Texas/New Mexico/Louisiana/Mexico Obs And Discussion Thread Part 5

[bubba hotep]

Ice on grass, but not on sidewalks or streets yet here at the house. 

[bubba hotep]

MESOSCALE DISCUSSION 2061   NWS STORM PREDICTION CENTER NORMAN OK   0628 PM CST THU DEC 05 2013   AREAS AFFECTED...WRN INTO NRN TX...SRN AND SERN OK   CONCERNING...WINTER MIXED PRECIPITATION    VALID 060028Z - 060530Z   SUMMARY...AREAS OF FREEZING RAIN AND SLEET WILL PERSIST THIS EVENING   IN A BROAD ZONE FROM SW TX INTO ERN OK...WITH SNOW DEVELOPING LATER   THIS EVENING ACROSS NWRN TX AND SWRN OK.   DISCUSSION...AS COLD AIR CONTINUES TO ADVANCE SWD OVER TX AND INTO   THE ARKLATEX...ISENTROPIC LIFT WILL PERSIST N OF THE SURFACE FRONT   WITH AREAS OF WINTER PRECIP AHEAD OF AN EMERGING NM SHORTWAVE   FEATURE.   PRIOR TO THE ARRIVAL OF THE AFOREMENTIONED SHORTWAVE WHICH WILL MOVE   ACROSS NW TX/OK LATER TONIGHT...TEMPERATURES ALOFT WILL BE RATHER   STAGNANT BENEATH A SWLY FLOW REGIME ALOFT. AS SUCH...CURRENTLY   OBSERVED PRECIPITATION TYPES ARE EXPECTED TO REMAIN LARGELY   UNCHANGED FOR THE NEXT SEVERAL HOURS...WITH FREEZING RAIN FROM SJT   NEWD ACROSS THE METROPLEX AND INTO SERN OK.   A WINTRY MIXTURE WILL PERSIST FROM NWRN TX INTO SRN OK AND INTO NWRN   AR. HOWEVER...COOLING PROFILES WILL OCCUR LATE   EVENING/OVERNIGHT...WITH PRECIP TURNING TO SNOW FROM NWRN TX INTO   CNTRL AND NERN OK.   ..JEWELL.. 12/06/2013

[1900hurricane]

Pretty prototypical freezing rain sounding out of FWD.

 

[bubba hotep]

Yep, been waiting on that all afternoon, was holding out hope for mostly sleet tonight. It looks like the 18z GFS backed off on the precipitation totals overnight but still has nearly an 1" in a lot of areas.

[Ed Lizard]

Breaking on KXAS-TV 5 site- I suspect this is overpass icing related...

 

 

 

A crash in Grapevine, reportedly involving several cars, has blocked a portion of state Highway 121. 

The Grapevine Fire Department and Grapevine Police Department confirm that several vehicles were involved in a crash along the southbound lanes of state Highway 121.

Authorities have shut down the ramp to southbound 121 N onto eastbound Interstate 635.

There were 15 vehicles reportedly involved in the crash.

No injuries have been reported related to the crash.

 

[Quixotic1]

Yep, been waiting on that all afternoon, was holding out hope for mostly sleet tonight. It looks like the 18z GFS backed off on the precipitation totals overnight but still has nearly an 1" in a lot of areas.

I wouldn't give up hope on it just yet. The last time i checked outside it was all sleet. Dallas Addison is reporting snow. Not sure about that one.

[bubba hotep]

I wouldn't give up hope on it just yet. The last time i checked outside it was all sleet. Dallas Addison is reporting snow. Not sure about that one.

 

I thought I saw snow just now but just chalked it up to "mist" and not really being snow.

 

ETA: Nope, it is snow!

 

ETA II: 

Explanation from FWD to explain reports of sleet and snow:

 

000

FXUS64 KFWD 060119

AFDFWD

AREA FORECAST DISCUSSION

NATIONAL WEATHER SERVICE FORT WORTH TX

719 PM CST THU DEC 5 2013

.UPDATE...

PRIMARY REASON FOR THE EARLY UPDATE WAS TO START THE WINTER

WEATHER ADVISORY EARLIER...NOW AT 10PM...ACROSS THE SOUTHERN

ZONES. VERY COLD AIR NEAR THE SURFACE CONTINUES TO SPILL SOUTH

THROUGH THE REGION AND NEAR FREEZING TEMPERATURES ARE ALREADY

REACHING THE WACO AREA NOW. PRECIPITATION WILL CONTINUE TO DEVELOP

TO OUR SOUTHWEST AND CURRENT SATELLITE LOOP SHOWS COOLING CLOUD

TOPS ACROSS THE BIG BEND REGION AS THE NEXT SHORTWAVE APPROACHES.

