Texas winter weather thread - Cold snap next week

[jeff]

SE TEXAS

Dramatic change in weather coming within the next 24 hours.

Numerous Winter Weather Advisories and Winter Storm Watches being issued.

All aspects will be discussed under each sub-heading:

Overall discussion:

Arctic boundary plowing southward this morning and into the TX panhandle. Temp is currently 28 at Amarillo and 70 at Dallas. Front will slow some today as low pressure forms over W TX ahead of deep western US upper trough. Once the low moves ENE tonight the arctic air mass surges southward very fast. As I suspected yesterday the forecast models are too slow with the frontal passage and will speed it up by 3-6 hours indicating frontal passage CLL around 600am and metro Houston between 800am and 1000am and off the coast by noon. Upper trough lags behind the arctic boundary and will bring winter storm conditions to TX on Thursday in the form of freezing rain, sleet, and snow. Incredible temperatures falls will be experienced with the front, with temps. from 68-74 in the morning falling in the mid 30’s by late afternoon with howling NW winds.

Severe Weather Threat:

Per latest SPC outlook most of SE TX will have a risk of severe weather early Thursday ahead of the cold front. Although instability will be lacking, shear profiles are quite supportive of severe weather. Frontal lift this evening along with nosing of polar and sub-tropical jet stream should provide the ingredients to produce a linear MCS over NC and C TX this evening that sweeps SE overnight ahead of the front. Main severe threat will be damaging winds.

P-type Issues:

Upper trough ejects through TX and OK Thursday with a very cold surface air mass in place. Feel current guidance numbers are still too warm given potential for wet bulbing and advecting of sub-freezing temps. southward from N TX. Per model thickness and evaporative cooling aspects across N TX suggest temps. will fall into the mid and upper 20’s with the onset of freezing rain and sleet in this region Thursday morning. This colder air should then be advected southward within strong cold air advection regime over the area. Surface freezing line appears to reach our NW counties by mid afternoon and continues southward into Grimes and Montgomery counties by early evening. Light cold rain may change to freezing rain along and north of a line from Columbus to Brenham to Willis to Lufkin and may mix with sleet by Thursday evening. Ground temps. will remain warm so little to no accumulation is expected on surface roads, however bridges and overpasses along with elevated objects may accumulate a thin glaze of ice. A Winter Weather Advisory may be needed for our northern counties Thursday and will break out the northern 1/3rd county area in the zone forecast at the bottom.


Temperatures:

As discussed above a significant temp. fall is likely. Temps. will fall 15-20 degrees within the first 5-10 minutes of frontal passage and continue to nose dive all day Thursday. Temps. will be into the low to mid 30’s for the evening rush hour with freezing conditions all areas N of I-10 Friday morning.

Wind:

Impressive pressure rises of 6-8mb over a 3hr period on Thursday will result in very strong surface winds. Winds will increase to 25-35mph sustained with gust of 40-45mph behind the front. Wind advisory will be needed inland and coastal counties with gale warnings already up for the offshore waters. Gust to 50mph will be possible downtown where winds are funneled between the tall buildings. Falling temps. and strong winds will result in wind chills in the 20’s and 30’s producing quite the shock to the body.

Marine:

Powerful offshore flow will develop in the post frontal air mass. Strong offshore winds will drive the water out of the northern heads of the bays and inlets. Tides will run 2.5-3.5 feet below normal likely grounding the Lynchburg Ferry. Seas will build 6-8 feet within Galveston and Matagorda Bays and 8-14 feet in the Gulf waters. Strong winds may result in minor tidal buildup along the north sides of Galveston Island and Bolivar as well as Matagorda Island as bay waters are driven southward.

Aviation:

Thursday will be a rough day for air travel as local terminals are blasted with strong low level wind shear. Expected 40-50kts of NNW wind across all terminals by midday. E/W runways will have big problems with the wind. Expect long delays from arriving and departing aircraft from surrounding airports to the N and W as strict de-icing operations will be in progress at multiple terminals as well as sanding of runways where winter precip. accumulates. May need de-icing restrictions at KCLL by Thursday PM.

Travel:

Winter Storm Watches have been issued for a large part of NC and N TX in expectation of significant ice and snow accumulations. 1-3 inches of ice, sleet, snow mixture is expected within the watch areas resulting in glazing of interstates across this portion of the state. Travel to N TX including the DFW metro area will be extremely difficult by midday Thursday as bridges and overpasses become glazed and ice coated. Track of potent upper low will determine how far south and how much ice/snow accumulates across this area of the state and if portions of SE TX will see icing. Sanding operations will be needed at various locations by Thursday midday into Thursday night.

