Hoosier Posted April 12, 2019 Share Posted April 12, 2019 Could end up not being much, but there is at least some possibility of a band of heavy, wet snow to the tune of several inches. Discuss Link to comment Share on other sites More sharing options...
hawkeye_wx Posted April 12, 2019 Share Posted April 12, 2019 The NAM is now farther southeast with the GFS/FV3/Canadian/UK. The euro is on its own showing snow through eastern Iowa. Link to comment Share on other sites More sharing options...
Hoosier Posted April 12, 2019 Author Share Posted April 12, 2019 Whether it's rain or snow at onset, precip looks to arrive here in the wee hours of Sunday morning. If it's snow, could lay down a layer prior to any possible sun angle factor. Link to comment Share on other sites More sharing options...
jrips27 Posted April 12, 2019 Share Posted April 12, 2019 Will be in Milwaukee Saturday-Tuesday for some family stuff. As someone from down south who doesn’t see much snow I’ll be keeping a close eye on this. Would love to see a couple of inches. Euro looked like a pretty good hit. Looked a little colder for the Milwaukee area but I think that was a byproduct of the low being a little SE of the 12z run. If anyone’s got the Kuchera map, would love to see it. Link to comment Share on other sites More sharing options...
hawkeye_wx Posted April 12, 2019 Share Posted April 12, 2019 00z Euro - Finally gave up on the nw track. Link to comment Share on other sites More sharing options...
CheeselandSkies Posted April 12, 2019 Share Posted April 12, 2019 5 hours ago, jrips27 said: Will be in Milwaukee Saturday-Tuesday for some family stuff. As someone from down south who doesn’t see much snow I’ll be keeping a close eye on this. Would love to see a couple of inches. Trade ya for some of Dixie Alley's severe. Link to comment Share on other sites More sharing options...
CoalCityWxMan Posted April 12, 2019 Share Posted April 12, 2019 NAM quite a bit snowier..pretty high totals with kuchera method still. Wonder how much would melt/compact right away with most of it falling during the day Link to comment Share on other sites More sharing options...
Baum Posted April 12, 2019 Share Posted April 12, 2019 good to see the winter trend of snowing just to my north and west is not just a seasonal thing. 3 1 Link to comment Share on other sites More sharing options...
michsnowfreak Posted April 12, 2019 Share Posted April 12, 2019 Hoosier, was Chicago's last 1" snow in Feb a record if it holds? Link to comment Share on other sites More sharing options...
Hoosier Posted April 12, 2019 Author Share Posted April 12, 2019 2 minutes ago, michsnowfreak said: Hoosier, was Chicago's last 1" snow in Feb a record if it holds? No, there have been like 9 times when the last 1" snow happened earlier than the currently valid last 1" snow. It would be very unusual to have a 1" snow in mid February and then skip over March and basically go 2 months until getting the next one... more on that later. Link to comment Share on other sites More sharing options...
Hoosier Posted April 12, 2019 Author Share Posted April 12, 2019 NAM is still running on the northern end on this 12z cycle, with other models farther south. We'll see about Euro. Link to comment Share on other sites More sharing options...
Cary67 Posted April 12, 2019 Share Posted April 12, 2019 2 hours ago, Baum said: good to see the winter trend of snowing just to my north and west is not just a seasonal thing. Locking it in for next years El Nino Link to comment Share on other sites More sharing options...
jrips27 Posted April 12, 2019 Share Posted April 12, 2019 Euro with a big shift south. Link to comment Share on other sites More sharing options...
Hoosier Posted April 12, 2019 Author Share Posted April 12, 2019 PIA-ORD and then up toward/just north of Saginaw is the axis of heaviest snow on 12z Euro. Link to comment Share on other sites More sharing options...
Hoosier Posted April 12, 2019 Author Share Posted April 12, 2019 Numerous questions with this 850 mb temps are cold enough on the nw flank going in, but how long will it take to cool the lower levels to support snow? What will precip rates be like? Exactly how warm will it get during the daytime on Sunday? All in all, I'd still say a band of 2-5" is in play, but it will probably be pretty narrow if it occurs. Even those amounts could be enough to make this the biggest snow this late in the season in about 40-50 years for some areas. Link to comment Share on other sites More sharing options...
