RU848789
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Everything posted by RU848789
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Advisories north of 276/195 are for 3" not 1" (and 2" south of 276/195); but advisories can be posted for less snowfall when freezing rain over 0.01" is expected, as we just saw today. Also, I was once told by a NWS person that the criterion for a county needs to be met for at least half of that county, i.e., a warning for Essex County, for example is where 6" is expected for at least half of the county (which is why so many counties with often sharp gradients are split in half). The maps below are at the linked website. https://www.weather.gov/phi/WinterWx 12 Hour Advisory Snowfall: 12 Hour Snowfall Warning Criteria Ice Storm Warning Crtieria
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Posted this 2 hours ago in the wrong thread, lol - hard to keep track. Nice to see the Euro beefing up precip/snowfall for 18Z vs. 12Z for the 2/11-12 event. Now the GFS, Euro, CMC and UK are all showing at least 4-8" for our region with the GFS showing 8-12"+ at 18Z. Extremely strong signal for a storm 5 days out.
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Ok, rank your excitement on a scale of 1 to Cantore-Thundersnow for next week vs. the mid-Jan pattern that was quite cold and produced some snow for our area, but had two major storm miss us to the south. :>)
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Nice to see the Euro beefing up precip/snowfall vs. 12Z. Now the GFS, Euro, CMC and UK are all showing at least 4-8" for our region with the GFS showing 8-12"+ at 18Z. Extremely strong signal for a storm 5 days out.
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Sorry, but Kuchera often sucks, as it uses a very crude algorithm based only on max column temp and ignores crystal growth parameters that "create" snow ratios. I much prefer 10:1, so I know exactly how much QPF goes into the calculation and can adjust easily low or high from that number based on other factors. Kuchera can be useful close to an event when column temps and snow growth parameters are much better known. The HRRR, RAP and some other models were high because they assumed snow and we got sleet at 2-3:1, which has a far lower ratio than Kuchera or obviously 10:1 snow - precip type is way more important than snow ratio estimates in this case. Also, if we knew most of the QPF was going to be sleet, it would've been a simple ~3 to 1 conversion to estimate the sleet accumulation vs. the 10:1 accumulation, whereas that would be very difficult with Kuchera.
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I was quite surprised, since they've often gone with the GFS and did that famously for the Jan-15 bust for our area, where they were the only ones predicting around a foot or so for NYC metro (per the GFS) vs. the 20-30" predicted by the NWS and others (likely following the euro which never wavered for days, but was wrong, as the storm was essentially displaced 70 miles east of the forecast). But the GFS is the least snowy model for this weekend, so not sure what they're following or if they make completely original forecasts now.
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We already have a couple of fairly snowy predictions being made by both News12 and TWC, which both have a lot more snow forecast than today's event, as per the maps below. On the other hand, as per below (since no map yet), the NWS is a bit less bullish with 1-3" from about 276/195 to 78 and 3-5" north of 78, but 1" or less south of 276/195 (including Philly/SNJ). Stay tuned. .SHORT TERM /FRIDAY THROUGH SUNDAY/... In terms of amounts, the current forecast calls for 0.40-0.70" of liquid QPF. Breaking this down into snow/sleet totals, anticipate a C-1" for the northern Delmarva and much of the I-95 corridor including the Philadelphia metro. Just north of the I-95 corridor up to and including the I-78 corridor, expecting 1-3". Once north of the I-78 corridor and especially north of I-80, amounts upwards of 3- 5" are possible. There will also be freezing rain accretion over most of the area, but amounts should generally range from a T-0.1" (locally higher). Considering this, Winter Weather headlines will likely be needed within the next 24-48 hours.
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Storm over for me as of about 8:15 am when it went to 33F and light rain and it's over for most of CNJ (especially along/SE of 95), at least; final measurement was 0.4" of mostly sleet, bringing my winter total up to 11.1". Temps up to 33-35F along and SE of 95 with light rain falling and the radar looks like the worst of the precip is over, although we still might get another 0.1-0.2" of rain - and this is very likely still sleet or maybe freezing rain 15-20 miles NW of 95 (i.e., a Doylestown to Morristown to Mahwah line where it's still in the 30-32F range and further NW of there where it's in the upper 20s.
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Storm over for me and most of CNJ, at least; final measurement was 0.4" of mostly sleet, bringing my winter total up to 11.1". Temp up to 33F and is 33-35F along and SE of 95 with light rain falling and the radar looks like the worst of the precip is over, although we still might get another 0.1-0.2" of rain - and this is very likely still sleet or maybe freezing rain 15-20 miles NW of 95 (i.e., a Doylestown to Morristown to Mahwah line where it's still in the 30-32F range and further NW of there where it's in the upper 20s.
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It's a kind of forecast bust, as per my recent post, since the snow predicted didn't materialize, but the mass of frozen precip that fell (0.5" of sleet is about the water equivalent of 1.5" of snow at 3:!) was spot on and the impacts have been substantial on the roads with regard to accidents and slips/falls, so definitely not a "big picture impact" bust at all.
