OT: Winter storm for 2/12 - Big Mess of Snow/Sleet/Rain (after minor snowfall on 2/11)
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That would've scared the crap out of me, given the history of planes icing up and crashes. I'm guessing you flew through a sub-32F layer aloft and it was raining from above that? Don't they circulate hot fluid to the wings to address that?
Icing generally happens in temps just above freezing, with high dew points.
If the temperatures are below freezing than the moisture in the atmosphere is already frozen / crystallized. No ice. At temps just above freezing, ice accumulates on the wings because of the relationship between Bernoulli and ideal gases.
Yes, that's something of a quiz. I await your solution. :)
Commercial jets pump engine bleed air (hot) through the wings. Turboprops have deicing boots which utilize pneumatic pulses to break up accumulated ice. It's not as effective, which is why a Q400 will be cancelled in bad weather before a jet.
Sorry, that's not generally right. Rain drops (in clouds) can be supercooled to well below 32F without crystallizing into solid ice/snow - it happens all the time with freezing rain, which remains liquid at <32F, but then freezes upon contact with surfaces (the ground/trees/etc.) that are 32F or less.
A similar thing can happen in flight. Planes can fly through clouds filled with supercooled water droplets that can be as cold as -40C that will easily freeze on the wing's surfaces, especially on the leading edge of the wings. And as we both know from aerodynamics, changing the thickness/roughness of the surface of the wings through ice build-up changes the wing profile cross section, generally reducing lift (as per our friend Bernoulli) and increases drag, which can eventually lead to loss of control of the plane (especially in autopilot).
I don't know of any examples of ice accumulating on wings at temps just above freezing in flight - I do know that due to radiative cooling, metal wings can actually be a few degrees colder than the ambient temperature, leading to ice accretion (frost) on wings of planes sitting out overnight, even if the ambient temp is a few degrees above 32F, since the wings can be at or below 32F.
Not quite sure what you meant by the relationship between Bernoulli's Equation and the Ideal Gas Law (PV=nRT). I can imagine thinking that with lower pressures on the upper surface of the wing (Bernoulli), the gas law would say that the temperature of the air (gas) flowing over that wing at reduced pressure would cool off a little bit, but I've never heard of anyone saying that would lead to icing when it's above 32F, especially since most of the time planes are flying through temps <32F (especially in winter) so the wings would generally be cold enough to freeze any supercooled droplets.
Most importantly, the excerpt, below, from AC 91-74 makes it clear that "nearly all aircraft icing occurs in supercooled clouds...in which water droplets are present below 32F."
AIRCRAFT ICING CONDITIONS. Nearly all aircraft icing occurs in supercooled clouds. These are clouds in which liquid droplets are present at temperatures below 0 C (32 F). At temperatures close to 0 C (32 F), the cloud may consist entirely of such droplets, with few or no ice particles present. At decreasing temperatures, the probability increases that ice particles will be found in significant numbers along with the liquid droplets. In fact, as the ice water content increases, the liquid water content tends to decrease, since the ice particles grow at the expense of the water particles. At temperatures below about -20 C (-4 F), most clouds are made up entirely of ice particles. The general rule is that the more ice particles and the fewer liquid droplets that are present, the less ice accumulation on the airframe. This is because the ice particles tend to bounce off an aircraft surface, while the supercooled droplets freeze and adhere. As a result, ice accumulation is often greatest at temperatures not too far below 0 C (32 F), where liquid water content can be abundant, and is usually negligible at temperatures below about -20 C (-4 F).
http://rgl.faa.gov/Regulatory_and_G...dd2f5233b5686256c9b0056f7a0/$FILE/AC91-74.pdf
Read more at: https://phys.org/news/2016-01-ice-formation-aircrafts-flight.html#jCp
We will get an inch or so Sunday night an inch or two on Tuesday followed by a bunch of rain which will wash it all away. Hence #'s gets his snow and I see it go away .Everyone is happy.
That’s Vanessa from the deli. She brought out the summer gear when the temperature heated up. I think she was ordering tongue from the deli guy.
