OmahaSnowFan Posted December 11, 2020 Report Share Posted December 11, 2020 What’s cool is that all the hi res models have consistently been showing that small bullseye on the north side of Omaha (me) and the county right north of me 2 Quote Link to comment Share on other sites More sharing options...
Grizzcoat Posted December 11, 2020 Report Share Posted December 11, 2020 Good AFD by DMX--- they too mention a later change than what CAM's are showing. But overall- a good setup for many. Also mention enhanced totals in NE IA for those peeps... Area Forecast Discussion National Weather Service Des Moines IA 404 PM CST Fri Dec 11 2020 .DISCUSSION.../Tonight through Friday/ Issued at 404 PM CST Fri Dec 11 2020 Synoptic and Meso Features: Main focus will be on the deformation zone developing over central Iowa this afternoon and evening with accumulating precipitation. Strong short-wave trough has developed negative tilt, with the axis extending from the Colorado Front Range to the Texas Gulf Coast. The strong CVA associated with the jet streak with this short-wave is phasing well with the surface cyclone, and the cyclone has continued to deepen this afternoon. The surface cyclone center will stay south of Iowa, but is on a northeast track as the jet stream begins to round the base. Within the deformation zone, there is quite a bit to look at. Analyzing frontogenesis fields, both synoptic scale models and CAMs show a strong ribbon that starts near Atlantic and moves ESE through the DSM Metro into east-central Iowa. This is largely concentrated between the H85 and H7 levels, though there are hints of more forcing around 925mb as well. This will move through between now and 12z Saturday. After 6z another area of enhanced frontogenesis develops near CID, but most of this becomes focused east of the forecast area, but will result in heavier snow for portions of eastern and northeast Iowa through Saturday Morning. These same areas are also characterized by moderate to strong Q- vector convergence, which makes sense with strong jet streak and associated kinematic reactions. Delving into model soundings, cloud- ice does not appear to be hard to come by for counties in Iowa mainly south of U.S. Hwy 20 to around U.S. Hwy. 34. With ice introduction, this leaves rain, rain-snow mix, or pure snow the viable precipitation type for this event. There may be a brief period of other wintry mixes, but overnight will transition to all snow. Temperatures will largely drive rain vs. snow this evening. Temperatures late this afternoon will remain near 35-36F, but should see some amount of cooling within the precipitation shield heading into the evening. By 06z, with temperatures between 32-34F and dewpoints closer to 30-31F, wetbulb temperatures should be near 32F and thus is when snow is expected to take over. One quick note about areas along and north of Hwy. 18, there does appear to be some strong frontogenesis that is starting but cross-section and vertical sounding analysis show a very dry layer above the surface, thus northern Iowa will be missing out on most of this precipitation event. Snow Amounts and Model Guidance Comparison: The bottom line up front, CAMs has been much more robust with respect to total snow then some of the synoptic models. However, both have the greatest snow accumulations along a line from near Red Oak, IA (south of Council Bluffs) through Des Moines to Marshalltown, with decreasing amounts then northwest of this line and southeast of it. This area is highlighted by the current Winter Weather Advisory. The differences, is the 12z HREF mean values have 4-6 inches within this band and localized pockets of 8-10 inches. In the 12z GEFS members, greatest amounts were 2-4 inches, and do not necessarily have the localized heavy amounts, but this is likely due to the coarse resolution. In a brief discussion with WPC, it was noted that several of the GEFS members were warm with respect to temperatures, and as a result was turning it into liquid rain for an extended period of time, while CAMs depicted a slightly quicker change to snow. Given the strong frontogenesis, as well as strong omega profiles through the DGZ, it is anticipated that there will be enough forcing to overcome a lot of these challenges presented by the warmer temperatures in the area of greatest accumulations. Therefore, will have a snowfall forecast that lies in between the HREF and GEFS members, but certainly could see some locally higher amounts where frontogenesis is strong. The warmer temperatures and melting are the reason to not go nearly as high as the 12z HREF mean, but the frontogenesis and lift through the DGZ justifies being higher than GEFS mean, and even the 12z deterministic GFS for that matter. Other considerations with this will be snowfall rate. 12z HREF was not overly robust with this, greatest 1 hr snowfall rates only reach about half an inch per hour. With the high moisture content, visibility could still drop to around 1 mile as the column saturates. With wind gusts only forecast up to 25 MPH, blowing snow is not expected to be a big issue. 2 Quote The two loudest sounds known to man: a gun that goes bang when it is supposed to go click and a gun that goes click when it is supposed to go bang. Link to comment Share on other sites More sharing options...