PRECIPITATION ALREADY COVERS MUCH OF THE NORTHWEST HALF OF THE

REGION AND SHOULD FILL IN ACROSS THE SOUTHERN ZONES AFTER 10PM.

ALTHOUGH A HALF INCH OF LIQUID QPF IS EXPECTED ACROSS THE ADVISORY

AREA TONIGHT...A LOT OF THIS WATER WILL RUN OFF BEFORE FREEZING AS

SURFACE TEMPERATURES WILL NOT BE QUITE COLD ENOUGH FOR A MAJOR ICE

EVENT THERE. STILL BRIDGES AND OVERPASSES ARE EXPECTED TO BE

TREACHEROUS IN THE MORNING ACROSS THE ADVISORY AREA.

00Z UPPER AIR SOUNDING SHOWS THIS COLD AIR IS VERY SHALLOW...WITH

TEMPERATURES WARMING TO NEAR 8C AT 7000FT. THIS IS ENSURING THAT

ALL PRECIPITATION GENERATED IS RAIN AT THIS LEVEL...BUT AS IT

FALLS INTO THE COLDER AIR NEAR THE SURFACE IT IS COOLING BELOW

FREEZING. IN THE REGION WHERE THIS COLD LAYER CONTAINS

TEMPERATURES BELOW -8C WE ARE SEEING SPONTANEOUS ICE NUCLEATION

WHICH IS RESULTING IN THIS RAIN BECOMING SLEET OR SIMPLE SNOW

STRUCTURES LIKE SINGULAR COLUMNS OR NEEDLES. A LITTLE LESSON ON

WHAT IS GOING ON IS THAT PURE RAIN DROPS REMAIN LIQUID AT TEMPS

WELL BELOW FREEZING BECAUSE THEY DONT KNOW HOW TO SETUP THE ICE

CRYSTAL STRUCTURE WITHOUT SOME HELP. THIS HELP IS USUALLY IN THE

FORM OF WHAT WE CALL AN ICE NUCLEI...SUCH AS A POLLUTANT OR POLLEN

PARTICLE...OR MOST OFTEN ANOTHER ICE CRYSTAL SHARD. RESEARCH SHOWS

THAT AT ABOUT -8C A SMALL PERCENTAGE OF THE DROPS HAVE THE

APPROPRIATE ICE NUCLEI AND BEGIN TO FREEZE...WHILE IT IS NOT UNTIL

-10C THAT MORE THAN 50 PERCENT OF WATER DROPS CAN FREEZE. ONCE

ONE WATER DROPLET FREEZES IT CAN SPLINTER INTO SEVERAL MORE AND

THIS ENDS UP TEACHING MANY OTHER NEARBY SUPERCOOLED DROPS HOW TO

FREEZE AS WELL. SO THE POINT IN ALL OF THIS IS WE ARE SEEING

MANY REPORTS OF SLEET MIXING IN WITH THE FREEZING RAIN NOW BECAUSE

THE -8C LINE HAS REACHED SHERMAN TO DFW TO COMANCHE LINE. NEAR

THIS LINE WE ARE SEEING SLEET AND RAIN CHANGING BACK AND FORTH AS

IT IS ESSENTIALLY RANDOM CHANCE AS TO WHETHER ICE NUCLEI ARE

PRESENT IN A PARTICULAR AREA TO TEACH SUPERCOOLED DROPS HOW TO BE

IN THE ICE PHASE. FARTHER NORTHWEST WHERE THE AIR IS A BIT

COLDER...IT IS MOSTLY SLEET NOW AS THE CHANCE FOR ICE PHASE

ACTIVATION IS MUCH HIGHER. MORE SLEET IS OBVIOUSLY GOOD NEWS FOR

MITIGATING DAMAGES TO TREES AND POWER LINES. THE BAD NEWS IS THAT

SLEET IS MORE EFFECTIVE AT COOLING ROAD TEMPERATURES TO WHERE ICE

WILL BEGIN TO FORM.

