21 January 2016

IS A BLIZZARD REALLY COMING & Blizzard Warning: High winds, about two feet of snow forecast for D.C. area 21JAN16
LOCAL weather forecasters are doing their best to incite hysteria about the blizzard that is supposed to hit Norther Virginia, D.C. and Maryland (convince me they aren't getting kickbacks from the grocery stores and hardware/home improvement stores). I have always found the weather forecasting from USWX reliable, and they still don't have blizzard warnings or any winter weather warning posted for any of these areas. Below is the forecast for Dulles Airport / Chantilly  and then the severe weather forecast for the entire U.S. Then there is the forecast from the +Capital Weather Gang  / +Washington Post . Are we doomed? I have bier, wein, coffee, chocolate, and TP AND I drive a JEEP so come on Mother Nature, bring it on!!!!!!

Thursday, January 21, 2016, 5:21 PM EST

Dew Point 11°F -12°C
Feels Like 20°F -7°C
Humidity 44 %
Pressure 30.28 in 1025.5 mb
Wind Dir NW 310°
Wind Speed 14 mph 22 kph
Ceiling Unlimited
Visibility 10 mi 16 km Severe | Temp | Dew | Feels | Humid | Pres | Speed | Dir
Coded METAR KIAD 212152Z 31012KT 10SM FEW045 FEW250 M01/M12 A3027 RMK AO2 SLP255 T10111117 =

