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2012

Quick thoughts on tonight’s/tomorrow’s snow

This rain-changing-over-to-snow event has been the main snow event to watch over the past few days, and now it looks like it will come to fruition… at least for those from DC and points north as the tail-end of precipitation rolls through the region between 2-5am.

The latest HRRR is putting down some light accumulation east of the mountains for those north of DC:

I would be a little weary for the total amount of accumulation east of the mountains, but it certainly is possible if the “thump” of snow is strong enough.

Some isolated flurries are also possible during the day tomorrow east of the mountains if enough moisture is available.

Snow today… more on the way?

Light to moderate snow and mixed precipitation is filling in across the region from D.C. and points south this afternoon, with many reports of flurries and snow already coming in (including Dulles and DCA).

The precipitation should continue through the evening hours and will try to expand northward to the Mason-Dixon line.

The wintry precipitation has been filling in over the last two hours, as shown below:

 
With surface temperatures in the upper 30s to lower 40s across the region, most will not see snow accumulation from this event. Areas with stronger, more persistent snowfall could get a dusting to an inch of snow.

—–

With the pattern change coming across the U.S., there is an increased probability of snow as we head into the last few weeks of January. If the temperatures can cool quickly enough, some snow is possible in the region Thursday night into Friday morning as an arctic front pushes through. Beyond this, the 12z GFS advertises more opportunity for snowfall, but right now it doesn’t have any support. While not discounting it, there could be something to watch next week for “snow map-worthy” snowfall.

First major lake-effect event of the season

Not going to put a map out on this one, but the first significant lake-effect snow storm of the season is nearly upon us. Locally, the mountains of West Virginia could see 6-12″ with localized amounts of 12-18″+ in the best-positioned areas. Similar totals can also be expected downwind of Lake Ontario and Lake Erie (though Ontario more so).

The story is starting to make itself known as the high-resolution models can start picking up on event QPF totals for the region:


(click to enlarge) …rendering courtesy of the Penn State E-Wall

Now, not all of that QPF is for snow… you will have to cut out about 0.25″-0.50″ of that for the highest elevations as they get hit by rain before the changeover. Even after that, you’re looking at a solid 0.5″-1.0″ of QPF for a lake-effect event that will likely be producing snowfall ratios of 15-25:1, yielding low-end ranges of 8-16″ and higher-end ranges of 12-24″ in the QPF bulls-eyes. Widespread 5-10″+ along the hilltops of West Virginia seems like a pretty solid forecast at this point.

However, if you are REALLY looking for a good lake-effect event, head up to the Tug Hill Plateau east of Lake Ontario. Look at the map above again… you’ll see what I’m talking about. If you don’t, the NWS certainly does:

URGENT – WINTER WEATHER MESSAGE
NATIONAL WEATHER SERVICE BUFFALO NY
921 AM EST SUN JAN 1 2012

NYZ006>008-012230-
/O.CON.KBUF.LE.W.0001.120102T0300Z-120103T1500Z/
OSWEGO-JEFFERSON-LEWIS-
INCLUDING THE CITIES OF…OSWEGO…WATERTOWN…LOWVILLE
921 AM EST SUN JAN 1 2012

…LAKE EFFECT SNOW WARNING REMAINS IN EFFECT FROM 10 PM THIS
EVENING TO 10 AM EST TUESDAY…

* LOCATIONS…THE EASTERN LAKE ONTARIO REGION AND TUG HILL
PLATEAU.

* ACCUMULATIONS…3 TO 5 INCHES OVERNIGHT…5 TO 10 INCHES
MONDAY…5 TO 9 INCHES MONDAY NIGHT…AND AN INCH OR LESS
TUESDAY…LEADING TO STORM TOTALS OF 1 TO 2 FEET IN THE MOST
PERSISTENT LAKE SNOWS.

* WINDS…WEST 25 TO 35 MPH WITH WIND GUSTS TO 55 MPH.

* TEMPERATURES…LOWS AROUND 30 OVERNIGHT. HIGHS IN THE LOWER
30S MONDAY. LOWS 5 BELOW TO 5 ABOVE ZERO MONDAY NIGHT. BETWEEN
5 BELOW AND 5 ABOVE ZERO TUESDAY.

* IMPACTS…THE COMBINATION OF LOCALLY HEAVY LAKE EFFECT SNOW AND
STRONG GUSTY WINDS WILL RESULT IN PERIODS OF WHITEOUT CONDITIONS
WHICH WILL MAKE TRAVEL VERY DIFFICULT OR EVEN NEARLY IMPOSSIBLE
AT TIMES WITH LOCALIZED BLIZZARD CONDITIONS. TRAVEL ALONG
INTERSTATE 81 AND ADJACENT ROADWAYS WILL BE SEVERELY IMPACTED
BY THE INCLEMENT WEATHER CONDITIONS.

There will quite possibly be enough moisture around after the lake-effect impacts the mountains to get flurries and maybe a stronger burst or two of snow east of the mountains… but don’t expect more than a dusting (unless you can get really, really lucky).