Texas/New Mexico/Louisiana/Mexico Obs And Discussion Thread Part 6

[bubba hotep]

39 and raining at a rate of an inch an hour.

This first wave seems be over performing with 1"+ falling in places. Still think we rack up some nice sleet totals tonight, even with the 18z NAM & GFS cutting totals back. The energy kicking out is kind of messy and likely not being handled properly by the models.

[Captmorg70]

This first wave seems be over performing with 1"+ falling in places. Still think we rack up some nice sleet totals tonight, even with the 18z NAM & GFS cutting totals back. The energy kicking out is kind of messy and likely not being handled properly by the models.

Yea it's looks like the NAM and GFS didn't handle this 1st wave well.

[Srain]

The models have underestimated the temperatures by about 4-6 degrees too warm and did not pick up on the disturbance feeding moisture in from the SW of the Baja Peninsula where a blow up of tropical convection has developed this afternoon. It will be interesting to see if the guidance picks up on this feature in the overnight runs into 12Z tomorrow.

 

[Srain]

Evening briefing from Jeff:

 

Winter Storm heading for much of TX

 

NWS has issued a Freezing Rain Advisory for ice accumulations of .03-.07 of an inch from 600pm Monday until 900am Tuesday for the following counties: Burleson, Madison, Houston, Brazos, Washington, Grimes, Walker, Montgomery, Trinity, Polk, San Jacinto, and Liberty.

 

Arctic cold front plowing southward across TX this afternoon with 78 at BUSH IAH and 19 in Amarillo to 21 in Lubbock. Temperature in Lubbock is running about 3-4 degrees colder than what model guidance suggested and temperatures over N TX including DFW are running about 3 degrees colder at this time than expected. In fact numerous reports of light to moderate sleet is already being reported across N TX about 3-5 hours earlier than expected. General model consensus continues to indicate surface freezing line making good progress into the area late Monday afternoon and evening off the sleet and ice covered land of N TX. Forecast soundings show strong warm air advection above the surface cold dome with temperatures nearing 50 degrees a couple thousand feet above the surface. This will limit P-type to rain or freezing rain across the region and make the most critical forecast element the surface air temperature.

 

Current indications is that the freezing line will extend southward along and north of a line from Columbus to Waller to Conroe to Cleveland overnight Monday into early Tuesday with light freezing rain and freezing drizzle along and north of this line. Elevated objects such as trees, power lines, and bridges/overpasses will likely accumulate a thin glaze of ice potentially resulting in hazardous travel in the advisory counties.

 

Freezing line could move a little bit more southward than currently expected and impact Austin, Waller,  and north/west Harris (Katy to Jersey Village to Kingwood). Current thinking is that these areas may just touch 32 for a few hours with some patchy ice possible. Only 1-2 degrees of additional cooling will make a big difference in this area between ice and no ice…so temperature trends will need very close monitoring on Monday, but this could also be offset by the current warm ground temperatures and warm bridge/overpass temperatures. Not very confident at exactly what temperature ice may form on bridges and overpasses given the recent warmth…experience last year suggested temperatures needed to fall into the 29-30 degree range…but that was also with pre-treatment solution applied.  

 

Freezing Rain/ice accumulation (>.01 of an inch) threat probabilities:

http://www.hpc.ncep.noaa.gov/pwpf/wwd_accum_probs.php?fpd=24&ptype=icez&amt=1&day=1&ftype=probabilities

 

Decision Support Matrix:

 

Burleson, Houston, Madison, Walker, Trinity, San Jacinto, Polk:

                Ice Accumulation: .03-.07 of an inch

                Timing: 600pm Monday-1000am Tuesday

                Temperatures: 28-30 degrees

                Winds: NNE 10-15mph

                Confidence: high

 

                Transportation: anti-ice operations likely

                Education: delays and cancellations possible

                Aviation: anti-ice operations likely

                Power: isolated outages possible

 

Brazos, Grimes, Washington, Montgomery, Waller, northern Liberty:

Ice Accumulation: .03-.05 of an inch

                Timing: 1000pm Monday-1000am Tuesday

                Temperatures: 30-32 degrees

                Winds: NNE 10-15mph

                Confidence: moderate

 

                Transportation: prepare for anti-ice operations

                Education: delays and cancellations possible

                Aviation: anti-ice operations likely

                Power: isolated outages possible

 

Austin, Colorado, north Harris (Katy-Jersey Village-Kingwood), central Liberty:

Ice Accumulation: patchy ice accumulation possible

                Timing: 1100pm Monday-900am Tuesday

                Temperatures: 31-33 degrees

                Winds: NNE 10-15mph

                Confidence: moderate

 

                Transportation: monitor trends/standby equipment and personnel

                Education: delays possible

                Aviation: anti-ice operations possible at Hooks and IAH

                Power: None

 

Fort Bend, southern Harris, Wharton, Jackson, Matagorda, Brazoria, Galveston, Chambers:

Ice Accumulation: None expected at this time

                Timing:  N/A

                Temperatures: 33-35 degrees

                Winds: NNE 14-18mph

                Confidence: moderate

 

                Transportation: None

                Education: None

                Aviation: None

                Power: None

 

[bubba hotep]

We are down to 32 with a mix of sleet/rain and elevated surfaces are starting to ice over 

 

 

[bubba hotep]

The models have underestimated the temperatures by about 4-6 degrees too warm and did not pick up on the disturbance feeding moisture in from the SW of the Baja Peninsula where a blow up of tropical convection has developed this afternoon. It will be interesting to see if the guidance picks up on this feature in the overnight runs into 12Z tomorrow.

