It's Always Sunny Posted December 7, 2013 Share Posted December 7, 2013 -RAIP here now. FML. Link to comment Share on other sites More sharing options...
eduggs Posted December 7, 2013 Share Posted December 7, 2013 Because nucleation sucks. You won't get much ice growth when the temp is 0 to -8C and the lift is occurring in that level. I know. I went back and looked at the sounding. And it's not good. I'm surprised nobody noticed that earlier today or yesterday (at least that I noticed). Models have been advertising very high thicknesses for days, but as far as I know, none of the guidance highlighted ZR potential for elevated areas, which would occur in such a scenario. Link to comment Share on other sites More sharing options...
Damage In Tolland Posted December 7, 2013 Share Posted December 7, 2013 Sleet mixing in just started 35.2 Link to comment Share on other sites More sharing options...
powderfreak Posted December 7, 2013 Share Posted December 7, 2013 Because nucleation sucks. You won't get much ice growth when the temp is 0 to -8C and the lift is occurring in that level. That's like one early season upslope event this past September that was freezing rain at the summits because the precip was being produced at like -3C temps and couldn't form flakes. So it ends up being an icy mix. We could probably get widespread sleet reports with this event if elevations of 2,000-5,000ft are below freezing but its marginal above that with no snow growth. Link to comment Share on other sites More sharing options...
N. OF PIKE Posted December 7, 2013 Share Posted December 7, 2013 KMHT showin a bunch of 35/32's wonder if there is less sleet in snh then over by s. berkshires . Link to comment Share on other sites More sharing options...
HoarfrostHubb Posted December 7, 2013 Share Posted December 7, 2013 well that ALB sounding doesn't get to a productive snow growth temp until 500 mb...and the majority of the lift is below that initially. so you're just producing super cooled water droplets and ultimately some sleet and garbage.That describes it to a tPinging here. Better sleet. Lol Link to comment Share on other sites More sharing options...
SnowMan Posted December 7, 2013 Share Posted December 7, 2013 well that ALB sounding doesn't get to a productive snow growth temp until 500 mb...and the majority of the lift is below that initially. so you're just producing super cooled water droplets and ultimately some sleet and garbage. When you say lift is below that do you mean it isn't strong enough to get the water droplets into the snow growth zone? sorry for noob question but I have zero understanding as to how this works... Link to comment Share on other sites More sharing options...
CoastalWx Posted December 7, 2013 Share Posted December 7, 2013 So does that mean sleet or could it fall as rain and then freeze? So water droplets can exist in a super cooled liquid state below -10C and esp -8C. The properties and spherical shape of a water droplets allow for it to remain liquid below 0C until -10C when almost 50% of a parcel of air is usually a mix of ice and super cooled droplets. The sounding did show potential for seeder-feeder, but it was drying a bit near 500mb. So if you have lift in a layer of super cooled droplets with little in the way of other ice nuclei for these droplets to freeze around...you can still have ptype issues of rain and sleet. Sleet would occur probably from the droplet getting some evapo cooling falling through that layer. That's not a very common thing to see at a level in that atmosphere because most of the time you have ice nucle above it...but it might be happening in this case. Link to comment Share on other sites More sharing options...
wxeyeNH Posted December 7, 2013 Share Posted December 7, 2013 35.2F and all sleet.33.8 and nothing happening here Link to comment Share on other sites More sharing options...
eduggs Posted December 7, 2013 Share Posted December 7, 2013 Those algorithms are a joke. You are better off the look at soundings and real time. They mess up with surface temps and count sleet as snow, but from what I can remember they take into account nucleation in the snow growth zone. Maybe I'm wrong. I read most of the forecast discussions early today, and I can't recall any mention of seeding or nucleation. ALB was going for 10 or 12:1 ratios. How did everyone miss that? I don't even think there is a "warm layer" that is melting flakes. It looks more like warm mid levels. Places south of here might be able to dynamically cool that zone. Link to comment Share on other sites More sharing options...
SnowMan Posted December 7, 2013 Share Posted December 7, 2013 KMHT showin a bunch of 35/32's wonder if there is less sleet in snh then over by s. berkshires . Still sleet here...not even a mangled flake...currently 36.3 Link to comment Share on other sites More sharing options...
macriver Posted December 7, 2013 Share Posted December 7, 2013 Sleet and moths here, Lol. Two things you don't normally expect to see at the same time. Link to comment Share on other sites More sharing options...
CoastalWx Posted December 7, 2013 Share Posted December 7, 2013 I know. I went back and looked at the sounding. And it's not good. I'm surprised nobody noticed that earlier today or yesterday (at least that I noticed). Models have been advertising very high thicknesses for days, but as far as I know, none of the guidance highlighted ZR potential for elevated areas, which would occur in such a scenario. It's localized to the nrn edge of the band..I don't think this is a widespread issue though. Link to comment Share on other sites More sharing options...
SnowMan Posted December 7, 2013 Share Posted December 7, 2013 So water droplets can exist in a super cooled liquid state below -10C and esp -8C. The properties and spherical shape of a water droplets allow for it to remain liquid below 0C until -10C when almost 50% of a parcel of air is usually a mix of ice and super cooled droplets. The sounding did show potential for seeder-feeder, but it was drying a bit near 500mb. So if you have lift in a layer of super cooled droplets with little in the way of other ice nuclei for these droplets to freeze around...you can still have ptype issues of rain and sleet. Sleet would occur probably from the droplet getting some evapo cooling falling through that layer. That's not a very common thing to see at a level in the atmosphere because most of the time you have ice nucle above it...but it might be happening in this case. Thanks for the explanation Link to comment Share on other sites More sharing options...
