January ’16 – Trail Condition: That time they predicted mind-boggling amounts of snow

[PotomacCyclist]

The forecast indicates a chance of snow around midday today, even though temperatures will be in the mid to upper 30s.

But snow is more likely on Friday. The forecast has been changing. Yesterday, the prediction was 1-3 inches for Friday. Now the prediction on Weather Underground is 8-12 inches on Friday and another 3-5 inches on Saturday.

I don’t remember if we had any major snowfalls last winter. I don’t think so, but maybe I forgot. In any case, next weekend will be a major storm. If the forecast continues to indicate such heavy snowfall, it’s easy to think that almost everything will be closed or canceled in the DC region on Friday and Saturday. Well, everything except for BAFS. I believe that will still go on…

—-

NBC Washington is only saying a mix of rain and snow, changing to all snow on Fri. evening and into Sat. morning. They haven’t mentioned specific snowfall totals yet.

The W. Post Capital Weather Gang hasn’t posted any forecasts for next weekend yet.

[PotomacCyclist]

An interesting article about why mornings remain dark in early January, even though the total time of sunlight increases each day in January (after the winter solstice). All of the extra daylight time is “added” onto the back end, in the evening.

https://www.washingtonpost.com/news/capital-weather-gang/wp/2016/01/15/why-does-the-sun-still-rise-so-late-the-dark-mornings-of-january-explained/

But after Jan. 11, sunrise started to arrive earlier each day while sunset continued to fall later each day. Thus daylight hours are now extended at both ends.

[consularrider]

@PotomacCyclist 132478 wrote:

The forecast indicates a chance of snow around midday today, even though temperatures will be in the mid to upper 30s.

But snow is more likely on Friday. The forecast has been changing. Yesterday, the prediction was 1-3 inches for Friday. Now the prediction is 8-12 inches on Friday and another 3-5 inches on Saturday…

Make sure you stock up on the essentials Thursday night (beer and toilet paper especially).

[Steve O]

@PotomacCyclist 132478 wrote:

I don’t remember if we had any major snowfalls last winter. I don’t think so, but maybe I forgot.

You forgot. Nice thing about these monthly trail conditions threads is you can go back to last January/February and remind yourself.
http://bikearlingtonforum.com/showthread.php?8140-February-2015-Trail-Conditions&p=108524#post108524

[DrP]

@PotomacCyclist 132478 wrote:

The forecast indicates a chance of snow around midday today, even though temperatures will be in the mid to upper 30s.

At 10:40 am is started snowing on me as I left Hains Point for the 14th St Bridge and continued to snow (getting heavier) on the MVT, 4MR, W&OD, and CT. By 11:40, snow was starting to stick to a few of the wooden bridges and some cyclists. But not a lot.

(Once home and warm, I see snow sticking on some of the trees, despite being above 32degF).

[PotomacCyclist]

@Steve O 132487 wrote:

You forgot. Nice thing about these monthly trail conditions threads is you can go back to last January/February and remind yourself.
http://bikearlingtonforum.com/showthread.php?8140-February-2015-Trail-Conditions&p=108524#post108524

No satire. I’m pretty good at willfully forgetting things if I want to, especially if there’s no need to remember. I honestly don’t remember much about last winter’s weather, except the “polar vortex” in February.

[PotomacCyclist]

The Capital Weather Gang finally posted about the possible winter storm at the end of the week. They say it’s too far out to make a solid forecast. There could be a major snow event, or there might be no snow at all in the DC region. The different forecast models disagree on where the possible storm could track. It could veer off to the north or the south, or move right through DC. Not much of an answer. But it helps to be aware of the possibility of a big snowstorm.

“Next chance of accumulating snow: January 21-24
Percent chance of at least one inch: 30 percent (low probability mainly due to number of days away)

Not unsurprisingly six days out, a boatload of uncertainty still exists concerning the storm details. The models continue to jump from solution to solution. Until they reach a consensus, making a definitive forecast so far in advance is foolish.”

https://www.washingtonpost.com/news/capital-weather-gang/wp/2016/01/17/potential-for-major-winter-storm-late-next-week-but-also-major-question-marks/

—-

Weather Underground continues to boost their forecast snow totals. Every time I check, the amount of snow predicted for Friday increases. Now the forecast is showing 12+ inches of snow on Friday, and another 1-3 inches on Saturday. The high temperatures would be at or slightly above freezing on both days, which will have a major effect on how much snow we actually get.

Highs will be back in the mid 40s next week, along with some rain. That could lead to some snowmelt, but also to some icy conditions overnight and in the early mornings.

Although The Weather Channel owns Weather Underground, TWC preliminary forecast differs from that of WU.

TWC shows 90% chance of precipitation on Friday, 5-8 inches of snow. 80% chance of snow on Sat., 1-3 inches.

