dallen7908

In case anyone is hoping that changing to 1991-2020 for the new climatological baseline will help us get cold anomalies next week and later this winter - the shift won't occur until sometime this spring - May? In case anyone is hoping increased cold anomalies due to the new baseline will improve our chances of getting snow ... I have a bridge to sell you

... but the impressive WAFz spans the troposphere and stratosphere suggesting that the upcoming SSW is occurring in an atmosphere pre-disposed to troposphere-stratosphere coupling, which may make the winter storm track further south than normal either here or in Asia as early as the last week of January - perhaps that elusive HA storm - given how low and stable the NAO/AO are forecast to be. ... Alternatively, we can skip the acronyms and focus on the January 3/4 period

Merry Christmas all. It can only get better from here.

Please move all 10-day EURO plots to the digital snow forum - Only half kidding. What I'd give to live in a world where the 10-day EURO map was climatology

I wonder when this will be .. The AO and NAO look stable and negative for the last few days of 2020 and the first week of 2021. The DC-proper snow means from the GEFS and EPS for the next 10-15 days are less than 1" (below the 2" amount that is typical this time of year) The good news is the large-scale pattern is not close-the-window-shades bad. Its been a decade since we've had anything in the mid-range to track in late December - still a chance this year.

five-sigma corresponds to about 1 in 3.5 million assuming a normal distribution So if we hear discussion of another 4 or 5 sigma event we should consider the source and/or unfollow Kayleigh McEnany

Just over 10% of the EPS members look promising for XMAS. Here is an extreme example.

12/16 0.6 " (College Park)

Finished? with 0.7" here in College Park - changed from snow to sleet to rain within the last hour. Surface temperature 32.4

Yes it shifted from sleet to light snow about 10 minutes ago. 32.9 degrees

Been sleeting in College Park for the last 5-10 minutes

Slowly rising surface temperature here. 29.7 at 6:40, 30.6 at 7:30, and now 31.5F

Euro 6z: Verbatim (without looking at the soundings), Similar or very slight worse than 00 UT, for DC it shows snow beginning between 11 AM and noon changing to mixed precipitation between 2 and 3, surface temperature of 34 degrees. Snow maximum still in central PA - just under 2 feet

In case anyone is wondering GDPS on the pivotal weather plot is the acronym for the operational "Canadian" model.

Are the ensembles still based off of the old GFS? If yes, it's less staggering

For comparison purposes here is the EPS panel, superficially they look similar ... although SE ridge is much stronger here - 50 N low too far east to help us?

How about this ... the EPS shows a positive EPO for much of this period while the CPC 3-4 week outlook gives us a > 60% chance of above normal temperatures as La Nina reasserts itself.

Based on my limited knowledge of this ... Warmings have strong correlation with winter temperatures in Europe; not so much in the northeastern U.S.. We'll have to wait and see. In any case, probably not much of a factor until mid-December

Saint Martin's summer; would use the more familiar Indian summer - if my back yard had experienced a freeze

The NWS forecast discussions out of Sterling are about to get more interesting - for snow lovers https://www.weather.gov/lwx/GarrettCecilTransfer

From the NWS discussion: Day IAD high/high min BWI high/high min DCA high/high min 11/8: 77(1987)/57(1977) 80(1975)/62(1975) 81(1975)/63(1975) 11/9: 78(1994)/56(1987) 78(1994)/61(1945) 79(1994)/64(1895) 11/10: 75(1985)/60(1966) 75(1999)/62(1966) 76(1999)/60(1975) 11/11: 78(2006)/55(2002) 77(2006)/59(1970) 78(1949)/58(1970)

https://frontierweather.dtn.com/WinterClimateDrivers.pdf Just in case you need background as to what a rising QBO value MAY mean for our winter weather.

The high-bias in the forecast values reminds me of last winter. Could the bias be due to a poor coupling between the ocean model and the atmospheric model? On the positive side, the high-bias may allow some fantasy storms to come up the coast. On the negative side, reality will be much more mundane. Not that the AO forecast has much to say about it but I'm rooting for a warm November. My hunch is that the correlation between November temperatures and winter temperatures is negative - perhaps -0.02. I'll take any advantage I can get. A depressing truth; the "smartest" forecast might be to use the ensemble with the most positive AO value. Another depressing feature of the time series is that it goes negative about when the forecast skill goes to zero or at least to 0.16^2.

4.9" in my College Park rain gauge. Several neighbors are wet-vacuuming their cars - glad ours was up on our driveway

https://reichlab.io/covid19-forecast-hub Tool for ensemble fans "The ensemble forecast combines models unconditional on particular interventions being in place with those conditional on certain social distancing measures continuing. To ensure consistency, only models with 4 week-ahead forecasts ahead are included in the ensemble."