CoastalWx Posted December 7, 2013 Share Posted December 7, 2013 They mess up with surface temps and count sleet as snow, but from what I can remember they take into account nucleation in the snow growth zone. Maybe I'm wrong. I read most of the forecast discussions early today, and I can't recall any mention of seeding or nucleation. ALB was going for 10 or 12:1 ratios. How did everyone miss that? I don't even think there is a "warm layer" that is melting flakes. It looks more like warm mid levels. Places south of here might be able to dynamically cool that zone. Albany was very bullish and I don't know why. However it only takes a weenie to measure 7" and then it verifies. Link to comment Share on other sites More sharing options...
Tropopause_Fold Posted December 7, 2013 Share Posted December 7, 2013 t/td spreads are pretty high off to the west in PA too. something to watch. where it's snowing...thus far it's pretty light. we'll want some of those heavier returns that are falling as R/R+ to be the snow for SNE. Link to comment Share on other sites More sharing options...
dendrite Posted December 7, 2013 Share Posted December 7, 2013 Nothing to produce nuclei? You really need to get down around -6C to -8C in the cloud to start producing ice crystals...then the crystals will grow via deposition and vapor pressure differences between the ice crystals and water droplets in the cloud. I'll let you google Bergeron process. Link to comment Share on other sites More sharing options...
wxmanmitch Posted December 7, 2013 Share Posted December 7, 2013 All snow now and beginning to coat the ground. Large aggregates. No sleet mixing in anymore. 32.4° F. Link to comment Share on other sites More sharing options...
eduggs Posted December 7, 2013 Share Posted December 7, 2013 It's localized to the nrn edge of the band..I don't think this is a widespread issue though. Probably. But it was "sleeting" pretty good up here for a while... and I didn't see a single flake. So I suspect it will pollute the column somewhat for other places further east, unless much deeper lift arrives. I don't think we were even close here so far. Link to comment Share on other sites More sharing options...
CapturedNature Posted December 7, 2013 Share Posted December 7, 2013 Yeah that may not be getting picked up by the ASOS. Wilkes-Barre/Scranton, PA with another 0.14" last hour and reporting moderate freezing rain at 33/30 now. Wasn't BGM looking to get crushed? I can't believe they've only had 0.01" of QPF so far. 31/27 with UP/Sleet, but precip is so light there it doesn't matter at the moment. I just talked to someone in Hazelton just south of there and they have sleet. No rain. No temp data available. Link to comment Share on other sites More sharing options...
Damage In Tolland Posted December 7, 2013 Share Posted December 7, 2013 All snow now and beginning to coat the ground. Large aggregates. No sleet mixing in anymore. 32.4° F.That is great news and ahead of schedule. It's coming SE Link to comment Share on other sites More sharing options...
CoastalWx Posted December 7, 2013 Share Posted December 7, 2013 You really need to get down around -6C to -8C in the cloud to start producing ice crystals...then the crystals will grow via deposition and vapor pressure differences between the ice crystals and water droplets in the cloud. I'll let you google Bergeron process. The only thing good about cloud physics...you can relate it to snow. Link to comment Share on other sites More sharing options...
eduggs Posted December 7, 2013 Share Posted December 7, 2013 Albany was very bullish and I don't know why. However it only takes a weenie to measure 7" and then it verifies. ALB is usually not particular bullish. And I agree they were probably a little too bold. But to be fair, last night's model consensus (a broad consensus) was for .4 - .8 LE across the area, with temps below freezing for the entire column for the northern 2/3 of the forecast area. Hard not to go a least 2-4 with that. Today's guidance only shifted slightly SE. Link to comment Share on other sites More sharing options...
Randy4Confluence Posted December 7, 2013 Share Posted December 7, 2013 Raining moths and 41. Link to comment Share on other sites More sharing options...
CoastalWx Posted December 7, 2013 Share Posted December 7, 2013 That is great news and ahead of schedule. It's coming SE It's about right. That heavier lift will probably start to turn many over to sleet and then snow after 10ish. From NNW-SSE of course. Link to comment Share on other sites More sharing options...
Damage In Tolland Posted December 7, 2013 Share Posted December 7, 2013 It's about right. That heavier lift will probably start to turn many over to sleet and then snow after 10ish. From NNW-SSE of course.I was thinking 10 or later for skeet so about an hour early Link to comment Share on other sites More sharing options...
Tropopause_Fold Posted December 7, 2013 Share Posted December 7, 2013 That is great news and ahead of schedule. It's coming SE it's not ahead of schedule. Link to comment Share on other sites More sharing options...
HoarfrostHubb Posted December 7, 2013 Share Posted December 7, 2013 Thanks Brian and Scoots I appreciate it Link to comment Share on other sites More sharing options...
CoastalWx Posted December 7, 2013 Share Posted December 7, 2013 Alright well enjoy. About to have some me time with son in bed and mom at neighbors. Smithwicks FTW. Link to comment Share on other sites More sharing options...
ma blizzard Posted December 7, 2013 Share Posted December 7, 2013 The only thing good about cloud physics...you can relate it to snow. that class .. and that prof hearing some pings mixed in with ra-, nearest wx station has 38.7 / 34.3 Link to comment Share on other sites More sharing options...
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