Grizzcoat Posted December 11, 2020 Report Share Posted December 11, 2020 I guess not really concerned as I was about this rain being shown as snow in few hours which is not happening. Never was supposed. The defo band is what counts. Good Luck to all the winter weather weanies!!! Quote The two loudest sounds known to man: a gun that goes bang when it is supposed to go click and a gun that goes click when it is supposed to go bang. Link to comment Share on other sites More sharing options...
bud2380 Posted December 11, 2020 Author Report Share Posted December 11, 2020 18z RDPS 1 1 1 Quote Link to comment Share on other sites More sharing options...
East Dubzz Posted December 11, 2020 Report Share Posted December 11, 2020 Nice to see snow again! Here is how it’s going so far.. 1 3 Quote Link to comment Share on other sites More sharing options...
clintbeed1993 Posted December 11, 2020 Report Share Posted December 11, 2020 I drove to my parents in Aurora, Nebraska to experience some snow since I've been missing it a ton. Glad I did. 4 inches down and probably a couple more to go this evening. Now i have 2 locations to utilize for chasing snowstorms. Double your odds. Not a bad startegy 3 Quote Link to comment Share on other sites More sharing options...
james1976 Posted December 11, 2020 Report Share Posted December 11, 2020 Nice write up from DMX. Good luck to you all. My backyard looks to get grazed but im up in St Paul so ill have to pop in to see how its going! Defo band is setting up nicely. 1 Quote Link to comment Share on other sites More sharing options...
Hawkeye Posted December 11, 2020 Report Share Posted December 11, 2020 Bud, I don't expect any accumulation here til after midnight. It's good that it's changing over to snow in Dubuque. It has to change there before here. Quote season snowfall: 34.8" '22-23: 30.2" '21-22: 27.1" '20-21: 52.5" '19-20: 36.2" '18-19: 50.2" '17-18: 39.5" Average snowfall: ~30" Link to comment Share on other sites More sharing options...
hlcater Posted December 11, 2020 Report Share Posted December 11, 2020 Most models put my backyard right on the wrong side of the cutoff. Quite a consensus for that, so it is probably correct. Gonna go with 1.5" in downtown IC and 4.5" in Hiawatha. Quote 2021-22 Snowfall: (Hiawatha) TOTAL: 10.2" (12/28: 3.0") (12/29: 0.8") (1/1: 6.4") Link to comment Share on other sites More sharing options...
bud2380 Posted December 11, 2020 Author Report Share Posted December 11, 2020 I see some slush on my windshield Quote Link to comment Share on other sites More sharing options...
bud2380 Posted December 11, 2020 Author Report Share Posted December 11, 2020 I have to head to anamosa and heard it’s changing to snow there already 1 Quote Link to comment Share on other sites More sharing options...
hlcater Posted December 11, 2020 Report Share Posted December 11, 2020 Mixing altitude is about 1200' AGL along I80. Quote 2021-22 Snowfall: (Hiawatha) TOTAL: 10.2" (12/28: 3.0") (12/29: 0.8") (1/1: 6.4") Link to comment Share on other sites More sharing options...
