Texas Winter 2013-2014

[TrekkerCC]

Wow it's cold! That wind makes it so much worse.

Anyway 850mb 0c is actually advancing a lot more than I thought. I wonder If the cold air is going to be deeper and puts out more sleet the models depicted, I certainly hope so! And also the freeze line is going much further south than we probably expected it's at the doorstep of northern-central Texas...impetus for Austin?

It might get dicey if you have to leave work later than 6pm

Good Morning Ntxw and everyone.

I was checking the model forecast soundings from yesterday afternoon (GFS) and yesterday evening (NAM) with the 12z FWD sounding. The FWD sounding and the model soundings do generally match up, but the FWD sounding is a little colder 10C is the warmest temperature of the "warm tongue" compared to around 13C to 14C on the model soundings. I do think that along with advancing deeper cold air coming from the north and slightly cooler atmospheric column, we could see a quicker transition to sleet. The precipitation will still start out as freezing rain, but I could see a sleet transition by early morning Friday. GFS 06z kept us in the bulls-eye for heavy precipitation, but the 06z NAM is less bullish.

[gboudx]

Morning email from jeff:

Powerful arctic cold front entering SE TX this morning.

Increasing potential for significant ice storm across N and NE TX Friday-Sunday with SE TX on the southern edge of the event

Arctic boundary has entered the area this morning with College Station now at 53 degrees and Houston at 72. Upstream observations are 37 at Dallas, 15 at Amarillo, and -10 at Denver. Front is making good southward progress and will be through the metro area before noon and offshore by mid afternoon. Temperatures will fall 20-25 degrees with the frontal passage and continue to cool quickly into the 40’s by afternoon possibly upper 30’s NW. Do not expect much rainfall with the front, but chances for rain will increase overnight into Friday.

Main portion of this forecast will be on the potential for freezing rain and freezing drizzle across the area Friday-Sunday and low temperatures next week.

1. Temperatures: Models continue to show slightly colder conditions as is usually the case with such shallow arctic air masses. This places near/sub-freezing surface temperatures across our NW counties as early as 300-400am Friday morning (College Station to Huntsville). Expect very little is any warming on Friday as cold air advection process continues to bring frigid air southward off the central plains and across extensive ice formation over N TX. May see temperatures hold steady in the 32-35 range all day Friday over our NW and N counties and in the upper 30’s to lower 40’s across the rest of the area. By Friday evening the freezing line will progress southward likely reaching a Hempstead to Conroe line overnight into Saturday morning. Highs on Saturday may stay very near freezing from Hempstead to Conroe northward. Saturday night into Sunday the freezing line moves southward again possibly reaching a line from Columbus to Tomball to The Woodlands. Many areas will fall into the 30’s tonight and not rise above 40 until maybe Sunday. Good news is that cloud cover will keep overnight lows in the upper 20’s NW to mid-upper 30’s coast.

2. Precipitation and Type: Forecast soundings show a classic overrunning situation with shallow cold air ranging anywhere from 900ft to nearly 2000ft deep across the region with a significant warm layer above that due to south winds riding up and over the surface cold dome. This supports a freezing rain profile with liquid rain falling out of the warm layer aloft and then freezing on contact forming a layer of ice. This will only work if the surface temperature is at or below freezing….otherwise it is all rain. The profiles do not support sleet or snow with such warm air aloft. In fact one item to keep in mind is that the rain drop will actually likely be slightly warmer than the surface air temperature due to its descent through such a warm layer aloft so even if the surface temperature is 32 it may be hard to get ice to form. Disturbances moving NE across the area will determine the best time periods for rainfall across the region…but expect amounts to be generally light.

Think there is at least a decent chance of freezing rain/drizzle over our NW counties as early as Friday and continuing into Sunday…this is mainly NW of a line from Brenham to Huntsville. Each night with the southward advance of the freezing line, the potential shifts SE for both Saturday and Sunday mornings and possibly includes the N and NW portions of Harris county, much of Montgomery County, Waller County, and portions of Austin County.

