DFWWeather

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!

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 

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.

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.

2 hours ago, cheese007 said:

5 inches for DFW. When averaged with the marginal amounts since 15-16 we actually end up at roughly our expected yearly average (about an inch per year)

The snow records at DFW only go back to 1940. The average annual snowfall at DFW from 1940 to today is exactly 2.44 inches per year. If we had a complete snow record back to 1899 it would likely be a bit higher.

Looks like the official low at DFW Airport might be -2°F. If true and not due to a rounding error off the 5 minute observations, it would be the coldest temps since January 31, 1949.

2 hours ago, EpicHECS said:

Posting Winter Storm Warnings for the total entirety of TX is a little laughable. A few inches of snow doesn't even warrant an advisory and having a Winter Storm Warning for areas such as Brazoria County on south is just a total exaggeration of the current situation. This is obviously just an attempt at filling the coffers with federal money. 

The criteria for a Winter Storm Warning is different based on where you live. This has always been the case. Those areas down there rarely see snow or accumulating snow. Like may once in 50 or 100 years. Plus, that region is a major agricultural region that is severely affected by such cold. The conditions warranted and met the local NWS office's criteria for that location for a Winter Storm Warning. It is not an attempt of anything.

6 hours ago, Chinook said:

I have been looking at weather maps for a long time. I cannot remember seeing a day when Texas was 50 degrees below average.  Hmm. Abilene TX climate report says that the high temp of 22 was 38 degrees below average. Tomorrows low will be 37 degrees below average.  Midland TX had 45 degrees below average for the high today and 28 degrees below average for the low that already occurred today.

Twice in my lifetime at DFW. December 1983 and December 1989. These types of cold spells are more common of a colder AMO than what we have seen the last 25 years. The 60s through the 80s it was fairly common to drop below 10 degrees at DFW every couple of years or so. It is easier for the temp to reach below 10 degrees in winter time than to reach 110 in summer which has only occurred 12 times in all weather records at DFW. Though I will admit getting below 5 is pretty rare and to get to 0 or lower is like once in a 30 year event. 

Other severe cold snaps (comparable to current) of note for DFW are January 1930,  January 1912, February 1949, February 1933, February 1905, and February 1899

21 minutes ago, TexMexWx said:

Measured roughly 0.25" of snow at my house... maybe the initial band "underperformed" slightly (I saw forecasts and model runs around a max of one inch) but it's still snowing lightly and so I'm pretty confident that we'll get a good deal more. 

Either way, this is the most I can remember at my house for the past 4 years haha (I don't think I'm missing any events)

The last time it snowed in significant amounts (= or greater than 2 inches) at DFW Airport was March 4, 2015, nearly 6 years ago. That is the longest stretch in weather record history. There has been no significant icing (0.25 or greater) in that time either. So, you are not missing any events. Though we still have a ways to go, but confident we will break the snow/ice drought before all said and done.

The sun was definitely unexpected but has nothing to do with what is about to happen. FWD NWS is actually increasing snow totals. See afternoon AFD. Calling for 4-8 inches now. They also said the storm mid week may actually be more significant. Still expect the coldest air in over 30 years on Monday. If we fail to reach 13°F for a daily high, then it will be an all time record.

The FWD NWS is upgrading the Winter Storm Watch to a Warning now. Interesting forecast discussion this afternoon.

Quote

Winter Storm Watch

URGENT - WINTER WEATHER MESSAGE
National Weather Service Fort Worth TX
351 PM CST Thu Feb 11 2021

...MAJOR WINTER STORM EXPECTED SUNDAY AND MONDAY...

