*** Latest storm update: S'now joke: Another major storm coming ***
(next update around 11 p.m.)

* Federal government closed tomorrow: Federal Eye *
* Winter Storm Warning Tues.-Wed. for most of metro area (map) *
* Making history? | Today's Q&A | Snowmageddon's incredible output *
* Watch out for ice dams | Measuring Snowmageddon's depth *
* Power outage maps for Dominion Electric | Pepco | BG&E *
* Outside now? Radar, temps & more: Weather Wall *
* News, traffic & storm coverage: Local home page | Get There *

As our previous update indicates, we're calling for 5-10" in D.C. and to the south and west, and 8-16" to the north and northeast for the upcoming storm. Our accumulation projections are less than the National Weather Service's (10-20"), Topper Shutt's (1 to 2 feet), Doug Hill's (12-16"), and Bob Ryan's (8-12"). The reason for this is that we see the possibility of a dry slot impacting southern half of the metro region. Having said that, we're going to analyze some data coming in between 9 and 11 p.m. tonight and will adjust our accumulation map in our 11 p.m. update as necessary.

Before we do so, it's your chance to weigh in by indicating how much snow you think will fall at Reagan National (DCA), and giving this storm a name. See the polls below....

Blizzard conditions and significant accumulation possible

* Winter Storm Warning Tues.-Wed. for most of metro area (map) *
* Making history? | Today's Q&A | Snowmageddon's incredible output *
* Watch out for ice dams | Measuring Snowmageddon's depth *
* Power outage maps for Dominion Electric | Pepco | BG&E *
* Outside now? Radar, temps & more: Weather Wall *
* News, traffic & storm coverage: Local home page | Get There *

There is still way too much snow outside to know what to do with and it is now increasingly likely we will be adding a big pile on top. The National Weather Service has now issued Winter Storm Warnings for tomorrow and Wednesday. As if that was not enough, this looks like quite the windy event, with blizzard conditions possible. Highs near freezing today and similar expected tomorrow will ensure that our snow base at the beginning of the event remains quite deep.

Through tonight: We see mostly clear skies early becoming cloudier as the night wears on. Temperatures fall to near 10 in the coldest spots to the mid-or-upper teens in the warmest.

CWG team snowfall forecast for Tues.-Wed. as of 3:30 p.m. Confidence: Medium.

Tomorrow (Tuesday): The day starts mostly cloudy before snow begins to arrive during midday and afternoon. Snow will pick up in intensity as we head into evening with the heaviest expected late at night and a possible lull prior to sunrise. Some mix with sleet is possible from around D.C. and to the south. Winds increase late at night, with gusts near and past 35 mph -- blizzard conditions are possible by morning. Highs should reach the upper 20s to lower 30s with lows in the low-or-mid 20s.

Wednesday: There may be a lull in the snow, or just some lighter stuff during the very early morning, but a second dose of moderate or heavy snow is possible as the storm pulls off to the east and the upper-level energy swings through. Highs probably rise to the upper 20s most spots. Strong northeasterly winds continue to be a concern through much of the day.

See Jason Samenow's forecast through the rest of the week and weekend.

What do you think about all this snow? Love it? Tired of it? Let us know, or start a different conversation, with a comment below. And if you haven't already, join us on Facebook and follow us on Twitter.

* Serious snow/wind risk late Tues into Wed | Live chat at 2 p.m. *

* Our Full Forecast thru weekend | Snowmageddon's incredible output *
* Winter Storm Watch Tues.-Wed. for most of metro area (map) *
* Watch out for ice dams | Measuring Snowmageddon's depth *
* Power outage maps for Dominion Electric | Pepco | BG&E *
* Outside now? Radar, temps & more: Weather Wall *
* News, traffic & storm coverage: Local home page | Get There *

Seasonal snowfall over the last two decades. 45" have fallen so far in 2009-2010, the most since 1995-1996.