3. Ice Accumulations: Ice will only form if the air temperature is 32 or lower at the surface. Think the best rain chances will be from midnight tonight until about noon on Friday when most of the area should be above freezing. As temperatures fall to the freezing point, rainfall should be on the decrease in intensity mainly just light rain and drizzle. Accumulations of ice from Friday evening –Sunday morning of .01 to .05 of an inch will be possible NW of a line from Brenham to Conroe to Livingston and this will mainly be on elevated surfaces such as trees and power lines. Could see a few icy bridges in this area also especially by Sunday morning as the pavement cools over time. Further southward the threat is much more conditional as the rain must fall in the short window when the temperature may be near freezing which reduces accumulation. Any light ice accumulation north of a line from Columbus to Tomball to The Woodlands would be in the trace to .05 of an inch and mainly on Saturday morning for a few hours and again on Sunday morning.

4. Impacts: Do not see much if any issues with trees and power lines across the area…although those NW continues will have to be watched closely as accumulations of up to .10 of an inch could begin to cause some widely scattered outages and downed tree limbs. Ground temperatures are warm so it will take time for the air mass to cool the pavement to the freezing point allowing ice formation on elevated surfaces (bridges and overpasses). Do not think there will be any problems on Friday. By Saturday morning a few bridges could have some ice in the College Station to Huntsville area and then by Sunday morning north of a Brenham to Conroe line. Again we are talking very light amounts, but freezing drizzle is one of the worst types of winter weather as it produces a very thin layer of ice on the pavement that almost appears dry. Right now think Harris County will not have ice formation on bridges and overpasses, but it could be close on Sunday morning N and W.

Uncertainty: As with all winter weather events in this area, there is always a degree of uncertainty as the difference of 1 degree can make the difference between rain and ice. Determining the exact freezing line location at any given time is fairly difficult, yet that determines where the rain/ice line will be. This is a moving target at this point and even during the event.

Winter Storm Warning/Ice Storm Warning area (N and NE TX):
Across N into NE TX conditions will be much worse with a significant ice storm expected from late tonight-Sunday. Surface temperatures in the mid to upper 20’s with liquid rain falling and freezing on contact is about as bad as an ice setup you can get. Rainfall amounts in this region may reach 1.0-1.25 inches with ice accumulation of .25 to .50 of an inch resulting in widespread heavy ice formation on trees and power lines. Ice accumulation will be more than enough to down large tree limbs and power lines resulting in potential widespread and prolonged power outages. Travel even on surface streets will be difficult if not impossible. This will be a prolonged event with temperatures falling below freezing tonight and likely not rising above freezing until sometime toward the middle of next week.

Next Week Cold:
Secondary arctic surge will arrive into the region Monday. Models continue to advertise extremely cold air moving southward with the 32F line pushing toward the coast and the 0F line reaching toward the Red River. With skies likely clearing, the setup will be for bitter cold conditions by Tuesday morning. Could see hard freeze criteria (25 or lower for 3 hours) north of I-10 by Tuesday morning. This is still a ways out and there could be some changes to the amount of cold that moves southward, but with a good snow cover over the central plains and N TX covered in ice, this air mass will not moderate much. Something to keep an eye on as this would require pipes to be protected across our region.

[wxman57]

I put together a series of meteograms for Houston, Austin and the D-FW area using both the 6Z NAM and 6Z GFS. Both models are colder than yesterday's runs. The GFS indicates the 0C 850 mb line reaching D-FW during the day on Saturday with precip that afternoon. That would mean some snow flurries. Tomorrow's event is all freezing rain and sleet, though. NAM indicates similar 850mb temps, but no precip in Dallas-Ft. Worth on Saturday.





Temps in Houston in the 30s with rain, but Harris County extends way to the NW of the city, so that NW tip could see a little freezing drizzle/rain. Not where most of the people live, though. Note that the GFS has temps below 50 in Houston over the next week. Time to move farther south...





As for Austin, the GFS and NAM disagree on the timing of the two precip events tomorrow & Saturday. The NAM has just one event tomorrow evening, with temps 2-3 deg colder than the GFS. Such an event would produce some significant freezing rain in Austin-proper (lunch for Portastorm?). GFS disagrees, however, having only very light precip tomorrow with temps above freezing. For Saturday, the GFS indicates temps below freezing with precip, but very light amounts.

[Ntxw]

Well we can start using the HRRR and it sets up a heavy band of precip that pretty much crawls from just east of San Angelo to the Metroplex. The NAM would be in deep water if that verified as temps begin to fall to freezing.