TXZ091>095-100>107-115>123-129>134-141-120600-
/O.NEW.KFWD.WS.A.0002.210214T0600Z-210216T0000Z/
Montague-Cooke-Grayson-Fannin-Lamar-Young-Jack-Wise-Denton-Collin-
Hunt-Delta-Hopkins-Stephens-Palo Pinto-Parker-Tarrant-Dallas-
Rockwall-Kaufman-Van Zandt-Rains-Eastland-Erath-Hood-Somervell-
Johnson-Ellis-Comanche-
Including the cities of Bowie, Nocona, Gainesville, Sherman,
Denison, Bonham, Paris, Graham, Olney, Jacksboro, Decatur,
Bridgeport, Carrollton, Denton, Lewisville, Flower Mound, Plano,
McKinney, Allen, Frisco, Greenville, Commerce, Cooper,
Sulphur Springs, Breckenridge, Mineral Wells, Weatherford, Briar,
Fort Worth, Arlington, Dallas, Rockwall, Heath, Terrell, Kaufman,
Forney, Canton, Grand Saline, Wills Point, Van, Edgewood, Emory,
East Tawakoni, Point, Cisco, Eastland, Ranger, Gorman,
Stephenville, Dublin, Granbury, Oak Trail Shores, Glen Rose,
Cleburne, Burleson, Waxahachie, Ennis, Midlothian, Comanche,
and De Leon
351 PM CST Thu Feb 11 2021

...WINTER STORM WATCH IN EFFECT FROM LATE SATURDAY NIGHT THROUGH
MONDAY AFTERNOON...

* WHAT...Heavy snow and blowing snow possible. Total snow
  accumulations of 3 to 7 inches possible. Bitterly cold
  temperatures expected. Near blizzard conditions possible.

* WHERE...Portions of north central and northeast Texas.

* WHEN...From late Saturday night through Monday afternoon.

* IMPACTS...Travel will become nearly impossible and could become
  life threatening. The cold wind chills as low as 15 below zero
  could result in hypothermia if precautions are not taken.

* ADDITIONAL DETAILS...Precautions should be taken now to secure
  pipes and anything susceptible to the extreme cold. Have plenty
  of food and ways to stay warm in case of power outages.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Monitor the latest forecasts for updates on this situation.

&&

$$

Dunn

Aggiegeog I'll tip my hat to you for calling this if it verifies. Though I still like the lesser amounts for now. Notice 3 to 6 being highlighted by Fort Worth NWS.

Starting to see trend in models of lesser snow amounts than what was seen yesterday for DFW. Of course this will change for each model iteration, we won't get a good handle on this until the system gets sampled by the upper air network tomorrow night. I am growing increasingly concerned with the powdery snow, winds being forecast (30 mph gusts) and extreme cold of near blizzard conditions at times Sunday night in and around DFW. The most impressive part is the fact that some type of frozen precip is likely to be seen all the way to Brownsville with this system. Practically the entire state. 

Of course the other impressive part is the extreme cold. At coldest point I call for 7°F to 10°F at DFW without snowpack, with snowpack temps could easily reach 0°F. So easily the coldest air in 30 plus years (since December 1989 anyway -1°F). If we somehow were to get to  -3°F (not sure about that)...it'll be the coldest in 120 years (since February 1899).

23 minutes ago, aggiegeog said:

I consider major being 0.25". That's enough to make travel impossible and to cause power issues.

I don't see us getting that much ice at DFW yet. If this were the case the National Weather Service would already be issuing a Winter Storm Warning or Ice Storm Warning, so far the majority of forecasters think amounts will be lighter than that. Based on what I have seen I tend to agree.

26 minutes ago, vwgrrc said:

I personally don't see this actually. I mean my standard of major ice event would be Dec 2013. I'm not seeing that happen tonight at least for DFW. Thought? 

No we will not be seeing the ice storm December 2013 tonight.

15 minutes ago, aggiegeog said:

Monday is perfection for a Texas snow storm. Western Gulf surface low, 1040s Plains surface high, TPV over Midwest, negative tilting shortwave and a Siberian air mass at the surface. 

