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3″

Winter Storm Threat: Mar 2-3 (Final Call)

UPDATE March 2nd, 2pm EST: After seeing the latest model forecasts and trends, I would probably shift the 4-8″ and 8-12″+ contours south by about 15-20 miles.

Shifting everything a bit south from the initial forecast and added locally 12″+ wording for the mountains. Accumulations are for snow and sleet, though it will be a mostly snow event in the higher total areas.

20140302-03_MAsnowFinal

If the sleet holds out for longer in the morning then totals may be cut down, but on the flip side once the cold air does arrive, we could start to see some higher ratio snowfall.

Models may continue to drift south, but I don’t think it will go much further south if they do. For the DC area, expect some rain to start tomorrow afternoon, which may briefly change over to freezing rain before the sleet moves in. After some sleet, over to all snow probably a little before morning rush hour… then snow through the afternoon hours.

And then we get hit by frigid air. Joy.

Winter Storm Threat: Mar 2-3 (Initial Call)

Meteorological spring is here, but winter isn’t done with us yet. Most of the region will actually start off as rain, but a very strong cold air mass will push southward, bringing the low-level air below freezing and changing areas over to freezing rain and sleet before finally transitioning to snow. The models are handling the speed of this cold air push differently, so there is still a fair amount of wiggle room with the snow totals.

20140302-03_MAsnowInitial

There is still room for this to move north or south by a decent margin. I’ll have a final update after the 18z models come in.

Winter Storm Threat: Jan 2-3 (Only/Final Call)

Seeing as light snow is already falling across the northern extent of my forecast map, this will be the only forecast issuance for tomorrow’s storm. Back from vacation and ready to welcome 2014 with some fresh snow!

Low-level temperatures initially above freezing will eventually cool and allow for a changeover and/or stickage of snow around the greater DC/MD/DE region. I would say there’s more downside potential than upside with my southern cut-off areas as the low gets cranking off the coast. Better ratios are expected north of the Mason-Dixon, where the highest totals are forecast. Some upside potential northeast of DC if the coastal low is stronger/closer.

20140102-03_MAsnowFinal

April 3, 2012 Texas tornado videos

U.S. Tornadoes owner/co-author Ian and I have been compiling tornado footage from the outbreak in Texas today. We’re still adding to it, but so far we’ve found 16 videos!

You can view them on the U.S. Tornadoes blog: http://www.ustornadoes.com/2012/04/03/videos-of-the-april-3-2012-tornado-outbreak/

It might take a few seconds to load due to pulling in the video previews from YouTube.

Here’s one of the videos out of Kennedale, Texas:

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).

SNOW possible in the higher elevations this weekend

A shot of cool air is expected this weekend up and down the eastern U.S., with lows in the 30s possible in the higher elevations and maybe even northern MD. DC looks like it will stay in the low to mid 40s at its coldest point on Sunday morning (and possibly Monday morning).

The 12z GFS is pretty aggressive with the cold, showing widespread 30s and even some 20s in the region Monday morning (similar to Sunday morning, only the 30s reach further east Monday morning as high pressure moves overhead):

On top of the cooler temperatures, some snow showers could develop Saturday morning in the higher elevations, with a flurry or two possible Sunday morning up in the mountains. Some minor accumulation is possible in the highest areas, otherwise the snow that does fall should not accumulate. I wouldn’t rule out seeing a flake or two in the air in northern VA/MD, but it looks unlikely at this point.

Mid-Atlantic Discussion – Aug 3, 2011

So… here we are a month after the last Mid-Atlantic write-up (the event failed, BTW) with a new threat and different variables as we look at tomorrow’s severe weather.

Gonna just list the pros and cons and go from there:

PROS:
– Good low-level speed and directional shear.
– Excellent low-level lapse rates.
– Upper-level support via 500mb vort. max and some influence from the jet.
– Winds are veering throughout the column.

CONS:
– Possible cloud cover from storms to the northwest could inhibit heating.
– Lackluster mid-level lapse rates (could change for the better if dynamics are stronger).
– Upper-level jet is perhaps too far away to have a significant impact and we are not in the ideal (upper-level divergence) part of the jet.
– Main line of storms could come in just a bit too early for optimal destablization.
– High LCLs.

With everything put together, it looks like a pretty mixed bag between meh and awesome. I’m going to put tomorrow’s chasing chances at 50%… some nowcasting is definitely for tomorrow’s storms, so there’s no reason to decide on anything now. No idea where I’m going to go yet, either (should I end up going). Primary threat is wind… could see a tornado or two out of it if the instability is good enough.

SPC’s thoughts:

…MID ATLANTIC REGION…
A RATHER STRONG SHORTWAVE TROUGH NOW OVER THE DAKOTAS WILL TRACK
ACROSS THE GREAT LAKES AND INTO THE MID ATLANTIC STATES ON
WEDNESDAY. SEVERAL CLUSTERS OF THUNDERSTORMS ARE ONGOING TODAY WITH
THIS FEATURE…AND WILL LIKELY PERSIST INTO TOMORROW. MODEL
GUIDANCE SUGGESTS THESE CONVECTIVE CLUSTERS WILL BE OVER PARTS OF
LOWER MI/NY/PA/OH AT 12Z. THERE IS CONSIDERABLE UNCERTAINTY
REGARDING THE EXTENT OF CLOUD COVER AHEAD OF THE STORMS…WHICH WILL
IMPACT THE DEGREE OF AFTERNOON DESTABILIZATION OVER THE MID ATLANTIC
REGION. HOWEVER…RATHER STRONG LOW AND MID LEVEL WIND FIELDS
ASSOCIATED WITH THE UPPER TROUGH POSE SUFFICIENT CONCERN TO INCLUDE
THIS REGION IN A SLIGHT RISK FOR SEVERE STORMS. THE MOST LIKELY
THREAT WOULD BE AN ORGANIZED MCS TRACKING THROUGH THE AREA DURING
THE AFTERNOON PRODUCING LOCALLY DAMAGING WIND GUSTS.

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