The Psuhoffman Storm

[weathervswife]

90 would be money for most. It looks a lot like most of the 6Z GFS individual ensembles, but the surface is still likely to be above freezing.

[Huffwx]

This run of the nam is about perfect for much of SW VA--

Temps are barely cold enough from the front side and the h5, h85 and h7 low takes a PERFECT track--- will look great at 84 hours.

[Scarlet Pimpernel]

well, I guess I meant miss as in snow

yeah, there's rain

I would add, though, that the rain would likely turn to a heavy wet snow as the 5H Low moved further north (after 84 hrs)

BL is not looking good. I guess it would be a cold rain possibly turning to wet snow near the end before it's gone.

[mitchnick]

Actually looks like a classic hit. Surface temps may be an issues, 850's at 0 just south of DC. Actually one of the better NAM hits if you ask me.

I'm going to post this for us, just don't let JI see this

[kurtstack]

I'd like to see the soundings for the Nam. 850s look to be around 0 at DCA on the map, maybe wet snow.

[33andrain]

Well, my own 2 cents here, I like where I stand right now as far as the NAM is concerned. I'll be looking forward to the 12Z GFS and 00Z NAM . Enjoy the rest of your day. And to finish things off a bit O/T here, but since the Ravens are out of it GO JETS Anybody but PITT

[WxLover]

If the NAM is correct, I believe its a big Improvement.

[mitchnick]

classic indeed

let's just hope for some miracle cooling

[Scarlet Pimpernel]

Well, my own 2 cents here, I like where I stand right now as far as the NAM is concerned. I'll be looking forward to the 12Z GFS and 00Z NAM . Enjoy the rest of your day. And to finish things off a bit O/T here, but since the Ravens are out of it GO JETS Anybody but PITT

Yeah, well regardless of what happens it's great that New England already got knocked out last weekend!!

[PhineasC]

This NAM run is fabulous. Not sure why anyone is upset by it.

[mitchnick]

This NAM run is fabulous. Not sure why anyone is upset by it.

I'm not upset

I'm hoping it can hold, but with some minor tweaks like the addition of some cold air

but I do believe even BWI would turn to snow post 84 hrs

[PhineasC]

classic indeed

let's just hope for some miracle cooling

The surface is warmish but the other layers seem cold enough. I'll take my chances the NAM is once again not seeing the depth of the cold air. That happens all the time on the models.

[Wonderdog]

So the NAM is similiar to the EURO it seems and the EURO has been consistent for the last couple of days, if I remember correctly. Time for the GFS to get closer to the coast.

[PhineasC]

I'm not upset

I'm hoping it can hold, but with some minor tweaks like the addition of some cold air

but I do believe even BWI would turn to snow post 84 hrs

OK, agreed. Surface temps seem to be the major issue. That is one thing the models do screw up with some regularity. Bottom-line this will be a marginal wet snow even with better surface temps.

[Scarlet Pimpernel]

This NAM run is fabulous. Not sure why anyone is upset by it.

In a way I agree. But my concern is that it's simply going to be too warm east of, say, the Blue Ridge, unless some cold air at and just above the surface can wrap in awfully quickly while the precip is falling. I can see wet snow falling at some point, but if it's 35 or so at the surface and just below freezing above there, I wonder how much it would really amount to. If I recall correctly from various previous posts yesterday, the idea of a front-end snow to rain to possibly snow is more or less gone...and we're hoping for enough cooling to change anything to snow after rain at the start?

[WinterWxLuvr]

Still concerned about precip amounts over here, but maybe with a more juiced system, a little more potent, that will happen. Hopefully the GFS and EC can add some continuity.

[PhineasC]

In a way I agree. But my concern is that it's simply going to be too warm east of, say, the Blue Ridge, unless some cold air at and just above the surface can wrap in awfully quickly while the precip is falling. I can see wet snow falling at some point, but if it's 35 or so at the surface and just below freezing above there, I wonder how much it would really amount to. If I recall correctly from various previous posts yesterday, the idea of a front-end snow to rain to possibly snow is more or less gone...and we're hoping for enough cooling to change anything to snow after rain at the start?

I think we are hoping the models are once again too warm at this range as they were with the last event and that dynamic cooling caused by heavy precip will take care of the marginal surface since the layers above are all cold enough. Bottom-line, there will be rain and a nasty cut-off line. Hope everyone is wearing their big-boy pants.

[Scarlet Pimpernel]

Just occurred to me, but could this almost be similar to the Dec. 5 snow from last year? I know, the set-up and other aspects are not (necessarily) the same. But in that case, it started with fairly heavy rain in the morning that changed to heavy, wet snow. It was above freezing when the snow began and it only stuck to rooftops and grass, but it did finally start to accumulate pretty well once the boundary layer cooled sufficiently.

(EDIT: By "last year" on Dec. 5, I'm of course referring to last winter in 2009, not 2010!)

[Dr No]

I vote rain. Warm ground temps and late January sun angle with marginal temps. Dynamics can't do it alone here in poor setup situations.

[mitchnick]

Just occurred to me, but could this almost be similar to the Dec. 5 snow from last year? I know, the set-up and other aspects are not (necessarily) the same. But in that case, it started with fairly heavy rain in the morning that changed to heavy, wet snow. It was above freezing when the snow began and it only stuck to rooftops and grass, but it did finally start to accumulate pretty well once the boundary layer cooled sufficiently.

I checked out the skewts on Accuwx and BWI is near isothermal from 850 on down, with the surface looking to be around +1.5C and I thought of the same storm

of course, that only gave BWI officially an inch so I would not want a repeat...unless it was followed in 2 weeks with 18"

[clskinsfan]

Still concerned about precip amounts over here, but maybe with a more juiced system, a little more potent, that will happen. Hopefully the GFS and EC can add some continuity.