Stormhunter87 Posted December 11, 2020 Report Share Posted December 11, 2020 Saw some flakes heading over to western Iowa but no full change yet Quote Link to comment Share on other sites More sharing options...
gabel23 Posted December 11, 2020 Report Share Posted December 11, 2020 View of my back yard. Shocked to say sitting at 4” of snow and hope to pick up another 2-4”! The Nam, euro, ukie and gdps model nailed that for me! 5 1 Quote Link to comment Share on other sites More sharing options...
Hawkeye Posted December 11, 2020 Report Share Posted December 11, 2020 Holy cow, it's snowing here! 3 1 Quote season snowfall: 34.8" '22-23: 30.2" '21-22: 27.1" '20-21: 52.5" '19-20: 36.2" '18-19: 50.2" '17-18: 39.5" Average snowfall: ~30" Link to comment Share on other sites More sharing options...
BMT Posted December 11, 2020 Report Share Posted December 11, 2020 Snowing here in Marion! 1 Quote Link to comment Share on other sites More sharing options...
Bellona Posted December 11, 2020 Report Share Posted December 11, 2020 It's changed in Waterloo, but weenie flakes so far. Quote Link to comment Share on other sites More sharing options...
bud2380 Posted December 11, 2020 Author Report Share Posted December 11, 2020 Snowing in spring villle 2 Quote Link to comment Share on other sites More sharing options...
bud2380 Posted December 11, 2020 Author Report Share Posted December 11, 2020 Snowing very hard 1 Quote Link to comment Share on other sites More sharing options...
bud2380 Posted December 11, 2020 Author Report Share Posted December 11, 2020 Down to 32° 1 Quote Link to comment Share on other sites More sharing options...
Stormhunter87 Posted December 11, 2020 Report Share Posted December 11, 2020 Still just sleet here 1 Quote Link to comment Share on other sites More sharing options...
Hawkeye Posted December 11, 2020 Report Share Posted December 11, 2020 It's snowing lightly here, but still 35º, so it's more like white rain. About 15 miles north it's 33º. Quote season snowfall: 34.8" '22-23: 30.2" '21-22: 27.1" '20-21: 52.5" '19-20: 36.2" '18-19: 50.2" '17-18: 39.5" Average snowfall: ~30" Link to comment Share on other sites More sharing options...
jcwxguy Posted December 11, 2020 Report Share Posted December 11, 2020 Oax 2 1 Quote Link to comment Share on other sites More sharing options...
OmahaSnowFan Posted December 12, 2020 Report Share Posted December 12, 2020 Still just a mix of crap falling. 33.4 degrees now. Guess it’s going to have to fall below 32 before it changes over Quote Link to comment Share on other sites More sharing options...
Hawkeye Posted December 12, 2020 Report Share Posted December 12, 2020 The snow is picking up a bit here, temp down to 34º. It's still melting on contact. Quote season snowfall: 34.8" '22-23: 30.2" '21-22: 27.1" '20-21: 52.5" '19-20: 36.2" '18-19: 50.2" '17-18: 39.5" Average snowfall: ~30" Link to comment Share on other sites More sharing options...
Hawkeye Posted December 12, 2020 Report Share Posted December 12, 2020 Big flakes are pouring down now and it's beginning to stick. I'm impressed by how quickly the changeover crashed south after sunset. It appears we'll get a couple hours of snow followed by a lull for a few hours. 1 Quote season snowfall: 34.8" '22-23: 30.2" '21-22: 27.1" '20-21: 52.5" '19-20: 36.2" '18-19: 50.2" '17-18: 39.5" Average snowfall: ~30" Link to comment Share on other sites More sharing options...
bud2380 Posted December 12, 2020 Author Report Share Posted December 12, 2020 I’m temporarily in Anamosa for the next hour or so and the flakes here are huge. Sticking to the grass. And the gravel roads. 2 Quote Link to comment Share on other sites More sharing options...
bud2380 Posted December 12, 2020 Author Report Share Posted December 12, 2020 These are the biggest snowflakes I think I’ve ever seen. 3 Quote Link to comment Share on other sites More sharing options...
