Texas Winter 2013-2014

[Tcu101]

DFW received .05" of liquid equivalent today which equated to around 1 inch of snow. 20 to 1 ratio? Impressive ratio

This is correct. The column was very efficient at making dendrites. Making the most out of very little qpf. The seasonal snow total (sleet and ice is counted as snow) is 4.1 inches.

Yep, this season is definitely making up for the last two lack luster ones.

Was anyone else questioning what the heck Steve McCauley posted earlier saying this was wet snow and that is reason for melting ??? This was extremely dry powdery 20-1 ratio snow and melted on streets quickly once solar radiation reached its peak this afternoon.....some of his posts are very puzzling!!

Also, Ntxw - checked out the new Euro weeklies yet ? has your - EPO back and in full effect towards end of Feb, early March , along with a possible - AO

I'm glad you mentioned that about Steve's post, because that was a bit puzzling to me too? The snow was very dry ! I guess he was not expecting such large snowflakes?? Can large snowflakes not be dry?

[SaskatchewanScreamer]

Here large snowflakes are always very wet. I've seen tons of dry snowflakes and they are always tiny.

2 cents worth from someone who has seen more snow then she ever wanted to (however this is based on a Northerner's experience).

[Tcu101]

Here large snowflakes are always very wet. I've seen tons of dry snowflakes and they are always tiny.

2 cents worth from someone who has seen more snow then she ever wanted to (however this is based on a Northerner's experience).

Then wonder why we saw some larger snowflakes if it was so dry? He did mention that clouds where the snow was created was over 20,000 feet thick causing the flakes to be larger than if they would have been if it was 10,000 feet??

[Texas Snowman]

Was Steve Mc was a little caught off guard by the strength and coverage of this storm?

[GRAYSONCO.WX]

Latest short range models look promising for some light precip across north Texas tomorrow.

[Ntxw]

Was Steve Mc was a little caught off guard by the strength and coverage of this storm?

He probably forgot to check the soundings and looked too closely at model qpf which constantly supported...flurries and virga. This winter has probably taught us the importance of looking at the entire column for precip type and amount, not just the surface and what the model has at 2m. Should be a case reference for years to come.

[TheProfessor]

Ok so the Skew-t for tomorrow morning according to nam and gas have the green line touching the red, then around 600-800mb it has warm cone and a dry layer. After that the warm cone disappears and the green and red touch each other again. What does this mean? no precip? rain?frz rain? sleet? snow?

[orangeblood]

Once again latest RAP soundings continue to show a much more saturated column for DFW compared to NAM/GFS.....shows completely saturated column from surface up to 825 mb (over 6,000 ft.) and a nearly saturated very thick column from 675mb to 400 mb where DGZ is in place even thicker than this mornings event. Sounding loop shows top down saturation taking place starting early Friday morning... With very light winds, wonder if we'll be dealing with freezing/fog drizzle late tonight before light snow begins during the day tomorrow ??

Would not be surprised to see WWA hoisted from DFW northwest once again....


The following post is NOT an official forecast and should not be used as such. It is just the opinion of the poster and may or may not be backed by sound meteorological data. It is NOT endorsed by any professional institution including storm2k.org. For official information, please refer to NWS products.

[orangeblood]

Ok so the Skew-t for tomorrow morning according to nam and gas have the green line touching the red, then around 600-800mb it has warm cone and a dry layer. After that the warm cone disappears and the green and red touch each other again. What does this mean? no precip? rain?frz rain? sleet? snow?

Look at RAP model soundings....GFS/NAM are not handling this setup very well. If you look closely at the soundings, starting around 06 UTC to 12 UTC tomorrow morning, you'll notice the the dry layer (where red and green lines are far apart) begins to shrink over time - this is top down saturation and is exactly what you look for in situations like this. Now, will it be enough to overcome the last 3000 - 4000 ft dry layer - I would think so towards late morning into early afternoon tomorrow....reliable sounding haven't gone out far enough to analyze that time frame quite yet


The following post is NOT an official forecast and should not be used as such. It is just the opinion of the poster and may or may not be backed by sound meteorological data. It is NOT endorsed by any professional institution including storm2k.org. For official information, please refer to NWS products.

[GRAYSONCO.WX]

Once again latest RAP soundings continue to show a much more saturated column for DFW compared to NAM/GFS.....shows completely saturated column from surface up to 825 mb (over 6,000 ft.) and a nearly saturated very thick column from 675mb to 400 mb where DGZ is in place even thicker than this mornings event. Sounding loop shows top down saturation taking place starting early Friday morning... With very light winds, wonder if we'll be dealing with freezing/fog drizzle late tonight before light snow begins during the day tomorrow ??

Would not be surprised to see WWA hoisted from DFW northwest once again....


The following post is NOT an official forecast and should not be used as such. It is just the opinion of the poster and may or may not be backed by sound meteorological data. It is NOT endorsed by any professional institution including storm2k.org. For official information, please refer to NWS products.

I concur with that! The other models are not handling this well and the RAP sounds are looking really healthy.

[katheria]

Oh wow, ok I just now get it

WFAA should have thought this through

was a fun drive home tonight to say for sure....side streets in my area are not too good it seems lol....and geez i just dont understand people...you have 3 lanes 2 are basically clear but everyone drives in the right lane that a sheet of snow and ice....????
4 wrecks on the way home....

today was nice
think i was the only one that appreciated it at all at work lol

[Meteorcane]

Here large snowflakes are always very wet. I've seen tons of dry snowflakes and they are always tiny.

2 cents worth from someone who has seen more snow then she ever wanted to (however this is based on a Northerner's experience).

