Texas Winter 2020-2021

[bubba hotep]

Wow, that DGZ looks primed on the latest 18Z Hi Res NAM forecast sounding throughout the Metroplex....

https://www.tropicaltidbits.com/analysis/models/sounding/images/nam3km_2021010818_fh51_sounding_32.77N_97.14W.png

That Omega peak is pretty nice.

[WinterMax]

FWIW, I feel like DFW will get some substantial snow out of this system. Up here on the Red River seems to be a little more on a razor thin edge. I have a feeling we will have to wait until Sunday to see if we get anything the way the models have been.

I think even folks in the Falls have a shot at snow and it never takes much to put some snow in WF. Don't get lost in the back and forth with amounts, since that discussion is who gets the most. The Red River's best shot is with the actual ULL itself.

Seems a little odd to me that there is already a winter storm watch posted for Huntsville texas. Caught me off guard.

[bubba hotep]

This from this afternoon's discussion from NWS Austin/San Antonio ... the more you know:

One thing to note is to be careful when looking at model snow
accumulation forecast graphics online. The algorithms that calculate
this field fail to look at microphysics related to snow production in
the dendritic growth zone of -10c to -20c. Snow depth graphics can be
better to look at in this case as they do account for microphysics.
For example the ECMWF shows 3-4 inches for our northern counties of
snow fall but only about an inch of snow depth.

Depending on the model, snow depth also can include melting. Those big southern totals showing up in model graphics are likely overdone based on likely surface temps. In the end, snow maps aren't too useful beyond just being fun to look at lol

[txtwister78]

18z GFS continues to miss DFW altogether (maybe a dusting). Really develops coastal low in the gulf and scours out moisture across N Texas. Been very consistent along with the ICON regarding this.

[Brent]

Forecast models suggest that most likely
corridor for heavy snow will be from the Big Country to Central
Texas, near a line from Eastland to Stephenville to Waco. These
locations may receive 2-4 inches of snow, with locally higher
amounts of up to 6 inches possible in some locations. Given the
steep lapse rates and strong ascent within the dendritic growth
zone, the potential for heavy banding snow will be likely, but
given the mesoscale nature of these types of bands, it is nearly
impossible to forecast with great confidence where these may occur
at this lead time.

The difficult decision to exclude the core of the Dallas/Fort
Worth Metropolitan Area was made with this forecast for a few
reasons. First, the deterministic snowfall forecast as well as
probabilistic guidance shows that the DFW area is likely to
remain below warning criteria. Secondly, there is still at least
36-48 hours before any potential snow onset in the Metroplex.
While the current forecast would potentially require an Advisory
if it were within 24 hours, we opted to hold off on the issuance
of a Watch at this time. Forecast users are strongly advised
,however, that a northward shift of about 30-40 miles in the
track of the forecast low and therefore the heaviest snowfall
amounts could place DFW within heavier snow. It is therefore
encouraged that folks across North Texas make any necessary
preparations for the potential for accumulating snowfall as
possibility certainly exists, even if it is not a strong
probability at this time.

[EnnisTx]

No WSW for DFW. Does this mean ince again little to no snow? Someone please advise.

You never know. I've seen it snow 2 or 3 inches with no type of watch in place and 6 + with a Winter Weather Advisory in effect. It's a lot of Now Casting.

[orangeblood]

18z GFS continues to miss DFW altogether (maybe a dusting). Really develops coastal low in the gulf and scours out moisture across N Texas. Been very consistent along with the ICON regarding this.

Why put so much weight into Global models that don't have great skill scores at this range ?

[orangeblood]

Forecast models suggest that most likely
corridor for heavy snow will be from the Big Country to Central
Texas, near a line from Eastland to Stephenville to Waco. These
locations may receive 2-4 inches of snow, with locally higher
amounts of up to 6 inches possible in some locations. Given the
steep lapse rates and strong ascent within the dendritic growth
zone, the potential for heavy banding snow will be likely, but
given the mesoscale nature of these types of bands, it is nearly
impossible to forecast with great confidence where these may occur
at this lead time.