National Weather Service Forecast
Seven Day Forecast Issued 9:27am EST -- Thu, Jan 21, 2016
Rest of today Sunny. Highs in the lower 30s. Northwest winds 5 to 10 mph.
Tonight Mostly clear. Lows in the lower 20s. Northwest winds 5 to 10 mph.
Friday Partly sunny with a chance of snow in the morning, then cloudy with snow likely in the afternoon. Snow accumulation around an inch possible. Highs in the lower 30s. Northeast winds 5 to 10 mph. Chance of snow 70 percent.
Friday night Snow. Snow may be heavy at times. Brisk with lows in the mid 20s. Northeast winds 10 to 15 mph with gusts up to 25 mph, increasing to 15 to 25 mph with gusts up to 35 mph after midnight. Chance of snow near 100 percent.
Saturday Snow. Snow may be heavy at times. Brisk with highs in the lower 30s. North winds 20 to 25 mph with gusts up to 35 mph. Chance of snow near 100 percent.
Saturday night Snow showers likely. Brisk with lows in the lower 20s. Chance of snow 70 percent.
Sunday Mostly sunny. Highs in the mid 30s.
Sunday night Partly cloudy. Lows 10 to 15.
Monday Mostly sunny. Highs in the upper 30s.
Monday night Mostly cloudy. Lows in the upper 20s.
Tuesday Partly sunny. Highs in the mid 40s.
Tuesday night Mostly cloudy. Lows in the mid 20s.
Wednesday Partly sunny. Highs in the upper 30s.
Type States
Freezing Rain Advisory NC SC
Freezing Fog Advisory TN
Winter Weather Advisory AL AR CA GA KS LA MO NC OH OK PA TN WA WV
Winter Storm Warning GA IL KY MD MO OH PA SC WA WV
Winter Storm Watch AR IN KY MO MS NC NJ NY OH PA TN
Tornado Warning LA MS TX
Tornado Watch LA MS TX
Severe Thunderstorm Warning LA MS TX
Lake Wind Advisory AR LA OK TX
High Wind Warning CA
High Wind Watch DE MD NJ VA
Flood Advisory AR IL MI MS TN
Dense Fog Advisory AL IA LA MN SD TN TX
Flash Flood Warning MS
Flash Flood Watch AL TN
Areal Flood Advisory WA
Areal Flood Warning IL MS
Areal Flood Watch GA WA
Blizzard Watch NJ NY
It’s a broken-record forecast that may lead to broken records: A textbook Mid-Atlantic severe winter storm is primed to unload snow totals measured in feet starting Friday afternoon and ending late Saturday night.
A blizzard warning spans the entire region from 3 p.m. Friday to 6 a.m. Sunday, when a vicious combination of heavy snow and strong winds will make travel difficult or impossible. (In Fauquier County, a winter storm warning is in effect instead of a blizzard warning because of forecast lesser wind speeds.). The visibility will drop to near zero in whiteout conditions. Some power outages are likely.
There is some chance that snow amounts will be so great that poorly built roofs and structures will collapse.
Snow totals are forecast to be at least 16 inches, with 24 to 30 inches or so possible in some areas, especially north and west of the District. Lesser amounts are likely in southern Maryland where snow is more likely to change to a wintry mix for a time.
This storm shares characteristics of many of D.C.’s greatest snow events, such as Snowmageddon in 2010 and the blizzard of 1996. Snow amounts will probably be comparable to those during Snowmageddon, and winds may be stronger.
This is a serious and life-threatening winter storm. Preparations should begin today and be completed by Friday afternoon. Wherever you happen to be Friday evening, plan to potentially be there into Sunday or early next week.
Key points
  • This is long-duration event, with snow forecast for 36 hours or so.
  • Models are converging on storm onset in the noon-to-5 p.m. period on Friday.
  • Conditions are the worst after dark Friday continuing through Saturday night.
  • Thunder snow is possible Saturday.
  • Winds may gust to 40 mph on Saturday, causing whiteout conditions and some blowing and drifting snow. Strong winds east of the District toward the bay.
  • Biggest forecast uncertainty is near and especially southeast of the District, where there remains some potential for a dry slot that would interrupt the snow and potentially result in a brief changeover from snow to sleet, cutting down accumulations.
Timeline for immediate metro area.
Noon to 5 p.m. Friday: Snow moves in from southwest to northeast. Temps: 30-35. An inch or less accumulation.
5 p.m. to 10 p.m. Friday: Light to moderate snow. Temps: 25-30. Storm total accumulation: 2-3 inches.
10 p.m. Friday to 7 a.m.  Saturday: Snow, heavy at times. Increasing winds. Temps: 25-30. Storm total accumulation: 8-12 inches.
7 a.m. to 5 p.m. Saturday: Snow heavy at times. Possible blizzard conditions. Temps: 25-30. Storm total accumulation: 16-20 inches.
5 p.m. Saturday to 1 a.m Sunday: Snow and blowing snow, gradually decreasing. Temps: 23-28. Storm total accumulation: about two feet.
Answers to frequent questions
When do I need to be off the roads on Friday? The snow will probably begin between the early and late afternoon. You may be able to sneak in a half-day at the office. However, the wiser move will be to telework as we want to avoid a mass exodus on the roads and a repeat of Wednesday evening. Even if traffic is light and the storm eases in initially, you definitely want to be home by dark Friday as snow will be increasing in intensity, with a few inches possible by around 10 p.m.
Where are power outages most likely? East of the city, but plausible anywhere in the region. The reason we think areas east of Washington and toward the Chesapeake Bay have the highest outage potential is because winds will be strongest there and the snow will have more of a heavy, wet consistency.
West of the District, the snow will have more of a powdery consistency, which will probably lead to to greater amounts but less clinging to trees and power lines. Also winds will tend to decrease the farther west you go in the region.
Will this be a true blizzard? The National Weather Service defines a blizzard accordingly:
A blizzard means that the following conditions are expected to prevail for a period of 3 hours or longer:
  • Sustained wind or frequent gusts to 35 miles an hour or greater; and
  • Considerable falling and/or blowing snow (i.e., reducing visibility frequently to less than a quarter mile.
These conditions are possible in the region, particularly on Saturday.
Could this storm underperform? Yes, but unlikely. The signal for a historic storm emerged days ago, and models have not wavered in their forecasts for extreme snow amounts. Capital Weather Gang winter weather expert Wes Junker says the possibility of snow changing to sleet could cut down on totals in some areas:
There is still a chance that the snow could mix with or change to sleet for a period of several hours in the city and especially for locations to the south and east. The 1996 snowstorm, which had a similar evolution, ended up having a period of sleet sandwiched between two periods of moderate to heavy snow. During big D.C. snowstorms, folks east of the city are usually at risk for mixing or even a changeover.
Junker noted that last night’s NAM model simulation introduced the potential for mixing even in the District.
orthy of the frenzy they caused. (Claritza Jimenez/The Washington Post) Could this storm overperform? Yes, by a little. The latest model forecasts are generally for at least near-20 inches of snow and up to 30 or so inches. We also must consider that the model snowfall amounts make the assumption that 10 inches of snow will fall for the equivalent of every inch of rain and, in some areas, particularly north and west of the District, perhaps 15 inches of snow will fall for every inch of rain, especially during the second half of the storm as colder air is drawn in. In general, model simulations advertise the equivalent of 2 to 3 inches of rain over the region. Someone in the region is likely to receive more than 30 inches.
Where will the heaviest snow fall? Some models have placed the snowfall bull’s-eye in west-central and northwest Virginia, while others place it closest to the immediate metro area. Based on D.C. snowstorm history, we favor the heaviest amounts in these western areas, especially near Interstate 81 from around Harrisonburg to Winchester and in the Blue Ridge. Having said that, where localized heavy bands set up is always a wild card, and that could even occur just east of the city.
“The models have a really hard time predicting where one of these bands will set up prior to their formation,” Junker says. “Where such a band sets and persists longest will determine who in the area will get plastered with the heaviest snow.”
What should I do about my flight? Many carriers have announced that you can change your flight plans without penalty. Check your airline. Flights should be able to get in and out of the airports for much of the daylight hours on Friday before conditions really deteriorate after dark. On Saturday, airports may need to shut down temporarily. Air travel is likely to be possible on Sunday, but expect considerable backlash delays and some cancellations.
What will Amtrak and Metro do? Metro has decided to shut down the rail and bus system for the entire weekend. Amtrak will attempt to continue operating, but consider that many trains were canceled during Snowmageddon in 2010.
What will schools and the federal government do? In past storms of this magnitude, even those that occurred over the weekend (many of them, in fact), schools and government closed up to several days in the week following.
As for Friday, many schools have already decided to close and we expect more will follow suit.
We think the Federal government will likely offer the telework option and may dismiss early on Friday.
Why might there be thunder snow? Yes, on Saturday, Junker says.  His technical discussion:
The forecast atmospheric profile or sounding from last night’s NAM and GFS both argued for a period of thunder snow though they differed on when. The NAM liked early Saturday morning while the GFS early Saturday afternoon. 
The GFS sounding below is a classic one trumpeting there is likely to be elevated instability, conducive to thunder.   Note that the unstable layer is located above the warm layer due to the east wind off the ocean and below the dry layer. You can tell that the sounding is unstable because the temperature and dewpoint lines are squeezed together and the slope of their line tilts to the left more than the curved dashed line on the sounding (below). 
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Jason is the Washington Post’s weather editor and Capital Weather Gang's chief meteorologist. He earned a master's degree in atmospheric science, and spent 10 years as a climate change science analyst for the U.S. government. He holds the Digital Seal of Approval from the National Weather Association.