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This pic popped up in my FB feed this morning. 10 years ago today when I was living just outside of Chicago. GHD I was something I’ll never forget. We got about 19” in Naperville. Best storm ever!

Parker wants to know how long until summer. I told him the sun angles are almost there brother

Had a huge cell move just north of my station. I recorded a gust to 35 mph, but no rain. 3 miles north, very heavy hail and fairly large for this area.

Took some pictures of the frost on the trees this morning. Very cool!

Looking decent for us over here in Spokane! YES, I am so loving it here!!!

Lower Yates Street. Victoria 1916

Euro Control more juiced than op.

At least we are not talking about death today!

NWS GRR: Both the GFS and ECMWF and their ensembles agree that 3 to 6 inches of snow over most of our CWA. This also agrees with WPC and their snowfall forecast. The ECMWF ensemble mean snowfall in MKG is 5 inches by noon on Friday. Curiously the GFS ensemble mean is nearly identical with the snowfall. None of the 50 members of the ECMWF 00z ensemble have less than 2 inches at MKG, the mean is around 5 inches. If I had a choice would chose not to travel in Southwest Michigan during the daytime on Friday. I'm glad i'll have the day off on Friday for my twins 2nd birthday!

A good read on Pivotal about snow maps-- lots of info here. Last updated 25 January 2020 Snow maps — love them or hate them, they're everywhere in the wintertime! When it comes to different snow map algorithms, confusion reigns. Although this is a messy topic with few simple answers, our aim is to clear up some of the confusion in a central location. What is snowfall? On Pivotal Weather, "snowfall" refers to snow that reaches Earth's surface over the specified time period. If a particular ground surface is warm enough for melting to occur, then the accumulated pile of snow you see on that surface at the end of a storm may be noticeably less than what we call snowfall. Suppose you had a snow board whose temperature you maintained at well below freezing, and you diligently went outside every hour to measure and clear new snow. Not much melting, sublimation, or compacting would occur during those hourly intervals, regardless of the weather conditions. The sum of all snow you cleared off the chilled snow board over the course of the storm would represent the observed "snowfall" that our 10:1 and Kuchera* snowfall maps attempt to forecast. To forecast the final accumulation on a ground surface at the end of a long-duration snowstorm is more complex. It will depend on the surface type, in addition to weather conditions at ground level and their evolution throughout the storm. Even solar radiation passing through clouds, and therefore time of day, can have an impact on melting. We do not attempt to forecast any of this explicitly, but our snowfall products are still often a useful proxy for the final accumulation on untouched natural surfaces. However, this may not be true when ground temperatures are warm, air temperatures are above freezing, or when a storm is particularly long in duration and compacting plays a large role. *The Kuchera method was originally formulated to fit a sample of observed snow depth measurements (e.g., a ruler measurement after a storm), so even our attempt to define “snowfall” has caveats — more below. Assessing model precipitation type Our primary snowfall product types, 10:1 and Kuchera, apply certain snow-to-liquid ratios (SLRs) to precipitation in the model we deem to have fallen as snow between data output times. But, hold on… do we really know how much fell as snow? ECMWF, UKMET, and Environment Canada models keep track of precipitation type in a precise way as the model integrates, so we know how exactly much precipitation falls in the form of snow (at least, based on the model’s internal diagnostics). This eliminates any concern about including sleet, graupel, or rain when we compute snowfall for those models. For NCEP models, the bookkeeping for precipitation types is less precise, so mis-categorizing some of the precipitation that fell between data output times is always a risk during mixed precipitation or precipitation that is rapidly changing type. We have adopted an approach that usually avoids erroneously treating sleet as snow for NCEP models, so you should not see a shield of "fake snow" extending well equatorward of the actual snow-sleet line in a large mid-latitude cyclone, for example. Still, it is inevitable that we will sometimes overestimate the fraction of mixed precipitation falling as snow in borderline and transitional environments (usually small in area). Snow-to-liquid ratio (SLR) Now, to the topic of the SLR (often informally called “snow ratio” or just “ratio”). After snow falls, we can melt it and measure the liquid equivalent precipitation it comprises. Dividing the snowfall by this liquid equivalent amount gives the SLR. Because current numerical weather prediction (NWP) models predict liquid equivalent precipitation directly, some SLR must be applied to the predicted liquid amount to get a meaningful snow forecast. For over a century in weather forecasting, a 10:1 SLR (1 inch of liquid = 10 inches of snow) has commonly been used as a default value. A large climatology of SLRs in the United States by Baxter et al. 2005 found a distribution of values centered near 12:1, with values between 10:1-12:1 being more common than any other bin (see their Fig. 9). Values ranging all the way from 6:1 to 18:1 are relatively common in the US, and can occasionally approach 2:1 on the low end and 44:1 on the high end. It is apparent that while 10:1 is a reasonable “default” value if you had to pick one, SLR errors >50% will be seen on a regular basis using that approach! From a physics perspective, SLR comes down to the structure and density of the snow crystals, the formation mechanisms of which are quite complex (see Takahashi et al. 1991). Like any such pinpoint-small detail, though, current NWP models can only parameterize (estimate) this based on larger-scale variables like the predicted air temperature, moisture, and wind. Within the model, these variables could theoretically be used in a nuanced way to estimate SLR with considerable accuracy, but this is rarely done in current operational NWP. Instead, external users like Pivotal Weather must estimate SLR themselves based on the more limited data provided publicly. In late 2004, then-graduate student Evan Kuchera of the Air Force Weather Agency developed what has since become widely known as the Kuchera SLR method. It is one attempt to link model-predicted variables with SLR, and is a linear function of just one value at each horizontal grid point: the warmest temperature in the air column from the surface to 500 mb. Describing to us the origins of his approach, Evan said: “I basically manually curve-fit data from various snow events I was aware of around that time [2004] until I was happy with it. Of note, the bifurcation at 271.16 K was to try to account for melting effects after the snow was on the ground for warmer events. So I really was trying to aim at the storm total snowfall that a COOP observer or member of the public would measure, not a pure, by-the-book snowfall properly measured and cleared from a snow board.” — Evan Kuchera Shortly after the method was developed, Evan’s colleague Earl Barker (www.wxcaster.com) implemented it for his online NWP graphics, and the rest is history — “Kuchera snowfall” is now part of almost every winter weather enthusiast’s vocabulary and computed by numerous NWP graphics providers! Although this method has not been published in a peer-reviewed scientific journal, it has grown in popularity due to its straightforward formulation and subjective usefulness, and verification work presented at academic conferences has also supported its utility. Air temperature does not exclusively determine SLR in the real world, but several published studies have demonstrated a fairly strong relationship between low-to-mid level temperatures and observed SLRs (e.g., Roebber et al. 2003; Alcott and Steenburgh 2010). If NWP users are looking to implement a simple approximation of SLR that will not grind their data processing to a halt or demand obscure model diagnostics they lack access to, they’re unlikely to do much better than Kuchera. Although Kuchera may depart from observed SLR significantly in some cases, it should still provide a first-order improvement over assuming a blanket 10:1 ratio. Its benefit may actually be most apparent when temperatures are borderline, a situation where it will correctly reduce snowfall below a 10:1 estimate, as Evan intended. Still, we emphasize that Kuchera is highly imperfect, as true SLRs depend on cloud and precipitation physics far more complex than a single statistic of the column temperature distribution. In the future, we are hopeful that NWP models may begin tracking snowfall internally using more physically sound diagnostics to estimate SLR at subhourly intervals, which could markedly improve snowfall forecasts over those derived from 10:1 and Kuchera SLRs.

