Feb. 11-12 2019 Wintry Mix Event

billg315 wrote:Heehaw and Scott beat me to the punch. Looking at the 6z runs I’d say throw out the snow/ice projections and focus on temps. There is no way the models can nail exact amounts on a system like this because the dynamics may be very localized. The 6z runs all show the cold air at the surface not budging for most of Tuesday. Many areas don’t get above freezing until after 3 or 4 pm - if then. Even at the 850 level the 0* line stays south of most of the area until afternoon.

This leads me to believe this will be far more snow sleet and freezing rain than just plain rain (which will come, but not until evening). The key to accumulation is exact timing of changeovers and intensity during those times. If the snow lasts just a couple hours longer somewhere, and it gets heavy during those couple hours, that’s a difference between maybe 2” vs 4 or 5”. If the sleet lasts four or five hours, while it doesn’t accumulate as fast as snow, it will accumulate. And all you need is an hour or two of freezing rain for all sorts of problems.
I think this will actually be a very disruptive storm Tuesday despite what may look like paltry snow totals to some. And I don’t think we’ll even get a fix on those totals until it’s happening.
The focus of this system should be more on the problems it can cause than pure amounts because it hits before AM rush and may actually continue almost into the PM rush for many before you see any non-frozen rain.

Very well said. I totally agree with your point about a disruptive storm. Surface temperatures mean a lot in that regard.

The GFS verbatim has you in snow or sleet until about midday SENJ. So whilevthis very much a nowcast event, I think you’ll have some wintry precip to look at in daylight. I hope so at least (for after all, once you changeover, my region is always next in line, lol).

heehaw453 wrote:

billg315 wrote:Heehaw and Scott beat me to the punch. Looking at the 6z runs I’d say throw out the snow/ice projections and focus on temps. There is no way the models can nail exact amounts on a system like this because the dynamics may be very localized. The 6z runs all show the cold air at the surface not budging for most of Tuesday. Many areas don’t get above freezing until after 3 or 4 pm - if then. Even at the 850 level the 0* line stays south of most of the area until afternoon.

This leads me to believe this will be far more snow sleet and freezing rain than just plain rain (which will come, but not until evening). The key to accumulation is exact timing of changeovers and intensity during those times. If the snow lasts just a couple hours longer somewhere, and it gets heavy during those couple hours, that’s a difference between maybe 2” vs 4 or 5”. If the sleet lasts four or five hours, while it doesn’t accumulate as fast as snow, it will accumulate. And all you need is an hour or two of freezing rain for all sorts of problems.
I think this will actually be a very disruptive storm Tuesday despite what may look like paltry snow totals to some. And I don’t think we’ll even get a fix on those totals until it’s happening.
The focus of this system should be more on the problems it can cause than pure amounts because it hits before AM rush and may actually continue almost into the PM rush for many before you see any non-frozen rain.

Very well said. I totally agree with your point about a disruptive storm. Surface temperatures mean a lot in that regard.

Yeah my concern is people will see 1-3, 2-4, 3-5 and think that’s not a big deal but if it’s during commuting time and you add sleet or ice . . . Very problematic

To that point look at what just a few inches of snow did in November when it wasn’t taken seriously. 4 hour commutes, people stuck on roads. Sometimes it doesn’t take a lot if timing is right.

Added bonus for you SENJ is you may get an inch or two from this minor precursor/opening act snow event tonight. Most of us north of you may just see flurries or a coating.

For me personally, I'm not a fan of these storms. I'm still a bit too immature about it all to truly embrace a front-end snow that gets immediately washed away. But what I saw so clearly on Feb 1, all it takes is the right 2-3 hours of snowy fun for this to be a genuine 'event' in the eyes a kid.

For some reason, it's real important to me that my kids get some snow on a yearly basis. There old enough to know that these aren't major snowstorms, but they're also old enough to know that a little snow beats no snow for sure and can also plenty of fun in its own right.