The difficult decision to exclude the core of the Dallas/Fort
Worth Metropolitan Area was made with this forecast for a few
reasons. First, the deterministic snowfall forecast as well as
probabilistic guidance shows that the DFW area is likely to
remain below warning criteria. Secondly, there is still at least
36-48 hours before any potential snow onset in the Metroplex.
While the current forecast would potentially require an Advisory
if it were within 24 hours, we opted to hold off on the issuance
of a Watch at this time. Forecast users are strongly advised
,however, that a northward shift of about 30-40 miles in the
track of the forecast low and therefore the heaviest snowfall
amounts could place DFW within heavier snow. It is therefore
encouraged that folks across North Texas make any necessary
preparations for the potential for accumulating snowfall as
possibility certainly exists, even if it is not a strong
probability at this time.

Probabilistic models showing greater than 50% chance of more than 3 inches across most of the Metroplex...interesting call but I guess they can always get more aggressive wording out tomorrow

[Cerlin]

18z GFS continues to miss DFW altogether (maybe a dusting). Really develops coastal low in the gulf and scours out moisture across N Texas. Been very consistent along with the ICON regarding this.

Why put so much weight into Global models that don't have great skill scores at this range ?

Exactly. Also something to remember about the GFS and the ICON is they both have a tendency to overestimate the strength of low pressure systems. Not sure if you guys followed along with the models during hurricane season, but it seemed like every other run, the GFS and ICON would both have some 950 mb hurricane slamming the gulf coast, when that didn’t verify most of the time. It’s also a big reason why the GFS and ICON are so ahead of the curve on predicting these snow systems weeks in advance—they just have stronger low pressure systems which can create better tracks for more southern snow. So, while it’s definitely something to monitor, the high res models will be way better at giving us a hint at what might actually happen now that we’re about 36 hours out.

[txtwister78]

18z GFS continues to miss DFW altogether (maybe a dusting). Really develops coastal low in the gulf and scours out moisture across N Texas. Been very consistent along with the ICON regarding this.

Why put so much weight into Global models that don't have great skill scores at this range ?

Not so sure when you say "great skill" at this range? We are now inside 48 hours. Again these are two models out of several, but the development of a coastal low would limit snowfall potential further north because it would become the more dominant feature and create a quicker dry slotting effect of the atmosphere on the backside of said low and pull more moisture closer to the low itself. Do I think it's a lock to happen? No. But to suggest the possibility doesn't exist would not be accurate either. I think that's why FWD has been a little more reluctant to go "all in" on accumulating snowfall for the Metroplex and points north.

I also think it's why forecast offices have been more conservative on snowfall totals. Obviously the more prudent thing to do until we closer to the event and one of these solutions begins to lock on.

[Haris]

GFS is an outlier I think. GEFS much colder and snowier uniformly.. Unchanged from 12z. Maybe a hair S

[txtwister78]

[url]https://i.ibb.co/vPd7vrt/GEFSSGP-prec-meansnacc-066.png [/url]

GFS is an outlier I think. GEFS much colder and snowier uniformly.. Unchanged from 12z. Maybe a hair S

It could very well be and I've definitely favored that area (Waco points NW and maybe east) in terms of greatest snowfall potential for the past day or so on here so I'm on board with the ENS potential, but the consistency of both ICON and GFS definitely give me some pause in terms of accumulations. I get everyone "wants" snow, so trust me I get it.

[WinterMax]

[url]https://i.ibb.co/vPd7vrt/GEFSSGP-prec-meansnacc-066.png [/url]

GFS is an outlier I think. GEFS much colder and snowier uniformly.. Unchanged from 12z. Maybe a hair S

What time central is this graph projected to be?

[orangeblood]

18z GFS continues to miss DFW altogether (maybe a dusting). Really develops coastal low in the gulf and scours out moisture across N Texas. Been very consistent along with the ICON regarding this.

