Texas Winter 2017-2018

[cctxhurricanewatcher]

From Ryan Maue:

Ryan Maue | weather.us
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8 hours ago


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Bit colder than usual in Siberia over next few days. Watch some stations like Oymyakon for -70°F

Perfect bike weather for Wxman57

[orangeblood]

Yes there is a risk it happens too far south for DFW. Past couple of NAM runs have not been as wet as the globals in general.

Let’s all hope the CMC is the only sane model currently. (Not likely but it’s all we got!)

Nam's runs have been unfavorable for TX as a whole. More lift a few thousand miles away in states east northeast[/quote

Precip appears to be plentiful for Texas, it's just further south across central and south Texas

[stormlover2013]

Yeah nam not good for us in Texas really, could be a dud

[gpsnowman]

What is the cause of the moisture being pushed south? Is the front coming in too quickly for North Texas?

[Ntxw]

Let’s all hope the CMC is the only sane model currently. (Not likely but it’s all we got!)

Nam's runs have been unfavorable for TX as a whole. More lift a few thousand miles away in states east northeast[/quote

Precip appears to be plentiful for Texas, it's just further south across central and south Texas

Compared to the globals it hasn't been that bullish for the state as whole. Yes there is some further south but its not as the globals. Austin is mostly a mix. Only a narrow band just north of there centered between there and hillsboro as some snow on eastward

[srainhoutx]

Sunday morning briefing from Jeff:

Winter Weather threat increasing across TX this week

Mixture of rain/freezing rain/sleet/snow across much of TX Tuesday and possibly again on Thursday

Mixture of rain/freezing rain/sleet potential increasingly across SE TX (N of HWY 105 on Tuesday)

I will start with the emphasis that any winter weather event in this area is low confidence and things will almost certainly change over the next 24-48 hours…residents should remain updated on changes to the forecast and possible impacts to travel both locally and across the state.

Discussion:
Very cold arctic air mass is on the move this morning and will surge southward across TX on Monday. Front will move off the coast late Monday with temperatures falling in the post frontal cold air advection. Freezing line will surge southward early Tuesday and likely reach our northern counties (College Station to Livingston) around sunrise on Tuesday. Freeze line may continue to build southward into the morning hours on Tuesday approaching the HWY 105 corridor while most of the rest of the region falls into the mid and upper 30’s under strong N winds. An upper level disturbance will approach and move across the region in the post frontal air mass on Tuesday and Tuesday evening. This feature will induce southerly winds over top of the surface cold dome result in an overrunning situation and the likely formation of precipitation across the region. Given the deepening cold air across the region nearly every P-type may be in play initially as rain and then changing to freezing rain (HWY 105 northward) Tuesday morning and then mixing with sleet and possibly snow during the afternoon hours as the air column cools. South of HWY 105 surface temperatures may remain a few degrees above freezing which would prevent freezing rain, but as the air column cools the rain may mix with sleet/snow. South of I-10 surface temperatures will likely remain well above freezing resulting in mostly rain with maybe some mixed in sleet.

It should be clearly noted that much of the forecast for Tuesday greatly hinges on surface temperatures and how far south the freezing line progresses as this will determine where any freezing rain and ice accumulation may occur. It is important that residents understand the uncertainty in a 48 hour temperature forecast and that only 1-2 degrees could make the difference P-type over a particular location and potential ice accumulations on bridges and overpasses.

P-type:
Forecast soundings show a warm layer of air above the surface cold dome on Tuesday which supports a rain or freezing rain setup. For freezing rain the surface temperatures must fall to 32 or below so it becomes critical where the freezing line establishes. Freezing rain is liquid water that falls into a shallow sub-freezing layer near the surface and freezes into ice on contact with “freezing” objects such as tree limbs, bridges, roofs, power lines, vehicles. During the day the surface cold layer will deepen and this may allow a mixture of rain/freezing rain/sleet across portions of the area…mainly N of HWY 105. Think snow is least likely given that the warm nose aloft only slowly erodes and will favor sleet over snow in this setup. Won’t rule out snow Tuesday afternoon and evening if the moisture lingers long enough for the air column to cool…think this is most likely N of HWY 105.

Accumulations:
Appears some degree of accumulation of ice will be possible on Tuesday especially in the corridor from Lake Somerville to Huntsville where surface temperatures will likely be below freezing much of the day. South of this line any ice accumulation will depend on the surface temperature falling to 32 or below. Travel across central TX into the W/NW portions of SE TX may become hazardous on Tuesday and into Tuesday night. Should have a better idea of any ice accumulation amounts later today into Monday.

Tuesday Night:
Very cold arctic air mass will entrench across the area with most locations falling into the 20’s. Disturbance will begin to pull E of the region allowing drying northerly winds to shut off precipitation. Upglide does continue into the evening hours around Matagorda Bay and may see the rain change over to freezing rain as the surface temperatures fall below freezing with some ice accumulation possible around the Victoria area NNE toward Colorado and Wharton Counties especially on bridges and overpasses. Will need to monitor how quickly the dry air advects into the region as this could either end or extend the precipitation over the region on Tuesday evening.

Additionally, any remaining residual water on bridges and overpasses may freeze. Will need to watch the southern progression of the freeze line Tuesday afternoon and evening for freezing of any leftover water which could remain in place into Wednesday morning.