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Thanks for the kind words. I was only using the word "bust" with reference to the forecast of 1-2" of "snow" by the NWS (their map had all of CNJ/NNJ in their 1-2" swath and point and click forecasts were around 1.2-1.5" for most) and many others for CNJ and beyond, as well as the predictions by most models showing 1-2" to 2-4" of snow, but the forecast was definitely not a bust with regard to impact, as we both agree that sleet is just as impactful to travel/removal as snow (maybe moreso as it melts more slowly), as sleet is just as difficult to drive/walk on as snow (maybe worse) and there are many, many accidents being reported. In hindsight it's interesting to look at the NAM in more detail, as it was the only one really showing <1" of snow due to an earlier changeover to sleet. This can be seen in the 0Z run last night, where the Pivotal snowmap shows <0.5" of snow for most, but the Tropical Tidbits map was showing ~2" of "snow" for most of NJ - but on TT, sleet is reported as 10:! ratio snow by the model, whereas Pivotal doesn't count sleet at all. 2" of sleet would be about 2/3" of "snow" on the ground given about a 3:1 sleet:liquid ratio (or even 1/2" at 2:1 ratio; sleet is often 2-4:1 ratio and I don't know what this sleet is), which is not far off my 0.4" and reports of 0.5" or more of sleet for many. By inference, the NAM was predicting about 2/3" of mostly sleet. I think there are some service providers that give actual snow and sleet accumulation forecasts, but I don't have access to those (I think NCEP has them), so I had to do the comparison/analysis by inference.
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Up to 32F but still sleeting with some freezing rain mixed in with 0.4" of mostly sleet on the ground. Looks like this is about over for us, as temps are above 32F to my S/SE/E and even NE. Temps still 30F or less from about New Hope to Somerville to Madison and NW of that line, so more frozen to go there.
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Still 31F here with sleet falling, but 33F reported in Carteret about 7-8 miles to my ENE - wonder if being a bit further west matters for this one with regard to being a little colder. Paved surfaces are very slippery.
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Everything is coated with a very slippery layer of snow/sleet and any untreated surfaces are treacherous; even the brined road we live on is very slippery. As I've said countless times, when it comes to impacts on travel and removal, frozen mass is way more important than depth (except for visibility impacts which are nil for sleet); also, sleet melts more slowly than snow once temps go above 32F, given the much lower surface area to volume/mass ratio (less surface area is exposed to warmer air per unit mass). Up to 31F now and worried about freezing rain coming, although still a mixture of maybe 80% sleet/20% snow.
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In my experience measuring sleet, it's more like a 3:1 ratio, although that ratio can range from 2-4:1. https://www.wral.com/story/how-to-measure-rain-snow-and-sleet/21158392/
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Snow/sleet mix here at 30F with about 1/4" of snow/sleet on the ground as of 5:30 am. Radar looks juicy. Wasn't supposed to be sleet yet. If we've already had a permanent changeover that's way early and means we're likely not going to get more than 1/2" or so of sleet (~1.5" of snow "equivalent" by mass). Sleet being reported in most CNJ locations from what I've seen. NAM for the win, if so, and a significant model and forecast bust for most, IMO, as the changeover to sleet wasn't supposed to occur until 7-8 am. I wonder if this also means we might get more freezing rain than expected, which would suck.
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Thought this might help and not take up 10 pages with maps, lol... 12Z models are in and are snowier and a bit wetter, in general. Tough forecast. Could see the NWS maybe bumping the initial snowfall thump up a little bit, but maybe not, as perhaps they have confidence in the warm air aloft coming in sooner, holding down snow/sleet amounts to the 1-2" forecast for most N of 276/195. We'll see. For the global models, the Euro and CMC are both about 2-4" for folks N of 276/195 through NYC metro (and 1-2" south of there for Philly and northern SNJ), UK is 3-5" for the whole Philly-NJ-NYC region, while the GFS is 1-2" along/N of 276/195, but 2-4" for NENJ/NYC. For the meso/short-term models, the HRRR and RAP are very bullish, still, with 3-5" for the entire region (a bit less for far SNJ), the RGEM shows 2-3" N of 276/195 (1" or so south of there) The NAM and NAM 3km are huge outliers showing <1" south of 80, with a bit of freezing rain, but mostly rain falling (1/4-1/2") and 1-2" of snow to freezing rain and rain north of there. Hard to take them too seriously given how much of an outlier they are - would be a huge coup if they were right. Almost all of the models showing a few inches or more of snow above do eventually show a changeover to sleet and rain (1/4" or more of rain as temps go above freezing in the mid/late morning for most) with some showing a brief transition featuring freezing rain first, especially along/NW of 95.
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The 06Z NAM is even more of an outlier now, showing very little snow south of 84, but having substantial ZR for many south of 84 down towards Philly, followed by a soaking 1/2"+ rain (which we could use). I know it can score a coup sometimes, especially in WAA/mix events, so it's worth watching how this plays out.
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As many have said, great signal for a snowstorm on Tues/Weds. The three major ensemble means just look so pretty side-by-side, as it's not that often one sees such consistently snowy output across all 3 models 7+ days out, especially given that the ensembles usually have a bunch of member runs with little to no snow that drag the mean down a lot, but not here. Is there a betting market for snowstorms? I also like The WPC 7-day outlook already having most of our area in the 50-75% probability of at least 2.5" of snow, which is almost unheard of this far out - as well as the comment from WPC's Cody Snell in the Twitter thread below, saying the last time he could recall a situation like this was Jan-2016... https://x.com/cody__snell/status/1887014767581389293
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All true, but the bottom line is that it's a close call on most model soundings and will likely be a close call in reality, plus no model in the world can get the entire column thermal profile exactly right at each time step, so this will be more of a radar and observational event than most. Would love all snow/ sleet with minimal ZR and rain...
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GFS and UK vs. the world for decent snow south of 78, except of course for the goofball NAM with snow only south of 276/195...
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Thanks! A friend in town said about 1/4". We've had 4 events with <1" that have added up to 1.5", so every little bit helps. Up to 10.7" on the winter.
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What did we get so far and let me know how that last band looks...damn I hate being away from home when it snows, lol...
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Agree it's very likely a bad prediction, but it's not wrong until it's wrong.