The GFS is blatantly absurd this morning for its predictions next week. I personally think the eventual track of the system will be much further south limiting accumulations this far north given past experience with this type of deep cold air setup. Please study the December 1983 outbreak. So while we may get snow in DFW, I don't think, at least yet, the GFS is depicting anything that will actually verify. I will have to see a lot more runs that show this before climbing on board such a record breaking event. The fact that it would snow in significant amounts with temperatures below 15°F at DFW is a record in of itself. Many ensemble members of the Canadian, ECMWF, and GFS are actually quite dry.  Let's not loose our heads yet! 

I would love to see it snow as much as all of you, however, I am cautious about going all out on significant snowfall with this upcoming event Sunday night into Monday across North Texas. Climatology strongly argues against it. In my lifetime, I have never seen it snow at DFW with temperatures in the low teens or single digits over the last 45 years. The air has to be extremely dry at the surface for temperatures to be that cold this far south. The only example I can find in climatology that may come close to this setup is the Arctic outbreak of February of 1899 where we got a little more than inch of snow with temperatures that cold. It was not all that much. Nearly all modeling is forecasting lows in the single digits to around 14 (depending on model) at DFW Sunday night. So, if it does snow greater than 2 inches, it will be one for the record books. 

Having said all that, it does look very impressive on the models. The cold coming off these same models is equally as impressive. Very confident lows below 12°F at DFW will be realized at some point making this the coldest outbreak since 1996. If we can get to 7°F it will be the coldest since December 1989 where it fell to 1 below zero.

1 hour ago, aggiegeog said:

Things are coming together nicely on most all models for a significant snow event early next week for most north of I-10. Closer to I-20 and north this looks to be a high ratio event (>15:1) with lower ratios (<10:1) along I-10. Before this event there will be freezing drizzle for DFW area this week, and a light mixed precip event on Saturday for the northern half of the state. Mid-week next week could feature another mixed precip event but that is over a week out so I will leave that one alone for now.

Past experiences with these deep Arctic airmass tells me it will be too dry for significant snows. In both December 1983 and 1989 (which this setup is similar too) it was just too dry to get it to precipitate. It tried several times, but it just ended up being flurries at best. It is going to be rather difficult to get it to precipitate in that type of Arctic air.  A cursory glance on some of the models show dewpoints getting below zero across good portion of North Texas, even down to 0 at DFW. Very difficult to get precipitation in a setup like that. The best setup for significant snow and ice is along and just behind the Arctic front with a decent system. Also, when Arctic air retreats you might can get a decent setup if it doesn't erode too quickly.

4 hours ago, vwgrrc said:

True~ but I'm actually more interested in the frozen precip it shows Sun/Mon timeframe at this point

Interesting forecast discussion from the Fort Worth NWS talking about the possibility of record to near record cold with this Arctic blast. While the all time record cold for DFW is 8 below zero set on Feb 12, 1899, I think we will likely be well safe from that. However, highs may be in jeopardy if some of the colder guidance verifies. I do think lows at some point in the single digits will be attainable, even in the heat island of DFW, but particularly at DFW Airport. I would also love for DFW to break its ice/snow drought. Going on 6 years almost now. Going on 25 years since we last hit the single digits. This should happen every 5 years according to climatology. We are also at the climatology point of a subzero reading, so wouldn't be surprised if that happens.

12z GFS is one for the record books at DFW. Three days in a row of temps around 0 (-1°F for two morning and 1°F one morning) with a high of 7°F on Sunday (that would be the coldest MAX ever by a wide margin). I don't think I have ever seen that on this model. Likely not going to be this extreme...but wow!

54 minutes ago, aggiegeog said:

After a bit of model carziness over the weekend things are becoming clearer. I am going with a blend of the ICON and GFS for my forecast as they have been largely consistent. Looks like the cold builds from 40s for highs mid week to 20s for highs over the weekend with lows in the single digits north of I-20 with sub zero temps in NW TX. The ripples will be nearly impossible to pin down, but some light frozen mixed precip seems likely late this week with snow being more likely this weekend and into next week. Looks a lot like early Feb 2011 but maybe colder. ICON threatens the all time state low temp record of -23.

