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Texas/Oklahoma Discussion & Obs Thread 2021


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17 hours ago, aggiegeog said:

Next week has lots of potential for Arctic cold and winter precip across the Southern Plains.

I completely agree! This is the best pattern and chance I've have seen this winter for significant cold air dump and, in particular, wintry precipitation. Some models spreads showing potential of upwards 30+ degrees below normal for the DFW area. This is an excellent pattern if you are a lover of winter weather. Unfortunately, if we get a Arctic dump of this magnitude, it will again put strain on agriculture, infrastructure and the power grid for much of the state, much like last February. What is interesting is nearly every major global model and much of their ensembles have been in remarkable agreement in the evolution of the pattern since Monday. Something to watch for sure!

Having said that though, I am a bit on the skeptical side on precip largely because we have been devoid of any significnat precip here for months now (what October last time we saw more than an inch?). Much of the state in entering into severe drought status.

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22 hours ago, DFWWeather said:

I completely agree! This is the best pattern and chance I've have seen this winter for significant cold air dump and, in particular, wintry precipitation. Some models spreads showing potential of upwards 30+ degrees below normal for the DFW area. This is an excellent pattern if you are a lover of winter weather. Unfortunately, if we get a Arctic dump of this magnitude, it will again put strain on agriculture, infrastructure and the power grid for much of the state, much like last February. What is interesting is nearly every major global model and much of their ensembles have been in remarkable agreement in the evolution of the pattern since Monday. Something to watch for sure!

Having said that though, I am a bit on the skeptical side on precip largely because we have been devoid of any significnat precip here for months now (what October last time we saw more than an inch?). Much of the state in entering into severe drought status.

Thankfully NE Texas had a good rain event recently, and I think that is where this event will focus also. The whole region will be very cold but heavy precip will likely be confined to eastern parts of the state. There will be more waves following the mid week system though and those will pull moisture further SW the following week. Several consecutive days below freezing for the northern parts of the state with sub zero possible near the Red River in areas that get snow. This will put great stress on agriculture and infrastructure.

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On 1/27/2022 at 11:45 AM, DFWWeather said:

What is interesting is nearly every major global model and much of their ensembles have been in remarkable agreement in the evolution of the pattern since Monday. Something to watch for sure!

I probably wouldn't be that bullish at this point tbh. Looks like Canadian suggested that in the last couple days and GFS came to agreement today but the latest Canadian just left the chat. Probably temporarily but still left the chat :D

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13 minutes ago, vwgrrc said:

I probably wouldn't be that bullish at this point tbh. Looks like Canadian suggested that in the last couple days and GFS came to agreement today but the latest Canadian just left the chat. Probably temporarily but still left the chat :D

I am not sure to what you are referring, but the latest 12z op Canadian has a low of 13°F at DFW on February 5th which is indicative of a significant Arctic air intrusion. Nearly every run of the 12z Canadian ensembles show QPF for DFW, which given temps would be some sort of snow or ice.  The operational does not have much in the way of precip. However, the op 12z GFS is icemeggedon! What I am strongly bullish on is a significant cold air dump.

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7 minutes ago, DFWWeather said:

I am not sure to what you are referring, but the latest 12z Canadian has a low of 13°F at DFW on February 5th which is indicative of a significant Arctic air intrusion. It does not have much in the way of precip. However, the 12z GFS is icemeggedon! What I am strongly bullish on is a significant cold air dump.

Oh yes I agree with the cold air part! I was just referring to a freezing rain/sleet event. Canadian was showing icemeggedon yesterday/Wed but now it seems that switched with GFS.

Also wanted to note that both 6z and 12z GFS is showing that, which certainly worth watching from now on. If Canadian decided to join the party this weekend, that spells pretty big trouble for DFW. Dec 2013 is not completely out of reach!

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18 minutes ago, vwgrrc said:

Oh yes I agree with the cold air part! I was just referring to a freezing rain/sleet event. Canadian was showing icemeggedon yesterday/Wed but now it seems that switched with GFS.

Also wanted to note that both 6z and 12z GFS is showing that, which certainly worth watching from now on. If Canadian decided to join the party this weekend, that spells pretty big trouble for DFW. Dec 2013 is not completely out of reach!

