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Radar forecast of the NAM model at 10 am Thursday. (PivotalWeather.com)
16:05 – Notice of winter conditions issued for the DC area; winter storm warning to Interstate 81
The National Meteorological Service has issued a winter weather forecast for the district and surrounding areas from 4 am to 1 pm Thursday. It provides up to one inch of slush and sleet and the possibility of a light ice storm (0.1 inch) of ice.
This notice extends up to 16 hours. in our far north and western suburbs, including Montgomery counties in the north-west, Fauquier in the north and Loudoun, where frozen precipitation will probably last longer due to colder temperatures. In these areas, there is a higher potential for ice enamel (up to 0.2 inches) above snow and ice pellets. In Frederick County, Maryland, and eastern North Maryland, the weather service predicts snow accumulation of one to two inches and slush.
Notices and warnings in effect Thursday. (National Meteorological Service)
Even further to the west, along the Interstate 81 corridor from Harrisonburg, Virginia, to Hagerstown, Maryland and to the west, a winter storm warning is in effect from Thursday at 4 am to Friday at 4 am for a maximum of 2 to 5 inches of snow and slush and an ice-cold glaze up to 0.25 inch thick .
Notices are not in effect in southern Maryland, where most precipitation is forecast.
From earlier …
An unusually cold storm in November brought snow and sleet as far south as Houston Tuesday and West Monroe, The., Wednesday. On Thursday, the storm will arrive in the Washington area, likely offering an assortment of types of precipitation: snow, sleet, rain and freezing rain. Part of this rainfall will fall heavily.
The most disturbing period is between about 7 am and 11 am, which coincides with the morning commute, when temperatures will be the lowest and the risk of freezing precipitation very high. This is the typical winter weather event in Washington, where conditions tend to deteriorate as you head into the coldest areas north and west of the Beltway. , where the risks of snow and slush accumulation and slush are optimal.
Precipitation can begin briefly as a light rain in the hours before dawn, before turning into snow and / or melted snow at dawn. The snow will likely be short-lived, as high-altitude temperatures will increase, but melted snow and pockets of freezing rain may persist throughout the morning. However, in areas to the south and east of the ring, any icy precipitation is expected to turn into pouring rain as the morning progresses.
By late morning and afternoon, precipitation from the Beltway and the northwest is expected to gradually turn into natural rains. Frozen precipitation will last the longest in our far northern and western regions, perhaps late into the afternoon, west and north of Warrenton, Leesburg and Frederick. Some of these areas are monitored by winter storms because of the potential for snow and slush accumulation, as well as freezing rain overlying them.
Radar forecasts of the NAM model early Thursday to Friday morning.
Inside the ring road and to the south and east, air and road temperatures should be high enough for the icy precipitation to fall, especially in the morning, to melt. However, some slippery points can not be ruled out during heavy gusts of freezing precipitation – which is possible during Thursday morning commutes.
Further north and west is the potential for snow-covered and snow-covered roads to increase, especially untreated ones, as well as bridges, ramps and overpasses.
Rainfall will be highest throughout the region between approximately 9 am and 3 pm, but areas of light rain and drizzle (possibly ice and drizzle in the coldest places) will persist until Thursday evening ( rain could mix with snow or change briefly to wet snow before ending in our northern regions). The equivalent of at least an inch of precipitation (from slush, ice and rain) is expected to fall in most areas. If Washington receives so much rainfall, it will rank fourth in the wettest calendar years ever recorded.
This is an event in which a few degrees will make all the difference in the amount of snow and snow in the winter and the places where surprises are possible or unlikely. This configuration makes it "difficult to say how long freezing temperatures will last in the north and west Beltway," said Wes Junker, a winter weather expert at the Capital Weather Gang.
This type of winter climate in Washington so early in the season is rare. If the accumulation of snow or sleet materializes in Washington, this is the first time in November since 1996.
[[[[It could snow in Washington on Thursday. How many times does this happen in November?]
Zone forecasts
As conditions vary considerably from most of the rains in southern Maryland to significant amounts of freezing precipitation toward the interstate corridor, 81 we have divided the area into four areas, as shown on the map below. below.
(Washington Post Staff / Washington, D.C.)
Here's how we see the evolution of the event, zone by zone, and the expected impact.
Zone 1: Northern Maryland, East Panhandle of West Virginia and Northwestern Virginia
(Includes Winchester, Hagerstown, Frederick and Westminster)
Moderate accumulations of snow and melted snow (one to three inches) and freezing rain ice are possible in this region, as temperatures are the lowest here, and precipitation will likely remain frozen for much of the year. ;event.
Precipitation should start as snow and melted snow early Thursday morning, then move to more slush and freezing rain over the morning. Some areas may turn into driving rain during the afternoon, but pockets of freezing rain may persist even in the evening in some of the colder valleys of the west of this area.
Temperature forecasts between Thursday morning and Thursday evening from the high resolution NAM model.
"The high-resolution models suggest that surface temperatures could remain below freezing for a long time in our typical coldest areas to the north and west of the city," Junker said.
Ice accumulation expected Thursday. (National Meteorological Service)
The predicted conditions correspond to a "disruptive" winter weather event of level 2 out of 5 in our territory. scale of winter storm impact. The effects will be magnified by the fact that the winter combination will coincide with the morning commute and that it is the first winter storm of the season, which means that people have less experience recent in this area.
(Washington Post)
Zone 2: North and West suburbs of Washington and Baltimore
(Includes Warrenton, Leesburg, Rockville, Columbia and Towson)
Mixed precipitation should begin just before dawn and it is likely that snow and / or slush will deposit a coating not exceeding one inch until mid-morning or thereabouts. More snow than snow is likely to fall. Road surfaces, especially those that are not treated, can become slippery.
Some areas may become rainy in the late morning, and most areas should be in the afternoon, but there may be some colder areas (sheltered valleys) where temperatures are barely fluctuating, which would allow for the development of some areas. 39, a layer of freezing rain.
The risk of freezing rain can be mitigated by the fact that precipitation sometimes falls very hard and prevents ice from adhering to surfaces such as trees and power lines. In addition, temperatures in this zone may oscillate around the freeze (between 30 and 34 degrees) – and should be lower for more ice accumulation.
Zone 3: Washington immediate area and Baltimore city
(Includes Gainesville, Manassas, Fairfax, Bethesda, Laurel and Annapolis)
Precipitation can start as light rain before dawn but turn into a winter mixture of slush and snow towards sunrise until mid-morning. Then the winter mix can become rainy. However, it is possible that pockets of melted snow and freezing rain persist in the early afternoon in some of the coldest regions.
Temperatures in this area will be near or above the freezing point, generally limiting accumulation. However, slippery points can form during strong gusts of frozen precipitation.
Even if ice travel does not materialize, the roads will be wet and visibility will be reduced due to the messy mix of falling precipitation – so allow more time to reach your destination.
Storm conditions do not deserve to be noted on our impact scale in this area. We generally do not expect delays or cancellations in this area unless the conditions are worse than expected.
"For snow enthusiasts, the combination of November and the high altitude storm track, located just north of where you want it, has virtually ruined our chances of getting significant snow around of the city, "said Junker.
Zone 4: southern and southern Maryland suburbs
(Includes Fredericksburg and La Plata)
Expect mostly a cold rain in this area. A little slush or wet snowflakes could mingle with the rain early in the morning, but the roads should remain mostly wet.
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