HAVE UPDATED THE FORECAST TO INCREASE SLEET ACCUMULATION TOTALS

TO A HALF INCH AND LOWER ICE ACCUMULATIONS TO 1/10 TO 1/4 INCH IN

THE NORTHWEST ZONES. HAVE ADDED QUARTER TO HALF INCH SLEET

ACCUMULATION ALONG THE AFOREMENTIONED -8C LINE BUT HAVE RETAINED

THE FORECAST OF QUARTER TO HALF INCH ICE ACCUMULATION TOTALS.

AGAIN WE ARE VERY CONCERNED ABOUT THE POTENTIAL FOR HEAVY

ICING...TREE DAMAGE AND POWER OUTAGES FOR

DENTON...GRAYSON...COLLIN...FANNIN...LAMAR AND NORTHERN TARRANT

COUNTIES WHERE MUCH OF THE PRECIP WILL STAY FREEZING RAIN AND

TEMPERATURES WILL BE IN THE MID TO UPPER 20S FOR OPTIMAL ICING.

AS THE UPPER LEVEL SHORTWAVE APPROACHES THE AREA AROUND MIDNIGHT

MID LEVEL INSTABILITY WILL INCREASE OVER THE AREA. IT APPEARS THAT

THE INTENSITY OF THE PRECIPITATION WILL PICK UP...WHICH MAY

FAVOR MORE OF A TRANSITION BACK TO ALL FREEZING RAIN AS RAIN DROPS

WILL FALL FASTER THROUGH THE SUB FREEZING LAYER IN THE LOWER

LEVELS AND NOT GET AS COLD TO FREEZE. THERE MAY BE ENOUGH ELEVATED

INSTABILITY IN THE MID LEVELS FOR ISOLATED LIGHTNING STRIKES TOO.

TR.92

[jhamps10]

if this keeps up there's going to be some major power issues in northern Tarrant county I believe.. the Ft Worth Mixmaster at 35W and 30 is a solid sheet of ice and has been since 6 or so

[bubba hotep]

We are back to a freezing rain / sleet mix

 

ETA:  Collin County has filled in on radar and Dallas Count is getting close

[jhamps10]

just heard on Fox 4 of another 15 car pileup on I-20 at the east 820 split, including where a person fell over the bridge... not good at all.. in my part of SW Ft Worth/Benbrook it's switching back and forth between sleet and freezing rain... if it goes to all freezing rain it could get really ugly down here I believe. So far the main problem has been the bridges and overpasses so far, mainly because it was nearly 80 yesterday.. just think how bad it would have been on the roads etc if it was cold all week...

[DFWWeather]

Temperatures are hovering around 29 to 32 across the immediate DFW Metroplex with little room for wet bulbing. That is not cold enough to ice over all roadways. Temps need to drop to 24 to 26 for that to occur and precipitation rates must pick-up, especially sleet to help cool the roadways.

[David Reimer]

Temperatures are hovering around 29 to 32 across the immediate DFW Metroplex with little room for wet bulbing. That is not cold enough to ice over all roadways. Temps need to drop to 24 to 26 for that to occur and precipitation rates must pick-up, especially sleet to help cool the roadways.

 

I don't know if you've been monitoring reports or not, but we have a ton of roads already icing up across D/FW. The sleet we've got going on and had earlier helped freeze the roads up (or get them cold enough) to support ice from freezing rain. We've got multiple 15+ car accidents in Tarrant county and western Dallas county has iced up big time since 8:30 PM. 

[jhamps10]

I don't know if you've been monitoring reports or not, but we have a ton of roads already icing up across D/FW. The sleet we've got going on and had earlier helped freeze the roads up (or get them cold enough) to support ice from freezing rain. We've got multiple 15+ car accidents in Tarrant county and western Dallas county has iced up big time since 8:30 PM. 

 

the large majority of accidents though have been on bridges and overpasses so far however, I feel that the roads will be a disaster by morning too but it being 80 yesterday really saved our butt in the metroplex from the roads being a disaster for the PM rush.. 

[DFWWeather]

I don't know if you've been monitoring reports or not, but we have a ton of roads already icing up across D/FW. The sleet we've got going on and had earlier helped freeze the roads up (or get them cold enough) to support ice from freezing rain. We've got multiple 15+ car accidents in Tarrant county and western Dallas county has iced up big time since 8:30 PM. 

 

No I haven't been monitoring too closely, but most reports I've heard about are just bridges and overpasses. I'm talking primary and secondary roadways with a solid sheet of ice, not slush. That is the only way I can get out of work tomorrow. Typically temps really need to get below 28°F for this to occur after readings near 80°F the day before.