0z and 12z op ECMWF appear on board...though the 12z is slowing the cold air intrusion keeping precip liquid. Typical bias of this model in this situation. It looks like a dense/shallow intrusion at least initially which might not get properly resolved until the NAM comes in range. This also points to more of a ice event vs snow this time.

Interesting note: 12z GFS ensemble average temp is down to 14°F for DFW. There is quite a few of them taking us into the single digits. Wow!

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15 minutes ago, DFWWeather said:

0z and 12z op ECMWF appear on board...though the 12z is slowing the cold air intrusion keeping precip liquid. Typical bias of this model in this situation. It looks like a dense/shallow intrusion at least initially which might not get properly resolved until the NAM comes in range. This also points to more of a ice event vs snow this time.

I can't wait to see the media hype probably starting this weekend if the trend holds. Given how bad and how refresh people's memory is on Feb-21 storm, there might be some serious hoarding coming soon (not a fan of that to be honest :()

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1 minute ago, vwgrrc said:

I can't wait to see the media hype probably starting this weekend if the trend holds. Given how bad and how refresh people's memory is on Feb-21 storm, there might be some serious hoarding coming soon (not a fan of that to be honest :()

I bet if the northeast was not having the big blizzard this weekend, the news would be all over this given what happened last year.

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Look like the entire suite of 0z guidance this morning and their ensembles from the GFS, Canadian, and ECMWF or onboard for a crippling ice storm for the DFW Metroplex for the Feb 4th timeframe.
6z gfs agrees even more

But very interesting writeup from FWD this morning. I guess they feel the pressure.

Global model snow/ice accumulation forecasts... - The temporal resolution (how many hours apart) of global models in the extended period is usually 6 hours. The model generates a precip-type forecast for the first hour of each time-step and keeps it constant for the entire 6 hour block of time. In the case of passing arctic fronts and/or changing temperatures, the precip type in the real-world will be continuously changing. However, the model is unaware of these temperature changes between time-steps and assumes a constant p-type for 6 hours. The model then generates a 6-hour QPF (Quantitative Precip Forecast or how much liquid water will fall) and assumes all of the QPF will fall as the pre-determined p-type for the entire 6 hours. If the meteorological situation involves rapidly changing temperatures, such as behind arctic fronts, this effect creates wildly unreliable and inaccurate snow & ice accumulation forecasts. Next week is one of these situations, so please take any model snow/ice forecast with a huge grain of salt for the next couple days.


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11 minutes ago, vwgrrc said:

6z gfs agrees even more

But very interesting writeup from FWD this morning. I guess they feel the pressure.

Global model snow/ice accumulation forecasts... - The temporal resolution (how many hours apart) of global models in the extended period is usually 6 hours. The model generates a precip-type forecast for the first hour of each time-step and keeps it constant for the entire 6 hour block of time. In the case of passing arctic fronts and/or changing temperatures, the precip type in the real-world will be continuously changing. However, the model is unaware of these temperature changes between time-steps and assumes a constant p-type for 6 hours. The model then generates a 6-hour QPF (Quantitative Precip Forecast or how much liquid water will fall) and assumes all of the QPF will fall as the pre-determined p-type for the entire 6 hours. If the meteorological situation involves rapidly changing temperatures, such as behind arctic fronts, this effect creates wildly unreliable and inaccurate snow & ice accumulation forecasts. Next week is one of these situations, so please take any model snow/ice forecast with a huge grain of salt for the next couple days.

 

I like how in that same discussion they said a 2% chance that we get as cold as last year. Um, that is like once in 30 year event. The fact that we are even talking chances on that is ridiculous. I have noted that nearly all 0z guidance is a bit warmer this morning at both the surface and H85. So any ice snow would make the difference on just how cold it gets.

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GGEM would be a nasty sleet storm for DFW, and GFS would be a nasty ice storm.
Awful...
I won't Buy that at this point to be honest, exactly like our friends at FWD office pointed out this morning. Models are overdoing that most likely.

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8 minutes ago, vwgrrc said:

I won't Buy that at this point to be honest, exactly like our friends at FWD office pointed out this morning. Models are overdoing that most likely.

Sent from my SM-G991U1 using Tapatalk
 

Today's 0z and 12z Canadian and all of its ensembles are are just as bad with ice/sleet for DFW if not worse, particularly the 12z op Canadian.

Should also note the ICON and JMA are showing stuff too.

