* Winter Storm Warning Wednesday from 1:00 pm to 7:00 pm. (except to 01.00 Thursday far to the west and northwest) | Winter Weather Consultancy Wednesday for Stafford County and Southern Maryland from 1:00 pm to 4:00 pm. | SchoolCast and FedCast for Wednesday | Announced school closures and delays *
9:30. – snow on the track to arrive before sunrise; Accumulation Slightly Slimmed
We reviewed the majority of the models in the late afternoon and evening, and the forecast is generally on track. However, due to the dry air in the region, it may take an hour or two for the snow to develop, as previously indicated, beginning at 6 am instead of 4 or 5 am. This reduces the snow period since the transition to Winter Mix is still expected between noon and noon.
In response to the shorter snow duration, the models have reduced their snowfall predictions for the immediate environment to about 2 to 3 inches. Here are the latest figures of afternoon and evening models for Washington:
- NAM: 2 inches
- SREF (average): 2.1 inches
- HRRR: 2.3 inches
- High Resolution NAM: 3 inches  European: 3 inches
Given the downward trend in model predictions, we are also reducing our forecast for snowfall accumulation around Washington from 2 inches to 5 inches by 2 to 4 inches and 3 inches by 7 inches in our northern and western areas at 3 to 6 inches.
Despite the lower upper end for the predicted volumes, we still expect snow, possibly hard times, during the morning commute, followed by a messy winter mix. This will lead to difficult driving conditions. Our ideas and schedules described below have not changed significantly.
This is our last update of the evening. We will continue reporting on Wednesday around 16:00.
6:00 pm – Forecasting remains on track, models indicating a lesser likelihood of a snow boom scenario
As this article was originally published, a number of other model simulations have been received to support the ideas listed below. They all predict about 2 to 4 inches of snow in the immediate area in the morning, followed by a wintry mix. However, these numbers are slightly lower than some forecasts made on Monday or even earlier. Here are, for example, the latest model snowfall forecasts compared to the same prediction made in parentheses 24 hours earlier:
- NAM: 2.3 inches (3.4 inches)
- High-resolution NAM: 3.8 inches (3, 5 inches)
- GFS: 3.0 inches (6.5 inches)
- SREF (average): 1.8 inches (3.6 inches)
We believe that the likelihood of a "boom scenario" of more than 5 inches has fallen in the immediate area. Still, we still expect snowfall during the commute on Wednesday, which will lead to challenging travel conditions, followed by a mix of mixed rainfall.
Original Afternoon Mail
For the second time this year, a winter storm warning covers much of the DC region on Wednesday for the likelihood of a dangerous combination of snow and ice.
We are most worried about the commuter ride on Wednesday morning. The snow is expected to pull in just before dawn and quickly become quite strong, which limits visibility and curvy roads during the typical shuttle time.
By Wednesday morning, the snow can quickly pile up (at a speed of about 1 inch per hour) and we expect extensive school closings. Airports are also likely to deal with delays and some canceled flights.
We recommend telework instead of commuting on Wednesday morning to avoid large reserves and give the crew room to operate. According to the National Meteorological Service
if you choose "very difficult" conditions, the snow period (without mixed rainfall) may not last long, as the models suggest that rainfall passes to sleet and then freezing rain in between Afternoon hours from south to north. The relatively fast changeover was supposed to limit the accumulation of snow in the immediate area to about 2 to 5 inches, slightly more to the north and west and a little less to the south and east.
If the shift to icy precipitation is delayed, snowfall could exceed our forecast. However, if the transition happens on the fast side, we could see more amounts in the range of 1 to 3 inches.
Something else you should look out for in this storm may be a localized zone of heavy snowfall. The models differ in terms of where exactly this will be, but some amounts in excess of six inches can not be ruled out. The overall pattern would support the jackpot amounts in our colder areas west and northwest of the city, but they can not be ruled out in the immediate subway area.