Thursday:
Cold arctic high pressure cell will begin to slowly retreat toward the east, but another disturbance will approach the region late Wednesday into early Thursday. Appears this disturbance could cause another round of mixed precipitation over the region. For now this event is still far out and will not attempt to determine any sort of P-type or accumulations…just making everyone aware and to pay attention.

Key Messages:

· Cold arctic front will arrive late Monday with temperatures falling into the 30’s on Tuesday

· A mixture of freezing rain/sleet/snow will be possible from Lake Somerville to College Station to Huntsville on Tuesday with some accumulation possible

· A mixture of rain/freezing rain/sleet/snow will be possible N of HWY 105 Tuesday with little to no accumulation currently expected

· Houston metro area should see mainly rain possibly mixed with sleet Tuesday afternoon…no accumulation currently expected

· Travel to central and north Texas on Tuesday will become hazardous…plan accordingly

· Lows Wednesday morning likely in the 20’s for many areas with wind chills in the teens

Uncertainty:

· Where the surface freezing line is located or how far southward it may move on Tuesday

· How much moisture will linger post front which determines the amount of precipitation and accumulations

· How long precipitation may linger in Tuesday evening as the freezing line progresses southward

[Ntxw]

Here is the 6z Nam without sleet or freezing rain

[Ntxw]

Here is the 12z NAM

[Ralph's Weather]

Here is the 12z NAM

That is generally what i am expecting the snow map to look like, maybe a touch more. Happy to see the NAM coming around. Sorry WF area this does nkt appear to be your event and DFW is iffy but should see a dusting to an inch especially on the east side.

[srainhoutx]

Both the 12Z 32 and 12km NAM suggests a travel nightmare across the Metro San Antonio/Austin areas possibly extending into to the West and NW areas of Metro Houston. Precip ends around hour 60 or so along the Coast, so we probably need another 24 hours to fine tune the sensible weather forecast and the potential travel impacts. That said each new NAM run seems to suggest more and more precipitation which is troublesome for the freezing rain/sleet possibilities across the Hill Country and S Central Texas.

[Texas Snow]

That is generally what i am expecting the snow map to look like, maybe a touch more. Happy to see the NAM coming around. Sorry WF area this does nkt appear to be your event and DFW is iffy but should see a dusting to an inch especially on the east side.

Yuck

[Shoshana]

Both the 12Z 32 and 12km NAM suggests a travel nightmare across the Metro San Antonio/Austin areas possibly extending into to the West and NW areas of Metro Houston. Precip ends around hour 60 or so along the Coast, so we probably need another 24 hours to fine tune the sensible weather forecast and the potential travel impacts. That said each new NAM run seems to suggest more and more precipitation which is troublesome for the freezing rain/sleet possibilities across the Hill Country and S Central Texas.

Yikes! I’ll need ice skates to get to and from work Tuesday!

[wxman57]

Whew! Just got back from an early-morning bike ride (sleeveless jersey/shorts). Wanted to get back to the house before it got too hot (above 40). Looking at all the data, here's what I'm thinking about Tuesday's event. I think that the DFW area will see SOME snow. Accumulations most likely between a trace and 1/2 inch. Wouldn't rule out up to an inch, but moisture still looks limited that far north.

For Portastorm & others in the Austin area, the front moves through early Tuesday morning. Temperature drops below freezing at the surface before sunrise. However, there will likely be an above-freezing layer aloft between 4000-7000 ft. With most of the precip column in above-freezing air, this points to precip starting out as light rain then changing to freezing rain and sleet. By 9am, temps at the surface will be well below freezing with moderate precip falling. The above-freezing layer will be around 5000-7000 ft but the precip column is deeper, meaning more sleet than freezing rain. By noon, most of that warm tongue aloft is gone but the moisture and precip are trailing off. I think the precip will finish up as snow there, but if models are correct, that warm layer aloft won't allow for much in the way of accumulations. More moisture than in the DFW area, but warmer aloft. Less than an inch of snow in Austin.

Here in Houston, cold rain is most likely. Quite a warm tongue aloft, much more so than Austin. This is NOT a snow setup for Houston. Freezing rain, if anything.

[South Texas Storms]

12z German ICON model is much wetter and snowier across a large part of TX. Snowiest run yet. I've been pretty impressed with this model so far. Curious to see how it performs with this event.

[Ntxw]

12z German ICON model is much wetter and snowier across a large part of TX. Snowiest run yet. I've been pretty impressed with this model so far. Curious to see how it performs with this event.

It looks a lot like the CMC and Euro. I wonder why it doesn't show sleet or ZR in the graphics?

[Captmorg70]

This looks like a big bummer for north of DFW Seems like we have had a lot of cold this winter up this way, but can’t get any precipitation

[dhweather]

The NAM is unfavorable for the Metroplex. Unfortunately I believe it will verify. Moisture is very limited, and the cold air is working against us drying the column.

[Ntxw]

This looks like a big bummer for north of DFW Seems like we have had a lot of cold this winter up this way, but can’t get any precipitation

It's only one model. You shouldn't hang your hat on it too much. The best advised way is to blend the guidance. And as earlier in the season, it hasn't happened yet to verify

[gpsnowman]

12z German ICON model is much wetter and snowier across a large part of TX. Snowiest run yet. I've been pretty impressed with this model so far. Curious to see how it performs with this event.

Deutschland Uber Alles!!!!

[downsouthman1]

12z German ICON model is much wetter and snowier across a large part of TX. Snowiest run yet. I've been pretty impressed with this model so far. Curious to see how it performs with this event.

Deutschland Uber Alles!!!!

Ich liebe das.