Texas Winter 2013-2014

[TheProfessor]

It is now 51 degrees here in roanoke. With nne winds of 15 mph

[katheria]

Shows about .25-.3 QPF in the metroplex.. About 10% more than the last run...

thanks joshkeety,
its already 1 hr past my bedtime...early early mornings for me.

ill read in the morning when i get up

have a good night guys/gals ( if there are any other gals )

[South Texas Storms]

According to the NWS office in Houston, the front is moving slightly faster than expected. It's now expected to arrive here in College Station around daybreak instead of late morning.
From the HGX evening update AFD: "AT 7 PM...A STRONG COLD FRONT EXTENDED FROM NEAR PARIS TO ABILENE TO NORTH OF MIDLAND. THE FRONT CONTINUES TO MAKE STEADY PROGRESS SOUTH AND WILL LIKELY CROSS MOST OF THE CWA ON THURSDAY MORNING. THE 00Z NAM 12 AND RAP13 GUIDANCE SUGGESTS THAT THE COLD FRONT WILL CROSS COLLEGE STATION AROUND 12Z AND WILL CROSS HOUSTON AROUND 15-16Z AND OFF THE COAST BY 21Z. WILL TREND TEMPS COOLER ON THURSDAY WITH A FASTER DROP ON THURS MORNING."

[joshskeety]

FYI guys.. The 21z SREF says the 0z NAM is on crack.. Has the bulk of the precip just on and north of the Metroplex with close to .7 QPF..

[Texas Snowman]

I thought ULLs usually result in a colder air column from top to bottom, typically resulting in more snow than frozen rain. You can still have big pockets of warm air above the service with an ULL passing over?

Well the GFS actually moves the ULL further north so it's mostly overrunning but you never know with those things. They usually go further south than predicted and create forecasting nightmares. SE TX/SW LA is ULL/coastal train capital of the south it seems

Just to add something ... I think it is also important to point out that often in winter in Texas when an upper-level low traverses the state, we see coastal surface low development somewhere off the Texas coast. Sometimes those coastal lows, if close enough and if the boundary layer temperatures (surface temps) are cold enough, can produce wintry precip in south central, east central, or southeast Texas. Seen it happen a number of times over the years.

That can also "steal" moisture away from North Texas storms, particularly in areas to the west and northwest of DFW.

I've seen some highly advertised storms for my area - Grayson County - fizzle as the radar lights up south and east of here.

I remember a Thanksgiving snowstorm back in the 1980s that was supposed to bring several inches here. It didn't because of the coastal low and where it developed. The heavy snow band was quite a bit further east (Paris to Texarkana and into Arkansas) as that coastal low moved towards the Mississippi Valley.

[Portastorm]

Good point. Yep. I've seen that happen as well. The interplay between ULLs and coastal troughs/lows can be fascinating, bring joy, or crushing heartache!

[Ntxw]

Shifting the focus on the 0z NAM run down south a little, I'm noticing it's a bit colder and wetter for south central Texas. Not only is the expanse of freezing rain a bit larger on Friday morning for my area but the NAM pops up freezing rain again Saturday morning and the 18z and 12z NAM runs weren't nearly this aggressive in this area. Should be interesting to watch if it is an anomaly or a model trend.

You need to keep close tabs on the system coming down later this weekend in association with the 2nd Arctic front on Monday since we are so focused on the immediate storm. That is some mighty vorticity and the models up to this point have ejected it into the central plains which I have a hard time believing given the cold air is already in place, it's going to keep going south, not a wimpy system either.

Edit: Where it goes there will likely be a trowal/comma head, it looks like a classic blizzard with the front.

[texas1836]

52 degrees in McKinney and windows wide open.

[joshskeety]

Shifting the focus on the 0z NAM run down south a little, I'm noticing it's a bit colder and wetter for south central Texas. Not only is the expanse of freezing rain a bit larger on Friday morning for my area but the NAM pops up freezing rain again Saturday morning and the 18z and 12z NAM runs weren't nearly this aggressive in this area. Should be interesting to watch if it is an anomaly or a model trend.

You need to keep close tabs on the system coming down later this weekend in association with the 2nd Arctic front on Monday since we are so focused on the immediate storm. That is some mighty vorticity and the models up to this point have ejected it into the central plains which I have a hard time believing given the cold air is already in place, it's going to keep going south, not a wimpy system either.

I think this is why the NWS has continued the keep POP chances for later in the weekend even though the models are bearish about it.. I have seen this set up a million times here in Texas where on the backside of arctic air the models show nothing, but keep RH in place and moisture, but little to no QPF then all of a sudden boom.. I would agree big time on this..

[Texas Snowman]

:uarrow:

Good point. Yep. I've seen that happen as well. The interplay between ULLs and coastal troughs/lows can be fascinating, bring joy, or crushing heartache!

The storm I remember the most for that occurrence was a big 1980s snow event where nearly a foot of snow fell near West (six inches fell in Waco, similar amounts fell in portions of East Texas).

It was a January storm (it was the same week that the Air Florida plane crashed into the frozen Potomac River in D.C.) that was supposed to deliver a few inches here in North Texas, particularly around DFW.

Instead, due to the coastal low development, the heavy snow set up in Central and East Texas. The next day, it snowed 14" in Memphis where my grandparents lived.

A huge snow event for some, but not a single flake here in Grayson County.

[Kludge]

Well, you will have cooling due to the upper level system coming in at the mid-levels. However, the depth of cold air near the surface is very shallow. There will be a warm tongue at about 5,000ft in the air. When you have very dry atmospheric column and then precipitation falling into it, you can get cooling due to the effects of evaporation of precipitation in very dry air. However, the column will already be saturated from the top down and little or no evaporative cooling will take place, so no cooling from evaporative processes will occur to cool the "warm nose".

