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Updated forecast: Arctic air to spill into area after rain and underperforming snow

Little or no snow fell despite a forecast of a coating to a couple of inches.

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Radar courtesy MyRadar | © OpenStreetMap contributors

* School delays/closings | News updates *

Key points and latest developments:

  • Despite earlier forecasts of accumulating snow, it was mostly rain that fell Thursday morning, with some non-accumulating flakes falling mainly north and west of downtown Washington before the precipitation ended.
  • We can’t rule out a brief period of snow or flurries in our southern suburbs this afternoon, especially toward Southern Maryland, but a coating or less is expected.
  • Temperatures in the mid- to upper 30s will remain steady or slowly fall this afternoon, but probably not fast enough for a flash freeze. This evening we can’t rule out a few icy spots developing if any wet areas linger as temperatures drop below freezing.
  • Very cold tonight, with lows in the teens and wind chills in the single digits.

11:05 a.m. — Precipitation ends in most of the region. Big story now is the cold (Final update)

Radar shows the rain and sparse flakes of wet snow have mostly exited the Washington region. Our far southern areas could see snow or snow flurries for a time this afternoon, especially toward Southern Maryland, but would probably experience a coating or less.

We await the Arctic blast. Temperatures in the mid- to upper 30s across the region should fall closer to freezing by sunset. As this process will take several hours, we don’t expect a flash freeze of wet surfaces. However, a few icy spots can’t be ruled out after dark. Tonight will be one of the coldest of the winter, with lows in the teens and wind chills in the single digits.

This is our last update. This afternoon, we’ll write a post mortem on what went wrong with this forecast.

10:10 a.m. — Precipitation ending west of Beltway, mainly rain to the east

The back edge of the rain, mixed with some snowflakes, has reached the western side of the Beltway, and the precipitation should end in the immediate area by 11 a.m. and in our eastern areas before noon.

9:40 a.m. — Rain mixing with and changing to a bit of wet snow west of Interstate 95

As the back edge of the precipitation advances into western Fairfax and central Montgomery counties, we are seeing some increasing reports of rain mixing with and changing to wet snow — as far east as Tysons Corner and Bethesda. This is mostly “conversational” snow — that is, mainly melting and not causing disruption.

Some flakes could be seen inside the District and its eastern suburbs over the next hour or so before the precipitation exits to the southeast.

9:05 a.m. — National Weather Service discontinues winter weather advisory for immediate area because of lack of snow

While some of our colder areas (upper Montgomery County and parts of Frederick and Loudoun counties) are seeing some conversational snowflakes, mostly rain continues to fall elsewhere, with temperatures in the mid-30s in our colder areas to around 40 in the District.

The National Weather Service has discontinued the winter weather advisory for all but upper Montgomery, western Howard, Frederick and Carroll counties because of a lack of snow. Our far northern areas could see a light accumulation of slushy snow, mainly on grassy areas, but this predicted snow event is a bust — no doubt about it.

8:20 a.m. — Snow struggling to develop even in western areas as potential for accumulation fades

While there are reports of snow in northern Maryland and parts of northwest Virginia, and even some reports of some sleet pellets and snowflakes into western Montgomery and western Fairfax and Loudoun counties, there is little sign of a transition to meaningful snowfall.

We can’t rule out some flakes gradually mixing in with the rain and perhaps a transition to a brief period of snow before precipitation ends later this morning, but this increasingly seems more like a snow bust than a snow burst.

7:50 a.m. — Weather Service scales back snow prediction

In an update around 7:30 a.m., the National Weather Service decided to keep the winter weather advisory in place for the region, despite the delayed transition from rain to snow. However, it now only calls for “up to one inch, mainly on grassy surfaces.” As of 9 p.m. Wednesday, it had called for 1 to 2 inches, with locally higher amounts of 3 to 4 inches.

7:20 a.m. — There are a few reports of snow toward western Loudoun County and Interstate 81, but changeover is occurring slowly

We’ve seen reports of rain changing to snow around Berkeley Springs and Charles Town in W.Va., and in Winchester and Hagerstown as well as parts of northern Maryland. However, the switch is occurring much slower than projected just 12 hours ago. Temperatures are still near 40 in the immediate area, cooling to the mid-30s in areas west of Frederick and Leesburg where a transition to snow should occur soon — see the tweet below from far western Loudoun County.

