After a cool October and a slightly heat November, a chilly December might effectively loom for the D.C. space. We mission temperatures 2 to 4 levels beneath the current 30-year common and wouldn’t be shocked whether it is even slightly colder.
Washington
D.C. should brace for a cold December with chances of snow
Our confidence within the month-to-month snow forecast may be very low, as only one substantial storm might simply surpass that quantity. We expect the possibility of a major snow occasion is considerably elevated.
This prediction for a chilly December is a reversal from our winter outlook issued on Nov. 15, as short-term influences on the climate sample have developed and trended extra wintry.
The massive elephant within the room is the event of a big excessive strain zone over Greenland, unanimously predicted by laptop fashions. As Capital Climate Gang’s Ian Livingston wrote earlier this week, such a Greenland block will increase the probability of chilly and typically snowy climate within the Mid-Atlantic.
Climate fashions present this characteristic flirting with depth data set in December 2010. That month, Washington was 7.1 levels colder than regular. It’s too quickly to know whether or not this yr’s Greenland block may have the identical impact on temperatures, but it surely stacks the deck for a colder-than-normal end result, significantly within the second half of December.
For the primary half of December, climate fashions don’t present a powerful impact from the Greenland block, with temperatures projected to be close to or simply barely beneath regular. However they do present chilly constructing to our north and northwest, which might effectively sink south in the course of the month’s second half.
The precipitation forecast is a problem. Greenland blocks are typically conducive to large winter storms, however the overarching La Niña sample tends to favor drier than regular circumstances. In December 2010, Washington posted barely above regular snowfall (2.1 inches), however beneath regular precipitation general. Washington has not seen extra snow than that in December previously 11 years.
Laptop fashions simulate beneath regular precipitation for the following two weeks, however confidence on this projection is low as a result of the fashions have a tough time forecasting storminess (or an absence thereof) greater than every week into the longer term.
Wanting again at November, it was hotter and drier than regular. The month-to-month common temperature of 52.6 levels was 2.6 levels hotter than the 30-year regular. The month-to-month rainfall complete of two.65 inches was 0.26 inches drier than regular. This was the eleventh warmest November on file in Washington and the 86th driest (tying 1927).
November began very heat, turned very chilly mid-month after which closed delicate.
Right here is the each day element breakdown:
Thanksgiving Day was our solely precisely regular temperature day.
The next data have been set in the course of the month:
In Washington (as measured at Reagan Nationwide Airport):
- Nov. 6: Report heat low of 66 levels (earlier file: 65 from 1938).
- Nov. 7: Report excessive of 81 levels (earlier file: 77 from 1975 and 1938).
At Dulles Worldwide Airport:
- Nov. 6: Report excessive of 81 levels (earlier file: 80 from 2003).
- Nov. 6: Report heat low set of 66 levels (earlier file: 63 file from 2015).
- Nov. 7: Report excessive of 79 levels; (earlier file: 76 from 2020).
In Baltimore (as measured at BWI Marshall Airport)
- Nov. 6: Report heat low of 64 levels (earlier file: 63 from 2015).
- Nov. 7: Report excessive of 81 levels (earlier file: 77 from 2020, 1975 and 1938).
- Nov. 20: Report low of twenty-two levels tied, final set in 1951.
Over meteorological autumn (September via November), Washington noticed a median temperature of 61.2 levels, a slight 0.2 levels hotter than the current 30-year common. The three-month rainfall complete of seven.7 inches was 2.8 inches drier than regular and the driest since 2017’s 5.45 inches.
In an replace a month in the past, we projected November to be 1 to five levels hotter than regular; the precise quantity was the two.6 levels above regular. We referred to as for rainfall between 2 and a couple of.5 inches; the precise quantity was 2.65 inches. These outcomes have been very near our forecast, meriting a grade of A-.