With the impending storm for tomorrow and Wednesday, we have a legitimate chance for an all-time (since records have been kept in the late 1800s) seasonal snow record.

Our big weekend storm surged Reagan National Airport's seasonal total to 45" with the balance of February and March yet to go. This places our current winter in position number three for the snowiest winters on record, behind 1995-96 (46") and the big one, 1898-99 (54.4"). Of course, that all-time record was set at a more downtown location (M Street), so some may argue the higher elevation and location away from the Potomac was an easier accomplishment. But in my mind, that makes this potential record season all the more notable.

The chart above tracks seasonal totals since the 1990-91 snow season. Just look at that volatility. Get this: our 45" this season is more than the last four winters COMBINED (which was only 35.5").

Keep reading for more on the chances for 2009-2010 to make snowfall history...

Blizzard conditions may return, especially N & E

* Our Full Forecast thru weekend | Snowmageddon's incredible output *
* Winter Storm Watch Tues.-Wed. for most of metro area (map) *
* Watch out for ice dams |Measuring Snowmageddon's depth *
* Power outage maps for Dominion Electric | Pepco | BG&E *
* Outside now? Radar, temps & more: Weather Wall *
* News, traffic & storm coverage: Local home page | Get There *

This morning's 12z Global Forecasting System model simulating snow over the region Wednesday morning and very strong winds (depicted by the closely packed lines of equal pressure or isobars in black).

The new data we're analyzing portrays a rather ominous picture for the region, beginning tomorrow afternoon. Two areas of low pressure, one from the north and one from the south, will likely merge off the mid-Atlantic coast developing into a very powerful storm Tuesday night and Wednesday. Though this storm will not have the same amount of moisture as Snowmageddon, models suggest a deeper storm (i.e. more intense meteorologically) which will pose a significant risk of high winds and additional power outages.

The probability of potentially dangerous conditions is highest north and east of the beltway and especially as you head towards Baltimore and Philadelphia. However, even our southern suburbs may experience periods of heavy snow and wind.

FREQUENT QUESTIONS

When will the snow start? Between mid-day and mid-afternoon tomorrow.

When it will end? Probably around late afternoon Wednesday -- later north and east.

How much?: Our best bet is 5-10" in the metro region, but 8-14" as you head north and east towards Baltimore. South and southwest of the Fairfax County, 3-6" is most likely.

Could it be more or less? Yes. Double digit totals (10" or more) remain a possibility throughout the metro region (25% chance). By the same token, if the coastal storm forms too far north, lighter amounts from 1-5" or so might do it.

How bad will the winds be? By very late Tuesday night and into Wednesday, sustained winds may reach 25-35 mph, with higher gusts. Assuming there is falling snow, this could create blizzard conditions.

Feb. 3-6, 2010: Simulations, satellites, radars, and maps

*** Remarkable winter brings new threat: Full Forecast ***

* Winter Storm Watch Tues.-Wed. for most of metro area (map) *
* A closer look at next snow threat: SLCB | Watch out for ice dams *
* Measuring Snowmageddon's depth | NWS totals | CWG snow reports *
* Power outage maps for Dominion Electric | Pepco | BG&E *
* Outside now? Radar, temps & more: Weather Wall *
* News, traffic & storm coverage: Local home page | Get There *

Radar estimated liquid equivalent totals (generally 1.5-2.5" inches of liquid) from the historic Snowmageddon which dropped as much as 2 to 3 feet of snow across the region. Note, radar does not always accurately demonstrate real totals; numbers on the edges of the radar scope are likely underestimated. Image courtesy: Weather Underground.

After Snowpocalypse in December, it would have been hard to imagine it would only end up "one of the biggest" storms of winter 2009-2010. But that was before Snowmageddon came along with its massive amounts of moisture. While the large-scale pattern was similar, and aided us in our high level of forecast confidence that a historic storm was in the offing, the way it came together was a little different. The moisture sources it tapped were far-reaching, ultimately helping it produce historic amounts of snow over the area.