That's certainly a possible scenario, as per the GFS model. However, every other model, right now, is showing more like 2-4/3-5" of snow, then a couple of inches of sleet (equiv mass to 7" of snow), then about 1" of rain as temps go above 32F at the surface. I would guess that maybe 1/3 of that would wash away, as the rain would largely be absorbed into the snow/sleet, forming a compacted slushy mess, although it won't freeze hard, as temps likely don't go back below 32F until Wednesday night. All snow would be much prettier, lol. Of course, we're still 3 days out, so much can still change with this forecast (and wetter/warmer is probably more likely than colder/snowier, just given the setup).
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So much for the model consensus we had yesterday afternoon, lol - never thought it would last, but we have serious model mayhem right now. Models showing everything from 1-2" of snow/sleet, then mostly rain (GFS), to 6"+ of mostly snow (UK still) and a few in-between at 2-4/3-6" (Euro/CMC) or so. As usual my comments are generally for Philly to NYC near 95; in a setup like this, more snow/sleet is likely NW of 95 and less towards the coast.
I will say this: many pros are pessimistic on this storm bringing more than a few inches of snow, since the primary low is going to our west and the coastal looks weak - normally that means some snow then mostly rain. But given model variability and generally poor forecasting from the NWS and many pros this winter, I'll reserve judgment for a couple more days, i.e., I have no frickin' clue what's going to happen on this one yet.
Will update with the model outputs later. Way too busy at work. Bottom line is we're probably going to need another day or two to know what's likely to happen here. Many solutions still on the table. One comment: starting to see more model support for ~1" of snow Sunday night/Monday morning (and maybe 2" or so south of 276/195), which could be slightly to moderately impactful with temps <32F through the morning rush hour on Monday.
12ZGFS
12Z CMC
12Z UK
12Z Euro
And below is a really interesting comparison between how model output services can differ widely when sharing what should be identical information. In the parent post is the 12Z GFS-FV3 from Tropical Tidbits, which reports about 8-10" of snow for the Philly-NYC corridor, but it includes sleet and counts it the same way it reports snow, i.e., as 10" of either per 1" of liquid, which is flawed, as sleet is usually about 3" of sleet per 1" of liquid (but has the same frozen mass as the snow, just not the same depth). The map shows 8-10" of snow, which is really about ~2" of snow + 2" of sleet (equiv to about 7" of snow).
Second is the 12Z GFS-FV3 from Pivotal Weather, which only shows pure snow at 10" snow per 1" of liquid, but excludes sleet entirely. This is also highly flawed, as the map makes it look like a minor ~2" snowfall, when in reality, we're really talking about ~2" of snow + about 2" of sleet (equivalent to ~7" of regular snow), as per above. I think the TT maps are better, as they at least are truly showing the total mass of frozen precip, which is about 8-10" worth of snow (or 0.8-1.0" of liquid equivalent). At least for shoveling, plowing and driving (apart from visibility), mass is the far more important number, not depth. As if predicting "snowfall" isn't hard enough, lol.
12Z GFS-FV3
The 0Z models mostly held serve, being close to where they were at 12Z earlier today. Looking like snow to sleet to rain, but how much of each is the question. Right now, apart from the GFS (which only shows ~2" of snow, followed by a lot of rain), for Philly to NYC, every model is showing at least 3-4" of snow then 1-2" of sleet (for close to 1" of liquid equivalent in frozen form) or 4-8" of snow then not much sleet, followed, in all cases by 1/2" to 1" of plain rain.
We have not had modest model consensus like this 3-4 days out for any of the other storms that "missed" us this year (they generally had 1 or 2 models showing decent snow, but 2-3 others showing much less; we had pretty good consensus for 11/15 by about 3 days out). Of course, that may all go into the crapper in future model runs, but it's starting to look likely that we'll get a decent thump of snow/sleet on the front end of the storm, followed by a fair amount of rain. Having said that solutions from an inch or so of snow then all rain to several inches of snow/sleet, then a fair amount of rain to 6-10" of snow and some rain are all still on the table.
