cyclone77 Posted February 27, 2011 Share Posted February 27, 2011 Man this is gonna be one hell of a difficult forecast for many areas. Pretty sad that at less than 18hrs out we're still getting relatively major shifts in precip patterns/temps. That's the way it's been lately though lol. Here in the QC I'm thinking we're going to be seeing more freezing rain/sleet than snow. Looks like we'll start as rain, and quickly go over to ice. Question is, how much glazing will actually occur, or will the sleet dominate? Based off the 12z NAM soundings, the layer of warm air is relatively shallow, so I think we'll be seeing quite a bit of wind driven sleet. Temps at 850mb don't cool below 0°C until about 2am here. Thicknesses remain above 540dm through about 4am. I think we'll eventually go over to snow, but am definitely not sold on heavy snow accums here. There may be a very thin band of decent snow accumulations from eastern Iowa to southern Wisconsin. I think many NWS offices will be tweaking precip type/amounts even after the onset of the storm. With such small bands of potential frozen/freezing precip it's going to be very difficult to pin down. Link to comment Share on other sites More sharing options...
turtlehurricane Posted February 27, 2011 Share Posted February 27, 2011 Tonight could be interesting, I love events that are up in the air like this. It's likely going south as the models say, but accounting for the GFS cold bias, which is very real due to incorrect accounting of diabatic processes I believe, I can easily see southern WI getting well into the frontal zone. The frontal zone is already starting to develop on reflectivity imagery from TX to IL, almost looks aimed at Wisconsin as it drifts north and east. Nice cells popping in MO and IL. Thunderstorming and in the 30s looking at obs in those. Way too warm low-levels from WAA for anything but rain that far south. Link to comment Share on other sites More sharing options...
BeastFromTheEast Posted February 27, 2011 Share Posted February 27, 2011 At least the Skilldog is paying attention.. Concern for a north and northwest suburban freezing rain and snow event growing February 27, 2011 9:00 AM | No CommentsColder than expected temperatures and a dynamic storm system ramping up over the Plains this morning may set the stage for a significant freezing rain, sleet and snow event for some of Chicago's northern and northwest suburbs tonight. The first wave of precipitation is not expected to arrive until after 4PM, with the heaviest rain, freezing rain and sleet occurring after 10PM. Check back for forecast updates throughout the day. Link to comment Share on other sites More sharing options...
turtlehurricane Posted February 27, 2011 Share Posted February 27, 2011 Also, whoever gets bullseyed might be looking at an inch of frozen precip (in whatever form it is), tons of Gulf moisture in play now since it's February. I expect the NAM to be closer to reality than the GFS when it comes to totals. Link to comment Share on other sites More sharing options...
Moneyman Posted February 27, 2011 Share Posted February 27, 2011 WRF-NMM looks to crush N. IL as well. Link to comment Share on other sites More sharing options...
cyclone77 Posted February 27, 2011 Share Posted February 27, 2011 I'm a bit concerned at how far south the RUC is. It was the first to catch on to the last minute southern trend with the last storm. Something to watch... Link to comment Share on other sites More sharing options...
A-L-E-K Posted February 27, 2011 Share Posted February 27, 2011 the HRRR paints a mess of a battle ground across northern Illinois, heavy returns about to move in and heights getting ready to crash. Link to comment Share on other sites More sharing options...
A-L-E-K Posted February 27, 2011 Share Posted February 27, 2011 I'm a bit concerned at how far south the RUC is. It was the first to catch on to the last minute southern trend with the last storm. Something to watch... I think you're golden for interesting weather. EDIT: looking at the last few runs of the HRRR, it's trending cooler/south as well. Link to comment Share on other sites More sharing options...
Organizing Low Posted February 27, 2011 Share Posted February 27, 2011 a couple days ago, Env Canada had highs near 15C for monday, now, people will be waking up to a winter storm for their morning commute here. only this year could a torch cutter trend so far SE. Link to comment Share on other sites More sharing options...
BeastFromTheEast Posted February 27, 2011 Share Posted February 27, 2011 Csnavywx I see you are lurking.. What are your thoughts on this thing?? Link to comment Share on other sites More sharing options...
