Stevo6899 Posted January 29, 2021 Share Posted January 29, 2021 7 minutes ago, AWMT30 said: Nice run on the NAMS for extreme SE Michigan!! This ain't ours dewd, let er go lol. Gotta move that block east before we get a respectable storm. 1 Link to comment Share on other sites More sharing options...
Jim Martin Posted January 29, 2021 Share Posted January 29, 2021 Link to comment Share on other sites More sharing options...
purduewx80 Posted January 29, 2021 Share Posted January 29, 2021 The coupled jet signature tomorrow evening is just classic for mesoscale shenanigans. Particularly when they're so curved like this. There is also tremendous diffluence (notice how the winds spread away from each other immediately NE-E of the upper low). 3 1 Link to comment Share on other sites More sharing options...
RCNYILWX Posted January 29, 2021 Share Posted January 29, 2021 I'm riding a fine line near I74. Models showing a later changeover now here. Hoping precip can arrive later. 3km nam was showing a better deformation band Sun. I didn't look closely specifically at your area, but for our far southern areas, without even looking at wet bulb, the 0C line just sneaking in there near southern Ford to me pointed toward evaporative and dynamic cooling doing a lot of work. The winds will be pulling from the departing high, so that'll help from an evaporative cooling sense and support for heavy precip maxes out dynamic cooling. Certainly uncomfortably close down there. Wish I could stay up to diagnose all the 12z guidance with everyone lol, but gotta get some sleep for another busy shift tonight. Sent from my SM-G965U using Tapatalk 4 Link to comment Share on other sites More sharing options...
janetjanet998 Posted January 29, 2021 Share Posted January 29, 2021 13 minutes ago, McHenrySnow said: There is definitely an increase in QPF across Missouri across both versions of the NAM and the 3K paints a relative QPF minima over central Indiana. I don't have time to delve into it more deeply than that right now. Just something to watch. I think I made a post yesterday about how the GFS run increased precip in central IL(max for the system at the time) but decreased it across northern IL on one run suggesting convection may be robbing some of the moisture transport for at least a little while perhaps the NAM also is hinting at it now??? time will tell Link to comment Share on other sites More sharing options...
hawkeye_wx Posted January 29, 2021 Share Posted January 29, 2021 Those of us in Iowa are wondering what happened to our big snow event that appeared as locked in as any storm could be a few days out. Nearly all models are either cutting the precip down, warming us up, or both. Even the HRRR, which nailed the colder, snowier late December storm, has now warmed us up and drops at least a few hours of mix crap here. The 6-9" snow event has been cut in half. Link to comment Share on other sites More sharing options...
Chicago Storm Posted January 29, 2021 Share Posted January 29, 2021 I think I made a post yesterday about how the GFS run increased precip in central IL(max for the system at the time) but decreased it across northern IL on one run suggesting convection may be robbing some of the moisture transport for at least a little while perhaps the NAM also is hinting at it now??? time will tell This storm system is not going to have the same sig/widespread convection further south, as the last storm system did. Also, moisture transport is great. PWATS were actually higher on 12z NAM than previous run as well. So no, there will be no moisture transport issues this time around. . 1 Link to comment Share on other sites More sharing options...
Stevo6899 Posted January 29, 2021 Share Posted January 29, 2021 13 minutes ago, hawkeye_wx said: Those of us in Iowa are wondering what happened to our big snow event that appeared as locked in as any storm could be a few days out. Nearly all models are either cutting the precip down, warming us up, or both. Even the HRRR, which nailed the colder, snowier late December storm, has now warmed us up and drops at least a few hours of mix crap here. The 6-9" snow event has been cut in half. Those of us in places that havent seen a 4+ event all winter are thinking nobody in iowa should be upset. 6 3 2 Link to comment Share on other sites More sharing options...
Luftfeuchtigkeit Posted January 29, 2021 Share Posted January 29, 2021 12Z 3k NAM pushes the heavier previp farther north and almost doubles the total QPF for MSN from the 6Z run from 0.40" to 0.75". Will be interesting to see if other models go in this direction too. 2 Link to comment Share on other sites More sharing options...
mimillman Posted January 29, 2021 Share Posted January 29, 2021 SREF largely held firm Link to comment Share on other sites More sharing options...