I’m only quoting this post so Dolt can see it!

Also I’m sure you guys all share the sentiment that the flips and flops on the models have been pretty exhausting the last couple weeks. I see there appears to be some upcoming potential once again but sometimes it’s nice just to take a back seat for a day or two and see how things evolve. Appreciate that I can count on many here to continue posting maps and useful model analysis despite all the ups and downs though. You keep this place running.

GFS

Yeah getting excited about anything past 120hrs is just Dumb.

12z Euro at 10:1 for weekend storm

I expect Blizzard Warnings for some areas of IA at sometime -- minimal I know is 3 hrs-- but with ditches full , this baby in rural IA is going to rock n roll. Throw in 2-4" of powder and its going to be a snow globe with 40+ mph winds in the country.

12Z GFS through 69--

06 GFSv16. Nice trends this morning. Should be a high ratio snow with wind and very cold temps.

Snowed late this afternoon, just a dusting. The next shower around 7p was 100% rain. This current shower started as rain turned to snow, no accumulation.

Block is definitely stronger and a bit further West on the Euro compared to the GFS at hour 96.

The low near Hawaii is trending much healthier in the home stretch.

I just looked at the ensembles. Quite improved! Run not quite done but looking much better

So glad it’s raining again, things were getting mighty dry out there... up to .59” on the day, currently 37 degrees.

0z GFS Mean

Looks good up here...just need it on the ground not in the models. Snowmobile clubs and news started talking about it today...the whole northwoods is giddy...finally!