Then wonder why we saw some larger snowflakes if it was so dry? He did mention that clouds where the snow was created was over 20,000 feet thick causing the flakes to be larger than if they would have been if it was 10,000 feet??

Being the cloud microphysics nerd that I am I dug up an old paper (Ohtake, 1969) regarding snowflake size distributions and came across this quote.

"From these observations it seems probable that in the aggregation of snow crystals into large snowflakes the most important factor is not the freezing of collected supercooled water, but the mechanical combination of their fine structure of branches regardless of the existence of liquid water or a warm temperature layer."

Also earlier in the paper he says the dendrites are much more likely to form aggregates, and that these aggregates did not often exhibit riming (freezing of supercooled water), I can assume this high aggregation efficiency is due to their needles/branches "tangling" together easier than other habits. So apparently (unless the results have since been challenged) it is actually the shape/habit of the snow crystal (in today's event due to the temperature profile and environmental humidity dendrites were very prominent) which has a greater effect on the ultimate size reached through aggregation. Rather than the water content (which plays a big role in raindrop growth processes, or hail/graupel growth) or the temperature (higher temperatures make ice crystals "stickier" traditionally thought to increase aggregation efficiency).

[Ntxw]

Also earlier in the paper he says the dendrites are much more likely to form aggregates, and that these aggregates did not often exhibit riming (freezing of supercooled water), I can assume this high aggregation efficiency is due to their needles "tangling" together easier than other habits. So apparently (unless the results have since been challenged) it is actually the shape/habit of the snow crystal (in today's event due to the temperature profile and environmental humidity dendrites were very prominent) which has a greater effect on the ultimate size reached through aggregation. Rather than the water content (which plays a big role in raindrop growth processes, or hail/graupel growth) or the temperature (higher temperatures make ice crystals "stickier" traditionally thought to increase aggregation efficiency).

Thank you for the information, very awesome work! In lay man's terms "they were pointy so they stuck together better!"

[Meteorcane]

Also earlier in the paper he says the dendrites are much more likely to form aggregates, and that these aggregates did not often exhibit riming (freezing of supercooled water), I can assume this high aggregation efficiency is due to their needles "tangling" together easier than other habits. So apparently (unless the results have since been challenged) it is actually the shape/habit of the snow crystal (in today's event due to the temperature profile and environmental humidity dendrites were very prominent) which has a greater effect on the ultimate size reached through aggregation. Rather than the water content (which plays a big role in raindrop growth processes, or hail/graupel growth) or the temperature (higher temperatures make ice crystals "stickier" traditionally thought to increase aggregation efficiency).

Thank you for the information, very awesome work! In lay man's terms "they were pointy so they stuck together better!"

Yep, that's basically how I understand it, their pointed branches intertwine easier, than plates/columns etc that tend to collide and bounce.

[TheProfessor]

If the models continue to trend towards more precipitation tomorrow, than I think it would be smart for NWS FWD to issue advisories in order to prevent what happened this morning.

[Longhornmaniac8]

So this questions goes back a bit to what wxman57 and I were discussing yesterday, but with some new conditions:

Tomorrow, the RAP for the Austin area is showing a very large temperature/dew point spread in the upper/middle atmosphere (which I'm interpreting as unfavorable conditions for precipitation). This is the case all the way until approximately 850 mb, where they suddenly come together (and stay together) all the way to the surface. From the time they come together, they're well below the 0C line, which I thought meant favorable conditions for snow. There is no warm nose present.

What's confusing me is the WWA issued by EWX talks primarily of freezing drizzle/sleet, with snow flurries mentioned only as a possibility. Is there something about the location of the saturation (that is, it's fairly close to the surface...5,000 ft or so) that would inhibit dendritic growth?

I just don't see how the formation of precipitation that falls through a saturated air column below freezing would be conducive to anything other than snow.

Any help here would be much appreciated! We're all trying to learn!

Cheers,
Cameron

[Ntxw]

So this questions goes back a bit to what wxman57 and I were discussing yesterday, but with some new conditions:

Tomorrow, the RAP for the Austin area is showing a very large temperature/dew point spread in the upper/middle atmosphere (which I'm interpreting as unfavorable conditions for precipitation). This is the case all the way until approximately 850 mb, where they suddenly come together (and stay together) all the way to the surface. From the time they come together, they're well below the 0C line, which I thought meant favorable conditions for snow. There is no warm nose present.

What's confusing me is the WWA issued by EWX talks primarily of freezing drizzle/sleet, with snow flurries mentioned only as a possibility. Is there something about the location of the saturation (that is, it's fairly close to the surface...5,000 ft or so) that would inhibit dendritic growth?

I just don't see how the formation of precipitation that falls through a saturated air column below freezing would be conducive to anything other than snow.

Any help here would be much appreciated! We're all trying to learn!

Cheers,
Cameron

Dendritic growth zone, the optimum temperature for them is -10C to -20C. Usually it's higher up in the atmosphere that this occurs (it can happen below but temperatures in your part of the world rarely gets that low near the surface up to 5k ft). You need 100mb+ layer (fairly deep) saturated for the best region to grow these dendrites otherwise the stuff you are seeing is graupel, melted snow, and all that other non uniform stuff, unfinished business.

[TheProfessor]

The rap still seems to look good for winter precip in North Texas, anyone else think so? What will it take for NWS FWD to issue advisories.

[GRAYSONCO.WX]

I may be wrong, but it appears that some light returns are beginning to show up on radar near Waco. Anyone else seeing this?

[JDawg512]

I am also perplexed about what the Austin area is to expect. Some model data wants to start freezing drizzle around 5 to 6 a.m. then continue through early to mid morning then possibly change to sleet or snow. Something tells me that they are not quite sure what will happen until it gets closer to the time.