Around Frederick and Leesburg themselves, the switch to snow should occur over the next hour or so before starting to edge closer to Fairfax and Montgomery County.

Some modeling (the HRRR) now only suggest a very brief period of snow later this morning following the rain in the immediate D.C. area before the precipitation ends.

6:20 a.m. — Change from rain to snow may not occur until between 8 and 10 a.m. in immediate area, meaning a lower accumulation potential

Overnight computer models have somewhat delayed their predictions for the timing of the change from rain to snow this morning. On Wednesday, it look like that the transition to snow might occur between 6 and 8 a.m. but it now looks like it could be delayed until between 8 and 10 a.m. The slower changeover reduces accumulation potential somewhat.

A burst of snow is still possible after the changeover but, at this point, we’d lean toward snowfall totals being closer to the lower end of the projections displayed in the map below (or around a coating to an inch, with some locally higher amounts). As a result, some areas (especially from the District south) may not see a lot of accumulation, especially on roads. However, we’d still urge caution as snow could still bring reduced visibility for a time and some slick spots, especially in our colder areas.

Temperatures at 6 a.m. are still near 40 inside the Beltway and to the east but have cooled into the upper 30s to the west and north. We’ll need to see temperatures drop toward the mid-30s before the switch to snow commences. That could start to happen in some of our far western areas between Interstate 15 and 81 over the next hour or so.

Original forecast from 5 a.m.

Today’s daily digit

A somewhat subjective rating of the day’s weather, on a scale of 0 to 10.

5/10: After Wednesday’s warmth, many are deflated, but leaving it higher rated since snow lovers are elated.

Express forecast

  • Today: Rain changing to snow in the morning, temperatures falling into the 30s.
  • Tonight: Partial clearing, very cold. Lows: 12-18
  • Tomorrow: Partly to mostly cloudy, breezy and cold. Highs: 24-28

Forecast in detail

Cold air comes muscling in today, changing our overnight rain to snow and then leaving us to shiver all weekend. That cold air keeps most moisture surging up from the south confined to southern Delmarva and southeastern Virginia on Friday night into Saturday morning, making the chance of seeing snowflakes locally slim.

Today (Thursday): Rain transitions to snow from northwest to southeast between about sunrise and 9 a.m. The main snow burst is likely to be between about 8 and 11 a.m. The snow should then gradually taper off by noon, but some flurries could linger into the early afternoon, mainly south of town. Accumulations of an inch or two are possible for most of the immediate metro area, although some areas may manage only a coating, especially south of town. Temperatures fall from the upper 30s to the low 30s during the day thanks to gusty north winds. Confidence: Medium

Tonight: Clouds diminish in the evening, and north winds persist but slowly ease. Overnight lows plummet into the teens with wind chills in the single digits. Confidence: Medium-High

Follow us on Facebook, Twitter and Instagram for the latest weather updates. Keep reading for the forecast through the weekend …

Tomorrow (Friday): Clouds are back on the increase in the morning, with mostly cloudy conditions much of the day. North winds are not that strong but accentuate the cold. Temperatures climb no higher than the mid- to upper 20s. Confidence: Medium-High

Tomorrow night: Despite mostly cloudy skies, temperatures still drop back into the low to midteens. A few snowflakes are possible, but anything significant should be confined well to our southeast. Winds are thankfully light from the north. Confidence: Medium-High

A look ahead

Skies gradually clear Saturday, but the Arctic air is still in place, and highs are capped in the upper 20s to low 30s. Overnight lows fall to the mid- to upper teens under partly cloudy skies. Confidence: Medium-High

Sunday is not quite as cold, with highs in the mid- to upper 30s. Skies are partly sunny, and winds are light, which helps the comfort factor. Overnight lows dip to the mid- to upper teens (lower 20s downtown). Confidence: Medium

Mainly sunny skies Monday still struggle to warm the area. Highs are likely to remain in the mid- to upper 30s. Confidence: Medium

Snow potential index

A daily assessment of the potential for at least 1 inch of snow in the next week, on a 0-10 scale.

5/10 (→): We better cash in with the snow this morning because the weekend chances are fading fast.

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