dallen7908

Weenie rule No. ? Why do you believe resolution is crucial here?

Hope so, especially since the ensembles are run off of an older version of the GFS.

Another contributing factor to our decrease in snowfall is the success of measures put into place to reduce sulfate emissions by power plants. Fifteen years ago, a sizable amount of the warming associated with greenhouse gases was offset by cooling by aerosols - no longer the case. As a side the decrease in aerosols may also play a role in the disappearance of the weekend effect. While I was never fully on-board with the idea, the rule held that large east-coast snow storms were much more likely on weekends than weekdays. If true, a possible explanation is day-of-the-week variations in aerosol emissions. Aerosols act as cloud-condensation nuclei with the number of aerosols affecting the rate and consequently the altitude at which cloud droplets turn into rain drops or graupel. Today, day-of-the week variations still occur but their amplitude is much weaker. Finally, while warming will continue for the foreseeable future, a sizable portion of our poor snow prospects the last several years may be due to decadal oscillations in the Pacific. Years with 20-30" of snow in the DC area may not be extinct. Each of the last 7 winters I've tracked the weather in DC and also in a New England location that I visit later in the winter. This year I'm going to the Winter Carnival in Quebec City. Last year I was in the southern Adirondacks the day of the MLK storm. Hopefully going all of the way to the Laurentian mountains will prove to be unnecessary but we'll see. Like many here I'm still hoping for snow next weekend and later this winter. May those proclaiming the death of the weekend effect, Alberta clippers, as well as packed isotherms on the north side of storms be dead wrong.

No but please send one if you are jumping into a 3 foot drift - make that snow drift

24-hours later at 12 UT next Saturday, the difference in low locations between the two simulations is less stark as most of the lows have jumped to the coast (re-developed). Unfortunately, yesterday's cluster at 12 UT on Saturday was off of the Carolina coast while today's cluster is off of the Virginia coast. We could know more soon as ensembles skill improves dramatically between day 8 and day 5.

On what date should we expect to have received 50% of our annual snowfall. I've always gone with January 22 but am curious when the actual date is ... based on the date above like it seems likely it is even later than the 22nd.

Typically, when we are waiting for a pattern transition in the 10-14 day range, discussion of possible stratospheric help in the 2-4 week time frame is filling these pages (for better or worse, usually the latter). Is there a reason we're not hearing about the possibility of stratospheric help yet this winter? Too early in the season? Not in the cards? Link too weak?

The problem with the mean is that the distribution is becoming increasingly skewed because the mean is low and bounded by zero. N=136 is a healthy sample size.

"The Week 3-4 Temperature and Precipitation Outlooks are based primarily on operational dynamical guidance including the GEFSv12, CFSv2, ECMWF, JMA, and experimental guidance from the Subseasonal Experiment (SubX) multi-model ensemble (MME) prediction systems, with additional considerations for Madden Julian Oscillation (MJO) states, the El Niño Southern Oscillation (ENSO), decadal climate trends, and the evolution of the pattern from the Week-2 forecast ." From last Friday's CPC forecast. While pattern chasing should be be looking at the JMA or MME too?

"Details we just can't know yet." Details --> Whether or not there will be an east-coast storm Details --> Whether it will snow in Washington, DC Too bad CAPE isn't referring to the latter.

... did you also observe a complete flip in the ensemble means of surface temperature for days 10-15? That would be a more interesting ... and probably still wouldn't be too surprising.

If you think we do wind well here you haven't been around much

Yes whenever it's windy here from mid-November through early April, the answer to the question: "Snow storm in (interior) Maine?" is usually yes I usually root for a warm October - it seems to be correlated with a cold/chances-for-snow winter. Of course, I'm sure the correlation if it exists is 0.1 or so. It'd be kind of cool to watch opening day in a flizzard - but other than that I'm ready to move on too.

1/3 7.5 1/7 2.25 1/16 2.25 1/28 0.5 2/13 0.1" (briefly reached 0.1" when T dropped to 34 during a snow shower just before 9) 3/12 0.4" 13" for the winter (College Park)

College Park no accumulation yet on the sidewalk driveway etc but certainly accumulating on the mulch and even on the grass. Transitioned from vertically-falling snow to fatties about 10 minutes ago - perhaps a good sign Temperature has creeped up a bit over the last half hour but it could be due to some stray light sneaking into the dog house (our dog has never entered it) where the sensor is ...

38 and sleet in College Park

Just dropped under 40 here in College Park has fallen 9 degrees since 6 AM - moderate to heavy rain

The probability values are an experimental automated product obtained using output from an ensemble of models. It is one of several tools including models, satellite, radar, and observations used by forecasters when obtaining the forecast value of 1-2".

Same plot shown above but for the College Park area. Nice omega within DGZ but as is usually the case; a warm nose to worry about

Spring Indeed 63/48 +/- 5 degrees beginning Monday and continuing as far as the ensembles can see ...

I was a teenager in northeast Iowa during the 1978 storm;; I spent the evenings listening to coverage from powerful WWWE. I was in the DC area during the 1993 storm; walking across snow/sleet drifts without sinking brought back memories of running across snow drifts as a youth in Iowa. I'm cautiously optimistic that areas in the >50% category (below) will have accumulating snow (> a trace) over the next 5-days.

The EPS snowfall mean at College Park for the next 15 days is 0.3" of which 0.1" "occurred" this morning. The mean exceeded the 75th PCTL, which was ~0.15". The GEFS snowfall mean for the next 10 days is also low ~0.1" mostly due to one member which gives us 3" on the 6th. This is quite unusual for February - in almost any pattern. I'd be nervous to take the "under" of these model "forecasts".

... Yes of course the ensemble mean adds little given how non-dispersive the members are and how skewed the precipitation distribution is at range but an ensemble of ensemble PCTLs is still useful, e.g., the 10th, 50th, and 90th percentiles of ensembles based on more than one operational model

Indeed, the percent of EPS members giving the DC-area > 3" of snow during the 27 Feb - 2 Mar period has dropped to 2% after bouncing between 15 and 25% over 7 cycles (3 1/2 days). Of course, there are only 2 possible outcomes. So if the best you can do is 25% you're probably headed to nada in the end. Hoping for a dead cat bounce over the next cycle or two to keep us interested. T-3 weeks to Hail Mary time. Hopefully, we'll experience a few "forward breaking waves" before then.