 

This is quite the cold spell! Severe cold at DFW is defined as a low temp of 10 or lower and/or a high of 20 or lower. This is on the table. A 51 member GEM ensemble average is showing a low of 9°F on Sunday at DFW with a high of 22°F. The 6z GFS is showing low of 3°F and a high of 12°F for Sunday (0z 11°F to 20°F with 6°F on Monday morning). I noticed the NBM numbers are coming down with a low of 15°F and high of 26°F (these are a blend of all the models) at DFW. We have to go back to Janaury of 2018 for anything approaching this kind of cold. If temps get below 12°F, it will be the coldest since February of 1996. Also, I am seeing a strong indication of multi days of consecutive subfreezing temps with this event. Some models showing 5 or 6 days possible. It should be noted that the ECMWF has finally come onboard after being in la la land over the weekend (it didnt even agree with its weeklies). It really was the only model wavering.

Texas is heading for the deep freeze beginning Tuesday next week! A nearly 1058 mb Arctic high will move out of the northwest territories and plunge into the lower 48. This will be the coldest of the season for many and for DFW, likely the coldest air in over two years (since January 2018). It also looks like a protracted cold air outbreak lasting until early the following week. The core of this outbreak looks to occur Thursday through the weekend of Valentine's where temperatures are likely to be in the teens at DFW (even in the heat island) with highs struggling to get out of the 20s. There could be multiple days of subfreezing temperatures. Also, there is some signal for light frozen precipitation, though it looks like moisture may be hard to come by given the setup. This Arctic blast also may send subfreezing temperatures into the lower Rio Grande Valley.

On 1/16/2021 at 2:11 PM, raindancewx said:

The 6-10 day outlook from CPC yesterday looked pretty warm for Texas. Long-term, a big +SOI December value is a very strong indicator for a warm February in the South, usually including Texas. Although the signal is weaker the further west you get. December 2020 was +16, 5th highest SOI value since 1931. I don't know that winter is over in Texas, but Texas weather is pretty strongly correlated to warmth when the PNA goes in the wrong phase like it is about to.

 

The 1931-32 winter in Texas (at least for DFW) was one of the hottest winters on record. In fact, during December through February the lowest minimum temp was only 29°F. However, March of 1932 was pretty cold and we finally recorded a low of 22°F. That month there was 9 consecutive days with temps 20 below normal on average. It is pretty alarming how close we are following that winter this season. The lowest minimum so far 27°F which ties the all time hottest record for a winter season set in 2015-2016. The vast majority of our winters see the temp dip below 20°F at least one time. 

NWS office upgraded Watch to a Winter Storm Warning. They went with a Winter Weather Advisory for the Metroplex. The southwest quadrant of Tarrant is likely to see more than 3 inches and because of that, I think Tarrant County should have been included in the Warning.

After looking at all the model data this morning. Nearly every model with the exception of the ECMWF shows Tarrant County meeting criteria, at least the southwestern portions of the county anywhere from 4 inches to 9 inches in that area (though this does not account for melting). SREF Member probabilistic guidance of Tarrant county receiving 6 inches of snow is greater than 50%. Some guidance has 4 inches plus as far north as DFW Airport. The ECMWF has shifted everything out west, and appears to be an outlier at this time. If the warmer temperatures verify, then it will be closer to being correct. Therefore, I would not be surprised if Tarrant County gets added to the watch and I fully expect the Watch to get upgraded to a Winter Storm Warning this afternoon. If the latest NAM and Canadian are correct then Dallas County, Ellis, Kaufman and Rockwall would likely need to be added. This does look to be a primarily south of I-20 event, thus the further southwest you are in the Metroplex south of I-20 the better your chances of seeing the most snow. There appears to be a rapid gradient to nothing north of I-30, particularly when you get into Denton and Collin counties.