[jhamps10]

No I haven't been monitoring too closely, but most reports I've heard about are just bridges and overpasses. I'm talking primary and secondary roadways with a solid sheet of ice, not slush. That is the only way I can get out of work tomorrow. Typically temps really need to get below 28°F for this to occur after readings near 80°F the day before.

 

by morning we'll be there, once that heavier batch out by Abilene gets into the metroplex they'll get bad and in a hurry i feel.

[DFWWeather]

by morning we'll be there, once that heavier batch out by Abilene gets into the metroplex they'll get bad and in a hurry i feel.

 

I hope your right! Not necessarily, because there is no more room hardly for the temperature to drop. That was my point. If precipitation rates get heavier as freezing rain, it will bring some of the warmer air aloft down to the surface and temps may actually rise a degree or two. In this scenario the primary and secondary streets will largely stay wet.

[bubba hotep]

Yeah, we have been stuck at 29 all evening but the 26 degree line isn't too far north of here.

 

ETA:  Lol, up to 31 since that post...

 

ETA II: Warm nose FTW again? Car is ice free after being caked in ice a bit ago, warm rain is winning now

 

ETA III: rain has slacked up some and car is icing back over

[NTXYankee]

Yeah, we have been stuck at 29 all evening but the 26 degree line isn't too far north of here.

 

ETA:  Lol, up to 31 since that post...

 

ETA II: Warm nose FTW again? Car is ice free after being caked in ice a bit ago, warm rain is winning now

 

ETA III: rain has slacked up some and car is icing back over

I got worried about the same thing here in Lewisville being around 32, however big sleet storm right now covering ground and pavement.

[bubba hotep]

I got worried about the same thing here in Lewisville being around 32, however big sleet storm right now covering ground and pavement.

 

That is showing up nicely on radar with some really heavy returns over that area. I'm not so interested in watching frz but would like to see some heavy sleet.

 

ETA: we topped out at 31.6 but are now back down to 31, IMBY

[DFWWeather]

It is now 32°F at DFW with a dewpoint of 30°F. This storm is a dud for the heart of the Metroplex. The streets will just be water in the morning. Temperatures cannot fall anymore with heavier precipitation. They need to fall below 28°F for several hours for the secondary and primary roads to ice.

[Ed Lizard]

It is now 32°F at DFW with a dewpoint of 30°F. This storm is a dud for the heart of the Metroplex. The streets will just be water in the morning. Temperatures cannot fall anymore with heavier precipitation. They need to fall below 28°F for several hours for the secondary and primary roads to ice.

 

 

Depends on how one defines 'dud'.

 

Texas Storm Chasers

12:20 AM UPDATE: Heavy freezing rain and sleet are moving into the D/FW Metroplex from the southwest. Oncor reports over 23,500 customers without power in North Texas and this number will continue to rise rapidly as ice continues to accumulate. We've still got several hours to go in this event and it's going to get worse. I've got an update on the current situation at http://www.texasstormchasers.com/?p=23404. -DavidR ‪#‎txwx

 

‬

[1900hurricane]

Here's how I analyzed the freezing line from the latest obs (at least as best as I could on my phone). Most of the precip area is below freezing at the surface.

 

[msp]

temp and td actually rising here.  35/32 at 1am; precip likely to begin within a couple hours

[SnowGoose69]

It is now 32°F at DFW with a dewpoint of 30°F. This storm is a dud for the heart of the Metroplex. The streets will just be water in the morning. Temperatures cannot fall anymore with heavier precipitation. They need to fall below 28°F for several hours for the secondary and primary roads to ice.

 

Its now changed over to PL in DFW that will ice things up very fast.

[DFWWeather]

Its now changed over to PL in DFW that will ice things up very fast.

 

Yes, completely iced over now in Arlington. Temperature of 28°F. I guess the H85 front helped dropped the temperature?

[bubba hotep]

Lots of pingers mixing in and 31, radar looks like there is still a lot of moisture left to work through the area, but yeah, seems like temps are staying just "warm" enough across a lot of the metroplex

 

ETA: maybe not, DFW airport is at 28 and it looks colder temps are slowly sagging in across the area

 

[Quixotic1]

school and work closed. back yard is covered in ice and sleet. icicles hanging from the house. so far this winter: winter precip: 1 warm nose: 1.