Forecast for Harris and Surrounding counties:

Today: cloudy and warm with a 30% chance of showers late. Near record highs in the lower 80’s. S winds 10-120mph.

Tonight: cloudy, warm and humid with a 40% chance of thunderstorms after midnight. Lows near 70. S winds 10-20mph.

Thursday: cloudy and turning much colder. Temps. falling from near 70 into the mid 30’s by late afternoon. An 80% chance of thunderstorms, some may be severe. S winds shifting to the NW and increasing 25-35mph with gust of 40mph, wind chills falling into the 20’s and 30’s.

For the counties of: Walker, Grimes, Brazos, Burleson, Houston, Trinity, and Polk: A 40% chance of rain possibly changing to freezing rain. Temps. falling to near or below freezing by midday afternoon. Little to no ice accumulation.

Thursday night: cloudy and cold with a 30% chance of light rain and drizzle possibly changing to freezing rain. Lows at or below freezing. NW winds 20-30mph and gusty with wind chills in the 20’s.

For the counties of: Walker, Grimes, Brazos, Burleson, Houston, Trinity, and Polk: cloudy with a 30% chance of light freezing rain possibly mixed with sleet. Lows near 30. Ice accumulation less than 1/10th of an inch.

Friday: clearing skies and cold. Highs near 50. NW winds 15-25mph and gusty.

Friday night: clear and cold. Lows 29-32. N winds 5-10mph

Saturday: sunny and cool. Highs in the low to mid 50’s.

Sunday: partly cloudy and turning windy. Lows near freezing and highs near 50. NW winds increasing 15-25mph and gusty.

[jasons2k]

Hey EWG a request - when you post images can you post static images using, say, imageshack or something? I've been reading thru last night's posts and all TWC temp maps you posted have updated to 9:15AM today....it would also help to have an archive of the threads as well. That way in a year or two if we look back at this event the maps are from today not 2007 or 2008 (or worse, a dead link).

Thanks if you can do this

[jasons2k]

Thanks Jeff for the wonderful synopsis!!

As long as those lows stay in the 29-32 range with this event, I'll be happy. All I'm asking for is for us to NOT have a hard freeze

[Stratosphere747]

Great insight as usual Jeff!

Who needs Joe B, or Ch. 2, 11, 13, 26...

[Tireman4]

Thanks Jeff. As usual you are spot on.

[Portastorm]

Yes, Jeff ... you and your posts are appreciated greatly!

Meanwhile, some of us are still searching the horizon in the hopes that Air Force Met and Wxman57 will join the discussion and offer their excellent insights!

[Kelarie]

What does it look like for the Austin area? I haven't really had a chance to look in detail. Thoughts?

Thanks,
Kel

[Portastorm]

What does it look like for the Austin area? I haven't really had a chance to look in detail. Thoughts?

Thanks,
Kel

Strong storms tonight and blustery tomorrow but no ice or snow. Very windy, cold, showery. Temps (tomorrow) falling into the 40s and 30s by late day. It'll be nasty outside but appears to be much worse further up I-35.

[jeff]

What does it look like for the Austin area? I haven't really had a chance to look in detail. Thoughts?

Thanks,
Kel

Per latest NAM 12Z run...Freezing rain line looks a tad further south but still north of the Austin area. Feel upper low will dry slot most of central TX as the temp falls to freezing or shortly after. There may be a short window for light freezing rain and freezing drizzle, but given very warm ground temps. I can not see much acc.

PER NAM forecast sounding at KFWD showing 1175 ft thick cold dome suggest freezing rain over N TX Thursday AM with the dome deepening to near 2500 ft by mid afternoon.

Still a tough call on winter precip. amounts and locations as freezing line, moisture, and upper support are all critical roles for Thurs. forecast.

[wall_cloud]

front came in to Amarillo around 3 AM. On my last shift (Sunday night), the GFS/NAM were both bringing the front into the area on Wednesday afternoon/evening. shows how much you can trust the guidance on such events. turns out undercutting guidance by a good 10+ degrees was the way to go for sure.

[Tireman4]

Wall Cloud,

Stay warm. What was your temperature drop in the first hour of the frontal passage?

[double D]

What does it look like for the Austin area? I haven't really had a chance to look in detail. Thoughts?

Thanks,
Kel

Strong storms tonight and blustery tomorrow but no ice or snow. Very windy, cold, showery. Temps (tomorrow) falling into the 40s and 30s by late day. It'll be nasty outside but appears to be much worse further up I-35.