Do chances for wintry excitement increase if there is a warm tongue at the mid levels instead of a warm nose?

But seriously folks, regarding the ULL discussion... it is noteworthy that there was a very distinct line between all-rain and all-snow in the pre-Thanksgiving event as the ULL passed over the Huntsville area. I'll bet Huntsville would've seen 1/2" of snow had the ground temp been sub-freezing. Areas just a few miles either side of Huntsville hardly saw anything frozen falling.

[Ntxw]

While we await the GFS, check out temperatures in Wyoming. This is early December...it's Canada cold. Even Ms Screamer would respect that.

[joshskeety]

While we await the GFS, check out temperatures in Wyoming. This is early December...it's Canada cold. Even Ms Screamer would respect that.

Nuts...... lol

[Portastorm]

Evening forecast discussions out of NWS San Angelo and NWS Midland/Odessa indicate that the cold front is ... big shocker here ... several hours ahead of schedule.

And, per some discussion from NWS D/FW ... they're going to be upping precip (i.e. ice) totals for northeast Texas due to the latest computer model information. Looks like this could be a crippling ice storm for our friend aggiecutter and those in NE Texas.

[joshskeety]

At the same time the FTW is saying the front stalled for a bit and most of the arctic air is just now coming out of Oklahoma.. So the front got here quicker, but stalled up.. Still think it will be ahead of schedule on its final push..

[joshskeety]

From FTW...

THE INITIAL FRONTAL BOUNDARY HAS BEEN SLOW TO PROGRESS SOUTHWARD...
AND AT NIGHTFALL...IT REMAINS DRAPED ACROSS THE DALLAS/FORT WORTH
METROPLEX. THE ARCTIC AIR IS STILL IN OKLAHOMA...BUT PRESSURE RISES
THERE SUGGEST THE AIR MASS WILL DEEPEN AND BEGIN SURGING SOUTHWARD
THIS EVENING. METROPLEX TAFS BEGIN WITH NORTH WINDS...SPEEDS
INCREASING AFTER MIDNIGHT WHEN THE ARCTIC AIR ARRIVES.

[Ntxw]

At the same time the FTW is saying the front stalled for a bit and most of the arctic air is just now coming out of Oklahoma.. So the front got here quicker, but stalled up.. Still think it will be ahead of schedule on its final push..

This is correct. Analysis just above the surface shows the wind shift and change in air mass reached a DFW to Abilene line and stalled for a time. The freezing line push is advancing quickly now out of Oklahoma and is about to cross the Red River.

http://www.spc.noaa.gov/exper/mesoanalysis/new/archiveviewer.php?sector=15&parm=925mb

[Snowman67]

:uarrow:

Good point. Yep. I've seen that happen as well. The interplay between ULLs and coastal troughs/lows can be fascinating, bring joy, or crushing heartache!

The storm I remember the most for that occurrence was a big 1980s snow event where nearly a foot of snow fell near West (six inches fell in Waco, similar amounts fell in portions of East Texas).

It was a January storm (it was the same week that the Air Florida plane crashed into the frozen Potomac River in D.C.) that was supposed to deliver a few inches here in North Texas, particularly around DFW.

Instead, due to the coastal low development, the heavy snow set up in Central and East Texas. The next day, it snowed 14" in Memphis where my grandparents lived.

A huge snow event for some, but not a single flake here in Grayson County.

I lived in Waco back then. I believe it was 1980 or 1981 when that occurred. Remember missing two days of school. Measured close to 7 inches of snow at our house.

[gboudx]

Email from Jeff

Arctic boundary moving southward this evening. Currently Amarillo is at 23 with Austin at 62. Boundary not surprisingly running a bit quicker than expected as is so common with these shallow dense cold air masses.

Will already have the boundary into our NW counties by sunrise and metro Houston by midday and to the coast by mid afternoon or about 3-5 hours faster than expected this morning. This will result in colder conditions on Thursday afternoon with widespread 40’s overtaking the area by sunset.

Other issue continues to be dense sea fog over the coastal areas and Gulf waters/bays as warm moist air flows over the cool shelf waters. Galveston has been bouncing around 1 mile visibility most of the afternoon and evening and expect some of this fog to spread inland over the next few hours possibly reaching US 59 SW of Houston and I-10 east of Houston.

Last issue is freezing rain and ice potential for parts of the area starting Friday evening and continuing into Sunday. Models have come in colder today with low temperatures now expected to fall into the upper 20’s over our northern counties Saturday morning and just barely get above freezing on Saturday in those areas. This supports freezing rain potential into our area starting Friday evening from College Station to Huntsville and possibly as far south as Brenham to Conroe by Saturday morning. Model QPF amounts look to be on the light side in the range of .01 to .05 of an inch and this would mainly be on elevated surfaces, but it does not cause much to result in slick bridges…in fact freezing drizzle is usually the worse type of freezing precipitation as is produces a very thin layer of ice which almost appears dry.

Things could get a little more interesting Saturday night with the freezing line further south in the area and slightly better rainfall production suggesting more potential for accumulation especially across our northern counties.

Note:
Winter Storm and Ice Storm Warnings have been issued for N and NE TX starting late Thursday for significant accumulations of ice (.25-.50 of an inch). This will have major impacts on surface travel N or our region starting early Friday and potential for significant disruption of power and heavy vegetation damage. SE TX will be on the southern edge of the more significant ice accumulation.

[Ntxw]

The GFS is not as forgiving as the NAM. It still has axis of very heavy precip on the I-30 corridor and keeps DFW in a long duration of freezing rain ending as sleet.