Ed, snow and hurricane fan Posted January 30, 2022 Share Posted January 30, 2022 I actually have no idea how to guess sleet over freezing rain, but cool 850s and subfreezing 925, I'm guessing sleet. 1 Link to comment Share on other sites More sharing options...
aggiegeog Posted January 30, 2022 Share Posted January 30, 2022 4 minutes ago, Ed, snow and hurricane fan said: I actually have no idea how to guess sleet over freezing rain, but cool 850s and subfreezing 925, I'm guessing sleet. That's a pretty good rule, obviously not going to work every time but a good general rule. 1 Link to comment Share on other sites More sharing options...
Powerball Posted January 30, 2022 Share Posted January 30, 2022 46 minutes ago, Ed, snow and hurricane fan said: I actually have no idea how to guess sleet over freezing rain, but cool 850s and subfreezing 925, I'm guessing sleet. A general rule for sleet would be 925mb temps of at least -5°C with 850mb temps in the +1-3°C range. 2 Link to comment Share on other sites More sharing options...
aggiegeog Posted January 30, 2022 Share Posted January 30, 2022 There likely will be a 50 to 100 mile wide swath of major freezing rain impacts. My initial guess for it is centered around a Del Rio to Paris line. North of I-20 and west of I-35 could see heavy snow that begins as sleet closer to I-35. Heavy rain ending as freezing rain south of that line. Maybe an area of light snow later in day Thursday along and north of I-20. Link to comment Share on other sites More sharing options...
Ed, snow and hurricane fan Posted January 30, 2022 Share Posted January 30, 2022 I wouldn't get too confident on anything until Euro and GFS converge. Globals not known for low level temp resolution, either, but it seems like mesoscale models aren't really good outside 48 hours, or Tuesday earliest to get *super* excited. Link to comment Share on other sites More sharing options...
vwgrrc Posted January 30, 2022 Share Posted January 30, 2022 I wouldn't get too confident on anything until Euro and GFS converge. Globals not known for low level temp resolution, either, but it seems like mesoscale models aren't really good outside 48 hours, or Tuesday earliest to get *super* excited.True. Also is notable that 12z euro stepped back on the frozen p quite a bit. That's hard to ignore given we're still about 4 days out.Sent from my SM-G991U1 using Tapatalk 1 Link to comment Share on other sites More sharing options...
aggiegeog Posted January 30, 2022 Share Posted January 30, 2022 18 minutes ago, Ed, snow and hurricane fan said: I wouldn't get too confident on anything until Euro and GFS converge. Globals not known for low level temp resolution, either, but it seems like mesoscale models aren't really good outside 48 hours, or Tuesday earliest to get *super* excited. Euro has proven itself to be very unreliable and inconsistent with these type events over the past few years. ICON and GFS to a lesser degree are king in this situation. The combo of two very strong forces, 1050mb Arctic high and strong negative tilt short wave, make it very difficult for models to resolve. My opinion is to go on past experience which is the shortwave will be more SW than modeled and the surface cold will bleed south faster than modeled except in far eastern Texas where the Ouachita Mountains will block it. 2 Link to comment Share on other sites More sharing options...
Ed, snow and hurricane fan Posted January 31, 2022 Share Posted January 31, 2022 18Z Euro may be trending closer to GFS. No school at least Thursday in DFW. I want Hwy 6 in the action... 1 Link to comment Share on other sites More sharing options...
aggiegeog Posted January 31, 2022 Share Posted January 31, 2022 If the low drives into Mexico then all bets are off. We should get much better idea tomorrow and especially tomorrow night once the system enters the balloon network. 1 Link to comment Share on other sites More sharing options...
vwgrrc Posted January 31, 2022 Share Posted January 31, 2022 6 hours ago, aggiegeog said: Euro has proven itself to be very unreliable and inconsistent with these type events over the past few years. ICON and GFS to a lesser degree are king in this situation. The combo of two very strong forces, 1050mb Arctic high and strong negative tilt short wave, make it very difficult for models to resolve. My opinion is to go on past experience which is the shortwave will be more SW than modeled and the surface cold will bleed south faster than modeled except in far eastern Texas where the Ouachita Mountains will block it. Thanks for sharing! Now at 12z, NAM starting to pick up this event. The frozen p amount seems lower than what GFS, CMC and ICON suggested at this point. I wonder how we read that? Is that a timing difference or mesoscale just has a better insight in this case? 1 Link to comment Share on other sites More sharing options...