15 minutes ago, aggiegeog said:

Ok let's call it cold air then. True Arctic air would not support snow. I think its more likely we see temps dropping into the 20s under the heavy bands given the cold temps at 850 and even at 925. Daytime temps for North Central TX outside of the heavy bands will likely be 33 to 35 so there may be some melting. Under the heavy bands we are looking at >2"/hr rates with temps at or below freezing and ground temps not crazy warm given time of year and current cool temps. I am very confident in storm max totals being in the range of a foot or perhaps greater with widespread 6".

I would agree with you given the impressive cold air aloft with this setup that surface temps should be colder. I would favor temps in the 28 to 32 range during the event with that kind of cold air aloft. I mean when was the last time you saw 528 thickness over DFW (forecast from 0z NAM) and an H85 temp of -7°C with a surface temp of 37°F? Something doesn't compute.  However, given the uncertainty still in this system, I would go with about half of what you are forecasting for right now. I think 2 to 6 looks reasonable, with heavier amounts likely south of I-20 in the Metroplex. However, if the surface temps verify colder, I would agree totals closer to what you have may not be out of the question.

3 hours ago, aggiegeog said:

RGEM seems to be handling the convective nature of this event well even if the QPF may be overdone. Though around 1" QPF for a dynamic system with great moisture is clearly possible. I believe and there will be a number of areas that receive near or over 12" with the area between Hillsboro  and Nacodoches being the most likely stretch to see that. All models give this area between 0.5 and 1.5" QPF with temps supporting primarily snow.

Texas has been waiting 11 years for a Gulf surface low, potent upper low combo pumping moisture into an Arctic air mass.

First off, there is no Arctic air associated with the system on Sunday. Let's be clear on the source region of the airmass. This airmass did not originate in the Arctic circle or Siberia. It exhibits none of the properties of Arctic airmasses.  It is modified continental and Rocky mountain air. We are all excited by the snow and some impressive amounts are being forecasted by the models. However, none of that is taking into account the amount of snow that will be wasted to melting on impact. Many of the models surface temps are between 34 and 38 degrees (these may be warm given all the models H85 temps), including the NAM, during this event. If temps are being correctly modeled, It is going to be a fight to get accumulations with surface temperatures that warm. So to be realistic, I think your totals are a bit much. Even the NWS is not forecasting anything like that based from this morning AFD, thus this event may not even meet Winter Storm Warning criteria for the Metroplex. What happened in February of 2010 was extraordinary, and I would love to be wrong and it happen again, it just is not likely.

As you know, we are in the longest stretch in Weather history of no significant snow or ice for DFW (~6 years). I very much like the pattern for Sunday for a potential winter storm, probably the best setup in years. Some of our best events come form such a 500mb pattern. However, I do see caveats. To bring this into perspective, the models have a had a cold bias at this time range all winter long. I still don't see a large reservoir of cold air to tap into, thus we will need to rely on the storm to manufacture its own cold air, much like the New Year's Eve storm. I am always skeptical on this type of winter storm as 9 times out of 10, it ends up as a cold rain. Assuming the models are correct in the their temperature forecasts, this may not be much of a problem with -25C air at 500mb with system itself. The models do show colder air at 850mb over our area anywhere from -2C to -8C (depending on the model). This translates roughly to 28 to 34 degrees at the surface during the event. Should clouds clear after and we do get some accumulating snow, then we could be dealing with some of the coldest temps so far this winter. This brings me to the next caveat which is the system itself and its eventual track.  It is still out over the water, thus any deviation from the modeled track or change in timing, could greatly effect our outcome. 12z NAM looks pretty good.

Speaking of cold air...I am also liking a transition to a colder period to close out the month. I think the potential is there to tap into some bona fide Arctic air. I am starting to see some of the models latch on to this idea. Perhaps this event will be the transition?