 

 

 

My biggest concern is that subsidence behind this first wave might be stronger than anticipated but that certainly is a lot of energy kicking out of the SW and Baja area.  

[DFWWeather]

My biggest concern is that subsidence behind this first wave might be stronger than anticipated but that certainly is a lot of energy kicking out of the SW and Baja area.  

 

A little subsidence may not be a bad thing as it will increase dewpoint depressions and allows for a little bit of evaporative cooling. This may help surface temps to cool further. Roads are very wet, thus residual moisture freezing is going to be problematic as well. Last thing we need is to wet bulb out at 30°F or something - lol! Also, today's heavier rainfall could have scoured low level moisture too much?

[Quixotic1]

Trifecta of sleet, snow and freezing rain. Patio furniture is encased in a mess.

[bubba hotep]

West Texas radar is kind of bleak right now. I would like to see some signs that lift is increasing and spreading east

[Quixotic1]

West Texas radar is kind of bleak right now. I would like to see some signs that lift is increasing and spreading east

Steve's satellite image shows it spinning up quite nicely. But I know what you mean.

[bubba hotep]

Steve's satellite image shows it spinning up quite nicely. But I know what you mean.

I guess it will be easy to get some sleep with nothing to track until early morning

The latest HRRR has spotty stuff on and off all night before things pick back up tomorrow morning. It has precipitation falling with temps in the mid 20s tomorrow.

[jhamps10]

It's started freezing in south ft worth at around 7:30... Just the elevated surfaces so far, but it's here..

[bubba hotep]

Newest HRRR is juiced up! First of the model runs to pickup on the influx of Pacific moisture?

 

ETA: This is with temps in the mid 20s, Ice scale maxed out 

 

[jhamps10]

Newest HRRR is juiced up! First of the model runs to pickup on the influx of Pacific moisture?

 

ETA: This is with temps in the mid 20s, Ice scale maxed out 

 

 

if that verifies, I think it will be safe to say that sleet amounts could need raised a bit.. granted those high res models don't depict convection well am I correct?

[Captmorg70]

This is the 4k 0Z NAM. Next 24 hrs all the second wave.

[bubba hotep]

This is the 4k 0Z NAM. Next 24 hrs all the second wave.

 

A blend of that and the HRRR would be a crush job for the DFW area.  Probably wide spread 1.5 - 2"+ sleet falling on already frozen ground and streets. 

[Chinook]

if that verifies, I think it will be safe to say that sleet amounts could need raised a bit.. granted those high res models don't depict convection well am I correct?

What in the world is going on with those zig-zaggy stripes of rain inside the ice storm?

[bubba hotep]

What in the world is going on with those zig-zaggy stripes of rain inside the ice storm?

 

You are supposed to be telling us that! 

[jhamps10]

What in the world is going on with those zig-zaggy stripes of rain inside the ice storm?

 

I wish I knew, only thing I could GUESS would be it's showing precip so heavy it maxes out on the scale and shows as rain???? I'm not a met so this is a guess

[Quixotic1]

What in the world is going on with those zig-zaggy stripes of rain inside the ice storm?

Goes right over DFW so I guess it's a contrail.

[jhamps10]

NBC 5's new Thunder Truck is out livestreaming in the Denton area.. looks like 35 at the split is closed due to icy bridges:

 

http://www.nbcdfw.com/news/local/Winter-Storm-Hits-DFW-293524621.html

[bubba hotep]

Finally, some returns starting to pop out near Midland   

[jhamps10]

Finally, some returns starting to pop out near Midland   

 

Yay!!!! Was honestly starting to wonder if this was all a bunch to do about nothing lol... have a great night, gotta get some rest in case I'm the only office in the entire metroplex that's open (if my boss is reading this, please close lol)

[vwgrrc]

Newest HRRR is juiced up! First of the model runs to pickup on the influx of Pacific moisture?

 

ETA: This is with temps in the mid 20s, Ice scale maxed out 

 

Is it the only model to show the amount? 

[DoctorMu]

This is the 4k 0Z NAM. Next 24 hrs all the second wave.

 

The firehose is set to blow:

 

http://www.goes.noaa.gov/GSSLOOPS/wcwv.html

[vwgrrc]

Accumulation decreased?

 

URGENT - WINTER WEATHER MESSAGE
NATIONAL WEATHER SERVICE FORT WORTH TX

1149 PM CST SUN FEB 22 2015

 

ACCUMULATIONS...SLEET ACCUMULATIONS BETWEEN 1/2 AND 1 INCH WITH
AREAS OF HIGHER AMOUNTS TO 2 INCHES THROUGH MONDAY.

[jhamps10]

We have thundersleet in SW Ft Worth near Benbrook

[Srain]

HGX suggesting the freezing line my drop precariously close to NW and N Harris County overnight as the latest short range guidance is coming in a bit colder than expected. Also there is a chance that the upper trough may become more negative tilted on Wednesday as it crosses the area and lift increases with a deeper cold layer suggesting sleet and possibly some grauple may fall Wednesday into the afternoon hours.

[bubba hotep]

Getting some pingers now, the first batch that moved through around 4:30 am sounded like mostly freezing rain

[aggiegeog]

Looks like this band currently crossing the Metroplex is the real deal. I bet most well pick up close to .25" of sleet out of it. There will be a few more of these type bands along with lighter stuff through the morning.

Around my place temps are just now getting to freezing and the initial batch that y'all got earlier is skirting to my north.