Yeah QPF may be a problem for us. At least we should not have to worry so much about temps. Between last night Euro and this mornings NAM I think we are actually in the perfect location for once.

[mdsnowlover]

I can remember many times in the past that it snowed quite heavily, and accumulated with temps well above the 32 degree mark, as high as 37/38 degrees in cent md for most of the event. I was in high school for one of those events, the forecast was for snow changing to rain, the snow started with the temp at 37 and it accumulated to 10 in , and never changed to rain. I was suirprised.

[derecho]

I vote rain. Warm ground temps and late January sun angle with marginal temps. Dynamics can't do it alone here in poor setup situations.

warm ground after last nights 9 degrees?

If the nam solution does play out, I would say snow west of I-95. Thicknesses on the nam at 84 hours out are not accurate.

[usedtobe]

This NAM run is fabulous. Not sure why anyone is upset by it.

It is on the warm side for people like dc. the surface temp is around 34 or 35 degrees taken literally and the layer just at or lightly above freezing extends around 4000 ft or so. That's a pretty dicey looking sounding. Guys to the north like you may do OK, same holds for back towards leesburg but many of th rest may have to wait for the latter half of the storm for the temps to fall enough to get accumulating snow and that's with a almost perfect snow track.

[TowsonWeather]

Late January sun angle?

LOL!

[PhineasC]

It is on the warm side for people like dc. the surface temp is around 34 or 35 degrees taken literally and the layer just at or lightly above freezing extends around 4000 ft or so. That's a pretty dicey looking sounding. Guys to the north like you may do OK, same holds for back towards leesburg but many of th rest may have to wait for the latter half of the storm for the temps to fall enough to get accumulating snow and that's with a almost perfect snow track.

It is the 84HR NAM. It will change many more times.

[mitchnick]

OK, here are the soundings from my house (2 miles N of BWI)....I'll take them at this range!

78 hours:

1004. 73.E 0.4 0.1 29.7 3.8

1000. 104. 0.1 -0.1 31.5 4.3

975. 307. -0.3 -0.4 64.1 8.2

950. 515. 0.3 0.1 91.4 9.1

925. 729. -0.1 -0.1 91.5 8.6

900. 948. -0.2 -0.2 91.3 8.2

875. 1173. -0.6 -0.6 87.9 7.2

850. 1405. -1.1 -1.1 83.6 6.0

825. 1643. -1.4 -1.4 81.7 4.1

800. 1888. -1.3 -1.3 138.4 1.4

775. 2142. -1.3 -1.3 207.9 4.3

81 hours:

998. 75.E 0.9 0.3 19.8 7.0

975. 262. -0.3 -0.4 28.1 12.3

950. 470. 0.7 0.4 47.7 15.0

925. 685. 1.0 0.5 53.7 13.6

900. 904. 0.5 0.2 58.4 12.7

875. 1131. -0.2 -0.3 60.2 11.8

850. 1363. -0.7 -0.8 59.0 11.6

825. 1601. -1.0 -1.1 57.4 10.4

800. 1846. -0.8 -1.0 53.2 6.1

775. 2100. -1.0 -1.1 81.9 3.4

84 hours:

996. 73.E 1.1 0.6 13.9 7.8

975. 244. 0.1 0.1 22.3 13.2

950. 452. 0.0 -0.1 38.4 18.8

925. 666. 0.2 0.1 48.9 20.6

900. 886. 0.2 0.1 47.7 18.9

875. 1111. 0.2 0.0 47.5 17.5

850. 1344. -0.1 -0.3 48.5 16.4

825. 1583. -0.4 -0.5 49.4 15.1

800. 1829. -0.8 -1.0 42.9 13.3

775. 2082. -1.4 -1.7 39.4 11.2

750. 2343. -2.2 -2.4 46.6 9.8

[Scarlet Pimpernel]

I checked out the skewts on Accuwx and BWI is near isothermal from 850 on down, with the surface looking to be around +1.5C and I thought of the same storm

of course, that only gave BWI officially an inch so I would not want a repeat...unless it was followed in 2 weeks with 18"

Yeah, we can hope for that I suppose! Actually I was surprised that BWI had relatively little as areas not far from there got a fair bit more. I got about 2.3" here, DCA had a meagre 0.2", but there were a lot of reports to the north and west of DC of 5-6" or so. Guess it depended on the banding and where they ended up, as I think most areas had a similar temperature profile for the most part if I'm not mistaken.

Actually, another storm comes to mind, Feb. 25 ( somewhere around that date?) in 2007. Got a good period of heavy, wet snow that ended as drizzle, about 5" or so of snow accumulated. Surface was barely at or below freezing but it was snowing hard. I heard later on that we had essentially a rather deep isothermal layer.

[BlizzardNole]

I think we are hoping the models are once again too warm at this range as they were with the last event and that dynamic cooling caused by heavy precip will take care of the marginal surface since the layers above are all cold enough. Bottom-line, there will be rain and a nasty cut-off line. Hope everyone is wearing their big-boy pants.

As others have said -- it just seems like this winter "wants" to be colder than models, etc predict. With the setup that last even had, we typically would have gotten to 35 or so, then struggled to get below 32 as the precip came in. Instead we stayed below 30 all day and got well down into the mid-20s during the event.

I'm with what most are hoping - that we have a wet storm precip type issues or not, rather than taking our chances with another storm too far east.

[usedtobe]

It is the 84HR NAM. It will change many more times.

That's the trouble. This still is not an ideal set up even with the nam track.