Hawkeye Posted December 12, 2020 Report Share Posted December 12, 2020 The temp here is down to 33º. First snow accum report of the event. At 6:00 PM CST, 1 NW Dubuque Regional A [Dubuque Co, IA] OFFICIAL NWS OBS reports SNOW of 1.10 INCH. 6 HOUR TOTAL. 3 1 Quote season snowfall: 34.8" '22-23: 30.2" '21-22: 27.1" '20-21: 52.5" '19-20: 36.2" '18-19: 50.2" '17-18: 39.5" Average snowfall: ~30" Link to comment Share on other sites More sharing options...
hlcater Posted December 12, 2020 Report Share Posted December 12, 2020 Snow in Iowa City. Temp 35.2 3 Quote 2021-22 Snowfall: (Hiawatha) TOTAL: 10.2" (12/28: 3.0") (12/29: 0.8") (1/1: 6.4") Link to comment Share on other sites More sharing options...
Stormhunter87 Posted December 12, 2020 Report Share Posted December 12, 2020 Been inside with some family so haven't been out but definitely have snow on the ground. Air temp and winds have dropped the temperature. Quote Link to comment Share on other sites More sharing options...
Stormhunter87 Posted December 12, 2020 Report Share Posted December 12, 2020 Man that radar makes it appear like this band is just crawling. Quote Link to comment Share on other sites More sharing options...
Grizzcoat Posted December 12, 2020 Report Share Posted December 12, 2020 1 Quote The two loudest sounds known to man: a gun that goes bang when it is supposed to go click and a gun that goes click when it is supposed to go bang. Link to comment Share on other sites More sharing options...
bud2380 Posted December 12, 2020 Author Report Share Posted December 12, 2020 23z HRRR with 6” for Iowa city and CR. 9” if you use 10:1 ratio Quote Link to comment Share on other sites More sharing options...
Hawkeye Posted December 12, 2020 Report Share Posted December 12, 2020 Heavier returns have moved back over CR on radar, but so far it's light snow with a bit of sleet mixed in. There has been no additional accumulation over the last hour. There is still only a bit of white on the grass. Quote season snowfall: 34.8" '22-23: 30.2" '21-22: 27.1" '20-21: 52.5" '19-20: 36.2" '18-19: 50.2" '17-18: 39.5" Average snowfall: ~30" Link to comment Share on other sites More sharing options...
East Dubzz Posted December 12, 2020 Report Share Posted December 12, 2020 14 minutes ago, bud2380 said: 23z HRRR with 6” for Iowa city and CR. 9” if you use 10:1 ratio Dubuque? Quote Link to comment Share on other sites More sharing options...
Grizzcoat Posted December 12, 2020 Report Share Posted December 12, 2020 Change over W side of DSM-- nothing accumulating but done with the cold miserable rain. Really like where I stt for main event. Several runs in a row of something similar to this and HRRR is getting into better range. Quote The two loudest sounds known to man: a gun that goes bang when it is supposed to go click and a gun that goes click when it is supposed to go bang. Link to comment Share on other sites More sharing options...
Grizzcoat Posted December 12, 2020 Report Share Posted December 12, 2020 Hydrometeror classification radar from COD has been spot on tonight. https://weather.cod.edu/satrad/nexrad/index.php?parms=DMX-HHC-1-12-100-usa-rad Quote The two loudest sounds known to man: a gun that goes bang when it is supposed to go click and a gun that goes click when it is supposed to go bang. Link to comment Share on other sites More sharing options...
Grizzcoat Posted December 12, 2020 Report Share Posted December 12, 2020 00Z RAP-- lining up well with HRRR for C.IA Quote The two loudest sounds known to man: a gun that goes bang when it is supposed to go click and a gun that goes click when it is supposed to go bang. Link to comment Share on other sites More sharing options...
Bellona Posted December 12, 2020 Report Share Posted December 12, 2020 Starting to whiten up a bit in Waterloo. Snowing at a decent rate. Quote Link to comment Share on other sites More sharing options...
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