Wouldn't it be funny if the track of that low shifted further south and gave the Austin area a little surprise

I think a lot of people will be in for a rude awakening in the afternoon. People will leave in the morning not expecting much and when they come home it will be the 30's with a stiff north breeze.

[Portastorm]

Hey double D .. that's NOT funny!

[double D]

Hmmm.. The new 12z GFS also shifts the freezing rain line further south. This is something new and I hope it does not become a trend.

[Kelarie]

Hmmm.. The new 12z GFS also shifts the freezing rain line further south. This is something new and I hope it does not become a trend.

Hey, don't get my hopes up like that. There would be nothing more than I would enjoy a day off in front of the fireplace with a cup of hot cocoa.

[Portastorm]

Sorry Kel, but I just don't think its going to happen. This time.

double D is right in that the threshold line is further south per the GFS 12z run.

I just tried to look closely at the new 12z run coming in. It seems like that critical 0-degree isotherm for 850mb reaches the I-35 corridor about the time the precip is sweeping out of our area.

[Kelarie]

Hey, let me have my wild thoughts, okay? And yes, I know they are just that, wild.

If I want cold, wintery weather, I need to move.

[rsdoug1981]

Speaking of next week's cold...I awoke to this in my Jackson, MS AFD.

THE FIRST AIRMASS THAT MOVES IN FRI WILL BE A COLD AIRMASS
BUT THIS WILL ONLY SET THE STAGE FOR MON AND TUE NEXT WEEK AS A MORE IMPRESSIVE AND COLDER AIRMASS WORKS SOUTH OUT OF CANADA. THERE ARE SOME IMPRESSIVE THINGS TO NOTE. PLACES IN SOUTHERN CANADA WITH THIS INITIAL AIRMASS ARE SETTING RECORD LOWS(HUNDRED YEAR OLD RECORD LOWS) BUT THE SECOND AIRMASS WHICH IS EXPECTED TO COME OUT OF THE NORTHWEST TERRITORY/YUKON REGION HAS TEMPS DOWN TO AS LOW AS -45. IN ADDITION TO THESE COLD AIRMASSES THERE WILL BE SNOW PACK OVER PORTIONS OF THE PLAINS AND MID MS VALLEY AND THIS IS VITAL TO GETTING THE COLD AIR DOWN HERE. MEX HAS LOWS IN THE MID TO UPPER 20S
FOR MOST OF THE AREA MON AND TUE MORNING AND THAT COULD BE TOO WARM!!! RAW MDL DATA FROM THE GFS IS SHOWING DEWPOINTS IN THE TEENS TO SINGLE DIGITS. WITH THE SECOND AIRMASS MOVING IN...REINFORCING AN ALREADY COLD ENVIRONMENT...OVER SNOW TO OUR NORTH...AND THE HIGH SITTING RIGHT OVERHEAD...WE COULD ACTUALLY SEE A FEW PLACES IN THE NORTH DROP INTO THE TEENS. WITH THAT I WILL ACTUALLY GO BELOW GUI FOR LOWS OVER MOST OF THE FORECAST BUT ESPECIALLY MON AND TUE. I WILL NOT BRING ANYONE BELOW THE LOWER 20S YET BUT WE COULD BE LOWERING LOWS FOR BOTH MON AND TUE SIGNIFICANTLY IN LATER FORECASTS.
ONE THING TO NOTE THE LL TEMPS ARE ON THE VERY COLD END OF OUR
CLIMATOLOGY RECORDS AND WE COULD VERY WELL SET SOME RECORD LOWS.

If I can't have snow, I'll take extreme cold. We'll see how this develops. The GFS is showing some decently cold temps, but the Euro is not quite as optimistic on seeing teens and lower 20s in this part of the world.

[double D]

Hmmm.. The new 12z GFS also shifts the freezing rain line further south. This is something new and I hope it does not become a trend.

Hey, don't get my hopes up like that. There would be nothing more than I would enjoy a day off in front of the fireplace with a cup of hot cocoa.

I did not mean to get your hopes up Kelarie as I also don't think this is our storm to deal with. The season is young and if this keeps up we might have several opportunties to get excited about.

[wall_cloud]

Wall Cloud,

Stay warm. What was your temperature drop in the first hour of the frontal passage?

we were cooling off already since we were already pretty dry at the surface, but we fell from 45 to 33 between obs (between 3 and 4 am). currently at 10 am, we are sitting at 25. so much for the max temp of 43 at the 00Z spit out. we are sitting 15 below under the 15z mav temp from last night. beware of what the model gives you.