In addition, given the very fine line on column temperature between the precip types and that we're still 3+ days before the event, when model uncertainty is still pretty high, my thinking is we won't have a good handle on this until Sunday. Even then there could be last minute surprises, since a 2-hour delay in a changeover to rain could mean 2-3" more snow or vice-versa, since it's going to be a potent system with ~2" of total precip (liquid equivalent) in about 24 hours from very early Tuesday through very early Wednesday morning.
The model outputs are below. Note that the GFS and GFS-FV3 maps show snow and sleet (as 10:1 ratio snow, where sleet is much more dense at 3:1 ratio of sleet to liquid), whereas the CMC only shows snow, excluding sleet. I looked at the soundings (column temperature profile) for the CMC and the map should really be showing the 3-4" of snow it has, plus about 2" of sleet (equiv to about 7" more snow). The Euro and UK just show snow and I don't have soundings (profiles of the column temperature over time) to estimate how much sleet falls for those two models.
Also, keep in mind that we still might see 1/2" to 1" of snow before dawn on Monday - could impact the morning rush with temps below 32F.
0Z GFS
0Z CMC
0Z UK
0Z Euro
In case anyone wonders what a column profile "sounding" on a model looks like, see the graphic below for the CMC from 7 pm Tuesday, after about 1" of precip has fallen in the form of 3-4" of snow and then about 2" of sleet (equiv to 6-7" of snow, by mass) falls. The reason I say 3-4" of snow is because that's what the CMC model shows for pure snowfall.
The reason I say 2" of sleet is that after the snow is done, about 0.7" more precip falls with the sounding as cool or cooler than the one in the graphic, which has the snow melting at 700 mbar (9000' feet up, where the red column temperature line on the left side graphic crosses the slanted blue 0C freezing line and goes over 32F), due to temps in the mid-30s from about 9000 feet up to about 2500 feet up in the column, but then the melted snow falls through the final 2500 feet down to the surface (the red column temp line crosses back below 32F at about 900 mbar or 2500 feet up) at <32F, refreezing the liquid into sleet pellets which will accumulate at the 32-33F surface temp.
The surface temp and sub-32F layer just above it then quickly all go above 32F not long after 7 pm, meaning about 1" of plain rain falls from then on. The surface temp gets up to about 40F or so by early Weds and then slowly falls to below 32F by Wednesday evening, so no flash freeze of the slush resulting from rain being mostly absorbed into the snow/sleet pack is predicted. Remember, this is what the CMC model is saying and is not a forecast.
You’re up late kiddo.The 0Z models mostly held serve, being close to where they were at 12Z earlier today. Looking like snow to sleet to rain, but how much of each is the question. Right now, apart from the GFS (which only shows ~2" of snow, followed by a lot of rain), for Philly to NYC, every model is showing at least 3-4" of snow then 1-2" of sleet (for close to 1" of liquid equivalent in frozen form) or 4-8" of snow then not much sleet, followed, in all cases by 1/2" to 1" of plain rain.
We have not had modest model consensus like this 3-4 days out for any of the other storms that "missed" us this year (they generally had 1 or 2 models showing decent snow, but 2-3 others showing much less; we had pretty good consensus for 11/15 by about 3 days out). Of course, that may all go into the crapper in future model runs, but it's starting to look likely that we'll get a decent thump of snow/sleet on the front end of the storm, followed by a fair amount of rain. Having said that solutions from an inch or so of snow then all rain to several inches of snow/sleet, then a fair amount of rain to 6-10" of snow and some rain are all still on the table.
In addition, given the very fine line on column temperature between the precip types and that we're still 3+ days before the event, when model uncertainty is still pretty high, my thinking is we won't have a good handle on this until Sunday. Even then there could be last minute surprises, since a 2-hour delay in a changeover to rain could mean 2-3" more snow or vice-versa, since it's going to be a potent system with ~2" of total precip (liquid equivalent) in about 24 hours from very early Tuesday through very early Wednesday morning.
The model outputs are below. Note that the GFS and GFS-FV3 maps show snow and sleet (as 10:1 ratio snow, where sleet is much more dense at 3:1 ratio of sleet to liquid), whereas the CMC only shows snow, excluding sleet. I looked at the soundings (column temperature profile) for the CMC and the map should really be showing the 3-4" of snow it has, plus about 2" of sleet (equiv to about 7" more snow). The Euro and UK just show snow and I don't have soundings (profiles of the column temperature over time) to estimate how much sleet falls for those two models.