Radtechwxman Posted January 29, 2021 Share Posted January 29, 2021 8 minutes ago, RCNYILWX said: I didn't look closely specifically at your area, but for our far southern areas, without even looking at wet bulb, the 0C line just sneaking in there near southern Ford to me pointed toward evaporative and dynamic cooling doing a lot of work. The winds will be pulling from the departing high, so that'll help from an evaporative cooling sense and support for heavy precip maxes out dynamic cooling. Certainly uncomfortably close down there. Wish I could stay up to diagnose all the 12z guidance with everyone lol, but gotta get some sleep for another busy shift tonight. Sent from my SM-G965U using Tapatalk I appreciate your input. Even hi resolution cams can struggle with timing of changeover due to dynamic cooling. Earlier timing could be detrimental here during warmer sfc temps. Going to be a very nowcasting situation. 1 Link to comment Share on other sites More sharing options...
Natester Posted January 29, 2021 Share Posted January 29, 2021 27 minutes ago, hawkeye_wx said: Those of us in Iowa are wondering what happened to our big snow event that appeared as locked in as any storm could be a few days out. Nearly all models are either cutting the precip down, warming us up, or both. Even the HRRR, which nailed the colder, snowier late December storm, has now warmed us up and drops at least a few hours of mix crap here. The 6-9" snow event has been cut in half. 12z HRRR still shows CR getting nearly 8 inches although that will possibly change in the 18z run. Let's see what the 15z RAP says. The good news is that with temps at 30-31F, there won't be any notable ice accretion during the 2-3 hour period of ZR before changing to sleet. Link to comment Share on other sites More sharing options...
hawkeye_wx Posted January 29, 2021 Share Posted January 29, 2021 1 minute ago, Natester said: 12z HRRR still shows CR getting nearly 8 inches Keep in mind this should be pretty wet stuff with a lousy ratio. 1 Link to comment Share on other sites More sharing options...
Natester Posted January 29, 2021 Share Posted January 29, 2021 Just now, hawkeye_wx said: Keep in mind this should be pretty wet stuff with a lousy ratio. Yeah, not good for the heart and back. Also not good for the damaged trees especially with the wind gusts. Link to comment Share on other sites More sharing options...
SchaumburgStormer Posted January 29, 2021 Share Posted January 29, 2021 Going to be snowing so hard in N IL that you will be coated after a short jeb walk. 4 Link to comment Share on other sites More sharing options...
Sciascia Posted January 29, 2021 Share Posted January 29, 2021 I’m supposed to work until 7pm Saturday. May be a tricky ride home if it’s going to be a wall of snow at onset. Link to comment Share on other sites More sharing options...
CheeselandSkies Posted January 29, 2021 Share Posted January 29, 2021 A quick question about ratios to make sure I'm understanding them right. A 10:1 ratio would mean you take the QPF and multiply it by 10 to get expected inches of snow, correct? In other words, 0.1" = 1"? 1 Link to comment Share on other sites More sharing options...
McHenrySnow Posted January 29, 2021 Share Posted January 29, 2021 Just now, CheeselandSkies said: A quick question about ratios to make sure I'm understanding them right. A 10:1 ratio would mean you take the QPF and multiply it by 10 to get expect inches of snow, correct? In other words, 0.1" = 1"? Correct. 1 Link to comment Share on other sites More sharing options...
nwohweather Posted January 29, 2021 Share Posted January 29, 2021 10 minutes ago, hawkeye_wx said: Keep in mind this should be pretty wet stuff with a lousy ratio. That's what I'm thinking could impact accums a bit as well. Getting that thick cement snowfall is going to lead to compaction for sure. Link to comment Share on other sites More sharing options...
Natester Posted January 29, 2021 Share Posted January 29, 2021 15 minutes ago, hawkeye_wx said: Keep in mind this should be pretty wet stuff with a lousy ratio. Off topic, but are you going to update your signature to account for the snow from this past Monday? 1 Link to comment Share on other sites More sharing options...
purduewx80 Posted January 29, 2021 Share Posted January 29, 2021 Temperatures are going to be dropping into the upper 20s in the band of heavy snow, at least in northern IL and WI, so I don't see this being as wet as some think. The reason it could be dense and lower ratio has more to due with cloud microphysics and how the smaller or rimed snowflakes are able to compact together. 5 Link to comment Share on other sites More sharing options...