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Today's 0z and 12z Canadian and all of its ensembles are are just as bad with ice/sleet for DFW if not worse, particularly the 12z op Canadian.
Should also note the ICON and JMA are showing stuff too.
Not trying to challenge you. Just curious and for learning - 12z ICON looks like a pure rain event for dfw. Also there's might be a warmer trend going on. Maybe I'm reading it correctly? Thanks

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11 minutes ago, vwgrrc said:

Not trying to challenge you. Just curious and for learning - 12z ICON looks like a pure rain event for dfw. Also there's might be a warmer trend going on. Maybe I'm reading it correctly? Thanks

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If your looking at the precipitation output, the icon only shows rain and snow. So it doesn’t pick up sleet or freezing rain. If you compare temps and precip maps, you get an better understanding of impacts. 

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23 minutes ago, vwgrrc said:

Not trying to challenge you. Just curious and for learning - 12z ICON looks like a pure rain event for dfw. Also there's might be a warmer trend going on. Maybe I'm reading it correctly? Thanks

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What we are dealing with here is a 1050 give or take mb Arctic high plunging into the US. The leading edge of the Arctic airmass plunging into Texas is very dense but shallow (at least initinally where much of the precipitation will likely fall). This points to more ice than snow. What you are likely seeing on the ICON model is (and I am not as familiar with this model's biases) that it likely is not resolving the low level cold air well. I could be wrong. It may also just be speeding the low up and delaying the cold air (not a likely scenario in this type of setup).

While I concede the NWS point about modeling and we should not get hung up on type or amounts at this point. When you have a preponderence of models showing a similar outcome, the main message is that the odds of some type of impactful Winter Storm affecting the region north of a line from El Paso, South of San Antonio, south of Austin into the northern suburbs of Houston area are increasing.

There was a slight increase in temps on the 0z data, but 12z is colder again. I am talking increase instead of severe cold (temps below 10 at DFW), just temps in the teens at the coldest point. We are not seeing an increase in temps like you are suggesting where this will be a borderline type event. If there is precip of anykind in temps like that it will cause problems regardless of amounts. Even the NDFD number is down to 16°F today at DFW.

Having looked at the 12z ICON...it has 2m temp of 19°F at DFW with precipitation. That would be freezing rain or sleet.

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If your looking at the precipitation output, the icon only shows rain and snow. So it doesn’t pick up sleet or freezing rain. If you compare temps and precip maps, you get an better understanding of impacts. 
That's exactly right. Thanks!

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Absolutiely, mind boggling totals coming off the 0z suite of data this morning. 2.00 inches of liquid into subfreezing air on some of these models...just wow! If that falls as freezing rain, we are talking a severe ice storm that would go down in the record books. The NWS is fully on board this morning. The latest concern is that DFW (presuming we get some type of ice or snow and it wouldn't take much) would have to deal with severe cold both Friday and Saturday mornings (ie, temps dropping below 10°F). Interestingly enough, the ECMWF is the warmest of all the models keeping us in the 20s the entire time. I believe it was also the warmest model last year. The 0z ensemble average off the GFS is 10°F for the low at KDFW on Friday morning, which says alot.

I wouldn't be surprised by tomorrow Winter Storm Watches start to get hoisted. If freezing rain still looks the predominant precip type, I bet some of us will make Ice Storm Warning criteria easily. Not to meniton a Hard Freeze Warning and Wind Chill Warning at some point too.

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9 hours ago, vwgrrc said:

IMO, the AFD tonight will be quite critical to watch if that is likely going to pan out or stay with a media hype!

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I take it based on the latest graphics out of FWD they're on the hype train

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Houston lost our ice storm, but with GFS and Euro having a pretty serious ice or sleet storm, they have to start putting out alerts.  The question is how much is freezing rain, (enough for trees on powerlines) and how much sleet.

My Mom and two sisters (Mom lives with 1) in Bedford have underground power cables, a good thing, but worst case, mostly freezing liquid and an inch, major trunk lines would go down and even underground neighborhood power doesn't protect against that.

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3 hours ago, cheese007 said:

I take it based on the latest graphics out of FWD they're on the hype train

Comparing the latest GFS to those op runs yesterday, there seems like a drier-trend underway for at least the immediate DFW metro (less freezing train or sleet?), I think that's a good thing. Will need to watch if 12z CMC and Euro can agree with that!

Edit: ECMWF does dial back on the frozen p a lot at 12z. Interesting!

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