[vern]

The GFS, an American global forecasting model that weather geeks will know about, just rolled out it’s most recent run. It indicates upwards of 2 to 3 feet of snow in these parts Friday/Saturday (and, of course, the details will change as we get closer to the event). A snowfall event like that would make for an interesting cycling challenge.

[PotomacCyclist]

Random Internet Photo (RIP)

[ATTACH=CONFIG]10506[/ATTACH]

[DrP]

CUSTIS TRAIL by STAFFORD St ~7am Water flowing across trail – Ice expected underneath it

There is water flowing across Custis on the eastern slope of the the eastern-most of the two sisters (about where it goes under Stafford St). It was doing this yesterday morning, but since it had stopped raining a few hours earlier, I thought maybe it was leftover from that. I would guess this will become a giant ice slick on the hill. And where is it coming from? That is just a retaining wall. Is there a gutter of sorts that goes to the wall that is leaking onto the trail? I will attempt to report to the county.

[consularrider]

@DrP 132516 wrote:

CUSTIS TRAIL by STAFFORD St ~7am Water flowing across trail – Ice expected underneath it

There is water flowing across Custis on the eastern slope of the the eastern-most of the two sisters (about where it goes under Stafford St). It was doing this yesterday morning, but since it had stopped raining a few hours earlier, I thought maybe it was leftover from that. I would guess this will become a giant ice slick on the hill. And where is it coming from? That is just a retaining wall. Is there a gutter of sorts that goes to the wall that is leaking onto the trail? I will attempt to report to the county.

That section is always wet close to the retaining wall, seems to seep out and usually only on the trail after a rain.

[DrP]

@consularrider 132519 wrote:

That section is always wet close to the retaining wall, seems to seep out and usually only on the trail after a rain.

Exactly – only after a rain. Since there had been some rain on Saturday (and not a lot), I was not overly concerned seeing it Sunday. There was no rain yesterday – only snow flurries that did not stick and dried up by late afternoon in most places. This was just odd today and it will ice over given the temperatures (not quite 20deg at the moment).

[scoot]

@PotomacCyclist 132479 wrote:

An interesting article about why mornings remain dark in early January, even though the total time of sunlight increases each day in January (after the winter solstice). All of the extra daylight time is “added” onto the back end, in the evening.

https://www.washingtonpost.com/news/capital-weather-gang/wp/2016/01/15/why-does-the-sun-still-rise-so-late-the-dark-mornings-of-january-explained/

But after Jan. 11, sunrise started to arrive earlier each day while sunset continued to fall later each day. Thus daylight hours are now extended at both ends.

Nice little animation included with that article.

The text is a bit misleading though. The two driving factors for the analemma (Earth’s 23-deg rotational axis tilt relative to the orbital plane along with the eccentricity of its orbit) both contribute to longer days (i.e. the time interval from one solar high noon to the next) near the winter solstice, so the effect is strongest now, and each day is about 24h 30s. But the effect on the equation of time due to the 23-deg axis tilt is actually larger than the effect due to perihelion/aphelion. This is glossed over in the article, because it’s easier to explain how eccentricity affects day lengths than to explain how an axis tilt affects day lengths, if you don’t want to show any math.

About 20 of those extra seconds at the winter solstice are due to axis tilt and the other 10s are due to higher orbital angular velocity at perihelion. The dominance of the axis tilt effect is why the time from one solar high noon to the next is also greater than 24 hours near the summer solstice. Aphelion would subtract 10s from day length, but the axis tilt again adds 20s since it’s a stationary point for solar declination, so the overall effect is days about 24h + 10s long at the summer solstice. The shortest days occur at the equinoxes, when the Earth’s rotational axis becomes perpendicular to the Earth-Sun vector: here the axis tilt subtracts about 20s (and eccentricity doesn’t do anything because we’re at the midpoint in distance from the Sun) so each day is about 24h – 20s long. If you closely examine the solar noon table accompanying the article, you can see how this all plays out.

I solved this physics problem from scratch one weekend in grad school when I had far too much time to kill. If only I had owned a bicycle then instead…

[PotomacCyclist]

Today’s update – more speculation. But there is increasing agreement that there will be at least some snow in the DC area.

https://www.washingtonpost.com/news/capital-weather-gang/wp/2016/01/18/confidence-growing-for-major-winter-storm-this-weekend-but-its-not-a-lock/

The current Capital Weather Gang forecast

Next chance of accumulating snow: Friday to Sunday

Chance of at least 1 inch: 70 percent

Chance of at least 4 inches: 40 percent

Chance of at least 8 inches: 20 percent

[Steve O]

@PotomacCyclist 132536 wrote:

Next chance of accumulating snow: Friday to Sunday

Chance of at least 1 inch: 70 percent

Which means a 30 percent chance of less than an inch.

[Author]

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