Also, keep in mind that we still might see 1/2" to 1" of snow before dawn on Monday - could impact the morning rush with temps below 32F.
0Z GFS
0Z CMC
0Z UK
0Z Euro
In case anyone wonders what a column profile "sounding" on a model looks like, see the graphic below for the CMC from 7 pm Tuesday, after about 1" of precip has fallen in the form of 3-4" of snow and then about 2" of sleet (equiv to 6-7" of snow, by mass) falls. The reason I say 3-4" of snow is because that's what the CMC model shows for pure snowfall.
The reason I say 2" of sleet is that after the snow is done, about 0.7" more precip falls with the sounding as cool or cooler than the one in the graphic, which has the snow melting at 700 mbar (9000' feet up, where the red column temperature line on the left side graphic crosses the slanted blue 0C freezing line and goes over 32F), due to temps in the mid-30s from about 9000 feet up to about 2500 feet up in the column, but then the melted snow falls through the final 2500 feet down to the surface (the red column temp line crosses back below 32F at about 900 mbar or 2500 feet up) at <32F, refreezing the liquid into sleet pellets which will accumulate at the 32-33F surface temp.
The surface temp and sub-32F layer just above it then quickly all go above 32F not long after 7 pm, meaning about 1" of plain rain falls from then on. The surface temp gets up to about 40F or so by early Weds and then slowly falls to below 32F by Wednesday evening, so no flash freeze of the slush resulting from rain being mostly absorbed into the snow/sleet pack is predicted. Remember, this is what the CMC model is saying and is not a forecast.
Again these clown maps are useless because of the strong possiblity of sleet and uncertainty of what falls where.
Yep. I don't sleep much when there's a potential winter storm, lol.
I was surprised to read the snowiest place on earth is in Japan.
Aomori... you should visit given your love of snow:D
Partly agree. Mixed precip events are really tough to convey well. Just posted the part in italics below on the weather boards, using the latest 12Z NAM to illustrate, as the models basically show a couple of inches of snow, then hours of sleet for CNJ/NNJ/NYC with about 1-2" of sleet likely (equiv to 3-6" of snow, by mass; for 95 it's about 1" of sleet, then about 1/2-1" of plain rain; NW is 2" of sleet then rain, as per the models). It's pretty tedious to really show what the models are showing, plus the models are going to change as we're still 2.5 days from the start of the event (late Monday night now and the early Monday snow from the initial system is creeping up towards our area, complicating things further).
Definitely one of those storms where one needs to look at multiple graphics to get the full story. For the 12Z NAM, the Pivotal map shows the snow through Tuesday early morning (more to the S of 195/276 due to the Monday system) and then the snow changes to sleet for most of CNJ/NNJ until early afternoon (where soundings from Trenton to NYC looks like sleet, changing to rain somewhere around 1-2 pm Tues), where one can estimate the amount of sleet by subtracting the Pivotal snow from the Tidbits "snow" (which is snow + sleet, all at a 10:1 ratio).
Kind of tedious, but no single map can really work. This can work for the NAM, GFS and FV3; pretty sure the CMC/Euro/UK maps are just snow, but not 100% sure on that and if that's right not sure if they show sleet some other way or if one has to count precip under sleet soundings manually - I'm sure there are better ways to do this - might be time to start paying for this kind of info, lol. Might not be worth this effort yet, 3 days out, since much will likely change, but it helps me, at least.
I've driven 50+ miles to see the snow/rain line a few times - one time, late at night, I got as far as Newton on 206 in Sussex County (the snow-rain line was around Dover) and they had nearly a foot of snow and it was pouring snow, so I stopped, filled my hatch up with snow, kept the heat off in the car, drove home to Edison, where it was all rain and built my then girlfriend a snowman that she woke up to. I did ok that morning, lol. Next winter I'm going to go somewhere in the snow belt for a major lake effect snowstorm and yeah, that area of northern Japan would be nice to visit.
lol, true for most years, although when we have a really snowy winter here, it's probably as bad or worse on sleep, since we'll get more storms to get our 50-70" in a big year, while they'll usually have a few huge lake effect storms, but a similar amount of total storms - and theirs are actually easier to forecast, since it's usually just how much snow, not all this snow/sleet/freezing rain/rain crap we have to negotiate.
remember those maps include any snow from Monday system as well which at my last glance was looking like it was staying more to a south of Trenton event
I love that story!