[DonWrk]

The HRRR usually does a fantastic job.

[orangeblood]

12z NAM goes towards the GFS bringing over 1/2 half precip across DFW. Much more serious scenario, bringing the lesser option off the table

[Ntxw]

Yep the metroplex will likely be paralyzed tomorrow. Best advice is to stay home and don't put yourself in danger.

[sooner101]

I wonder if the NWS will issue an ice storm warning for DFW? Counties in southern Oklahoma are under one, and east of DFW.

[RedRiverRefuge]

Just had a brief shower pass over the Refuge in far north Fannin county. Yup got glaze of light ice on the foliage and it froze QUICK. A little sampling of things to come. Just wanted to say, once that freezing rain starts things will go from good to bad quickly IMHO

[DonWrk]

If the precip values are there then this thing will get bad in a hurry.

[vbhoutex]

Wxman57, how likely, if at all, do you think it is that SE TX/Houston metro will see the air column wet up enough to drop the temps enough for us to Wintry precip in our area? BTW, how far South are you thinking of moving? LOL!!!

[ThunderSleetDreams]

I'm very confident that Montgomery, Waller, Brazos, Walker and Trinity counties are going to see ice accumulation.

Brazos County looks particularly dicey early a.m. tomorrow.... around the 4 a.m. mark. I think Brazos will go straight to a Winter Storm Warning and the other counties will go to a Winter Weather Advisory or Winter Storm Watch.

As srain said, wouldn't surprise me to see Harris County get a WWA.

[TheProfessor]

Is there a chance of ponds freezing in Denton county

[Longhornmaniac8]

GFS 0Z had Austin warming back up late in the day today from a daily low of 44 after the initial surge to 48...it's already 38 here and dropping. I'm starting to get worried.

[ThunderSleetDreams]

Models handled temps poorly, but that's expected.

[Tireman4]

Track the front...it is moving....


http://www.wunderground.com/wundermap/

[lukem]

Things are deteriorating pretty quickly here in Midland. I woke up around 6:30 this morning and the temperature was right around freezing with a light mist. We started getting a light wintery mix around 7:30, and when I went to turn my car on it already was covered in a layer of ice. It was 29 degrees when I left my house and 24 by the time I reached the office with a moderate to heavy wintry mix. It looks like it is mostly freezing rain at this point with a little sleet and snow mixed in.

[Tireman4]

Interesting. HGX has predictions of Freezing Precipitation for me....hummm....


Today A 30 percent chance of showers after noon. Areas of fog before 10am. Otherwise, cloudy, with a temperature rising to near 72 by 11am, then falling to around 61 during the remainder of the day. West wind 10 to 15 mph becoming north in the afternoon.
Tonight Showers likely. Cloudy, with a low around 35. North wind 10 to 15 mph. Chance of precipitation is 60%.
Friday Rain or drizzle before 9am, then showers after 9am. High near 45. North wind around 15 mph, with gusts as high as 20 mph. Chance of precipitation is 80%.
Friday Night A chance of rain before 4am, then a chance of rain or freezing drizzle. Cloudy, with a low around 34. North wind around 15 mph, with gusts as high as 20 mph. Chance of precipitation is 30%. Little or no ice accumulation expected.
Saturday A chance of rain or freezing drizzle before 3pm, then a chance of rain. Cloudy, with a high near 38. North wind 10 to 15 mph, with gusts as high as 20 mph. Chance of precipitation is 50%. Little or no ice accumulation expected.
Saturday Night A chance of rain before midnight, then a chance of rain or freezing rain. Cloudy, with a low around 34. Chance of precipitation is 50%.
Sunday A chance of rain or freezing rain before 8am, then a chance of rain showers. Mostly cloudy, with a high near 46. Chance of precipitation is 30%.

[Meteorcane]

The SREF ensembles give about an equal probability for sleet and freezing rain for Dallas at about 09z tomorrow, this appears to be right as the heaviest of the precip moves through, so impacts could vary considerably depending on which variables.

http://www.spc.noaa.gov/exper/sref/fplu ... YP=roadmap

[TeamPlayersBlue]

Driving to Austin today, my concern is, i wont have an opportunity to get back to Houston. I dont mind staying till about Sat morning in Austin as i have many friends there, but i dont want to be stuck till monday