Looks like nw of the city has a chance for some much larger accumulations. Hopefully you can stay mostly all snow. Small ticks s and e in a coastal low would have a more pronounced impact for you all, yes?

And yes, Bill, we have now racked a few of these northern fringe/glancing blow opportunities down here. We could max out at about 1" tonight and another 2-3" Mon-Tue before the change. With the right timing, I could see being able to smile a bit thru the rain monsoon liquid godzilla that follows.

I’m with you SENJ. I hate these types of storms as well. Snow to slop to rain is not my ideal. That said, I’ve had less than 2” of snow total at my house from Dec 1 to Feb 10. So if I get 3 or 4” Snow Tuesday morning and a prolonged sleet storm (NOT prolonged freezing rain - which I don’t want), I’ll take it. Better than 45* and pouring rain all day

Beggars can't be chooser in this winter peeps so we'll take what is our best wintry storm since Nov 15th and run.
The HP is being modelled a tad stronger at 1040ish and that is good news - why? The Low level cold arctic air will be tough to scour our and the Dew Points
This si ealry AM Wednesday morning

2M Temps

Ice NNJ

Ye steh 12Z Nam peeps

GFS seeing the cold for a warm biased model this is tell tale, red flag that this LLC means business

Dp

2M Temps


Don't have wet bulb maps but this is trending to a more wintry storm than a rain maker for I 78 and North - again NNJ and LHV.

From a good amateur: The trend towards the less amplified system has been pretty clear. In conjunction with the nicely placed/timed HP to the north, this will lead to the nice front end thump/sleetfest across the greater tri-state area.

Tuesday will be NO SCHOOL for many in the NNJ and LHV regions at this time unless this slows up but once they hear ice = close up the shop! WAA always start earlier.

Looks like another soaker, beautiful!

I can see schools possibly being closed Tuesday with the morning being very messy especially N of 78

Question I know the city is getting snow to sleet to freezing rain then rain blah blah blah. I just want to know how long will the city stay sleet and freezing rain

Shore peeps, Mount Holly issued a WWA for tonight/tomorrow morning from the Delmarva up to about I 195. Widespread 2" possible with mostly snow. This is just for tonight. The Canadian model has liked tonight as a Shore special all week... 12z has up to 3". 12z Nam follows suit. As we get closer, tonight may become more of a show down here than the next one.

...WINTER WEATHER ADVISORY IN EFFECT FROM 10 PM THIS EVENING TO NOON EST MONDAY... * WHAT...MIXED PRECIPITATION EXPECTED. TOTAL SNOW ACCUMULATIONS UP TO TWO INCHES EXPECTED AND ICE ACCUMULATIONS OF A LIGHT GLAZE POSSIBLE. PRECIPITATION IS EXPECTED TO BE MAINLY SNOW NORTH OF DELMARVA BUT MAY BE MIXED WITH SLEET AND FREEZING RAIN FARTHER SOUTH. LOCALLY HIGHER AMOUNTS OF SNOW ARE POSSIBLE, ESPECIALLY IF LITTLE MIXING OCCURS. * WHERE...PORTIONS OF SOUTHERN NEW JERSEY, SOUTHEAST PENNSYLVANIA, NORTHEAST MARYLAND, AND CENTRAL AND NORTHERN DELAWARE. * WHEN...FROM 10 PM THIS EVENING TO NOON EST MONDAY. *

Just saw that. WWA for southern jersey. Maybe we squeeze 3" out of this. I'll take it, with mon night-tue looking more of a rain event for us in south jersey. Hopefully for our northern friends they do much better tues.

frank 638 wrote:Question I know the city is getting snow to sleet to freezing rain then rain blah blah blah. I just want to know how long will the city stay sleet and freezing rain

To be honest I think the city stays snow and sleet most of the morning and sleet then a little freezing rain most of the afternoon. I don't know if the city goes to plain rain until sometime after 4 p.m. Tuesday.