Even if precipitation changes from snow to ice, the danger of dangerous conditions is far from being attained, especially at our colder locations. The visibility tends to improve when the snow changes to sleet and the sleet does not accumulate as fast as snow. Untreated roads and sidewalks, however, remain smooth in the afternoon. The exception can be found in our milder areas south and east of Washington, where temperatures rise above freezing and precipitation turns to rain.
Later in the afternoon and evening hours along Wednesday and west of Interstate 95 (zones 1 and 2 of the above map), the sleet will shift to more freezing rain. Freezing rain forms an icy glaze on contact with cold surfaces. In addition to smooth untreated surfaces, it can accumulate on supply lines and break branches, resulting in power outages.
In our northern and western zones (Zone 1), there is a high risk that at least one light thawing glaze (or 0.1 inches), sufficient to cause tree damage and power outages. In these areas, temperatures stay low or slightly below freezing on Wednesday night or in the coldest locations (northwest Virginia and northern Maryland) until just before Wednesday. Near Interstate 95, we expect temperatures to be slightly above freezing by Wednesday night. Medium freezing rain would turn into simple rainfall before more ice accumulation sets in. But some school delays and closures are likely on Thursday morning due to earlier rainfall. Some untreated roads, parking lots and sidewalks will likely remain slippery until Thursday.
Detailed Timeline of the Storm
3 to 6 am: Snow developing southwest to northeast. It could start as a sleet or sleet mixture, but should turn to snow. Temperatures 28 to 34 from northwest to southeast. Accumulation of a coating to about one inch.
6 to 10 o'clock in the morning: Snow, sometimes strong. Could start mixing with south of Washington or switch to sleet. Temperatures 27 to 32 from northwest to southeast. Accumulation of 2 to 4 inches, less south.
10 am to 2 pm .: Snow is everywhere to sleet, except in the south and southeast. The rainfall decreases slightly. Temperatures 28 to 33 from northwest to southeast. Up to one or two inches of additional snow and sleet collection, highest values north of Washington.
14-18: The sleet changes along the west of Interstate 95 (Zones 1 and 2) in cold rains elsewhere. Temperatures 30 to 35 from northwest to southeast. In colder areas, a slight glaze is possible.
6 pm Thursday, midnight: Freezing rain in colder areas north and west of Washington (zone 1), while freezing rain near Interstate 95 (zone 2) turns into rain. Rain elsewhere. Temperatures 31 to 36 from northwest to southeast. Coating of ice accumulating in colder areas (zone 1).
Midnight to 4:00 pm Thursday: Precipitation is decreasing. Temperatures 32 to 37 from northwest to southeast.
See how much snow the various models in the Washington area predict:
- SREF (average of 24 simulations): 1.8 inches (range: lane to 4.5 inches) [NAM:23inches
- GFS: 3 inches
- European: 3 inches
- High Resolution NAM Model: 3.8 inches
- HRRR: 3.8 inches
- Canada: 4, 8 inches
- Canadian resolution: 7.2 inches
Note that some of these model predictions classify sleet as snow, while sleet limits snow accumulation.
"The big question mark is whether or not the largest snow band reaches us to the north in Pennsylvania like the high-resolution NAM model, and to a lesser extent the European model, predicts or lands like the Canadian models right in front of us," says Wes Junker , Winter Weather Expert of the Capital Weather Gang.
Less snow concentrates precipitation along a frontline A valley boundary that forms in the north between the warm air flowing north into Kentucky and west from West Virginia, "Junker said "This often happens with such systems – we spend a few hours with a snowstorm that turns into sleet and then easier freezing rain and eventually rain."
"The latter development, which would lead to more snow, is rarer but can not be completely ruled out seems to me to be the more unlikely scenario of the two. It would be a boom scenario since s is still possible and explains why there are still such big differences between snow forecasts from different sections.
Predictions from Other Operations
National Weather Service
(This section is unchanged from the assessment of Monday)