Continue on for more imagery related to the historic February 2010 storm.

Chance of snow Tues/Wed; quieter thereafter

* Winter Storm Watch Tues.-Wed. for most of metro area (map) *
* A closer look at next snow threat: SLCB | Watch out for ice dams *
* Measuring Snowmageddon's depth | NWS totals | CWG snow reports *
* Power outage maps for Dominion Electric | Pepco | BG&E *
* Outside now? Radar, temps & more: Weather Wall *
* News, traffic & storm coverage: Local home page | Get There *

Today's Daily Digit

 

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

 

Sun and temperatures near/above freezing to aid big dig out.

 

Get tomorrow's 'Digit' on Twitter tonight

EXPRESS FORECAST

Today: Mostly sunny. 32-36. | Tonight: Increasing clouds late. 12-18. | Tomorrow: Snow and/or sleet likely in the afternoon. 29-33. | Tomorrow night: Snowy and windy, especially from D.C. and to the northeast. 23-28. | A Look Ahead | Get Express Forecast by E-mail

FORECAST IN DETAIL

Our exceedingly snowy winter may deliver another blow Tuesday into Wednesday before we finally get an opportunity to recover late in the week. There is an outside chance one more bout of winter weather impacts the region late Friday into Saturday (again), but current indications are that chances are better we'll remain calm and dry for the upcoming holiday weekend.

Today (Monday): The day gets off to a frigid start (single digits to teens), but the sun will go to work, helping temperatures climb to around the freezing mark, or even slightly above in the afternoon. So everyone should experience some modest melting of the deep snowpack. Winds will be light, from the west at around 10 mph. Confidence: High

Tonight: After clear skies for the first half of the night, some high clouds will likely start to build into the region. It will be very cold yet again, with lows from the low teens in the colder suburbs to the upper teens downtown. Confidence: Medium-High

Keep reading for the forecast through the week...

Some accumulating snow likely, but amounts may vary

* Sunny start and end to week: CWG's Full Forecast *
* Winter Storm Watch Tues.-Wed. for most of metro area (map) *

Next Chance of Accumulating Snow: Tuesday P.M.-Wednesday
Probability of Accumulating Snow (1" or more): 85%

A complex storm system developing in the center part of the country today likely spells some trouble for our region as Tuesday progresses. An area of low pressure in the Deep South looks to join forces with an energetic disturbance diving south along the Polar jet stream Tuesday night.

Light snow, possibly mixed with sleet, will break out across the region between mid-day Tuesday and Tuesday evening as moisture ahead of the southern low streams northward. As the northern stream disturbance interacts with the southern low off the mid-Atlantic coast, an area of heavier snow is likely to develop overnight. The exact location of this interaction will help determine exactly how much of the area gets the heavy snow.

At the moment, it appears the best chance of any heavy snow will be from the District and to the northeast. Areas to the south and southwest may get "dry slotted" as the energy from the northern disturbance shifts to off the coast. In other words, places like Baltimore and Philadelphia have a better chance of getting heavy snow than the D.C. metro area and especially our southern suburbs.

Keep reading for additional discussion of the Tues-Wed snow potential

* Winter Storm Watch Tues.-Wed. for most of metro area (map) *
* Watch out for ice dams | E-mail this forecast to a friend *
* Measuring Snowmageddon's depth | NWS totals | CWG snow reports *
* Power outage maps for Dominion Electric | Pepco | BG&E *
* News, traffic & storm coverage: Local home page | Get There *

The snowy scene out there is stunning, but I know for a lot of people enough is enough. Like it or not, the reality is that the latest information this evening points to a moderate, if not major in some places, snowstorm Tuesday into Wednesday.

It's exciting news for snow fans who are no doubt giddy about the prospect of this winter becoming D.C.'s second snowiest on record (need only around 1 inch to surpass the current No. 2: 46.0" in 1995-96) or the snowiest on record (need about 9 inches to pass the current No. 1: 54.4" in 1898-99), but sobering for those still without power or still unable to get out of their neighborhood.