12z runs continue to show the cold air hanging real tough through the day Tuesday. Dewpoints remain low as well. NAM has a crazy prolonged sleet storm for a lot of people after a decent front end thump of snow in the early morning. GFS isn't that much different actually.

Larry, 3 parts here for us.

Part 1 is tonight/tomorrow. That looks good for another 1-3" with the upside from there improving the further south you are from I 195.

Part 2 is Tomorrow night and then into a critical, still to be determined point on Tuesday. We look good for another 1-3", with the upside improving the further up the Shore you are. Timing of the change over.

Part 3 starts at the changeover, hopefully in the late morning, early afternoon (safer and funner). After some sleet and maybe a tiny bit of frz, we'll rain the rest of the day and night.

12z GFS and 12k NAM bring some really decent front end totals 6+" to everyone north and west of the city for tomorrow night.

Monday here gets to freezing around 900am then climbs to a balmy 37. After 400pm it does start to drop hovering right around the 32-33 mark Monday night. Can the cold air hold after that to give us something Monday night? Very close. I will be watching

Another difficult forecast with thermal profiles. Obviously north and west will have more prolonged periods of frozen precip and north of 84 I don't think surface gets above freezing which may mean icing problems Tuesday night. I'm expecting 4-6 of snow followed by sleet and ZR. Models often have a hard time with CAD situations and when and where the secondary develops could have big impact on both precip types and duration. I really think this is going to be another nowcast storm.

This sucker is going to be a pain in the butt to forecast. Total nowcast situation. If it went to all rain by Noon I wouldn't be shocked. If it stayed all snow and sleet until 7 p.m. I wouldn't be shocked. Models are showing the cold air staying entrenched most of the day so I'm going with that for now, but it is very susceptible to change.

As I said above though, and mugs pointed out as well, the GFS has been very quick to project these systems (mostly correctly) as warmer and rainier this year, so the fact it is showing the cold hanging in there is interesting to me.

hyde345 wrote:Another difficult forecast with thermal profiles. Obviously north and west will have more prolonged periods of frozen precip and north of 84 I don't think surface gets above freezing which may mean icing problems Tuesday night. I'm expecting 4-6 of snow followed by sleet and ZR. Models often have a hard time with CAD situations and when and where the secondary develops could have big impact on both precip types and duration. I really think this is going to be another nowcast storm.

lol. great minds think alike, and post simultaneously.

Here is this morning's Mt Holly NWS discussion which gives a more NW/central/south Jersey perspective:

A strong surface low will develop in the central plains/Midwest
by Tuesday morning, with a zonally-oriented baroclinic zone
extending to the central Mid-Atlantic coast. Isentropic lift
atop and poleward of the baroclinic zone should allow for
broadening/increasing precipitation Monday night and Tuesday
across the area. A key feature for this portion of the event is
a building high in southeast Canada and adjacent New England,
which will likely keep near-surface cold air stubbornly in place
most of Monday night before its retreat as the surface low
lifts toward the Great Lakes on Tuesday.

This setup will be favorable for a wide variety of
precipitation types in our area, from snow on the north side of
the precipitation shield to a mix of snow, sleet, freezing rain,
and rain farther south. The transition from snow to
sleet/freezing rain to rain will be from southwest to northeast
and will likely be at least somewhat slower than model progs,
owing to their general tendency to scour near-surface cold air
too quickly. NAM BUFKIT soundings Monday night and Tuesday
morning are indicative of a lengthy period of sleet north of
I-76, with at least some duration of freezing rain thereafter
before profiles become warm enough for all rain as the day wears
on. North of I-78 (and especially north of I-80), the cold air
will linger much of the day, which spells trouble. This could be
a lengthy period of sleet/freezing rain, with a healthy dose of
icing possible. Did not go nuts with the forecast yet,
particularly given the poor agreement model-to-model on thermal
profiles and precipitation type transition. Nevertheless, will
need to watch areas northwest of the Fall Line (in particular)
for significant icing potential. Of course, preceding this will
be a healthy period of snow/sleet, which could lead to
accumulations of advisory-to-warning levels in much of the same
region. Impacts could be felt as far southeast as the urban
corridor, though amounts of snow/sleet/freezing rain should
trend downward to the southeast. For Delmarva and southern New
Jersey, this portion of the event should be primarily rain.