Hoosier Posted April 12, 2019 Author Share Posted April 12, 2019 imo it looks like there could be rates around 1" per hour at times... as long as temps get close enough to freezing. Realizing those heavy rates will be important to the overall forecast and whoever can get that during the daytime would help since we have an August like sun angle. Link to comment Share on other sites More sharing options...
beavis1729 Posted April 12, 2019 Share Posted April 12, 2019 43 minutes ago, Hoosier said: Numerous questions with this 850 mb temps are cold enough on the nw flank going in, but how long will it take to cool the lower levels to support snow? What will precip rates be like? Exactly how warm will it get during the daytime on Sunday? All in all, I'd still say a band of 2-5" is in play, but it will probably be pretty narrow if it occurs. Even those amounts could be enough to make this the biggest snow this late in the season in about 40-50 years for some areas. Agree - good summary at the moment. In such a marginal set-up, it will probably come down to nowcasting...or, at a minimum, another 1-2 sets of model runs. Still a lot of uncertainty in modeled QPF for being only 36 hours out. 12z NAM shows 1.00+" liquid in Chicago metro, with the GFS and FV3 around 0.5" (although quite a bit more further south). Not sure about the Euro, although you mentioned that ORD gets hit pretty good verbatim. The track seems to be converging on a general solution...but of course even 10-20 miles can make a big difference for the metro. Link to comment Share on other sites More sharing options...
Hoosier Posted April 12, 2019 Author Share Posted April 12, 2019 5 minutes ago, beavis1729 said: Agree - good summary at the moment. In such a marginal set-up, it will probably come down to nowcasting...or, at a minimum, another 1-2 sets of model runs. Still a lot of uncertainty in track for being only 36 hours out. 12z NAM shows 1.00+" of liquid in Chicago metro, with the GFS and FV3 around 0.5" (although quite a bit more further south). The city is in a good spot if you blend everything together. Another thing I'm wondering is if lake temps have warmed up enough to be a factor in keeping temps a bit warmer there. Hard to say for sure... there is a huge difference in current water temps between the Chicago shore and Chicago crib (48 vs 37). I'm guessing the shore temps are very sensitive and could drop by several degrees in the next few days so my guess is that if the lake ends up being a factor, it would only be right near the shore and not out toward MDW or ORD. Link to comment Share on other sites More sharing options...
beavis1729 Posted April 12, 2019 Share Posted April 12, 2019 Looks like the 18z NAM ticked a *bit* SE from the 12z NAM, but is still not nearly as far SE as the Euro/GFS/FV3. From a liquid precip standpoint, looks like a nice hit for Chicago metro...around 1" QPF. Is it worth analyzing NAM soundings at 36-60 hours to determine precip type?? Link to comment Share on other sites More sharing options...
Hoosier Posted April 12, 2019 Author Share Posted April 12, 2019 RC afd .LONG TERM... 400 PM CDT Saturday Night through Friday... The main concern and focus is on the potential for a rare mid April accumulating wet snow event late Saturday night into Sunday. After this, we`ll quickly warm back to above normal on Tuesday, followed by the active pattern resuming in the mid to late week period. The message for Sunday`s snow is that a fairly narrow swath of noteworthy accums of 2+" is becoming increasingly likely across portions of northern Illinois, with possibility of some road impacts where it snows heaviest. Backdoor cold front passage will flip winds to north/northeast Saturday evening, and allow colder air to bleed in at the low levels. At the same time, strong negatively tilted trough/ULL and attendant sub 1000 mb surface low will be ejecting northeastward. This system will be accompanied by widespread intense convection in the warm sector (note SPC Day 2 Moderate Risk for areas near Gulf Coast) as it lifts northeast toward our area Saturday night. It appears that the ingredients could be in place for moderate to heavy precip rates in the cold sector of the surface low, aiding in dynamic cooling of otherwise fairly marginal thermal profiles that you would expect for mid April. Potentially supporting factors include: steep mid-level lapse rates; high PWAT values above 0.6" for a snow producing system; and likelihood of strong low and mid-level frontogenetically driven banding given tight baroclinic zone that system will be interacting with/intensifying. There are some lingering uncertainties and possible red flags, however, that will be discussed below. Precipitation shield will rapidly spread northward through Saturday night and into early Sunday, with northern extent dependent upon exact track and strength of the surface low. Overall trend on the global models and ensembles has been for a more southeastward track of the surface low and perhaps a hair weaker system. Suspect that the most recent 12km NAM runs are stronger and wetter outliers vs GFS/ECMWF consensus. Temperatures by early Sunday should fall to the mid to high 30s and arrival of steady to heavy precip rates by Sunday morning should even cool them slightly. All in all readings should largely flatline given the precipitation, clouds and strong northeast winds gusting to 30-35+ mph. These strong northeast winds off a now fairly mild Lake Michigan could also make it very tough for snow to accumulate immediately lakeside, including downtown Chicago. One of the largest sources