for SE Tx for friday morning. Unfortunately, the models are showing the precip staying further south or off the coast. Key will be where the divergence and the most lift from overrunning occurs.
So in my opinion, whatever falls out of the sky in SE Tx will be wintery, not just a flat rain.

I'm still a bit of a novice on where gulf lows form under certain situations and also have trouble finding data in the models for divergence. These two things are key with the ULL rolling through big bend area. The setup is pretty nice for SE Tx, as long as the cold air is in place. Very similar to 2004 snowstorm, but it was much colder in 2004.

I've been observing/studying West Gulf Lows (WGL) since the late 1970s. A prerequisite for a WGL is a stalled cold front offshore. Typically, cold air accelerates southward down the TX coast all the way to the Bay of Campeche, trapped by the higher terrain along the coast of Mexico. The same push does not exist off the Louisiana coast. This leads to an east-west oriented front across the northern Gulf and a north-south oriented front from the lower TX coast southward. The bend in this front is the focus for a WGL. As I was taught at A&M, once the 500mb vorticity max reaches west Texas, the WGL forms along the natural bend in the front. As the upper trof progresses east, the WGL strengthens and moves east off the northern Gulf Coast. Steady, moderate precipitation can be expected northwest and north of the low due to isentropic lifting (overrunning). Once the low axis passes, the precip ends. I would add that the models are forecasting this WGL to track a little farther south, which is why precip will be limited across the upper Texas coast. You want the WGL to be close enough to the coast to provide the moisture, but not too close to the coast to cause a significant warm layer aloft. It's a very delicate balance between cold rain and snow, depending on the track of the WGL.

A WGL typically precedes most winter weather events along the Gulf Coast. The strongest WGL I've ever seen occurred on March 12-13 of 1993. This was the "Storm of the Century" (https://en.wikipedia.org/wiki/1993_Storm_of_the_Century). It produced heavy snow along the Gulf Coast all the way to the Florida Panhandle and wind gusts over 100 kts offshore and in a squall line out ahead of it that hit the Florida Peninsula. See the link for more details. As is often the case across south TX and the Gulf Coast in general, we occasionally have cold enough air for snow aloft, but there is no moisture available. If a strong cold front moves offshore but then stalls, a developing WGL can provide the moisture necessary for snow.

We've seen a number of WGLs so far this winter, more than normal. That's why I've said if the air ever gets cold enough this winter then we would have a good chance of a Gulf Coast snow event. So far, the cold air has been too shallow this far south. I can't say whether that will be the case in February, which is a month of most frequent heavy snow events in SE TX. So far, the pattern hasn't been right to push deep enough cold air this far south. It's getting close this week, though.

[Brent]

Next week looks interesting if the Arctic Front arrives a little sooner, before this stout S/W kicks out of the southwest....Euro starting to go there

https://images.weatherbell.com/model/ecmwf-deterministic/central/z500_anom/1642593600/1643090400-5fdNENwMs9Y.png
https://images.weatherbell.com/model/ecmwf-deterministic/central/instant_ptype/1642593600/1643101200-XexLxSNQTnY.png

I really hope so I'm tired of watching snow to the east

At least that weekend storm over there seems to be trending bad for a lot of them

[wxman57]

Next week looks interesting if the Arctic Front arrives a little sooner, before this stout S/W kicks out of the southwest....Euro starting to go there

https://images.weatherbell.com/model/ecmwf-deterministic/central/z500_anom/1642593600/1643090400-5fdNENwMs9Y.png
https://images.weatherbell.com/model/ecmwf-deterministic/central/instant_ptype/1642593600/1643101200-XexLxSNQTnY.png

I really hope so I'm tired of watching snow to the east

At least that weekend storm over there seems to be trending bad for a lot of them

12Z Euro has only a trace of snow for you next Tuesday. GFS is similar or even less with the snow for you next Tuesday. Still 6 days out, though.