I think if I was in a beautiful inn with a fire place, no obligations and endless supplies.
I would take it all in, go outside and play in 30 feet of snow, and have a ball
Sleet makes you fall on your ass with two pizzas in your arm after leaving Star, that end up on the sidewalk.
Or in your case two Jimmy Buff Dogs all the way.
Her dad is actually Tito Puenteyou mean Audrey Puente lol
Thanks, I do that in an inch of snow, lol.
Ahhh, I miss Star Tavern - my favorite pizza in the State and I only get up there every few years. I'm assuming the pizzas on the ground is autobiographical, lol...
yes...she actually came along way from when she first started and was sort of awkward
Reminds me of when we had a house up at Mt. Snow: we'd sit in the jacuzzi soaking up beer until we were overheating,then go run outside and roll in the falling snow. In our swimsuits.
The 0Z models mostly held serve, being close to where they were at 12Z earlier today. Looking like snow to sleet to rain, but how much of each is the question. Right now, apart from the GFS (which only shows ~2" of snow, followed by a lot of rain), for Philly to NYC, every model is showing at least 3-4" of snow then 1-2" of sleet (for close to 1" of liquid equivalent in frozen form) or 4-8" of snow then not much sleet, followed, in all cases by 1/2" to 1" of plain rain.
We have not had modest model consensus like this 3-4 days out for any of the other storms that "missed" us this year (they generally had 1 or 2 models showing decent snow, but 2-3 others showing much less; we had pretty good consensus for 11/15 by about 3 days out). Of course, that may all go into the crapper in future model runs, but it's starting to look likely that we'll get a decent thump of snow/sleet on the front end of the storm, followed by a fair amount of rain. Having said that solutions from an inch or so of snow then all rain to several inches of snow/sleet, then a fair amount of rain to 6-10" of snow and some rain are all still on the table.
In addition, given the very fine line on column temperature between the precip types and that we're still 3+ days before the event, when model uncertainty is still pretty high, my thinking is we won't have a good handle on this until Sunday. Even then there could be last minute surprises, since a 2-hour delay in a changeover to rain could mean 2-3" more snow or vice-versa, since it's going to be a potent system with ~2" of total precip (liquid equivalent) in about 24 hours from very early Tuesday through very early Wednesday morning.
The model outputs are below. Note that the GFS and GFS-FV3 maps show snow and sleet (as 10:1 ratio snow, where sleet is much more dense at 3:1 ratio of sleet to liquid), whereas the CMC only shows snow, excluding sleet. I looked at the soundings (column temperature profile) for the CMC and the map should really be showing the 3-4" of snow it has, plus about 2" of sleet (equiv to about 7" more snow). The Euro and UK just show snow and I don't have soundings (profiles of the column temperature over time) to estimate how much sleet falls for those two models.
Also, keep in mind that we still might see 1/2" to 1" of snow before dawn on Monday - could impact the morning rush with temps below 32F.
0Z GFS
0Z CMC
0Z UK
0Z Euro
In case anyone wonders what a column profile "sounding" on a model looks like, see the graphic below for the CMC from 7 pm Tuesday, after about 1" of precip has fallen in the form of 3-4" of snow and then about 2" of sleet (equiv to 6-7" of snow, by mass) falls. The reason I say 3-4" of snow is because that's what the CMC model shows for pure snowfall.
The reason I say 2" of sleet is that after the snow is done, about 0.7" more precip falls with the sounding as cool or cooler than the one in the graphic, which has the snow melting at 700 mbar (9000' feet up, where the red column temperature line on the left side graphic crosses the slanted blue 0C freezing line and goes over 32F), due to temps in the mid-30s from about 9000 feet up to about 2500 feet up in the column, but then the melted snow falls through the final 2500 feet down to the surface (the red column temp line crosses back below 32F at about 900 mbar or 2500 feet up) at <32F, refreezing the liquid into sleet pellets which will accumulate at the 32-33F surface temp.
