Original article from the afternoon
Computer models are slightly colder for the winter weather event forecast in the Washington area on Monday afternoon and night, increasing the likelihood of slippery travel. Meanwhile, a second potential winter storm on Wednesday night versus Thursday is watching, but could eventually bypass the area.
A storm late Monday promises to bring a winter mix to the region, with the highest levels of frozen rain and the threat of slippery roads north and west of downtown Washington. However, if heavy rainfall breaks out Monday night, much of the area, with the exception of southern Maryland, may see some slipperiness and a slight build-up of frozen rainfall.
While the quantities are highly uncertain, most likely there is a cover of frozen precipitation in the immediate vicinity with up to one to three inches of snow and sleet north of Lisburg, Rockville and Baltimore. However, such amounts cannot be ruled out even in the immediate vicinity of the Washington area if there is heavy snowfall and sleet on Monday night, as some models suggest (boom scenario).
In addition to any snow and sleet, a light glaze of icy rain is possible north and west of downtown Washington.
The period of greatest concern is between about 1
A more significant ice cover, which can cause damage to the trees and power outages, is possible to the Interstate 81 corridor, which is being monitored by a winter storm.
Storm schedule from Monday to Tuesday
13:00 to 17:00 on Monday: Precipitation starts from southwest to northeast. It can start as short as rain before turning into snow and sleet. It may rain in our southern and eastern regions. Temperatures in the mid to early 1930s in the early afternoon dropped to low temperatures until the mid-1930s.
17:00 to 22:00 Monday: Sun and / or snow around Washington and especially points to the west and north. Some accumulation is possible (snow accumulation north of Lisburg, Rockville and Baltimore). More rain or rain and sleet in the south. Temperatures near freezing are close to the Washington area, just below zero north and west of the Beltway and just above zero south and east.
22:00 from Monday to 3 am on Tuesday: The sun and / or snow changes to icy rain north and west of downtown Washington with temperatures near zero. Mostly rain elsewhere with temperatures just above zero.
3 am to noon Tuesday: Ice rain / rain may persist in our colder areas north and west of the Beltway before turning to uneven rain after sunrise and then ending. Temperatures rise from the low 30s to the mid-30s. Elsewhere, light rain and rain gradually decreased, with temperatures rising in the mid to early 1930s.
Complications in the forecast on Monday and Monday night
Knowing exactly what types of frozen rainfall and when and where is complicated. Computer models differ in where the dividing lines for snow, sleet, icy rain and rain will be set.
As precipitation begins late Monday afternoon, temperatures will drop to freezing in the immediate vicinity and just below zero to the north and west. This is likely to lead to a mixture of snow and sleet in the immediate vicinity of the DC area and to the north, at least initially.
How much snow can accumulate will depend on the intensity of precipitation and what percentage falls as snow relative to sleet. Around Washington, temperatures above are projected to have a fairly deep layer just around freezing. This will maintain snow, but will warm each part of this layer to a little more than a degree above freezing and precipitation will fall like sleet, which will keep the accumulations, but can still leave ice on the roads, at least for a while.
With the wear on Monday night, a warm layer will develop, and the snow and snowfall will change to icy rain to the west and north of the city and ordinary rain to the south and east.
Heavier rainfall and cold temperatures are expected to mean more snow and ice extending further south. But if the rainfall is light and the temperatures are on the warm side of the forecasts, it will be mostly a rainy event, with icing reserved for our farthest colder regions to the north and west.
Chance of a storm on Wednesday night and Thursday
The chance of a big snowstorm on Wednesday night against Thursday is doubtful, but light snow can fall, even if there are no significant amounts.
Deviating from its forecast for a major snow event, the American model (GFS) joined the European model in forecasting only light amounts of snow.
The Canadian model is still forecasting light to moderate snow in the region, but has reduced its forecast quantities compared to its forecasts on Saturday.
With the storm after 3½ days, it is possible that the models will return to the north, increasing the chance of significant snowfall. So far, here are how many different models are designing for Washington:
- American: 0.8 inches
- Canadian: 3.4 inches
- European: 0.8 inches
- UKMet: 0 inches
The bottom line is that the chances of a significant storm have decreased, but the event requires close monitoring.