aggiegeog Posted January 31, 2022 Share Posted January 31, 2022 28 minutes ago, vwgrrc said: Thanks for sharing! Now at 12z, NAM starting to pick up this event. The frozen p amount seems lower than what GFS, CMC and ICON suggested at this point. I wonder how we read that? Is that a timing difference or mesoscale just has a better insight in this case? NAM at this range is fantasy land. I'll start paying attention to the NAM and other meso models on Tuesday. I do not think we will gain much insight tomorrow with the storm offshore. 1 Link to comment Share on other sites More sharing options...
cheese007 Posted January 31, 2022 Share Posted January 31, 2022 LONG TERM... /NEW/ /Tuesday Onward/ Key Points: * There is potential for a winter storm to impact the region Wednesday evening into Thursday. There is only about a 10% chance of seeing only cold rain Wednesday night with only light accumulations of sleet/snow Thursday. * Widespread rain Wednesday afternoon is expected to transition to freezing rain/sleet overnight. Where this transition occurs, ice and sleet accumulation is likely. Accumulating snow is likely across Western North Texas Wednesday night and Thursday. * Very cold air will move into the region Wednesday night and bring dangerously cold wind chills Thursday and Friday mornings regardless of winter precip. Temperatures are not expected to rise above freezing until Friday for most and Saturday for some. * Travel and other ice-related impacts would linger into Friday with some lingering into Saturday. * There is still uncertainty regarding where/when the transition from rain to winter precip will occur. Snow and ice forecast amounts are very low confidence and will likely change. Meteorological Details/Discussion: The data continues to favor a winter storm impacting the region Wednesday night into Thursday, however, it is still not a "slam dunk" forecast. While it is more likely than not, there is still about a 10-20% chance that only minor impacts are seen outside of a few locations within North Texas. We have decided to hold off on the issuance of a Winter Storm Watch until we are more confident of which locations will/won`t see major disruptions or impacts. A cold front will move into the region Wednesday with falling temperatures behind the front. Expect temperatures to drop below freezing from northwest to southeast Wednesday night. It`s worth noting that we can`t completely ignore the fact that some guidance keeps the sub-freezing air to our north until closer to daybreak Thursday. Shallow arctic fronts have a tendency to outpace the coarser mesoscale/global guidance in the long-range, therefore we have continued to side with the faster guidance. The meteorological setup for this event is very favorable for a freezing rain and sleet event, particularly across North Texas. It really is just a matter of how fast the sub-freezing temperatures arrive. A faster progression of the cold air would mean a more significant winter precip event while delayed cold air would lead to mainly minor impacts. The consensus and our current forecast, however, is that the cold air will arrive Wednesday night and bring winter precip to just about all of North and Central Texas Wednesday night and Thursday. Wednesday will start mild under thick cloud cover with steadily deteriorating conditions through the day. The cold front will bring a northerly wind shift, dense cloud cover, and falling temperatures. The shallow front will undercut the lower density air ahead of it and develop dense stratus with strong low-level isentropic ascent as the air rides overtop of the cold air. Meanwhile, a deep upper trough will remain planted over the SW CONUS through the end of the week. A potent shortwave trough will eject out of this low and move overtop of Texas Wednesday night into Thursday. As the ascent associated with the trough taps into the moist low-level isentropic ascent, widespread rain will develop behind the front. It should start to develop around noon Wednesday then become most widespread overnight. The precip will continue through the night and Thursday morning before coming to an end Thursday afternoon as the trough moves east. Current P-Type Forecast: - All precip should fall as rain during daylight hours Wednesday. An initial transition to freezing rain is likely across Western North Texas around nightfall. Freezing rain should approach the Metroplex around midnight, Waco around 3 AM, then the Brazos Valley and our far southeastern counties around daybreak Thursday. We then expect sleet to develop somewhat quickly (within an hour or so) after the changeover to freezing rain, with several hours of sleet and/or freezing rain. As temperatures continue to fall through the night, freezing rain will become less likely with the precip becoming almost all sleet. Shortly after this, snow will likely mix in for those generally north and west of the Metroplex. Western North Texas will likely see a full changeover to snow early Thursday. If precip lingers much into Thursday, it will be all snow for North Texas and a mix of freezing rain/sleet for our eastern Central Texas counties. - Please keep in mind the coldest air will be across Western North Texas with the warmest temperatures over