So, how much snow are we talking, and when?

The next storm: Precipitation, primarily snow as it looks now but maybe mixed with sleet at the start, is on track to arrive Tuesday afternoon or evening. Snow, or briefly a snow/sleet mix, may be on the light side at first before probably becoming moderate to heavy overnight into Wednesday.

At least 4 inches is looking like a decent bet, with 8 inches or more a possibility. Here are our accumulation probabilities, which are likely to change as the storm gets closer:

15%: Less than 2"
25%: 2-5"
35%: 5-8"
25%: 8"+

Before the storm: After a mostly clear and cold night tonight with lows in the mid-teens downtown, and low teens in the suburbs with some upper single digits in the coldest spots, temperatures struggle again tomorrow as they probably max out around 30-35. Cold again tomorrow night with lows mainly in the teens and clouds increasing overnight or toward morning. Under cloudy skies, Tuesday highs should make the low-to-mid 30s before precipitation arrives by afternoon or evening.

SchoolCast (Mon.) (D.C. schools, which earlier announced a 2-hour delay, now indicates they will close)
FedCast (Mon.)

*** More snow Tues/Wed, are you kidding?: Full Forecast ***

* Federal government closed Monday: Federal Eye *
* Detailed look at next snow threat: SLCB | Watch out ice dams *
* Measuring Snowmageddon's depth | NWS totals | CWG snow reports *
* Power outage maps for Dominion Electric | Pepco | BG&E *
* Outside now? Radar, temps & more: Weather Wall *
* News, traffic & storm coverage: Local home page | Get There *

Capital Weather Gang will have a fresh, new analysis of this potential storm around 6 p.m., including our latest thoughts about accumulations

Full Statement from National Weather Service (map):

...WINTER STORM WATCH IN EFFECT FROM TUESDAY AFTERNOON THROUGH WEDNESDAY AFTERNOON...

THE NATIONAL WEATHER SERVICE IN STERLING VIRGINIA HAS ISSUED A WINTER STORM WATCH...IN EFFECT FROM TUESDAY AFTERNOON THROUGH WEDNESDAY AFTERNOON.

* PRECIPITATION TYPE...SNOW.

* ACCUMULATIONS...POTENTIAL FOR 5 OR MORE INCHES OF SNOW.

* TIMING...MID TO LATE TUESDAY AFTERNOON THROUGH WEDNESDAY AFTERNOON.

* TEMPERATURES...TEMPERATURES AT OR JUST ABOVE FREEZING AT THE ONSET TUESDAY AFTERNOON. TEMPERATURES WILL DROP INTO THE MID TO UPPER 20S TUESDAY NIGHT AND WEDNESDAY.

* WINDS...LIGHT SOUTHEASTERLY WINDS TUESDAY BECOMING NORTH-NORTHWESTERLY 15 TO 25 MPH WEDNESDAY.

*** More snow Tues/Wed, are you kidding?: Full Forecast ***

* Detailed look at next snow threat: SLCB | Watch out ice dams *
* NWS snow totals | Report snow to CWG (see reports) *
* Power outage maps for Dominion Electric | Pepco | BG&E *
* Outside now? Radar, temps & more: Weather Wall *
* News, traffic & storm coverage: Local home page | Get There *

My final snow total at 5:31 PM Saturday near Oakton, VA.

What weather topic is more debated now in Washington than global warming? The answer is measuring snow at Reagan National Airport. National Airport is almost always on the low-end for snow reports in our area. Their snowfall totals do not compare well to nearby locations, and this has been consistent for many years.

My theory is that the low snowfall numbers result from the airport being located near sea level and surrounded by the warmer waters of the Potomac River. Basically, Reagan National Airport has a relatively warm micro-climate that does not favor heavy snow accumulations, particularly compared to nearby, elevated locations.

Keep reading for the photos of snow measurements...