The surface temp and sub-32F layer just above it then quickly all go above 32F not long after 7 pm, meaning about 1" of plain rain falls from then on. The surface temp gets up to about 40F or so by early Weds and then slowly falls to below 32F by Wednesday evening, so no flash freeze of the slush resulting from rain being mostly absorbed into the snow/sleet pack is predicted. Remember, this is what the CMC model is saying and is not a forecast.
The little appetizer system late Sunday into early Monday is looking a little more robust with 1" or so now possible for most of CNJ/NNJ/NYC and 2-3" or so possible from 195/276 southward. This will potentially be impactful on the Monday am commute with temps below 32F. The main event then rolls in late Monday evening and will bring a very mixed bag of precip from then through late Tuesday night. Still waiting on NWS updates on discussions/snowmaps.
The 12Z models today almost all trended colder/snowier, due to the primary midwest to Great Lakes low being weaker and the secondary coastal low which forms late Monday being a little stronger (but not a powerful storm), keeping colder air locked in place longer. This is not a done deal yet, but with pretty good model consensus on at least a few inches of snow and some sleet before any changeover and i
For the Philly-NYC corridor, we're looking at maybe a few to several inches of initial snow by Tuesday around sunrise, depending on the model, followed by possibly several hours of sleet as a warm nose aloft (at 700-850 mbar or 5000-9000' feet above the surface) melts the falling snow, but the resulting rain then refreezes into sleet pellets in the bottom ~2500 feet (below 900 mbar) of the column, producing maybe 1-2" of sleet (equivalent to 3-6" of typical 10:1 snow).
Then, depending again on the model, the sleet would then eventually change to rain, probably in the mid afternoon and we'd likely get 1/2" to maybe 1" of plain rain with surface temps in the mid/upper 30s. A couple of models are showing more like 4-8" of snow before any changeover to sleet and some models are showing 0.1-0.25" of freezing rain during that transition, especially NW of 95, which would be quite dangerous.
Still lots of uncertainty for the Tuesday system, in particular, as it's about 60 hours from starting (vs. the 7 am EST model data inputs for the 12Z model runs), but the uncertainty is decreasing with modest model consensus on at least an early thump of snow/sleet for the area. It also should go without saying that in a storm transitioning from snow to rain eventually, there will be more snow/sleet as one travels NW of 95 towards NE PA/NW NJ and N of 287 in the Hudson Valley, as well as less snow/sleet as one travels towards the coast. With the exception of the Monday snow likely being more S of 195/276.
I still don't think we'll have a great handle on this until Sunday and even after that there could be surprises, since a 2-hour delay in a changeover to rain could mean 2-3" more snow or vice-versa, since it's going to be a potent system with ~2" of total precip (liquid equivalent) in about 24 hours.The model outputs are below.
12Z GFS, still the least wintry model, but it was a bit snowier/sleetier than earlier runs; this is showing both snow and sleet (at 10:1 ratio).
12Z GFS-FV3, where about 2-3" of this is snow and the rest of the frozen is sleet, as modeled.
18Z NAM, which just came out and is a sleetfest for most (90% of that "snow" is sleet, as modeled)
12Z CMC (note that one should add 2" of sleet for most of CNJ/NNJ/NYC to this map, which only shows snow.
12Z UK (has been the snowiest model, consistently; it supposedly only shows snow - trying to confirm that)
12Z Euro, which also trended colder (also just snow and trying to confirm that)
And here's the NWS NYC snowmap. Not much snow for the early Monday system north of 78, so this is basically all for system 2. They've said there could be some sleet and freezing rain in addition to this, especially inland of NYC.