Thundersnow12 Posted February 27, 2011 Share Posted February 27, 2011 I agree with Alek that LOT needs some type of winter heading for the northern half of their CWA. afternoon AFD will sure be interesting. Link to comment Share on other sites More sharing options...
Moneyman Posted February 27, 2011 Share Posted February 27, 2011 HRRR looks a lot mroe north then the RUC right now. I think this thing trends NW yet tbh. Link to comment Share on other sites More sharing options...
cyclone77 Posted February 27, 2011 Share Posted February 27, 2011 RUC pulling a coup again? Link to comment Share on other sites More sharing options...
snowstormcanuck Posted February 27, 2011 Share Posted February 27, 2011 Congrats Mike! Took you awhile, but we're pretty much in a virtual tie with snowfall to date now. Thanks Tim. It's that time of the year again. Already compressed to 2.5" of slush. Link to comment Share on other sites More sharing options...
roardog Posted February 27, 2011 Share Posted February 27, 2011 This kind of reminds me of something we would see in April where the forecast goes from SW winds and 70F with severe weather to NE winds and 40F with startiform rain in a matter of a day or so. I would guess the extreme cold that is sitting just north of the US/Canadian border may be helping to shove everything south along with the storm itself obviously being weaker. Link to comment Share on other sites More sharing options...
A-L-E-K Posted February 27, 2011 Share Posted February 27, 2011 RUC pulling a coup again? Going by the current set up, it's a lot more believable than a far NW option. Looking at the moisture vectors and orientation of the trough i don't see how the action can be pulled too far north. There's going to be a p-type battle ground somewhere across northern illinois. Link to comment Share on other sites More sharing options...
turtlehurricane Posted February 27, 2011 Share Posted February 27, 2011 A few dendrites flying now, and even drizzle drops (though there's no above freezing layer). Definitely just some weak miscellaneous forcing, but it shows how moist the atmosphere is already. Link to comment Share on other sites More sharing options...
Moneyman Posted February 27, 2011 Share Posted February 27, 2011 I would go something like the NAM track imo. That seems reasonable. Link to comment Share on other sites More sharing options...
cyclone77 Posted February 27, 2011 Share Posted February 27, 2011 Going by the current set up, it's a lot more believable than a far NW option. Looking at the moisture vectors and orientation of the trough i don't see how the action can be pulled too far north. There's going to be a p-type battle ground somewhere across northern illinois. Every other model is in almost unanimous agreement as far as I can tell, so the RUC is definitely a huge outlier. It would be remarkable if it ends up being correct again. It would also be a piss poor fail by the other operational models. Link to comment Share on other sites More sharing options...
snowstormcanuck Posted February 27, 2011 Share Posted February 27, 2011 NAM clownage requires a 50 miles further SE adjustment to get me into that finger band of snow. GFS clownage (2m temp maps) have the 0c sfc line bisecting me throughout the event. Soundings gonna be interesting. Still fairly confident in mostly RA here. Link to comment Share on other sites More sharing options...
Moneyman Posted February 27, 2011 Share Posted February 27, 2011 Model agreement means nothing now imo, it's all about now-casting. 0z yesterday showed S. WI getting pounded, every model showed it. Now everything shifted south again on the 12z models. They don't have a clue. Link to comment Share on other sites More sharing options...
cyclone77 Posted February 27, 2011 Share Posted February 27, 2011 RGEM shifted a bit south as well, and actually looks a bit further south than the NAM/GFS. Link to comment Share on other sites More sharing options...
A-L-E-K Posted February 27, 2011 Share Posted February 27, 2011 Model agreement means nothing now imo, it's all about now-casting. 0z yesterday showed S. WI getting pounded, every model showed it. Now everything shifted south again on the 12z models. They don't have a clue. The event is ongoing and i'm just not seeing signs of a NW shift or reasons to buy into the more northern models. I think you'll continue to see the HRRR correct south towards the RUC. Link to comment Share on other sites More sharing options...