QPF with this second phase looks formidable, and in places
where precipitation is mostly rain, there looks to be at least
some risk of flooding too. A solid 1-2 inches of liquid-
equivalent precipitation looks probable for much of the area
between tonight and Tuesday night, so hydro concerns are
certainly present as well. The WPC has placed much of the area
in a marginal risk of excessive rainfall for this portion of the
event. Of particular interest is a rather convective-looking
end to the event Tuesday evening/night, with rain rates high
enough to be fairly problematic quickly during this time frame.

Precipitation looks to move out quickly by daybreak Wednesday
as the low (and its secondary development along/near the coast)
continues its trek northeastward.

SNEJ, trending a tad colder for Monday the high was forecasted to be 37, now 36. Lol. It looks like for you in Bayville you will be right at the 32 mark from 9pm Monday to 9am Tuesday. Then it will climb. Possible you could stay snow for that 12hr period.

Larry, I would have no complaints there. And that's as of now. Some 36 hrs to go, so let's keep it trending!


This could very well be a board wide event...and yet, little or no excitement. Cuz of the inevitable washout?

So TWC has me 4-8” Tuesday. Accuweather has me 2-4” but increased the % chance of 4-8”. I still think these may be bullish but we are inside of 36 hours and they aren’t backing off. I would also note yesterday my forecast high today was 40*. I briefly hit 34* and just dropped to 33* with thickening clouds so I think I’ll be 5-6* colder today than forecast. Foreshadowing the strength of the cold?? Hmm.

SENJ, I attribute the quiet board to three things:
1. Frank and Scott have not said much which some people may mistake as this not being a threat - not aware Frank is overseas and not tracking and Scott is busy this weekend;
2. This event has been under-hyped because the initial totals looked low wit a change to rain. Modeling is since trending to a colder solution with more frozen than wet precip, but mainstream outlets are just catching up to that;
3. This winter has been so awful everyone is gun-shy about getting excited for anything - especially a storm as complex as this which has a good upside, but also high bust potential.

This forecast is gonna a royal pain in the rear end for example - 10 miles south of me maybe raining and me sleetfest.
That HP has trended from a 1032 to a 1040ish since Friday and with that the snow range has upped by an inch


This is if the cold air hangs in for about 3-4 more hours and we snow instead of sleet by precip maps

billg315 wrote:SENJ, I attribute the quiet board to three things:
1. Frank and Scott have not said much which some people may mistake as this not being a threat - not aware Frank is overseas and not tracking and Scott is busy this weekend;
2. This event has been under-hyped because the initial totals looked low wit a change to rain. Modeling is since trending to a colder solution with more frozen than wet precip, but mainstream outlets are just catching up to that;
3. This winter has been so awful everyone is gun-shy about getting excited for anything - especially a storm as complex as this which has a good upside, but also high bust potential.

I think the main reason most people aren't posting today is because more than half of total precipitation will fall as rain for the majority of the area. There is a warm nose both at 925 Mb and 700 Mb. The one thing that's very concerning is the slow onset of precipitation as shown on most guidance the last few days. Nws is very clear on what can bust this forecast either way and that was one of them. Euro doesn't start precipitation for New York City proper until 8 a.m. Tuesday with warm nose is already pushing it. I'm calling for a few hours of snow and sleet and then mainly rain along the coast obviously freezing rain the further Inland you go just not a good setup we needed that primary to be much much weaker and try and come under us. Doesn't look like that's happening we shall see