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Upton
The global models have warmed a bit faster in the low levels
the last 24 hours and this is supported by a strong elevated
warm nose with the NAM and SREF. The latter of which often can
be too aggressive with the warm aloft. Accounting for this
uncertainty and precipitation developing toward daybreak, still
raises the potential for a quick hitting 1-3 inches of
snow/sleet at the coast before going over to rain in the
afternoon. Across the interior, the transition will be later
with 2 to 5 inches of snow/sleet and a tenth or two of ice
accretion possible. The highest amounts at this time will be
across interior NE NJ, the Lower Hudson Valley, and northern
portions of Fairfield and New haven counties in CT.
Additionally, the location of the frontal wave that develops to
the south will be critical in determining the direction of the
low-level winds. A significant ice accretion is possible across
the interior, however, model soundings are supporting a
prolonged period sleet with a transition over to plain rain
across most locations as temperatures gradually rise above the
freezing mark Tuesday evening. Regardless, based on the parent
low being across the Great Lakes, warm air will come in aloft
for a transition to rain. Secondary low development occurs much
too late and close to the region for this not to happen.
The greatest uncertainty with this forecast reside on the front
end and how quickly the transition to rain occurs. Small timing
differences could have a significant impact on snow/ice totals
The global models have warmed a bit faster in the low levels
the last 24 hours and this is supported by a strong elevated
warm nose with the NAM and SREF. The latter of which often can
be too aggressive with the warm aloft. Accounting for this
uncertainty and precipitation developing toward daybreak, still
raises the potential for a quick hitting 1-3 inches of
snow/sleet at the coast before going over to rain in the
afternoon. Across the interior, the transition will be later
with 2 to 5 inches of snow/sleet and a tenth or two of ice
accretion possible. The highest amounts at this time will be
across interior NE NJ, the Lower Hudson Valley, and northern
portions of Fairfield and New haven counties in CT.
Additionally, the location of the frontal wave that develops to
the south will be critical in determining the direction of the
low-level winds. A significant ice accretion is possible across
the interior, however, model soundings are supporting a
prolonged period sleet with a transition over to plain rain
across most locations as temperatures gradually rise above the
freezing mark Tuesday evening. Regardless, based on the parent
low being across the Great Lakes, warm air will come in aloft
for a transition to rain. Secondary low development occurs much
too late and close to the region for this not to happen.
The greatest uncertainty with this forecast reside on the front
end and how quickly the transition to rain occurs. Small timing
differences could have a significant impact on snow/ice totals
Mt holly disco for the Sunday night event for some
As high pressure moves farther off the coast, a cold front from
the north is anticipated to drop into our region on Sunday
night. Meanwhile, a mid level short wave trough and an
associated weak surface wave of low pressure are expected from
the west. The weather systems are forecast to bring a light
wintry mix to our region. Based on the forecast temperature
profiles, the precipitation type should be mainly snow in
eastern Pennsylvania and northern and central New Jersey, and a
mix across much of northeastern Maryland, Delaware and southern
New Jersey. It continues to appears as though the greatest
potential for precipitation will be across the southern half of
our forecast area, with the possibility that the precipitation
could miss far northern New Jersey entirely.
Snowfall amounts around an inch to an inch and a half are
possible, mainly from southeastern Pennsylvania, extreme
northeastern Maryland and northern Delaware into southern New
Jersey. A light glaze of ice may occur in northeastern Maryland,
Delaware, southern New Jersey and far southeastern
Pennsylvania.
As high pressure moves farther off the coast, a cold front from
the north is anticipated to drop into our region on Sunday
night. Meanwhile, a mid level short wave trough and an
associated weak surface wave of low pressure are expected from
the west. The weather systems are forecast to bring a light
wintry mix to our region. Based on the forecast temperature
profiles, the precipitation type should be mainly snow in
eastern Pennsylvania and northern and central New Jersey, and a
mix across much of northeastern Maryland, Delaware and southern
New Jersey. It continues to appears as though the greatest
potential for precipitation will be across the southern half of
our forecast area, with the possibility that the precipitation
could miss far northern New Jersey entirely.
Snowfall amounts around an inch to an inch and a half are
possible, mainly from southeastern Pennsylvania, extreme
northeastern Maryland and northern Delaware into southern New
Jersey. A light glaze of ice may occur in northeastern Maryland,
Delaware, southern New Jersey and far southeastern
Pennsylvania.