eastern Central Texas, so the evolution above may not be representative of every location within our forecast area and is a generalizations for what you can expect. Please see our "point and click" forecast for a detailed breakdown at your location. Accumulation Forecast: ICE: - It appears that the highest ice accumulation will occur to the northeast of the Metroplex. At this point, the highest ice accumulation is expected in a band from about Paris to DFW to Stephenville with 0.10-0.25" of ice possible in this region, with higher amounts NE of DFW. - DFW and Waco have a low chance of receiving 0.25" of ice but a high chance of receiving between 0.10-0.25" of ice. Paris has a moderate chance of receiving 0.25" of ice. - Less than 0.10" of ice is forecast across Western North Texas where precip should transition to sleet/snow earlier. Less than 0.10" of ice is also forecast in and east of the Brazos Valley where temperatures remain above freezing or only drop into the low 30s while precip is falling. NOTE: We usually want to have temperatures at or below 28 F to receive significant ice accumulations. That is not necessarily true with this event due to brisk north winds around 20-25 mph. Strong winds will help expel heat from surface objects, but will be very efficiently expel heat from the individual water droplets as they fall & make contact with the surface. Due to this, we can start to receive significant ice accumulation with temperatures around 30-31 F instead of the typical 28 F threshold. SLEET/SNOW: - The highest sleet/snow accumulations should remain over Western North Texas, however at least a trace of sleet/snow is possible for just about everyone. - At this time between 2-3" of sleet/snow is possible for our far western row of counties, with between 1-2" of snow possible NW of the Metroplex. - As far as sleet alone...The highest sleet accumulation is likely to remain along & north of I-20 and west of ~Sherman. Sleet accumulations between 0.75-1.5" are not out of the question at this point. - Any sleet and snow that falls will accumulate easily as it settles on a layer of ice. The forecast above would likely cause significant travel impacts across the region Thursday. Most high rise overpasses would become glazed over with ice and untreated surface roads could also become slick. Ice accumulation on utility lines with winds gusting to 30-35 mph could also cause power outages. With temperatures not rising above freezing Thursday, ice would likely not melt until Friday for most or Saturday if significant accumulations were experienced. While most of our attention has been on the precipitation, we are more confident about the post-precipitation temperature forecast late in the week. Overnight lows Friday and Saturday mornings will likely fall into the single digits and teens. Gusty winds Friday will cause wind chill values well into the single digits for everyone and below zero from those west of I-35/35W. Please remember the 4 P`s and protect sensitive People, Pets, Plants, and Pipes. Temperatures should warm Saturday and Sunday, but still remain about 10-20 degrees below normal. Bonnette 1 Link to comment Share on other sites More sharing options...
DFWWeather Posted January 31, 2022 Share Posted January 31, 2022 The delay in the Winter Storm Watch is because of the NAM. This model is usually king in its handling of shallow/dense Arctic airmasses and it is delaying the arrival of the coldest air. It is the model that has thrown the monkey wrench into this forecast - lol! This has huge impacts on forecast amounts with the NAM showing hardly any accumulation. It also is keeping the storm track a bit further north. I must say this is pretty unusal. It also should be noted, the entire 0z suite of CMC ensembles have warmed from where they were, though the operational has not really. The ECMWF, ICON never get us below 20°F with this event, or just barely in the case of the ICON. The ECMW is also a bit delayed on the 32°F arrival of air into the Metroplex. Given past experiences with 1050 mb Arctic highs, I don't see what would hold up cold air like that. I would side with the colder faster solutions. The amounts forecasted above by the FWD NWS is in line with Winter Storm Watch criteria. I would have issued the Watch. It can always be canceled or downgraded to an Advisory (that is exactly what a Watch is for anyhow). If they were making a decision on a Warning, I would have held off. 1 Link to comment Share on other sites More sharing options...
aggiegeog Posted January 31, 2022 Share Posted January 31, 2022 Agreed that without meso model support it is ok to delay a bit in watches, unless agreement comes before they may wait until tomorrow. The GFS has been amazingly consistent, though if meso models do not come into agreement by 12Z tomorrow the forecast is gonna be very difficult. If the high was over the Dakota's it would be much more of a slam dunk but it's a bit far east from ideal position so that especially East Texas has a couple mountain ranges in between. I still think areas west of a Waco to Tyler to Paris line are very likely to have significant icing. Longview to Texarkana are much more borderline. Link to comment Share on other sites More sharing options...