Why put so much weight into Global models that don't have great skill scores at this range ?

Not so sure when you say "great skill" at this range? We are now inside 48 hours. Again these are two models out of several, but the development of a coastal low would limit snowfall potential further north because it would become the more dominant feature and create a quicker dry slotting effect of the atmosphere on the backside of said low and pull more moisture closer to the low itself. Do I think it's a lock to happen? No. But to suggest the possibility doesn't exist would not be accurate either. I think that's why FWD has been a little more reluctant to go "all in" on accumulating snowfall for the Metroplex and points north.

The coastal low is in place on every model regardless and appears to be of similar strength, don't think that's the deciding issue here...it's the strength and trajectory of the ULL that appears to be in dispute. NAM further north and stronger - closed low , ICON weakest of all and comes in as more of an open wave. Moisture is there, its strength and location of lift that appears to be the biggest question mark

[txtwister78]

Why put so much weight into Global models that don't have great skill scores at this range ?

Not so sure when you say "great skill" at this range? We are now inside 48 hours. Again these are two models out of several, but the development of a coastal low would limit snowfall potential further north because it would become the more dominant feature and create a quicker dry slotting effect of the atmosphere on the backside of said low and pull more moisture closer to the low itself. Do I think it's a lock to happen? No. But to suggest the possibility doesn't exist would not be accurate either. I think that's why FWD has been a little more reluctant to go "all in" on accumulating snowfall for the Metroplex and points north.

The coastal low is in place on every model regardless and appears to be of similar strength, don't think that's the deciding issue here...it's the strength and trajectory of the ULL that appears to be in dispute. NAM further north and stronger - closed low , ICON weakest of all and comes in as more of an open wave. Moisture is there, its strength and location of lift that appears to be the biggest question mark

Read Portastorms post this morning. It's something I mentioned yesterday on here as well. Again I get all of us "want" snow in our own backyard, but all I'm doing is discussing possibilities and as of right now (at least) the FWD agrees with that in terms of lower probability of accumulating snow the further north and NE you go into the Metroplex. The models are the models. We can all agree that this is still a wait and see scenario. My opinions are just that. Don't let it bother you.

[bubba hotep]

18z GFS-P

[bubba hotep]

Who's going on record? Do we see the north & west shift in qpf placement over the next 24 hrs that has been the trend in models here the past few months?

[rwfromkansas]

Hallelujah I successfully posted a photo.

Iweathernet/Chris Robbins used to work for the NWS in DFW and is legit, writing his master’s on winter weather. When he says snow, I trust him. And he hasn’t said snow once this winter. He seems to be leaning toward at least light accumulations for the metro.

[EnnisTx]

Who's going on record? Do we see the north & west shift in qpf placement over the next 24 hrs that has been the trend in models here the past few months?

I'm going with the North trend. But, I don't want to let that bother anyone.

[weatherdude1108]

Looks like I am in the Winter Storm Watch.

URGENT - WINTER WEATHER MESSAGE
National Weather Service Austin/San Antonio TX
226 PM CST Fri Jan 8 2021

TXZ172-173-194-090430-
/O.NEW.KEWX.WS.A.0001.210110T1800Z-210111T0600Z/
Burnet-Williamson-Lee-
Including the cities of Burnet, Georgetown, and Giddings
226 PM CST Fri Jan 8 2021

...WINTER STORM WATCH IN EFFECT FROM SUNDAY AFTERNOON THROUGH
SUNDAY EVENING...

* WHAT...A rain/snow mix with a transition to all snow possible.

* WHERE...Burnet, Williamson and Lee Counties.

* WHEN...From Sunday afternoon through Sunday evening.

* ADDITIONAL DETAILS...Snowfall accumulations are forecasted to be
up to an inch with locally higher amounts possible

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Monitor the latest forecasts for updates on this situation.

&&