of uncertainty is exactly where the heaviest f-gen driven banding sets up in the system deformation axis. In this likely narrow swath will be the best chance to overcome the strong mid April sun, above freezing temps and mild antecedent ground temps for snow to even accumulate on road surfaces, with event totals of 2-4" or even higher. Dynamic cooling will be a necessity to enable more than non-accumulating wet snow, which seems like a distinct possibility outside of wherever the heaviest banding occurs. Lowered ratios to 7:1 or less considering the aforementioned factors, with possibility of locally higher ratios again wherever the heaviest banding occurs. Another concern I have is that the intense convection in the warm sector could ultimately rob some of the moisture and dynamics in the cold sector, which could be playing a role in much farther southeast and weaker system on 12z Canadian. Everything discussed above will also determine where rain/snow line is, which is currently indicated south of a Valpo to Pontiac line. Ultimately, suspect that the extreme totals on some of the models are overdone, but once we have honed in the specifics, it is possible a headline may be needed for counties where confidence is highest in travel impacts. Official forecast snow amounts of 1-4" along/north of I-80 in IL will certainly be refined as trends become more clear. After the storm exits, Monday`s temps will recover to just shy of seasonable and likely melt any lingering snow. Then strong southwesterly warm advection Tuesday will bring temps all the way back up to the upper 60s to lower 70s, quite a change from Sunday! The next stronger weather system in what continues to be an active pattern across the CONUS will be during the Tuesday night/Wednesday- Thursday period, when periods of showers are probable, along with the threat for some thunderstorms. Unseasonably cool temps will likely return Friday in the wake of the mid week storm system. Castro Link to comment Share on other sites More sharing options...
Jonger Posted April 12, 2019 Share Posted April 12, 2019 Not sure if I really want this. 1 Link to comment Share on other sites More sharing options...
CoalCityWxMan Posted April 12, 2019 Share Posted April 12, 2019 The long range RAP looks pretty good for N IL Link to comment Share on other sites More sharing options...
Baum Posted April 12, 2019 Share Posted April 12, 2019 This is our storm.. 2 Link to comment Share on other sites More sharing options...
Hoosier Posted April 13, 2019 Author Share Posted April 13, 2019 45 minutes ago, CoalCityWxMan said: The long range RAP looks pretty good for N IL Sleet would be particularly cruel at this time of year. I am expecting the rain/snow line to not be too far away, one way or another. Will be interesting to see how much daytime warming the RAP and HRRR have on later runs. Be aware that they could be too aggressive with that. 1 Link to comment Share on other sites More sharing options...
Hoosier Posted April 13, 2019 Author Share Posted April 13, 2019 3 minutes ago, Hoosier said: Sleet would be particularly cruel at this time of year. I am expecting the rain/snow line to not be too far away, one way or another. Will be interesting to see how much daytime warming the RAP and HRRR have on later runs. Be aware that they could be too aggressive with that. Pulled a few forecast soundings and some of that sleet area could actually be snow. I think the model could be having trouble resolving the precip type because saturation aloft is a bit iffy and there is a relatively deep layer aloft with temps like 0C to -1C. Link to comment Share on other sites More sharing options...
Baum Posted April 13, 2019 Share Posted April 13, 2019 when you don't really want snow bet on snow. 1 Link to comment Share on other sites More sharing options...
Powerball Posted April 13, 2019 Share Posted April 13, 2019 3 hours ago, Jonger said: Not sure if I really want this. I guess there's a first for everything. The relative lack of activity in this thread speaks for itself, lol. Link to comment Share on other sites More sharing options...
Hoosier Posted April 13, 2019 Author Share Posted April 13, 2019 7 minutes ago, Baum said: when you don't really want snow bet on snow. I probably would've bet money a week or two ago on accumulating snow being done. Have had some nice spring days, stuff is blooming and locally, snow has almost shut off entirely for the past couple months. Oops This one is a little more tolerable than other April snows because of the likely period of heavy rates, possible historical aspects and the quick warm up coming early next week. Link to comment Share on other sites More sharing options...
Hoosier Posted April 13, 2019 Author Share Posted April 13, 2019 It would be funny if the south side of Chicago gets some revenge on the nw burbs. Link to comment Share on other sites More sharing options...
Baum Posted April 13, 2019 Share Posted April 13, 2019 14 minutes ago, Hoosier said: I probably would've bet money a week or two ago on accumulating snow being done. Have had some nice spring days, stuff is blooming and locally, snow has almost shut off entirely for the past couple months. Oops This one is a little more tolerable than other April snows because of the likely period of heavy rates, possible historical aspects and the quick warm up coming early next week. as I've said before the beautiful woman I married back in 1984 was born in a decent snow event on April 14,1961. This could be a repeat. Sorta neat. Couldn't help the rhyme. Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now