Powerball Posted January 31, 2022 Share Posted January 31, 2022 1 hour ago, DFWWeather said: The delay in the Winter Storm Watch is because of the NAM. This model is usually king in its handling of shallow/dense Arctic airmasses and it is delaying the arrival of the coldest air. It is the model that has thrown the monkey wrench into this forecast - lol! This has huge impacts on forecast amounts with the NAM showing hardly any accumulation. It also is keeping the storm track a bit further north. I must say this is pretty unusal. It also should be noted, the entire 0z suite of CMC ensembles have warmed from where they were, though the operational has not really. The ECMWF, ICON never get us below 20°F with this event, or just barely in the case of the ICON. The ECMW is also a bit delayed on the 32°F arrival of air into the Metroplex. Given past experiences with 1050 mb Arctic highs, I don't see what would hold up cold air like that. I would side with the colder faster solutions. The amounts forecasted above by the FWD NWS is in line with Winter Storm Watch criteria. I would have issued the Watch. It can always be canceled or downgraded to an Advisory (that is exactly what a Watch is for anyhow). If they were making a decision on a Warning, I would have held off. I definitely think waiting for the 12z model cycle at least is the best move. Those 00z/06z model runs might have been the start of a trend towards a relatively less signifucant event. Link to comment Share on other sites More sharing options...
DFWWeather Posted January 31, 2022 Share Posted January 31, 2022 49 minutes ago, Powerball said: I definitely think waiting for the 12z model cycle at least is the best move. Those 00z/06z model runs might have been the start of a trend towards a relatively less signifucant event. Looks like 12z NAM has come aboard. Winter Storm Watch probably will get issued this afternoon. 2 Link to comment Share on other sites More sharing options...
Powerball Posted January 31, 2022 Share Posted January 31, 2022 5 minutes ago, DFWWeather said: Looks like 12z NAM has come aboard. Winter Storm Watch probably will get issued this afternoon. If you look closely, the NAM spares the heart of the Metroplex from much (if any) ice, with only advisory criteria amounts in the outer suburbs. (^^^Oh, Thank Heaven!!!) Different story along the OK border around Sherman though. Link to comment Share on other sites More sharing options...
DFWWeather Posted January 31, 2022 Share Posted January 31, 2022 6 minutes ago, Powerball said: If you look closely, the NAM spares the heart of the Metroplex from much (if any) ice, with only advisory criteria amounts in the outer suburbs. (^^^Oh, Thank Heaven!!!) Different story along the OK around Sherman though. It is still ingesting data, and I bet those amounts go up a bit into tomorrow. It is forecasting an inch plus of sleet which is still Watch criteria. Remember a Watch can be upgraded or downgraded to a Warning or Advisory. It also came in significantly colder with temps and much quicker with the 32°F freeze line in line with the other models. 1 Link to comment Share on other sites More sharing options...
vwgrrc Posted January 31, 2022 Share Posted January 31, 2022 5 minutes ago, Powerball said: If you look closely, the NAM spares the heart of the Metroplex from much (if any) ice, with only advisory criteria amounts in the outer suburbs. (^^^Oh, Thank Heaven!!!) Different story along the OK border around Sherman though. Not sure if I'm looking at the same thing - but at least the 12KM NAM i'm looking at, Thursday 9-15z has DFW under mostly freezing ice and sleet. That's 6 hours under icing condition! Link to comment Share on other sites More sharing options...
Powerball Posted January 31, 2022 Share Posted January 31, 2022 8 minutes ago, DFWWeather said: It is still ingesting data, and I bet those amounts go up a bit into tomorrow. It is forcasting and inch plus of sleet which is still Watch criteria. Remember a Watch can be upgraded or downgraded to a Warning or Advisory. The headlines (or lack thereof) really don't matter to me. I hate ice (along with the extreme cold coming behind it) and I'm not looking forward to any amount of it. I'm hoping it does trend to a nothingburger. Link to comment Share on other sites More sharing options...