[aggiegeog]

Warmth is holding in East Texas. Downgraded to a winter weather advisory for a mix if temps drop as expected. Areas west of here are not so lucky though.

[Srain]

Morning Update form Meteorologist Jeff L (Harris County Flood Control District):

 

Damaging ice storm in progress over N TX this morning.

 

Potential for light ice accumulations over SE TX today into Saturday.

 

Winter Weather Advisory issued for: Brazos, Burleson, Grimes, Houston, Walker, Madison, and Washington Counties until 300pm today

 

N/NW/NE TX Ice Storm:

Crippling ice storm in progress overnight over this part of the state. Dallas has been reporting freezing rain and sleet for the last 12 hours with temperatures in the mid to upper 20’s. Abilene has reported freezing rain with a temperature of 19 which is just insane. Nearly everything that is falling over this area is freezing on contact forming a now thickening layer of ice and sleet. Widespread power outages are already in progress over this region with 150,000 outages reported and this is going to be going up quickly this morning as trees and power lines are at their breaking point. Travel even on surface roads has become nearly impossible in the warning areas with TXDOT crews unable to keep enough sand on the roadways to keep them open due to the heavy nature of the falling precip. Moderate to at times heavy freezing rain will continue for the next several hours over this part of the state with ice accumulations reaching between .50 -.75 of an inch possibly an inch in some areas which is going to be devastating to the above ground power system. Temperatures are forecast to drop dangerously low by Saturday morning over this part of the state (10-18F) and likely remain at or near freezing into early next week keeping ice and power issues ongoing for several days.  

 

SE TX:

Temperatures have fallen only a few degrees since last evening over the area and range from 34-35 NW to 37-39 Houston to 39-43 along the coast. Light rain has develop over parts of the area this morning, but surface temperatures remain warm enough to keep it from freezing. The College Station sensor has been reporting freezing rain…but this is incorrect with an air temperature of 34. Temperatures may drop another degree or tow today across our NW counties as cold air advection across the ice coated N TX draws some colder air southward. Some very light ice on elevated surfaces would be possible in the mentioned advisory area…but think this is very marginal and most bridges/overpasses will be ok. Rain and drizzle is falling from a very warm layer about 3000-5000ft above the surface with temperatures in the 50’s so the liquid is actually fairly warm and 31-32 will likely not cause much freezing. As noted overnight the biggest problems have been where surface temperatures have dropped to the mid and upper 20’s.

 

Tonight-Saturday:

Better potential for the surface temperature to fall to or below freezing across the northern ½ of the area (roughly north of I-10) by Saturday morning. Not looking at much rainfall tonight, but moisture begins to increase on Saturday ahead of another disturbance aloft moving into from the SW. Given very warm conditions aloft and warm ground conditions with very marginal freezing surface temperatures (30-32) this still does not look to be any significant ice potential. With that said could see some minor ice accumulations on Saturday into Saturday evening over areas north of I-10 with a few icy spots on bridges and overpasses. Expect amounts to range from a trace to .05 of an inch, but it should be made very clear that even .01 of ice on a bridge is potentially dangerous and especially so when they appear dry and in fact have frozen over from freezing drizzle. Freezing drizzle is about the worse winter precipitation as people tend not to exercise caution on bridges as they appear dry but will have a very thin layer of very slick ice. Think a winter weather advisory will be issued later today and may include portions of Harris County and areas N and W for the potential for minor ice accumulation Saturday into Saturday night. Temperatures will fall into the mid 30’s tonight and hover between 30-34 all day Saturday.

 

Sunday-next week:

Cold arctic dome remains locked in place and a secondary surge arrives around Monday keeping the entire state very cold. Lows will continue to be at or below freezing through the period over portions of the area with highs not much above 40-45 each day. Jet stream remains active and shows potential for more bouts of precipitation early next week…again could be dealing with some mixture of P-types depending on cold air depth and surface temperatures.

 

Will update again this evening.

[Srain]

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE FORT WORTH TX
704 AM CST FRI DEC 6 2013

...PRELIMINARY SLEET / FREEZING RAIN ACCUMULATIONS AS OF 7 AM...

LITTLE ELM 3.5
DECATUR 2.5
SHERMAN2.0
DENISON2.0
KELLER1.8
GRANBURY1.5
HURST1.5
FORT WORTH1.5
RICHARDSON1.0

THIS DATA IS NOT COMPLETE AND WILL BE UPDATED THROUGHOUT THE DAY.