A high impact winter storm is headed for Texas and will affect most of the population centers around the state. What we can expect for Houston remains a watch and wait with increasing confidence that ice and maybe some snow is on the way.
What we know:
The National Weather Service has issued a Winter Storm Watch for Austin, San Antonio, areas south of Dallas and into Shreveport. This Winter Storm Watch or Winter Weather Advisory is likely to be expanded to the south and east to include parts of the Houston area and areas as far south as Corpus Christi.
A Winter Storm Watch means winter storm conditions are possible with major travel impacts within 36 hours. If this is upgraded to a warning, then winter storm conditions are expected within 24 hours and significant travel impacts are likely.
A Winter Weather Advisory means that minor travel impacts from freezing rain, sleet or snow are possible in the advised area.
An arctic front will plow through the Houston area very early on Tuesday morning. Temperatures throughout the day will tumble with many areas falling to near freezing by early afternoon.
In an unusual development, precipitation will linger behind the front allowing for a transition from rain to sleet/freezing rain to eventually some snow. Any frozen precipitation is expected to remain fairly light with light accumulations possible.
What we don't know:
A lot. We're not totally sure about the dominate precipitation type (freezing rain, sleet or snow) or how much accumulations (if any) we can expect and where.
While the atmosphere will be cooling throughout the day Tuesday to allow for a transition from rain to frozen precipitation, when that occurs and how much we can expect remain a mystery.
All indications at this time indicate that the rain may begin to mix with sleet/freezing rain as early as noon for downtown Houston with the biggest winter storm impacts coming from ice and not snow. However, these details are almost guaranteed to change as the event gets underway.
TIMING
Areas north of town including College Station, Huntsville, Madisonville and points north may see the transition from rain to ice to snow very early in the morning, before 6 a.m. Travel impacts will be most severe in these areas as they will spend the most time below freezing.
The transition line to sleet/freezing rain and snow will shift south throughout the day reaching a Woodlands, Tomball, Sealy line as early as 9 a.m. and downtown Houston around noon and eventually reaching the coastal counties by 7 p.m.
Accumulations:
Accumulations, per the National Weather Service will be possible area wide -- even at the coast -- with the main accumulations coming from ice totaling less than one tenth of an inch. While this will be enough to glaze area roadways and bridges, it won't be enough to bring down power lines or trees. Travel will become hazardous by Tuesday noon for most areas -- especially those north of Highway 105 in Conroe.
While a transition to snow will be possible, even in Houston, the biggest snow chances will remain north of the Houston metro area with the best chance of accumulating snowfall occurring across the northern counties into the Piney Woods.
As we saw with the December 7th/8th snowfall where the forecast called for a dusting but most ended up with 2 to 3 inches (5 inches in College Station!), there always tends to be a surprise with these winter weather events. As with anything, any banding that sets up could result in much higher accumulations in localized areas. If the air is colder than forecast or moves in faster than models indicate, that could equate to a more impactful event for southeast Texas.
State Wide Travel:
Travel Monday evening into Tuesday will become very dangerous across San Antonio, Austin and Dallas with many area roadways becoming slick with ice. It is strongly advised that any travel north and west of Houston be postponed until later in the week.
Locally, we too could see icing issues on area roadways but how much remains to be seen.
In a nut shell:
-A high impact winter storm is becoming more likely for the hill country of central Texas.
-Impacts on Houston may prompt a Winter Weather Advisory or Winter Storm Watch by Monday morning for the area
-Ice will be the main impact on area roadways around Houston with more significant accumulations the further north you are.
-Currently, less than a tenth of an inch of ice could accumulate around the area with the best chance being north of Highway 105.
-The best chance of any snow or snow accumulations will be in the northern counties where the cold air is deepest and coldest. A quick transition to snow in Houston can't be ruled out, either.
-Some travel impacts can be anticipated in Houston with crippling driving conditions towards Austin, San Antonio and points northward.