After the last few years of reading most of the posts in this forum and the analysis that has gone on, I've reached the conclusion that long range forecasts are a myth. They just don't work, period. No one can tell you with any degree of accuracy other than predicting climo what might happen to finish off this "winter", spring, next winter, etc. It is pretty much pointless and is just a guess. Sometimes these guesses work out, just like the Farmer's Almanac. Perhaps that will change someday with improved monitoring, models, and computing, but we are nowhere near that point at the moment. I suppose it is still something we will guess at and talk about and I will be here for that.

Was all snow here for about 15 minutes. Temp is 34 degrees.

So much weenie-ing on here. Meanwhile the EPS is trying to bring this thing all the way back.

Sometimes I'll get a double score.

Well since my most recent post the temp went from 41 to 33 and we now have a dusting of snow. So we probably won't have any problems getting snow to accumulate...

Mostly snow coming down now, very wet, the flakes are barely surving the trip to the ground.

Not what I asked for Tim. So literally thanks for nothing.

I think I might have missed like one full day of posting yesterday. I guess I’m flattered my short absence didn’t go at all unnoticed though. I feel loved And wouldn’t you say weenie reacts have been more my go to with you lately?

Tracking 3 different weather events that might affect my area.

18z NAM ups the game with a foot for MBY. God bless that piece of junk. 3km also jumps way NW from the 12z run. We need fresh snow to reach the full potential of the polar vortex.

FYI for anyone not aware, those colors show the change in heights from the last run, not the anomaly from normal like you'd usually see on a map like that.

Can I not be fringed? All I ask for. Just one time don't fringe me

I keep seeing these maps from 10-14 days away...but looking at the ensembles, you'd be a fool to believe anything past day 5 at this point.

12z GDPS is pretty bullish from Iowa to Lake Michigan.

Wow, the literal calm before the storm in Eastern Iowa Thursday.

He's going to be freezing his little pecker off this weekend....

6z Euro Control continues to trend well. More coverage this run. I only have 10:1 available with this map.

GFSv16 06Z- not so suppressed---

DMX talking 1"+ hourly rates and blizzard to near blizzard conditions. Attention overall is on later this week into this weekend as a period of high impact and weather headline worthy events unfold. On Wednesday, a potent shortwave trough will be moving into the Pacific Northwest and quickly make its way into the Rockies by Thursday morning and to Iowa by Thursday night. Surface low pressure will develop over the central Plains on Thursday and pass near or over southeast Iowa late in the day with an attendant strong cold front passing through the state on Thursday as well. Ahead of this front, there will be a surge of low level thermal lift from Missouri into Illinois clipping eastern Iowa with QG convergence along this front. Temperatures will be warm enough ahead of the front for much of the precipitation to initially be rain. However, as the cold front plows through the state, the temperature profile will turn colder in the low levels with rain changing to snow. Regarding the flash freeze potential, it will come down to when does the drop occur and how much of a drop. During the heart of the day with a slower drop will be less of a concern than a quick and sharp drop around sunrise and rush hour. As the rain turns to snow, the ice introduction layer and dendritic growth zone with be saturated and there will be moderate lift in this zone to promote a short period of high snow rates. This evening`s 3z SREF run is already showing some low probabilities of 1"/hr rates. The lift wanes through the afternoon as strong subsidence moves across the state. However, forecast soundings show low level instability, which could promote snow showery bursts into the early evening hours. While snow amounts will not be profound given recent winter storms, the impacts will be greatly enhanced by the developing strong winds gusting over 40 mph with the potential for near blizzard conditions. The winds would also seemingly tap into the existent snow on the ground with Iowa cooperative observers reporting snow depths of at least 3 inches as of 12z Monday morning. While much of this has a crust from the recent freezing drizzle and rain, winds of this magnitude would be able to erode the crust layer and get down to the powdery, blowable snow further aiding in very poor visibility and travel conditions. The winds will remain blustery overnight into Friday morning with both NAM and GFS BUFKIT soundings show the boundary layer remaining mixed. This would keep at a minimum blowing snow going over northern Iowa.

DSM and ALO on pace for Top 10 snowfall. DSM is 2nd place through end of JAN!!!!

Well the models aren't the best, and I'm feeling a bit beat down with my knee and Birthday on Superbowl Sunday looking ahead this year and praying I do not have to have another surgery. I'm thankful everyday and I say it several times. I think it helps keep us grounded and stay in perspective.

One of the best features of the new forum:

Looks good. Always nice to have the Euro on your side.