Baum Posted January 29, 2021 Share Posted January 29, 2021 I don't think I've seen an Alek call on this event. Perhaps missed it. 1 Link to comment Share on other sites More sharing options...
SchaumburgStormer Posted January 29, 2021 Share Posted January 29, 2021 Just now, purduewx80 said: Temperatures are going to be dropping into the upper 20s in the band of heavy snow, at least in northern IL and WI, so I don't see this being as wet as some think. The reason it could be dense and lower ratio has more to due with cloud microphysics and how the smaller or rimed snowflakes are able to compact together. ratios definitely overperformed locally for the last storm, albeit slightly. But with this much QPF, a minor change is average ratio will add up. 1 Link to comment Share on other sites More sharing options...
Natester Posted January 29, 2021 Share Posted January 29, 2021 Still sticking to my call of 6 inches although it might need to be lowered by an inch if the models keep cutting forecast totals. However, if CR does indeed get 6 or more inches of snow with this very wet consistency, it's going to be detrimental to the trees, especially with the wind gusts. HRRR and NAM have temps flirting at freezing during the bulk of the snow. Link to comment Share on other sites More sharing options...
CheeselandSkies Posted January 29, 2021 Share Posted January 29, 2021 5 minutes ago, purduewx80 said: Temperatures are going to be dropping into the upper 20s in the band of heavy snow, at least in northern IL and WI, so I don't see this being as wet as some think. The reason it could be dense and lower ratio has more to due with cloud microphysics and how the smaller or rimed snowflakes are able to compact together. It's a tradeoff between raw numbers with the fluffier stuff and I think higher impacts with the wetter stuff. Harder to shovel and it sticks to your car tires and further reduces traction. The first notable accumulating snow we had (the one before Christmas which mostly melted by then) was wet and heavy, and I had to charge the hill out of my apartment building's parking lot about ten times praying my car wouldn't get stuck before I finally made it up to the road. Had the pedal to the metal, front wheels spinning like mad spraying snow everywhere, and moving at maybe 2 MPH. That, plus spinning out twice this winter on just the thin-packed layer left on secondary roads from snow events days earlier, prompted me to get new tires. 1 Link to comment Share on other sites More sharing options...
RCNYILWX Posted January 29, 2021 Share Posted January 29, 2021 Temperatures are going to be dropping into the upper 20s in the band of heavy snow, at least in northern IL and WI, so I don't see this being as wet as some think. The reason it could be dense and lower ratio has more to due with cloud microphysics and how the smaller or rimed snowflakes are able to compact together.On that note, what are your thoughts on blowing/drifting potential? It's a good point about the actual air temperatures. The moisture content of the snow and overall density will be high but maybe it can still be blown around when temps are 28-30 instead of 31-33.Sent from my SM-G965U using Tapatalk 1 Link to comment Share on other sites More sharing options...
mimillman Posted January 29, 2021 Share Posted January 29, 2021 GFS finally caved 1 Link to comment Share on other sites More sharing options...
Radtechwxman Posted January 29, 2021 Share Posted January 29, 2021 1 minute ago, mimillman said: GFS finally caved Definitely an improvement but I still feel it's thermals may be too warm, esp on southern flank Link to comment Share on other sites More sharing options...
RCNYILWX Posted January 29, 2021 Share Posted January 29, 2021 The coupled jet signature tomorrow evening is just classic for mesoscale shenanigans. Particularly when they're so curved like this. There is also tremendous diffluence (notice how the winds spread away from each other immediately NE-E of the upper low). This is one of the "under the hood" items I was mentioning, and I overlooked it last night. It's very easy to get caught up on model run QPF, but when you have this caliber of jet divergence, excellent moisture transport, top of the chart PWAT, and there's a disconnect with QPF, probably safe to side on the higher QPF guidance. With the pretty decent difference between the 12km and 3km NAM, I was wondering if the 12km's BMJ convective parameterization scheme could be messing with the output some and the 3km explicitly forecasting the embedded convective elements could do a better job in this case. Sent from my SM-G965U using Tapatalk 3 Link to comment Share on other sites More sharing options...
Natester Posted January 29, 2021 Share Posted January 29, 2021 15z RAP gives CR 7.2 inches of cement on Saturday evening. Also winds are somewhat weaker as shown on the NAM 3k. Link to comment Share on other sites More sharing options...
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