csnavywx Posted February 27, 2011 Share Posted February 27, 2011 RUC pulling a coup again? Kind of somehow doubt that. Recall the RUC taking the last storm over W/NW Missouri at T-15 hr? Look how that one worked out. According to those runs, you should have walked away with 4-6"+. In this time range, the 4km-WRF and NAM did very well with the system. Speaking of which, the 4km WRF is showing some dry air impinging on the precip shield again this time, but not nearly as bad as the last time. There's a wave that comes in aloft around 3-6Z (9-12 CST) that should send in some nice elevated thunderstorms, and I'm seeing some instability in the BUFKIT soundings during the snow period as well. The big question is surface temperatures tonight. My hunch is that those temps will hover at or just above freezing, since the warm layer aloft is so thick and the low level subfreezing level is extremely thin. Furthermore, latent heat release from that freezing rain may offset accretion and prevent it from becoming a serious event. But this is just a hunch at this point, as it looks to be extremely close, and we're going to be dealing with quite a bit of convection, which tends to do strange things to the temp profile and p-type. Link to comment Share on other sites More sharing options...
A-L-E-K Posted February 27, 2011 Share Posted February 27, 2011 RGEM shifted a bit south as well, and actually looks a bit further south than the NAM/GFS. I think the writing is on the wall at this point and am expecting over half our QPF to be someting other than plain rain. Link to comment Share on other sites More sharing options...
Moneyman Posted February 27, 2011 Share Posted February 27, 2011 Alec, I realize that the storm is on-going right now, but the precip etc hasn't even developed yet. A NW trend is possible once the storm fully develops, and I wouldn't rule it out at all. I'm just saying 0z/6z runs were in "agreement" and then 12z runs all shifted south so who knows. This is a now casting event though considering we are within 24 hours of this starting. All soultions are still on the table though. Link to comment Share on other sites More sharing options...
A-L-E-K Posted February 27, 2011 Share Posted February 27, 2011 Kind of somehow doubt that. Recall the RUC taking the last storm over W/NW Missouri at T-15 hr? Look how that one worked out. According to those runs, you should have walked away with 4-6"+. In this time range, the 4km-WRF and NAM did very well with the system. Speaking of which, the 4km WRF is showing some dry air impinging on the precip shield again this time, but not nearly as bad as the last time. There's a wave that comes in aloft around 3-6Z (9-12 CST) that should send in some nice elevated thunderstorms, and I'm seeing some instability in the BUFKIT soundings during the snow period as well. The big question is surface temperatures tonight. My hunch is that those temps will hover at or just above freezing, since the warm layer aloft is so thick and the low level subfreezing level is extremely thin. Furthermore, latent heat release from that freezing rain may offset accretion and prevent it from becoming a serious event. But this is just a hunch at this point, as it looks to be extremely close, and we're going to be dealing with quite a bit of convection, which tends to do strange things to the temp profile and p-type. thanks for your thoughts. 4km-wrf looks like a fun ride so i could live with that. Link to comment Share on other sites More sharing options...
snowstormcanuck Posted February 27, 2011 Share Posted February 27, 2011 NAM BUFKIT for YYZ is mostly rain, but 2m temps at 33-34 throughout the event. It has a cold bias so I'm not too concerned at this point. However, any last minute SE adjustment (a la the Friday storm) is going to be huge. Link to comment Share on other sites More sharing options...
cyclone77 Posted February 27, 2011 Share Posted February 27, 2011 09z SREF mean Link to comment Share on other sites More sharing options...
Thundersnow12 Posted February 27, 2011 Share Posted February 27, 2011 Kind of somehow doubt that. Recall the RUC taking the last storm over W/NW Missouri at T-15 hr? Look how that one worked out. According to those runs, you should have walked away with 4-6"+. In this time range, the 4km-WRF and NAM did very well with the system. Speaking of which, the 4km WRF is showing some dry air impinging on the precip shield again this time, but not nearly as bad as the last time. There's a wave that comes in aloft around 3-6Z (9-12 CST) that should send in some nice elevated thunderstorms, and I'm seeing some instability in the BUFKIT soundings during the snow period as well. The big question is surface temperatures tonight. My hunch is that those temps will hover at or just above freezing, since the warm layer aloft is so thick and the low level subfreezing level is extremely thin. Furthermore, latent heat release from that freezing rain may offset accretion and prevent it from becoming a serious event. But this is just a hunch at this point, as it looks to be extremely close, and we're going to be dealing with quite a bit of convection, which tends to do strange things to the temp profile and p-type. A repeat of weds night FTW lol 4 different precip types in an hour thanks to convection, that was awesome. Link to comment Share on other sites More sharing options...
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