Powerball Posted January 31, 2022 Share Posted January 31, 2022 2 minutes ago, vwgrrc said: Not sure if I'm looking at the same thing - but at least the 12KM NAM i'm looking at, Thursday 9-15z has DFW under mostly freezing ice and sleet. That's 6 hours under icing condition! I'm looking at the Total Accumulated Freezing Rain QPF map on Pivotal Weather. Do note, rain can technically fall with air temperatures below freezing but still not actually accumulate much because of residual warm air on surfaces. Link to comment Share on other sites More sharing options...
vwgrrc Posted January 31, 2022 Share Posted January 31, 2022 1 minute ago, Powerball said: The headlines (or lack thereof) really don't matter to me. I hate ice (along with the extreme cold coming behind it) and I'm not looking forward to any amount of it. I'm hopefully it does trend to a nothingburger. 100% agree. Like other had posted above - the takeaway at this point is that NAM is trending towards GFS, which is not a good new for the power grid. Link to comment Share on other sites More sharing options...
DFWWeather Posted January 31, 2022 Share Posted January 31, 2022 2 minutes ago, Powerball said: I'm looking at the Total Accumulated Freezing Rain QPF map on Pivotal Weather. Do note, rain can technically fall with air temperatures below freezing but still not actually accumulate much because of residual warm air on surfaces. Technically not in this case because of the wind moving heat away from the rain droplets. It actually will freeze closer to 32°F on contact than the usual 28°F. Great techncial discussion on that in the FWD AFD this morning. This setup is almost a classic textbook case of ice and sleet for this area. 2 Link to comment Share on other sites More sharing options...
Ed, snow and hurricane fan Posted January 31, 2022 Share Posted January 31, 2022 Fact from last big Houston ice storm- spraying CaCl2 brine solution on the road keeps bridges and overpasses ice free ***only*** if significant liquid rain doesn't fall first and wash it off. Houston highway flyways were treated and still a disaster. 1 Link to comment Share on other sites More sharing options...
vwgrrc Posted January 31, 2022 Share Posted January 31, 2022 Someone tell me I'm reading this wrong please - 12z GFS seems even more bullish on the frozen QPF for most of the DFW. Almost X2 from 0z last night?! That's very concerning Link to comment Share on other sites More sharing options...
DFWWeather Posted January 31, 2022 Share Posted January 31, 2022 1 hour ago, vwgrrc said: Someone tell me I'm reading this wrong please - 12z GFS seems even more bullish on the frozen QPF for most of the DFW. Almost X2 from 0z last night?! That's very concerning The 12z GFS is forecasting at DFW Airport 1.7 inches of sleet and 0.26 of an inch of freezing rain. The 12z Canadian is going for approximately 0.10 of an inch ice accretion across the Metroplex and 2.00 inches of sleet all across the Metro. 1 Link to comment Share on other sites More sharing options...
vwgrrc Posted January 31, 2022 Share Posted January 31, 2022 42 minutes ago, DFWWeather said: The 12z GFS is forecasting at DFW Airport 1.7 inches of sleet and 0.26 of an inch of freezing rain. Good thing is CMC stepped down a little bit on QPF compared to yesterday. If GFS holds thru out tonight, I may need to start thinking abt what to prepare for a power outrage to be honest. Link to comment Share on other sites More sharing options...
DFWWeather Posted January 31, 2022 Share Posted January 31, 2022 1 minute ago, vwgrrc said: Good thing is CMC stepped down a little bit on QPF compared to yesterday. If GFS holds thru out tonight, I may need to start thinking abt what to prepare for a power outrage to be honest. Not really, it is going for more sleet as opposed to freezing rain. Link to comment Share on other sites More sharing options...
vwgrrc Posted January 31, 2022 Share Posted January 31, 2022 1 minute ago, DFWWeather said: Not really, it is going for more sleet as opposed to freezing rain. Yes that's what I mean. I think sleet is easier on trees and powerlines as it doesn't stick to surface like FR does, which is always the main concern for event like this in DFW. I was in Richardson in December 2013. I remember the power went out not even too long after the FR begins. I can't open my car the next morning Link to comment Share on other sites More sharing options...
Ed, snow and hurricane fan Posted January 31, 2022 Share Posted January 31, 2022 All my family in Bedford/Hurst/Euless have underground supplied electricity, so ice would need to be enough to take down larger above ground major transmission lines, usually taller than surrounding trees and thicker than neighborhood transmission lines. No idea if Dallas is the same. Neighborhood lines thinner and vulnerable to tree branches falling/ 1 Link to comment Share on other sites More sharing options...
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